Susceptibility to antimicrobial agents among bovine mastitis pathogens isolated from North American dairy cattle, 2002-2010.

PubMed

Lindeman, Cynthia J; Portis, Ellen; Johansen, Lacie; Mullins, Lisa M; Stoltman, Gillian A

2013-09-01

Approximately 8,000 isolates of Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, Staphylococcus aureus, and Escherichia coli, isolated by 25 veterinary laboratories across North America between 2002 and 2010, were tested for in vitro susceptibility to beta-lactam, macrolide, and lincosamide drugs. The minimal inhibitory concentrations (MICs) of the beta-lactam drugs remained low against most of the Gram-positive strains tested, and no substantial changes in the MIC distributions were seen over time. Of the beta-lactam antimicrobial agents tested, only ceftiofur showed good in vitro activity against E. coli. The MICs of the macrolides and lincosamides also remained low against Gram-positive mastitis pathogens. While the MIC values given by 50% of isolates (MIC50) for erythromycin and pirlimycin and the streptococci were all low (≤0.5 µg/ml), the MIC values given by 90% of isolates (MIC90) were higher and more variable, but with no apparent increase over time. Staphylococcus aureus showed little change in erythromycin susceptibility over time, but there may be a small, numerical increase in pirlimycin MIC50 and MIC90 values. Overall, the results suggest that mastitis pathogens in the United States and Canada have not shown any substantial changes in the in vitro susceptibility to beta-lactam, macrolide, and lincosamide drugs tested over the 9 years of the study.

Pharmacodynamic analysis of ceftriaxone, gatifloxacin,and levofloxacin against Streptococcus pneumoniae with the use of Monte Carlo simulation.

PubMed

Frei, Christopher R; Burgess, David S

2005-09-01

To evaluate the pharmacodynamics of four intravenous antimicrobial regimens-ceftriaxone 1 g, gatifloxacin 400 mg, levofloxacin 500 mg, and levofloxacin 750 mg, each every 24 hours-against recent Streptococcus pneumoniae isolates. Pharmacodynamic analysis using Monte Carlo simulation. The Surveillance Network (TSN) 2002 database. Streptococcus pneumoniae isolates (7866 isolates) were stratified according to penicillin susceptibilities as follows: susceptible (4593), intermediate (1986), and resistant (1287). Risk analysis software was used to simulate 10,000 patients by integrating published pharmacokinetic parameters, their variability, and minimum inhibitory concentration (MIC) distributions from the TSN database. Probability of target attainment was determined for percentage of time above the MIC (%T > MIC) from 0-100% for ceftriaxone and area under the concentration-time curve (AUC):MIC ratio from 0-150 for the fluoroquinolones. For ceftriaxone, probability of target attainment remained 90% or greater against the three isolate groups until a %T > MIC of 70% or greater, and it remained 90% or greater against susceptible and intermediate isolates over the entire interval (%T > MIC 0-100%). For levofloxacin 500 mg, probability of target attainment was 90% at an AUC:MIC < or = 30, but the curve declined sharply with further increases in pharmacodynamic target. Levofloxacin 750 mg achieved a probability of target attainment of 99% at an AUC:MIC ratio < or = 30; the probability remained approximately 90% until a target of 70 or greater, when it declined steeply. Gatifloxacin demonstrated a high probability (99%) of target attainment at an AUC:MIC ratio < or = 30, and it remained above 90% until a target of 70. Ceftriaxone maintained high probability of target attainment over a broad range of pharmacodynamic targets regardless of penicillin susceptibility (%T > MIC 0-60%). Levofloxacin 500 mg maintained high probability of target attainment for AUC:MIC ratios 0-30; whereas, levofloxacin 750 mg and gatifloxacin maintained high probability of target attainment for AUC:MIC ratios 0-60. Rate of decline in the pharmacodynamic curve was most pronounced for the two levofloxacin regimens and more gradual for gatifloxacin and ceftriaxone.

Antimicrobial Activity Of Essential Oils Against Vancomycin-Resistant Enterococci (Vre) And Escherichia Coli O157:H7 In Feta Soft Cheese And Minced Beef Meat

PubMed Central

Selim, Samy

2011-01-01

Eleven essential oils (EOs) were evaluated for their antibacterial properties, against Vancomycin-Resistant Enterococci (VRE) and E. coli O157:H7. EOs were introduced into Brain Heart Infusion agar (BHI) (15ml) at a concentration of 0.25 to 2% (vol/vol) to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for each pathogen evaluated. Results showed that the most active essential oils against bacteria tested were thyme oil, with MIC90 and MBC90 for the VRA strains of 0.25% and 0.5%, respectively. Eucalyptus, juniper and clove oils were the least potent agent, with MIC90 and MBC90 of 2%. Furthermore, the inhibitory effect of these EO were evaluated against VRE and E. coli O157:H7, experimentally inoculated (103 cfu/g) in Feta soft cheese and minced beef meat, which was mixed with different concentrations (0.1%, 0.5% and 1%) of the EO and stored at 7 °C for 14 days. Out of eucalyptus, juniper, mint, rosemary, sage, clove and thyme oils tested against target bacteria sage and thyme showed the best results. Clove and mint did not show any effect on VRE and E. coli O157:H7 in both kinds of studied foods. The addition of thyme oil at concentrations of 0.5 and 1% caused best significant reduction in the growth rate of VRE and E. coli O157:H7 in cheese and meat at 7 oC. It is concluded that selected plant EOs can act as potent inhibitors of both microorganisms in a food product. The results revealed the potential of thyme oil as a natural preservative in feta soft cheese and minced beef meat against VRE and E. coli O157:H7 contamination. PMID:24031620

Tannic Acid as a Potential Modulator of Norfloxacin Resistance in Staphylococcus Aureus Overexpressing norA.

PubMed

Diniz-Silva, Helena Taina; Cirino, Isis Caroline da Silva; Falcão-Silva, Vivyanne Dos Santos; Magnani, Marciane; de Souza, Evandro Leite; Siqueira-Júnior, José P

2016-01-01

Tannins have shown inhibitory effects against pathogenic bacteria, and these properties make tannins potential modifying agents in bacterial resistance. The minimum inhibitory concentration (MIC) of tannic acid (TA), gallic acid (GA) and norfloxacin (Nor) against Staphylococcus aureus SA-1119 (NorA-effluxing strain) was determined using broth microdilution tests. To assess the modulation of antibiotic resistance, the MIC of Nor was determined in growth media with or without TA or GA at a subinhibitory concentration (1/4 MIC). The checkerboard method was performed to obtain the fractional inhibitory concentration index (FICI) for the combined application of TA and Nor. TA displayed a weak inhibitory effect (MIC 512 μg/ml) against S. aureus SA-1119, while no inhibitory effect was displayed by GA (MIC >512 μg/ml). However, when TA was tested at a subinhibitory concentration in combination with Nor, the MIC of Nor against S. aureus SA-1119 decreased from 128 to 4 μg/ml (32-fold); this effect was not observed for GA. In the checkerboard assay, the MIC of TA and Nor decreased from 512 to 128 μg/ml (4-fold) and from 128 to 8 μg/ml (16-fold), respectively. The combination of TA and Nor presented an FICI as low as 0.31, which indicates a synergistic interaction. TA is a potential agent for increasing the clinical efficacy of Nor to control resistant S. aureus. © 2016 S. Karger AG, Basel.

In vitro interactions between different beta-lactam antibiotics and fosfomycin against bloodstream isolates of enterococci.

PubMed Central

Pestel, M; Martin, E; Aucouturier, C; Lemeland, J F; Caron, F

1995-01-01

The effects of 16 different beta-lactam-fosfomycin combinations against 50 bloodstream enterococci were compared by a disk diffusion technique. Cefotaxime exhibited the best interaction. By checkerboard studies, the cefotaxime-fosfomycin combination provided a synergistic bacteriostatic effect against 45 of the 50 isolates (MIC of cefotaxime at which 90% of the isolates were inhibited, >2,048 micrograms/ml; MIC of fosfomycin at which 90% of the isolates were inhibited, 128 micrograms/ml; mean of fractional inhibitory concentration indexes, 0.195). By killing curves, cefotaxime (at 64 micrograms/ml) combined with fosfomycin (at > or = 64 micrograms/ml) was bactericidal against 6 of 10 strains tested. PMID:8619593

Minimum inhibitory concentration and killing properties of rifampicin against canine Staphylococcus pseudintermedius isolates from dogs in the southeast USA.

PubMed

Ho, Karen K; Conley, Austin C; Kennis, Robert A; Hathcock, Terri L; Boothe, Dawn M; White, Amelia G

2018-05-29

Meticillin-resistant (MR) staphylococcal pyoderma in dogs has led to increased use of alternate antibiotics such as rifampicin (RFP). However, little information exists regarding its pharmacodynamics in MR Staphylococcus pseudintermedius. To determine the minimum inhibitory concentration (MIC) and killing properties of RFP for canine Staphylococcus pseudintermedius isolates. The MIC of RFP was determined using the ETEST ® for 50 meticillin-susceptible (MS) and 50 MR S. pseudintermedius isolates collected from dogs. From these isolates, two MS isolates (RFP MIC of 0.003 and 0.008 μg/mL, respectively) and two MR isolates (RFP MIC of 0.003 and 0.012 μg/mL, respectively) were subjected to time-kill studies. Mueller-Hinton broth was supplemented with RFP at 0, 0.5, 1, 2, 4, 8, 16 and 32 times the MIC for 0, 2, 4, 10, 16 and 24 h. The number of viable colony forming units in each sample was determined using a commercial luciferase assay kit. The MIC 50 and MIC 90 were the same for MS and MR isolates, at 0.004 μg/mL and 0.008 μg/mL, respectively. Rifampicin kill curves were not indicative of concentration-dependency, suggesting time-dependent activity. Two isolates (MS 0.003 and 0.008 μg/mL) exhibited bacteriostatic activity, whereas two others (MR 0.003 and 0.012 μg/mL) exhibited bactericidal activity. This study demonstrated that MS and MR S. pseudintermedius isolates were equally susceptible to rifampicin and that dosing intervals should be designed for time-dependent efficacy. These data can support pharmacokinetic studies of RFP in dogs with susceptible infections caused by S. pseudintermedius. © 2018 ESVD and ACVD.

In vitro activity of various antibiotics against clinical strains of Legionella species isolated in Japan.

PubMed

Miyashita, Naoyuki; Kobayashi, Intetsu; Higa, Futoshi; Aoki, Yosuke; Kikuchi, Toshiaki; Seki, Masafumi; Tateda, Kazuhiro; Maki, Nobuko; Uchino, Kazuhiro; Ogasawara, Kazuhiko; Kurachi, Satoe; Ishikawa, Tatsuya; Ishimura, Yoshito; Kanesaka, Izumo; Kiyota, Hiroshi; Watanabe, Akira

2018-05-01

The activities of various antibiotics against 58 clinical isolates of Legionella species were evaluated using two methods, extracellular activity (minimum inhibitory concentration [MIC]) and intracellular activity. Susceptibility testing was performed using BSYEα agar. The minimum extracellular concentration inhibiting intracellular multiplication (MIEC) was determined using a human monocyte-derived cell line, THP-1. The most potent drugs in terms of MICs against clinical isolates were levofloxacin, garenoxacin, and rifampicin with MIC 90 values of 0.015 μg/ml. The activities of ciprofloxacin, pazufloxacin, moxifloxacin, clarithromycin, and azithromycin were slightly higher than those of levofloxacin, garenoxacin, and rifampicin with an MIC 90 of 0.03-0.06 μg/ml. Minocycline showed the highest activity, with an MIC 90 of 1 μg/ml. No resistance against the antibiotics tested was detected. No difference was detected in the MIC distributions of the antibiotics tested between L. pneumophila serogroup 1 and L. pneumophila non-serogroup 1. The MIECs of ciprofloxacin, pazufloxacin, levofloxacin, moxifloxacin, garenoxacin, clarithromycin, and azithromycin were almost the same as their MICs, with MIEC 90 values of 0.015-0.06 μg/ml, although the MIEC of minocycline was relatively lower and that of rifampicin was higher than their respective MICs. No difference was detected in the MIEC distributions of the antibiotics tested between L. pneumophila serogroup 1 and L. pneumophila non-serogroup 1. The ratios of MIEC:MIC for rifampicin (8) and pazufloxacin (2) were higher than those for levofloxacin (1), ciprofloxacin (1), moxifloxacin (1), garenoxacin (1), clarithromycin (1), and azithromycin (1). Our study showed that quinolones and macrolides had potent antimicrobial activity against both extracellular and intracellular Legionella species. The present data suggested the possible efficacy of these drugs in treatment of Legionella infections. Copyright © 2018 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Resistance to phenicol compounds following adaptation to quaternary ammonium compounds in Escherichia coli.

PubMed

Soumet, C; Fourreau, E; Legrandois, P; Maris, P

2012-07-06

Bacterial adaptation to quaternary ammonium compounds (QACs) is mainly documented for benzalkonium chloride (BC) and few data are available for other QACs. The aim of this study was to assess the effects of repeated exposure to different quaternary ammonium compounds (QACs) on the susceptibility and/or resistance of bacteria to other QACs and antibiotics. Escherichia coli strains (n=10) were adapted by daily exposure to increasingly sub-inhibitory concentrations of a QAC for 7 days. Three QACs were studied. Following adaptation, we found similar levels of reduction in susceptibility to QACs with a mean 3-fold increase in the minimum inhibitory concentration (MIC) compared to initial MIC values, whatever the QAC used during adaptation. No significant differences in antibiotic susceptibility were observed between the tested QACs. Antibiotic susceptibility was reduced from 3.5- to 7.5-fold for phenicol compounds, β lactams, and quinolones. Increased MIC was associated with a shift in phenotype from susceptible to resistant for phenicol compounds (florfenicol and chloramphenicol) in 90% of E. coli strains. Regardless of the QAC used for adaptation, exposure to gradually increasing concentrations of this type of disinfectant results in reduced susceptibility to QACs and antibiotics as well as cross-resistance to phenicol compounds in E. coli strains. Extensive use of QACs at sub-inhibitory concentrations may lead to the emergence of antibiotic-resistant bacteria and may represent a public health risk. Published by Elsevier B.V.

In vitro activity of echinocandins against 562 clinical yeast isolates from a Romanian multicentre study.

PubMed

Mares, Mihai; Minea, Bogdan; Nastasa, Valentin; Rosca, Irina; Bostanaru, Andra-Cristina; Marincu, Iosif; Toma, Vasilica; Cristea, Violeta Corina; Murariu, Carmen; Pinteala, Mariana

2018-06-01

The study presents the echinocandin susceptibility profile of a multi-centre collection of pathogenic yeast isolates from Romanian tertiary hospitals. The 562 isolates were identified using ID32C strips, MALDI-TOF MS and DNA sequencing. Minimal inhibitory concentrations (MICs) of caspofungin (CAS), micafungin (MCA), and anidulafungin (ANI) were assessed and interpreted according to EUCAST guidelines. Minimal fungicidal concentrations (MFC) were determined by plating content from the clear MIC wells. The activity was considered fungicidal at MFC/MIC ≤ 4. The three echinocandins had strongly correlated MICs and high percentages of MIC essential agreement. Most often, MCA had the lowest MICs, followed by CAS and ANI. Against C. parapsilosis and C. kefyr, CAS had the lowest MIC values. The MIC50 values were between 0.03 and 0.25 mg/l, except C. parapsilosis. The MIC90 values were usually one dilution higher. MFCs and MICs were weakly correlated. ANI and MCA had the lowest MFC values. The MFC50 values were between 0.06 and 0.5 mg/l, except C. parapsilosis, C. guilliermondii, and C. dubliniensis. The MFC90 values were usually two dilutions higher. Based on EUCAST breakpoints, 47 isolates (8.4%) were resistant to at least one echinocandin, most often ANI. Most resistant isolates were of C. albicans, C. glabrata, and C. krusei. There were 17 isolates (3%) resistant to echinocandins and fluconazole and most belonged to the same three species. MCA and ANI had the highest rates of fungicidal activity. The high rates of echinocandin resistance and significant multidrug resistance make prophylaxis and empiric therapy difficult.

Activity of nadifloxacin (OPC-7251) and seven other antimicrobial agents against aerobic and anaerobic Gram-positive bacteria isolated from bacterial skin infections.

PubMed

Nenoff, P; Haustein, U-F; Hittel, N

2004-10-01

The in vitro activity of nadifloxacin (OPC-7251), a novel topical fluoroquinolone, was assessed and compared with those of ofloxacin, oxacillin, flucloxacillin, cefotiam, erythromycin, clindamycin, and gentamicin against 144 Gram-positive bacteria: 28 Staphylococcus aureus, 10 Streptococcus spp., 68 coagulase-negative staphylococci (CNS), 36 Propionibacterium acnes, and 2 Propionibacterium granulosum strains. All strains originated from bacterial-infected skin disease and were isolated from patients with impetigo, secondary infected wounds, folliculitis and sycosis vulgaris, and impetiginized dermatitis. In vitro susceptibility of all clinical isolates was tested by agar dilution procedure and minimum inhibitory concentrations (MICs) were determined. Nadifloxacin was active against all aerobic and anaerobic isolates. MIC(90) (MIC at which 90% of the isolates are inhibited) was 0.1 microg/ml for S. aureus, 0.78 microg/ml for both Streptococcus spp. and CNS, and 0.39 microg/ml for Propionibacterium spp. On the other hand, resistant strains with MICs exceeding 12.5 mug/ml were found in tests with the other antibiotics. For both CNS and Propionibacterium acnes, MIC(90) values > or =100 microg/ml were demonstrated for erythromycin. Ofloxacin, cefotiam, erythromycin, clindamycin and gentamicin exhibited MIC(90) values < or =1 microg/ml for some bacterial species tested. Both oxacillin and flucloxacillin were active against all investigated bacterial species with MIC(90) values < or =1 microg/ml. In summary, nadifloxacin, a topical fluoroquinolone, was found to be highly active against aerobic and anaerobic bacteria isolated from patients with infected skin disease, and seems to be a new alternative for topical antibiotic treatment in bacterial skin infections.

A survey of Clostridium spiroforme antimicrobial susceptibility in rabbit breeding.

PubMed

Agnoletti, Fabrizio; Ferro, Tiziana; Guolo, Angela; Marcon, Barbara; Cocchi, Monia; Drigo, Ilenia; Mazzolini, Elena; Bano, Luca

2009-04-14

Rabbit meat breeding may be heavily affected by enterotoxaemia due to Clostridium spiroforme. Data on its antimicrobial susceptibility are insufficient, presumably because of difficulties in cultivating and identifying the pathogen. Our aim is therefore to provide this information to veterinary practitioners by focusing on a panel of therapeutics used in intensive rabbit units. Lincomycin was also checked in order to investigate the origin of resistance to macrolides. Minimal inhibitory concentrations (MICs) were determined with the agar dilution method according to the CLSI M11-A7 protocol (2007). MIC(50) and MIC(90) were, respectively, 64 and 64microg/ml for tiamulin, 32 and 32microg/ml for norfloxacin, 0.063 and 0.125microg/ml for amoxicillin, and 8 and 16microg/ml for doxycycline. MIC(50) and MIC(90) were 256microg/ml for sulphadimethoxine, spiramycin and lincomycin. Our results have shown that intrinsic or acquired antimicrobial resistances are diffuse in the C. spiroforme population and suggest focusing on prevention rather than on treatment of clostridial overgrowth, by reducing risk factors and using antimicrobials prudently.

Cytotoxicity and anti-Sporothrix brasiliensis activity of the Origanum majorana Linn. oil.

PubMed

Waller, Stefanie Bressan; Madrid, Isabel Martins; Ferraz, Vanny; Picoli, Tony; Cleff, Marlete Brum; de Faria, Renata Osório; Meireles, Mário Carlos Araújo; de Mello, João Roberto Braga

The study aimed to evaluate the anti-Sporothrix sp. activity of the essential oil of Origanum majorana Linn. (marjoram), its chemical analysis, and its cytotoxic activity. A total of 18 fungal isolates of Sporothrix brasiliensis (n: 17) from humans, dogs and cats, and a standard strain of Sporothrix schenckii (n: 1) were tested using the broth microdilution technique (Clinical and Laboratory Standard Institute - CLSI M27-A3) and the results were expressed in minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC). The MIC 50 and MIC 90 of itraconazole against S. brasiliensis were 2μg/mL and 8μg/mL, respectively, and the MFC 50 and MFC 90 were 2μg/mL and >16μg/mL, respectively, with three S. brasiliensis isolates resistant to antifungal. S. schenckii was sensitive at MIC of 1μg/mL and MFC of 8μg/mL. For the oil of O. majorana L., all isolates were susceptible to MIC of ≤2.25-9mg/mL and MFC of ≤2.25-18mg/mL. The MIC 50 and MIC 90 were ≤2.25mg/mL and 4.5mg/mL, respectively, and the MFC 50/90 values were twice more than the MIC. Twenty-two compounds were identified by gas chromatography with a flame ionization detector (CG-FID) and 1,8-cineole and 4-terpineol were the majority. Through the colorimetric (MTT) assay, the toxicity was observed in 70-80% of VERO cells between 0.078 and 5mg/mL. For the first time, the study demonstrated the satisfactory in vitro anti-Sporothrix sp. activity of marjoram oil and further studies are needed to ensure its safe and effective use. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Antimicrobial Susceptibility of Udder Pathogens Isolated from Dairy Herds in the West Littoral Region of Uruguay

PubMed Central

2002-01-01

A total of 522 strains belonging to streptococci, enterococci and staphylococci isolated from sub-clinical and clinical cases of bovine mastitis from the west littoral region of Uruguay were analysed for their susceptibility to several antimicrobial agents. The susceptibility patterns were studied by agar disk diffusion methods (ADDM) and broth micro-dilution to determine the minimum inhibitory concentration (MIC). The concentration that inhibits 90% (MIC90) of the analysed strains reported in micrograms per millilitre, for Staphylococcus aureus were > 8, 8, ≤ 0.5, ≤ 4, ≤ 1, ≤ 0.5, > 64, ≤ 0.25, 0.5, ≤ 1 and ≤ 1 to penicillin, ampicillin, oxacillin, cephalotin, gentamicin, erythromycin, oxitetracycline, enrofloxacin, trimethoprim/sulfamethoxazole, neomycin, and clindamycin, respectively. Coagulase-negative staphylococci (CNS) had different values for penicillin (4) and ampicillin (2), while the other antimicrobial agents had the same MIC90 values as reported for S. aureus. The MIC90 values for streptococci were 0.12, 0.25, ≤ 4, 16, ≤ 0.25, 0.5, 0.25 for penicillin, ampicillin, cephalotin, gentamicin, erythromycin, oxytetracycline and trimethoprim-sulfamethoxazole, whereas MIC90 for enterococci were 4, 4, 4, ≤ 0.5, 2, > 8 for penicillin, ampicillin, gentamicin, erythromycin, oxytetracycline and trimethoprim-sulfamethoxazole, respectively. Of 336 strains of S. aureus, 160 (47.6%) were resistant to penicillin. For 41 CNS strains, 10 (27%) presented penicillin-resistance. All the streptococcal strains were susceptible to penicillin, while 3 (7%) of the 43 enteroccocal strains were resistant. Non significant statistical differences were found between the results obtained by ADDM and broth micro-dilution for classifying bacterial isolates as susceptible or resistant according to the National Committee of Clinical Laboratory Standards. PMID:12071114

The activity of silver nanoparticles against microalgae of the Prototheca genus.

PubMed

Jagielski, Tomasz; Bakuła, Zofia; Pleń, Małgorzata; Kamiński, Michał; Nowakowska, Julita; Bielecki, Jacek; Wolska, Krystyna I; Grudniak, Anna M

2018-05-01

To investigate the in vitro activity of silver NPs (AgNPs) against pathogenic microalgae of the Prototheca genus. The antialgal potential of AgNPs against Prototheca species of both clinical and environmental origin was assessed from minimum inhibitory (algistatic) and algicidal concentrations. The in vitro cytotoxicity of AgNPs against bovine mammary epithelial cell line was evaluated by means of the standard MTT assay. AgNPs showed a strong killing activity toward Prototheca algae, as the minimal algicidal concentration (MAC) values matched perfectly the corresponding minimum inhibitory concentration (MIC) values for all species (MAC = MIC, 1-4 mg/l), except P. stagnora (MIC > 8 mg/l). The concentrations inhibitory to pathogenic Prototheca spp. (MIC, 1-4 mg/l) were below the concentrations at which any toxicity in epithelial cells could be observed (CC 20 > 6 mg/l). The study emphasizes the potential of AgNPs as a new therapeutic tool for the management of Prototheca infections.

Pharmacokinetic/pharmacodynamic integration and modelling of oxytetracycline for the porcine pneumonia pathogens Actinobacillus pleuropneumoniae and Pasteurella multocida.

PubMed

Dorey, L; Pelligand, L; Cheng, Z; Lees, P

2017-10-01

Pharmacokinetic-pharmacodynamic (PK/PD) integration and modelling were used to predict dosage schedules of oxytetracycline for two pig pneumonia pathogens, Actinobacillus pleuropneumoniae and Pasteurella multocida. Minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) were determined in broth and porcine serum. PK/PD integration established ratios of average concentration over 48 h (C av0-48 h )/MIC of 5.87 and 0.27 μg/mL (P. multocida) and 0.70 and 0.85 μg/mL (A. pleuropneumoniae) for broth and serum MICs, respectively. PK/PD modelling of in vitro time-kill curves established broth and serum breakpoint values for area under curve (AUC 0-24 h )/MIC for three levels of inhibition of growth, bacteriostasis and 3 and 4 log 10 reductions in bacterial count. Doses were then predicted for each pathogen, based on Monte Carlo simulations, for: (i) bacteriostatic and bactericidal levels of kill; (ii) 50% and 90% target attainment rates (TAR); and (iii) single dosing and daily dosing at steady-state. For 90% TAR, predicted daily doses at steady-state for bactericidal actions were 1123 mg/kg (P. multocida) and 43 mg/kg (A. pleuropneumoniae) based on serum MICs. Lower TARs were predicted from broth MIC data; corresponding dose estimates were 95 mg/kg (P. multocida) and 34 mg/kg (A. pleuropneumoniae). © 2017 The Authors. Journal of Veterinary Pharmacology and Therapeutics Published by John Wiley & Sons Ltd.

[Activity of butenafine against ocular pathogenic filamentous fungi in vitro].

PubMed

Xu, Yan; Pang, Guang-ren; Zhao, Dong-qing; Gao, Chuan-wen; Zhou, Lu-tan; Sun, Sheng-tao; Wang, Bing-liang; Chen, Zu-ji

2010-01-01

To investigate antifungal activity of butenafine in comparison with that of natamycin, amphotericin B and fluconazole against ocular pathogenic filamentous fungi in vitro. It was an experimental study. Susceptibility tests were performed against 260 isolates of ocular pathogenic filamentous fungi by broth dilution antifungal susceptibility test of filamentous fungi approved by the Clinical and Laboratory Standards Institute (CLSI) M38-A document. The isolates included Fusarium spp. (136), Aspergillus spp. (98), Alternaria alternata (9), Curvularia lunata (3), and unusual ocular pathogens (14). Final concentration ranged from 0.008 to 16.000 mg/L for butenafine, from 0.031 to 16.000 mg/L for amphotericin B and natamycin, and from 0.5 to 256.0 mg/L for fluconazole. Following incubation at 35 degrees C for 48 h, minimal inhibitory concentration (MIC) was determined according to the CLSI M38-A document. For amphotericin B and natamycin, the MIC was defined as the lowest drug concentration that prevented any discernible growth. For butenafine and fluconazole, the MIC was defined as the lowest concentration in which an approximately 75% reduction compared to the growth of the control was observed. Candida parapsilosis ATCC22019 was used as quality control strains to validated the results. Mean MIC and MIC range, the MIC at which 50% of the isolates tested were inhibited (MIC(50)) and the MIC at which 90% of the isolates tested were inhibited (MIC(90)), were provided for all the isolates tested by using descriptive statistical analysis with the statistical SPSS package (version 13.0). MIC(90) of butenafine, natamycin, amphotericin B and fluconazole were 4, 8, 2 and 512 mg/L for Fusarium spp., respectively; 0.063, 32.000, 2.000 and 256.000 mg/L for Aspergillus spp., respectively; 0.5, 8.0, 2.0 and 128.0 mg/L for Alternaria alternate, respectively; 0.125, 2.000, 0.500 and 4.000 mg/L for Curvularia lunata, respectively; and 1, 4, 1 and 256 mg/L for unusual ocular pathogens, respectively. Butenafine exhibits potent antifungal activity against a wide variety of ocular pathogenic fungi, especially for Aspergillus spp., Alternaria alternata, Curvularia lunata, and some unusual ocular pathogens and may have a role in future studies of antifungal eye drops and treating fungal keratitis.

Vancomycin AUC/MIC and Corresponding Troughs in a Pediatric Population

PubMed Central

Lardieri, Allison B.; Heil, Emily L.; Morgan, Jill A.

2017-01-01

OBJECTIVES Adult guidelines suggest an area under the curve/minimum inhibitory concentration (AUC/MIC) > 400 corresponds to a vancomycin trough serum concentration of 15 to 20 mg/L for methicillin-resistant Staphylococcus aureus infections, but obtaining these troughs in children are difficult. The primary objective of this study was to assess the likelihood that 15 mg/kg of vancomycin every 6 hours in a child achieves an AUC/MIC > 400. METHODS This retrospective chart review included pediatric patients >2 months to <18 years with a positive S aureus blood culture and documented MIC who received at least two doses of vancomycin with corresponding trough. Patients were divided into two groups: group 1 initially receiving ≥15 mg/kg every 6 hours, and group 2 initially receiving any other dosing ranges or intervals. AUCs were calculated four times using three pharmacokinetic methods. RESULTS A total of 36 patients with 99 vancomycin trough serum concentrations were assessed. Baseline characteristics were similar between groups. For troughs in group 1 (n = 55), the probability of achieving an AUC/MIC > 400 ranged from 16.4% to 90.9% with a median trough concentration of 11.4 mg/L, while in group 2 (n = 44) the probability of achieving AUC/MIC > 400 ranged from 15.9% to 54.5% with mean trough concentration of 9.2 mg/L. The AUC/MICs were not similar between the different pharmacokinetic methods used; however, a trapezoidal equation (Method A) yielded the highest correlation coefficient (r2 = 0.59). When dosing every 6 hours, an AUC/MIC of 400 correlated to a trough serum concentration of 11 mg/L. CONCLUSIONS The probability of achieving an AUC/MIC > 400 using only a trough serum concentration and an MIC with patients receiving 15 mg/kg every 6 hours is variable based on the method used to calculate the AUC. An AUC/MIC of 400 in children correlated to a trough concentration of 11 mg/L using a trapezoidal Method to calculate AUC. PMID:28337080

Vancomycin AUC/MIC and Corresponding Troughs in a Pediatric Population.

PubMed

Kishk, Omayma A; Lardieri, Allison B; Heil, Emily L; Morgan, Jill A

2017-01-01

Adult guidelines suggest an area under the curve/minimum inhibitory concentration (AUC/MIC) > 400 corresponds to a vancomycin trough serum concentration of 15 to 20 mg/L for methicillin-resistant Staphylococcus aureus infections, but obtaining these troughs in children are difficult. The primary objective of this study was to assess the likelihood that 15 mg/kg of vancomycin every 6 hours in a child achieves an AUC/MIC > 400. This retrospective chart review included pediatric patients >2 months to <18 years with a positive S aureus blood culture and documented MIC who received at least two doses of vancomycin with corresponding trough. Patients were divided into two groups: group 1 initially receiving ≥15 mg/kg every 6 hours, and group 2 initially receiving any other dosing ranges or intervals. AUCs were calculated four times using three pharmacokinetic methods. A total of 36 patients with 99 vancomycin trough serum concentrations were assessed. Baseline characteristics were similar between groups. For troughs in group 1 (n = 55), the probability of achieving an AUC/MIC > 400 ranged from 16.4% to 90.9% with a median trough concentration of 11.4 mg/L, while in group 2 (n = 44) the probability of achieving AUC/MIC > 400 ranged from 15.9% to 54.5% with mean trough concentration of 9.2 mg/L. The AUC/MICs were not similar between the different pharmacokinetic methods used; however, a trapezoidal equation (Method A) yielded the highest correlation coefficient (r 2 = 0.59). When dosing every 6 hours, an AUC/MIC of 400 correlated to a trough serum concentration of 11 mg/L. The probability of achieving an AUC/MIC > 400 using only a trough serum concentration and an MIC with patients receiving 15 mg/kg every 6 hours is variable based on the method used to calculate the AUC. An AUC/MIC of 400 in children correlated to a trough concentration of 11 mg/L using a trapezoidal Method to calculate AUC.

In Vitro Activities of Various Antimicrobials Alone and in Combination with Tigecycline against Carbapenem-Intermediate or -Resistant Acinetobacter baumannii▿

PubMed Central

Scheetz, Marc H.; Qi, Chao; Warren, John R.; Postelnick, Michael J.; Zembower, Teresa; Obias, Arlene; Noskin, Gary A.

2007-01-01

The activities of tigecycline alone and in combination with other antimicrobials are not well defined for carbapenem-intermediate or -resistant Acinetobacter baumannii (CIRA). Pharmacodynamic activity is even less well defined when clinically achievable serum concentrations are considered. Antimicrobial susceptibility testing of clinical CIRA isolates from 2001 to 2005 was performed by broth or agar dilution, as appropriate. Tigecycline concentrations were serially increased in time-kill studies with a representative of the most prevalent carbapenem-resistant clone (strain AA557; imipenem MIC, 64 mg/liter). The in vitro susceptibility of the strain was tested by time-kill studies in duplicate against the average free serum steady-state concentrations of tigecycline alone and in combination with various antimicrobials. Ninety-three CIRA isolates were tested and were found to have the following antimicrobial susceptibility profiles: tigecycline, MIC50 of 1 mg/liter and MIC90 of 2 mg/liter; minocycline, MIC50 of 0.5 mg/liter and MIC90 of 8 mg/liter; doxycycline, MIC50 of 2 mg/liter and MIC90 of ≥32 mg/liter; ampicillin-sulbactam, MIC50 of 48 mg/liter and MIC90 of 96 mg/liter; ciprofloxacin, MIC50 of ≥16 mg/liter and MIC90 of ≥16 mg/liter; rifampin, MIC50 of 4 mg/liter and MIC90 of 8 mg/liter; polymyxin B, MIC50 of 1 mg/liter and MIC90 of 1 mg/liter; amikacin, MIC50 of 32 mg/liter and MIC90 of ≥32 mg/liter; meropenem, MIC50 of 16 mg/liter and MIC90 of ≥128 mg/liter; and imipenem, MIC50 of 4 mg/liter and MIC90 of 64 mg/liter. Among the tetracyclines, the isolates were more susceptible to tigecycline than minocycline and doxycycline, according to FDA breakpoints (95%, 88%, and 71% of the isolates were susceptible to tigecycline, minocycline, and doxycycline, respectively). Concentration escalation studies with tigecycline revealed a maximal killing effect near the MIC, with no additional extent or rate of killing at concentrations 2× to 4× the MIC for tigecycline. Time-kill studies demonstrated indifference for tigecycline in combination with the antimicrobials tested. Polymyxin B, minocycline, and tigecycline are the most active antimicrobials in vitro against CIRA. Concentration escalation studies demonstrate that tigecycline may need to approach concentrations higher than those currently achieved in the bloodstream to adequately treat CIRA bloodstream infections. Future studies should evaluate these findings in vivo. PMID:17307973

Revised Ciprofloxacin Breakpoints for Salmonella: Is it Time to Write an Obituary?

PubMed

Girish, Revathy; Kumar, Anil; Khan, Sadia; Dinesh, Kavitha R; Karim, Shamsul

2013-11-01

To determine the minimum inhibitory concentration of ciprofloxacin among 50 blood stream isolates of Salmonella enterica. A total of 50 consecutive isolates of Salmonella enterica were tested for susceptibility to antimicrobials using the Kirby Bauer disk diffusion method. Minimum inhibitory concentrations were determined using Hi-Comb strips. All results were interpreted according to the CLSI guidelines. Of the 50 isolates 70%were Salmonella Typhi, 4% Salmonella paratyphi A, 2% Salmonella paratyphi B and the remaining 10% were identified only as Salmonella species. Using the CLSI 2011 breakpoints for disc diffusion, 86% (43/50) were resistant to nalidixic acid(NA), 22% (11/50) to ciprofloxacin, 12% to azithromycin, 6% to cotrimoxazole, 4% to ampicillin and 1% to chloramphenicol. The MIC50 and MIC90 of ciprofloxacin for S.Typhi were 0.181 μg/mL and 5.06 μg/mL respectively. While the same for S. paratyphi A was 0.212μg/mL and 0.228μg/mL respectively. None of the isolates were multi drug resistant and all were susceptible to ceftriaxone. Using the CLSI 2012 revised ciprofloxacin breakpoints for disc diffusion (>31mm) & MIC (<0.06 μg/mL), 90% (45/50) of these isolates were found to be resistant. MIC's of ciprofloxacin should be reported for all salmonella isolates and should be used to guide treatment. Blindly following western guidelines for a disease which is highly endemic in the subcontinent will spell the death knell of a cheap and effective drug in our armamentarium. Therefore it will be too premature to declare that "the concept of using ciprofloxacin in typhoid fever is dead!"

Synergistic action of starch and honey against Candida albicans in correlation with diastase number

PubMed Central

Boukraa, Laïd; Benbarek, Hama; Moussa, Ahmed

2008-01-01

To evaluate the synergistic action of starch on the antifungal activity of honey, a comparative method of adding honey with and without starch to culture media was used. Candida albicans has been used to determine the minimum inhibitory concentration (MIC) of five varieties of honey. In a second step, lower concentrations of honey than the MIC were incubated with a set of concentrations of starch added to media to determine the minimum synergistic inhibitory concentration (MSIC). The MIC for the five varieties of honey without starch against C. albicans ranged between 40% and 45% (v/v). When starch was incubated with honey and then added to media, a MIC drop has been noticed with each variety. It ranged between 7% and 25%. A negative correlation has been established between the MIC drop and the diastase number (DN). PMID:24031175

Allicin from garlic inhibits the biofilm formation and urease activity of Proteus mirabilis in vitro.

PubMed

Ranjbar-Omid, Mahsa; Arzanlou, Mohsen; Amani, Mojtaba; Shokri Al-Hashem, Seyyedeh Khadijeh; Amir Mozafari, Nour; Peeri Doghaheh, Hadi

2015-05-01

Several virulence factors contribute to the pathogenesis of Proteus mirabilis. This study determined the inhibitory effects of allicin on urease, hemolysin and biofilm of P. mirabilis ATCC 12453 and its antimicrobial activity against 20 clinical isolates of P. mirabilis. Allicin did not inhibit hemolysin, whereas it did inhibit relative urease activity in both pre-lysed (half-maximum inhibitory concentration, IC50 = 4.15 μg) and intact cells (IC50 = 21 μg) in a concentration-dependent manner. Allicin at sub-minimum inhibitory concentrations (2-32 μg mL(-1)) showed no significant effects on the growth of the bacteria (P > 0.05), but it reduced biofilm development in a concentration-dependent manner (P < 0.001). A higher concentration of allicin was needed to inhibit the established biofilms. Using the microdilution technique, the MIC90 and MBC90 values of allicin against P. mirabilis isolates were determined to be 128 and 512 μg mL(-1), respectively. The results suggest that allicin could have clinical applications in controlling P. mirabilis infections. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

[Activity of macrolides and fluoroquinolones against intracellular Legionella pneumophila].

PubMed

Yu, Ling-ling; Hu, Bi-jie; Huang, Sheng-lei; Zhou, Zhao-yan; Tao, Li-li

2011-06-01

To evaluate the activity of macrolides and fluoroquinolones against Legionella pneumophila by intracellular susceptibility testing. Minimum inhibitory concentration (MIC) was determined by standard agar dilution test according to the CLSI. For intracellular assays, legionella pneumonia was used to infect human monocytic cell line THP-1. Erythromycin, azithromycin, levofloxacin and moxifloxacin at 1 × MIC, 4 × MIC, 8 × MIC were added following phagocytosis. Number of viable bacteria was enumerated at 24 h on BCYE (buffered charcoal yeast extract) agar in duplicates using standard plate count method. The result was expressed as percentage inhibition. Mann-Whitney U test was used to determine the significant differences in mean percentage inhibition between agents. Percentage inhibition at 24 h were as follows: Erythromycin 1 × MIC (50.18 ± 27.29)%, 4 × MIC (79.48 ± 20.08)%, 8 × MIC (91.46 ± 8.70)%; Azithromycin 1 × MIC (66.77 ± 26.18)%, 4 × MIC (91.73 ± 8.72)%, 8 × MIC (97.10 ± 3.37)%; Levofloxacin 1 × MIC (99.84 ± 0.25)%, 4 × MIC (99.99 ± 0.02)%, 8 × MIC (99.99 ± 0.01)%; Moxifloxacin 1 × MIC (99.90 ± 0.10)%, 4 × MIC (99.99 ± 0.03)%, 8 × MIC (99.99 ± 0.03)%. The fluoroquinolones showed greater inhibitory activity than macrolides against legionella pneumophila(u = 1.0, 2.0, 5.0, P < 0.05). Levofloxacin and moxifloxacin had the same intracellular activity against legionella pneumophila (u = 190, 183, 217, P > 0.05). Azithromycin was more effective than erythromycin in inhibiting intracellular legionella pneumophila (u = 132, 125, 128, P < 0.05). The fluoroquinolones were more active than macrolides against legionella pneumophila. The intracellular activity of levofloxacin against legionella pneumophila appeared to be similar to moxifloxacin. Azithromycin was demonstrated to have superior activity against legionella pneumophila compared with erythromycin.

Evaluation of the in vitro antimicrobial activity of an ethanol extract of Brazilian classified propolis on strains of Staphylococcus aureus

PubMed Central

Pamplona-Zomenhan, Lucila Coelho; Pamplona, Beatriz Coelho; da Silva, Cely Barreto; Marcucci, Maria Cristina; Mimica, Lycia Mara Jenné

2011-01-01

Staphylococcus aureus (S. aureus) is one of the most frequent causes of hospital acquired infections. With the increase in multiple drug resistant strains, natural products such as propolis are a stratagem for new product discovery. The aims of this study were: to determine the in vitro antimicrobial activity of an ethanol extract of propolis; to define the MIC50 and MIC90 (Minimal Inhibitory Concentration – MIC) against 210 strains of S. aureus; to characterize a crude sample of propolis and the respective ethanol extract as to the presence of predetermined chemical markers. The agar dilution method was used to define the MIC and the high performance liquid chromatography (HPLC) method was used to characterize the samples of propolis. MIC results ranged from 710 to 2,850 µg/mL. The MIC50 and MIC90 for the 210 strains as well as the individual analysis of American Type Culture Collection (ATCC) strains of Methicillin-susceptible Staphylococcus aureus (MSSA) and Methicillin-resistant Staphylococcus aureus (MRSA) were both 1,420 µg/mL. Based on the chromatographic analysis of the crude sample and ethanol extracted propolis, it was concluded that propolis was a mixture of the BRP (SP/MG) and BRP (PR) types. The results obtained confirm an antimicrobial activity in relation to the strains of the S. aureus tested. PMID:24031749

Characterisation of penicillin and tetracycline resistance in Staphylococcus aureus isolated from bovine milk samples in Minas Gerais, Brazil.

PubMed

Martini, Caroline L; Lange, Carla C; Brito, Maria Avp; Ribeiro, João B; Mendonça, Letícia C; Vaz, Eliana K

2017-05-01

This Regional Research Communication describes the characterisation of ampicillin, penicillin and tetracycline resistance in Staphylococcus aureus isolated from bovine subclinical mastitis in Minas Gerais State, Brazil. Ninety S. aureus isolates from bovine mastitis exhibiting phenotypic resistance to ampicillin, penicillin and/or tetracycline were selected for this study. The minimum inhibitory concentration (MIC) of each antibiotic was determined using the E-Test® and the production of beta-lactamase was determined by cefinase disks. The resistance genes blaZ, tet(K), tet(L), tet(M), and tet(O) were investigated by PCR in all of the isolates. The MIC results classified 77, 83 and 71% of the isolates as resistant to ampicillin, penicillin and tetracycline, respectively. The MIC50 and MIC90 were, respectively, 1 and 2 µg/ml for ampicillin, 0·5 and 1 µg/ml for penicillin and 32 and 64 µg/ml for tetracycline. Eighty-six per cent of beta-lactamase producing isolates were detected. Of the 90 isolates investigated, 97% amplified blaZ, 84% amplified tet(K), 9% amplified tet(L), 2% amplified tet(M) and 1% amplified tet(O). Seventy-nine isolates (88%) showed blaZ together with at least one tet gene. S. aureus isolates showed high MIC50 and MIC90 values for the three antimicrobials. The blaZ and tet(K) genes were widespread in the herds studied, and most of the isolates harboured blaZ and tet(K) concomitantly.

[Preoperatively administered flomoxef sodium concentration in aqueous humor].

PubMed

Miyamoto, Mariko; Watanabe, Yoichiro; Mizuki, Nobuhisa

2007-04-01

We intravenously administered flomoxef sodium (FMOX) 0.5-3.5 hours before cataract surgery and measured the concentration of the agent in the aqueous humor to investigate its penetration into the aqueous humor and its efficacy in the prevention of postoperative endophthalmitis. 56 patients who underwent cataract surgery were enrolled in this study. They received 1 g FMOX via a 20-minute intravenous drip beginning 0.5-3.5 hours before the operation. Aqueous humor was aspirated from the anterior chamber and assayed for FMOX concentration using high-performance liquid chromatography. The mean intraoperative FMOX concentrations in the patients' aqueous humor were 0.79 +/- 0.24 microg/ml (administered 3.5 hours before surgery)--1.47 0.79 microg/ml (administered 1.5 hours before surgery). These concentrations administered 0.5-3.0 hours before surgery sufficiently exceeded the minimum inhibitory concentration (MIC) 90 values against Staphylococcus epidermidis, Staphylococcus aureus and Propionibacterium acnes, but did not achieve the MIC90 values against Enterococcus faecalis and Pseudomonas aeruginosa. The FMOX concentrations in the aqueous humor sampling were adequate to kill bacteria in vitro. This drug may be efficacious in the prevention of postoperative endophthalmitis in patients undergoing cataract surgery.

In vitro antifungal activity of isavuconazole against 345 mucorales isolates collected at study centers in eight countries.

PubMed

Verweij, P E; González, G M; Wiedrhold, N P; Lass-Flörl, C; Warn, P; Heep, M; Ghannoum, M A; Guinea, J

2009-06-01

Although mucormycoses (formerly zygomycoses) are relatively uncommon, they are associated with high mortality and treatment options are limited. Isavuconazole is a novel, water soluble, broad-spectrum azole in clinical development for the treatment of invasive aspergillosis and candidiasis. The objective of this report was to collate data on the in vitro activity of isavuconazole against a collection of 345 diverse mucorales isolates, collected and tested at eight study centers in europe, mexico and North America. Each study center undertook minimum inhibitory concentration (MIC) susceptibility testing of their isolates, according to EUCAST or CLSI guidelines. Across all study centers, isavuconazole exhibited MIC(50 )values of 1-4 mg/l and MIC(90 )values of 4-16 mg/l against the five genera. There were also marked differences in MIC distributions, which could be ascribed to differences in inoculum and/or endpoint. EUCAST guidelines appeared to generate modal MICs 2-fold higher than CLSI. These results confirm that isavuconazole possesses at least partial antifungal activity against mucorales.

Efficacy of taurolidine against periodontopathic species--an in vitro study.

PubMed

Eick, Sigrun; Radakovic, Sabrina; Pfister, Wolfgang; Nietzsche, Sandor; Sculean, Anton

2012-06-01

The antimicrobial effect of taurolidine was tested against periodontopathic species in comparison to chlorhexidine digluconate in the presence or absence of serum. Minimal inhibitory concentrations (MIC), microbiocidal concentrations (MBC), as well as killing were determined against 32 different microbial strains including 3 Porphyromonas gingivalis, 3 Aggregatibacter actinomycetemcomitans, and 15 potentially superinfecting species with and without 25% v/v human serum. The MIC(50) of taurolidine against the tested microbial strains was 0.025% and the MIC(90) 0.05%. The respective values for the MBCs were 0.05% and 0.1%. Addition of 25% serum (heat-inactivated) did not change the MIC and MBC values of taurolidine. In contrast, MICs and MBCs of chlorhexidine (CHX) increased by two steps after addition of serum. Taurolidine killed microorganisms in a concentration and time-dependent manner, the killing rate of 1.6% taurolidine was 99.08% ± 2.27% in mean after 2 h. Again, killing activity of taurolidine was not affected if serum was added, whereas addition of inactivated serum clearly reduced the killing rate of all selected bacterial strains by CHX. Therefore, taurolidine possesses antimicrobial properties which are not reduced in the presence of serum as a main component in gingival crevicular fluid and wound fluid. Taurolidine may have potential as an antimicrobial agent in non-surgical and surgical periodontal treatment.

What Is the 'Minimum Inhibitory Concentration' (MIC) of Pexiganan Acting on Escherichia coli?-A Cautionary Case Study.

PubMed

Jepson, Alys K; Schwarz-Linek, Jana; Ryan, Lloyd; Ryadnov, Maxim G; Poon, Wilson C K

2016-01-01

We measured the minimum inhibitory concentration (MIC) of the antimicrobial peptide pexiganan acting on Escherichia coli , and found an intrinsic variability in such measurements. These results led to a detailed study of the effect of pexiganan on the growth curve of E. coli, using a plate reader and manual plating (i.e. time-kill curves). The measured growth curves, together with single-cell observations and peptide depletion assays, suggested that addition of a sub-MIC concentration of pexiganan to a population of this bacterium killed a fraction of the cells, reducing peptide activity during the process, while leaving the remaining cells unaffected. This pharmacodynamic hypothesis suggests a considerable inoculum effect, which we quantified. Our results cast doubt on the use of the MIC as 'a measure of the concentration needed for peptide action' and show how 'coarse-grained' studies at the population level give vital information for the correct planning and interpretation of MIC measurements.

In vitro susceptibility of filamentous fungi from mycotic keratitis to azole drugs.

PubMed

Shobana, C S; Mythili, A; Homa, M; Galgóczy, L; Priya, R; Babu Singh, Y R; Panneerselvam, K; Vágvölgyi, C; Kredics, L; Narendran, V; Manikandan, P

2015-03-01

The in vitro antifungal activities of azole drugs viz., itraconazole, voriconazole, ketoconazole, econazole and clotrimazole were investigated in order to evaluate their efficacy against filamentous fungi isolated from mycotic keratitis. The specimen collection was carried out from fungal keratitis patients attending Aravind eye hospital and Post-graduate institute of ophthalmology, Coimbatore, India and was subsequently processed for the isolation of fungi. The dilutions of antifungal drugs were prepared in RPMI 1640 medium. Minimum inhibitory concentrations (MICs) were determined and MIC50 and MIC90 were calculated for each drug tested. A total of 60 fungal isolates were identified as Fusarium spp. (n=30), non-sporulating moulds (n=9), Aspergillus flavus (n=6), Bipolaris spp. (n=6), Exserohilum spp. (n=4), Curvularia spp. (n=3), Alternaria spp. (n=1) and Exophiala spp. (n=1). The MICs of ketoconazole, clotrimazole, voriconazole, econazole and itraconazole for all the fungal isolates ranged between 16 μg/mL and 0.03 μg/mL, 4 μg/mL and 0.015 μg/mL, 8 μg/mL and 0.015 μg/mL, 8 μg/mL and 0.015 μg/mL and 32 μg/mL and 0.06 μg/mL respectively. From the MIC50 and MIC90 values, it could be deciphered that in the present study, clotrimazole was more active against the test isolates at lower concentrations (0.12-5 μg/mL) when compared to other drugs tested. The results suggest that amongst the tested azole drugs, clotrimazole followed by voriconazole and econazole had lower MICs against moulds isolated from mycotic keratitis. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Comparison of Neisseria gonorrhoeae MICs obtained by Etest and agar dilution for ceftriaxone, cefpodoxime, cefixime and azithromycin.

PubMed

Gose, Severin; Kong, Carol J; Lee, Yer; Samuel, Michael C; Bauer, Heidi M; Dixon, Paula; Soge, Olusegun O; Lei, John; Pandori, Mark

2013-12-01

We evaluated Neisseria gonorrhoeae Etest minimum inhibitory concentrations (MICs) relative to agar dilution MICs for 664 urethral isolates for ceftriaxone (CRO) and azithromycin (AZM), 351 isolates for cefpodoxime (CPD) and 315 isolates for cefixime (CFM). Etest accurately determined CPD, CFM and AZM MICs, but resulted in higher CRO MICs.

Evaluation of the in vitro activity of levornidazole, its metabolites and comparators against clinical anaerobic bacteria.

PubMed

Hu, Jiali; Zhang, Jing; Wu, Shi; Zhu, Demei; Huang, Haihui; Chen, Yuancheng; Yang, Yang; Zhang, Yingyuan

2014-12-01

This study evaluated the in vitro anti-anaerobic activity and spectrum of levornidazole, its metabolites and comparators against 375 clinical isolates of anaerobic bacteria, including Gram-negative bacilli (181 strains), Gram-negative cocci (11 strains), Gram-positive bacilli (139 strains) and Gram-positive cocci (44 strains), covering 34 species. Minimum inhibitory concentrations (MICs) of levornidazole, its five metabolites and three comparators against these anaerobic isolates were determined by the agar dilution method. Minimum bactericidal concentrations (MBCs) of levornidazole and metronidazole were measured against 22 strains of Bacteroides fragilis. Levornidazole showed good activity against B. fragilis, other Bacteroides spp., Clostridium difficile, Clostridium perfringens and Peptostreptococcus magnus, evidenced by MIC90 values of 0.5, 1, 0.25, 2 and 1mg/L, respectively. The activity of levornidazole and the comparators was poor for Veillonella spp. Generally, levornidazole displayed activity similar to or slightly higher than that of metronidazole, ornidazole and dextrornidazole against anaerobic Gram-negative bacilli, Gram-positive bacilli and Gram-positive cocci, especially B. fragilis. Favourable anti-anaerobic activity was also seen with levornidazole metabolites M1 and M4 but not M2, M3 or M5. For the 22 clinical B. fragilis strains, MBC50 and MBC90 values of levornidazole were 2mg/L and 4mg/L, respectively. Both MBC50/MIC50 and MBC90/MIC90 ratios of levornidazole were 4, similar to those of metronidazole. Levornidazole is an important anti-anaerobic option in clinical settings in terms of its potent and broad-spectrum in vitro activity, bactericidal property, and the anti-anaerobic activity of its metabolites M1 and M4. Copyright © 2014 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Synergies of carvacrol and 1,8-cineole to inhibit bacteria associated with minimally processed vegetables.

PubMed

de Sousa, Jossana Pereira; de Azerêdo, Geíza Alves; de Araújo Torres, Rayanne; da Silva Vasconcelos, Margarida Angélica; da Conceição, Maria Lúcia; de Souza, Evandro Leite

2012-03-15

This study assessed the occurrence of an enhancing inhibitory effect of the combined application of carvacrol and 1,8-cineole against bacteria associated with minimally processed vegetables using the determination of Fractional Inhibitory Concentration (FIC) index, time-kill assay in vegetable broth and application in vegetable matrices. Their effects, individually and in combination, on the sensory characteristics of the vegetables were also determined. Carvacrol and 1,8-cineole displayed Minimum Inhibitory Concentration (MIC) in a range of 0.6-2.5 and 5-20 μL/mL, respectively, against the organisms studied. FIC indices of the combined application of the compounds were 0.25 against Listeria monocytogenes, Aeromonas hydrophila and Pseudomonas fluorescens, suggesting a synergic interaction. Application of carvacrol and 1,8-cineole alone (MIC) or in a mixture (1/8 MIC+1/8 MIC or 1/4 MIC+1/4 MIC) in vegetable broth caused a significant decrease (p<0.05) in bacterial count over 24h. Mixtures of carvacrol and 1,8-cineole reduced (p<0.05) the inocula of all bacteria in vegetable broth and in experimentally inoculated fresh-cut vegetables. A similar efficacy was observed in the reduction of naturally occurring microorganisms in vegetables. Sensory evaluation revealed that the scores of the most-evaluated attributes fell between "like slightly" and "neither like nor dislike." The combination of carvacrol and 1,8-cineole at sub-inhibitory concentrations could constitute an interesting approach to sanitizing minimally processed vegetables. Copyright © 2011 Elsevier B.V. All rights reserved.

In vitro effect of subminimal inhibitory concentrations of antibiotics on the biofilm formation ability of Acinetobacter baumannii clinical isolates.

PubMed

Bogdan, Maja; Drenjancevic, Domagoj; Harsanji Drenjancevic, Ivana; Bedenic, Branka; Zujic Atalic, Vlasta; Talapko, Jasminka; Vukovic, Dubravka

2018-02-01

The ability of A cinetobacter baumannii strains to form biofilm is one of the most important virulence factor which enables bacterial survival in a harsh environment and decreases antibiotic concentration as well. Subminimal inhibitory concentrations (subMICs) of antibiotics may change bacterial ultrastructure or have an influence on some different molecular mechanisms resulting in morphological or physiological changes in bacteria itself. The aim of this study was to determine effects of 1/2, 1/4, 1/8 and 1/16 minimal inhibitory concentrationsof imipenem, ampicillin-sulbactam, azithromycin, rifampicin and colistin on biofilm formation ability of 22 biofilm non-producing and 46 biofilm producing A. baumannii strains (30 weak producing strains and 16 moderate producing strains). Results of this study indicate that 1/2-1/16 MICs of imipenem, azithromycin, and rifampicin can reduce bacterial biofilm formation ability in moderate producing strains (p < 0.05), whereas 1/16 MIC of imipenem and 1/4-1/8 MICs of rifampicin reduce the biofilm formation in weak producing strains (p < 0.05). Statisticaly significant effect was detected among biofilm non-producing strains after their exposure to 1/16 MIC of azithromycin (p = 0.039). SubMICs of ampicillin-sulbactam and colistin did not have any significant effect on biofilm formation among tested A. baumannii strains.

Tetracycline improved the efficiency of other antimicrobials against Gram-negative multidrug-resistant bacteria.

PubMed

Mawabo, Isabelle K; Noumedem, Jaurès A K; Kuiate, Jules R; Kuete, Victor

2015-01-01

Treatment of infectious diseases with antimicrobials constituted a great achievement in the history of medicine. Unfortunately, the emergence of resistant strains of bacteria to all classes of antimicrobials limited their efficacy. The present study was aimed at evaluating the effect of combinations of antibiotics on multi-drug resistant Gram-negative (MDRGN) bacteria. A liquid micro-broth dilution method was used to evaluate the antibacterial activity of 10 different classes of antimicrobials on 20 bacterial strains belonging to six different species. The antimicrobials were associated with phenylalanine β-naphthylamide (PAβN), an efflux pump inhibitor, and with other antimicrobials at their sub-inhibitory concentrations. The effectiveness of each combination was monitored using the minimal inhibitory concentration (MIC) and the fractional inhibitory concentration (FIC). Most of the antimicrobials tested showed low antibacterial activity with a MIC value of 128 mg/L on a majority of the bacterial strains, justifying their multidrug-resistant (MDR) profile. Synergistic effects were mostly observed (FIC≤0.5) when ampicillin (AMP), cloxacillin (CLX), erythromycin (ERY), chloramphenicol (CHL), kanamycin (KAN) and streptomycin (STR) were combined with tetracycline (TET) at the sub-inhibitory concentration of MIC/5 or MIC/10. The results of the present work suggest that the association of several antimicrobials with TET could improve the fight against MDRGN bacterial species. Copyright © 2014 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.

Short communication: Pharmacokinetics of intramammary hetacillin in dairy cattle milked 3 times per day.

PubMed

Lindquist, Danielle A; Baynes, Ronald E; Smith, Geof W

2015-03-01

Mastitis remains a critical disease in the dairy industry and the use of intramammary antibiotics plays a critical role in mastitis treatment. Hetacillin is currently approved as an intramammary antibiotic that is used to treat mastitis in dairy cows. It is approved for once a day administration and can be used for a total of 3 d. An increasing number of dairy farms are milking 3 times per day (instead of the traditional 2 times per day) and very little pharmacokinetic data exists on the use of intramammary drugs in a 3×system. The primary purpose of this study was to determine if once a day intramammary infusion of hetacillin is sufficient to maintain therapeutic drug concentrations in cattle milked 3 times per day. Eight Holstein cattle milked 3 times per day were used in this study. After collecting a baseline milk sample, each cow received intramammary infusions of hetacillin in the left front and right rear quarters once a day for 3 d. Milk samples from each of the treated quarters were collected at each milking and frozen until analysis. Milk samples were analyzed for ampicillin concentrations using an ultra-performance liquid chromatography method. All treated quarters had antibiotic concentrations well above the minimum inhibitory concentration (MIC) for gram-positive mastitis pathogens at 8 and 16 h postinfusion. Milk concentrations had fallen well below the MIC by the 24-h period (before the next infusion). All 8 cows in this study consistently had individual quarter milk ampicillin concentrations below the FDA tolerance of 0.01 μg/mL (10 ppb) within 48 h of the last infusion. Based on this study, milk ampicillin concentrations exceed the minimum inhibitory concentration required to inhibit the growth of 90% of organisms (MIC90) for at least 65% of the dosing interval, which is sufficient for once-daily dosing with most cases of gram-positive mastitis. Therefore, intramammary hetacillin should be an effective treatment for the vast majority of gram-positive mastitis pathogens when used according to label (once per day) in cows milked 3 times per day. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

In Vitro Anti-Listerial Activities of Crude n-Hexane and Aqueous Extracts of Garcinia kola (heckel) Seeds

PubMed Central

Penduka, Dambudzo; Okoh, Anthony I.

2011-01-01

We assessed the anti-Listerial activities of crude n-hexane and aqueous extracts of Garcinia kola seeds against a panel of 42 Listeria isolates previously isolated from wastewater effluents in the Eastern Cape Province of South Africa and belonging to Listeria monocytogenes, Listeria grayi and Listeria ivanovii species. The n-hexane fraction was active against 45% of the test bacteria with zones of inhibition ranging between 8–17 mm, while the aqueous fraction was active against 29% with zones of inhibition ranging between 8–11 mm. The minimum inhibitory concentrations (MIC) were within the ranges of 0.079–0.625 mg/mL for the n-hexane extract and 10 to >10 mg/mL for the aqueous extract. The rate of kill experiment carried out for the n-hexane extract only, revealed complete elimination of the initial bacterial population for L. grayi (LAL 15) at 3× and 4× MIC after 90 and 60 min; L. monocytogenes (LAL 8) at 3× and 4× MIC after 60 and 15 min; L. ivanovii (LEL 18) at 3× and 4× MIC after 120 and 15 min; L. ivanovii (LEL 30) at 2, 3 and 4× MIC values after 105, 90 and 15 min exposure time respectively. The rate of kill activities were time- and concentration-dependant and the extract proved to be bactericidal as it achieved a more than 3log10 decrease in viable cell counts after 2 h exposure time for all of the four test organisms at 3× and 4× MIC values. The results therefore show the potential presence of anti-Listerial compounds in Garcinia kola seeds that can be exploited in effective anti-Listerial chemotherapy. PMID:22072929

In vitro anti-listerial activities of crude n-hexane and aqueous extracts of Garcinia kola (heckel) seeds.

PubMed

Penduka, Dambudzo; Okoh, Anthony I

2011-01-01

We assessed the anti-Listerial activities of crude n-hexane and aqueous extracts of Garcinia kola seeds against a panel of 42 Listeria isolates previously isolated from wastewater effluents in the Eastern Cape Province of South Africa and belonging to Listeria monocytogenes, Listeria grayi and Listeria ivanovii species. The n-hexane fraction was active against 45% of the test bacteria with zones of inhibition ranging between 8-17 mm, while the aqueous fraction was active against 29% with zones of inhibition ranging between 8-11 mm. The minimum inhibitory concentrations (MIC) were within the ranges of 0.079-0.625 mg/mL for the n-hexane extract and 10 to >10 mg/mL for the aqueous extract. The rate of kill experiment carried out for the n-hexane extract only, revealed complete elimination of the initial bacterial population for L. grayi (LAL 15) at 3× and 4× MIC after 90 and 60 min; L. monocytogenes (LAL 8) at 3× and 4× MIC after 60 and 15 min; L. ivanovii (LEL 18) at 3× and 4× MIC after 120 and 15 min; L. ivanovii (LEL 30) at 2, 3 and 4× MIC values after 105, 90 and 15 min exposure time respectively. The rate of kill activities were time- and concentration-dependant and the extract proved to be bactericidal as it achieved a more than 3log(10) decrease in viable cell counts after 2 h exposure time for all of the four test organisms at 3× and 4× MIC values. The results therefore show the potential presence of anti-Listerial compounds in Garcinia kola seeds that can be exploited in effective anti-Listerial chemotherapy.

Combined Activity of Colloid Nanosilver and Zataria Multiflora Boiss Essential Oil-Mechanism of Action and Biofilm Removal Activity.

PubMed

Shirdel, Maryam; Tajik, Hossein; Moradi, Mehran

2017-12-01

Purpose: The aim of this study was to investigate antimicrobial and biofilm removal potential of Zataria multiflora essential oil (ZEO) and silver nanoparticle (SNP) alone and in combination on Staphylococcus aureus and Salmonella Typhimurium and evaluate the mechanism of action. Methods: The minimum inhibitory concentration (MIC), and optimal inhibitory combination (OIC) of ZEO and SNP were determined according to fractional inhibitory concentration (FIC) method. Biofilm removal potential and leakage pattern of 260-nm absorbing material from the bacterial cell during exposure to the compounds were also investigated. Results: MICs of SNP for both bacteria were the same as 25 μg/ mL. The MICs and MBCs values of ZEO were 2500 and 1250 μg/mL, respectively. The most effective OIC value for SNP and ZEO against Salm. Typhimurium and Staph. aureus were 12.5, 625 and 0.78, 1250 μg/ mL, respectively. ZEO and SNP at MIC and OIC concentrations represented a strong removal ability (>70%) on biofilm. Moreover, ZEO at MIC and OIC concentrations did a 6-log reduction of primary inoculated bacteria during 15 min contact time. The effect of ZEO on the loss of 260-nm material from the cell was faster than SNP during 15 and 60 min. Conclusion: Combination of ZEO and SNP had significant sanitizing activity on examined bacteria which may be suitable for disinfecting the surfaces.

Potential of tara (Caesalpinia spinosa) gallotannins and hydrolysates as natural antibacterial compounds.

PubMed

Aguilar-Galvez, Ana; Noratto, Giuliana; Chambi, Flor; Debaste, Frédéric; Campos, David

2014-08-01

Gallotannins obtained from tara pod extracts (EE) and from the products of acid hydrolysis for 4 and 9h (HE-4 and HE-9) were characterised for their composition, antioxidant activity, antimicrobial activity (AA) and minimum inhibitory concentration (MIC). Results of AA and MIC showed that EE exerted the highest inhibitory activity against Staphylococcus aureus, followed by Pseudomonas fluorescens; and among these bacteria, the antibacterial potency was enhanced after EE hydrolysis only against S. aureus. The lowest minimum inhibitory concentration (MIC) value (0.13mg gallic acid equivalent (GAE)/ml) was exerted by HE-4 against S. aureus. These results indicate that tara gallotannins have the potential to inhibit pathogenic bacteria with potential application in foods as antimicrobials and their AA can be enhanced by acid hydrolysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

In vitro susceptibility testing of Malassezia pachydermatis to gentamicin.

PubMed

Silva, Freddy A; Ferrer, Otilia; Déniz, Soraya; Rosario, Inmaculada; Conde-Felipe, Magnolia; Díaz, Esther L; Acosta-Hernández, Begoña

2017-08-01

Two studies have observed that growth media containing gentamicin can inhibit the growth of the yeast organism Malassezia pachydermatis. The minimum inhibitory concentration (MIC) of this bactericidal antibiotic for this organism has not been previously determined. To evaluate the susceptibility of M. pachydermatis isolates to gentamicin. The MIC of gentamicin was determined using a modified version of the M27-A3 microdilution method following the guidelines of the Clinical and Laboratory Standards Institute. A modified Christensen's urea broth was used to enhance the growth of the M. pachydermatis isolates. Visual and spectrophotometric end-point readings were performed to detect the presence or absence of yeast growth. The MIC50 and MIC90 of gentamicin were 8.12 μg/mL and 32.5 μg/mL, respectively; M. pachydermatis strains were classified as susceptible (S), intermediate (I) and resistant (R). The susceptibility of these isolates to gentamicin in vitro, by visual and spectrophotometric end-point reading, was: S, 54-56%; I, 40-41%; and R, 3-6%. Prospective MICs for M. pachydermatis have been established for gentamicin. © 2017 ESVD and ACVD.

Growth Inhibition and Morphological Alterations of Trichophyton Rubrum Induced by Essential oil from Cymbopogon Winterianus Jowitt Ex Bor

PubMed Central

de Oliveira Pereira, Fillipe; Alves Wanderley, Paulo; Cavalcanti Viana, Fernando Antônio; Baltazar de Lima, Rita; Barbosa de Sousa, Frederico; de Oliveira Lima, Edeltrudes

2011-01-01

Trichophyton rubrum is one of the most common fungi causer of dermatophytosis, mycosis that affect humans and animals around the world. Researches aiming new products with antifungal activity become necessary to overcome difficulties on treatment of these infections. Accordingly, this study aimed to investigate the antifungal activity of essential oil from Cymbopogon winterianus against the dermatophyte T. rubrum. The antifungal screening was performed by solid medium diffusion method with 16 T. rubrum strains, minimum inhibitory concentration (MIC) and minimum fungicide concentration (MFC) were determined using the microdilution method. The effects on mycelial dry weight and morphology were also observed. Screening showed essential oil in natura inhibited all the tested strains, with inhibition zones between 24-28 mm diameter. MIC50 and MIC90 values of the essential oil were 312 μg/mL for nearly all the essayed strains (93.75 %) while the MFC50 and MFC90 values were about eight times higher than MIC for all tested strains. All tested essential oil concentrations managed to inhibit strongly the mycelium development. Main morphological changes on the fungal strains observed under light microscopy, which were provided by the essential oil include loss of conidiation, alterations concerning form and pigmentation of hyphae. In the oil presence, colonies showed folds, cream color and slightly darker than the control, pigment production was absent on the reverse and with evident folds. It is concluded that C. winterianus essential oil showed activity against T. rubrum. Therefore, it could be known as potential antifungal compound especially for protection against dermatophytosis. PMID:24031626

Antimicrobial Susceptibility Patterns of Enterococcus faecalis and Enterococcus faecium Isolated from Poultry Flocks in Germany.

PubMed

Maasjost, J; Mühldorfer, K; Cortez de Jäckel S; Hafez, H M

2015-03-01

Between 2010 and 2011, 145 Enterococcus isolates (Enterococcus faecalis, n = 127; Enterococcus faecium, n = 18) were collected during routine bacteriologic diagnostics from broilers, layers, and fattening turkeys in Germany showing various clinical signs. The susceptibility to 24 antimicrobial agents was investigated by broth microdilution test to determine minimum inhibitory concentrations (MICs). All E. faecalis isolates (n = 127) were susceptible to the beta-lactam antibiotics ampicillin, amoxicillin-clavulanic acid, and penicillin. Corresponding MIC with 50% inhibition (MIC50) and MIC with 90% inhibition (MIC90) values of these antimicrobial agents were at the lower end of the test range (≤ 4 μg/ml). In addition, no vancomycin-resistant enterococci (VRE) were found. High resistance rates were identified in both Enterococcus species for lincomycin (72%-99%) and tetracycline (67%-82%). Half or more than half of Enterococcus isolates were resistant to gentamicin (54%-72%) and the macrolide antibiotics erythromycin (44%-61%) and tylosin-tartate (44%-56%). Enterococcus faecalis isolated from fattening turkeys showed the highest prevalence of antimicrobial resistance compared to other poultry production systems. Eighty-nine out of 145 Enterococcus isolates were resistant to three or more antimicrobial classes. Again, turkeys stood out with 42 (8 1%) multiresistant isolates. The most-frequent resistance patterns of E. faecalis were gentamicin, lincomycin, and tetracycline in all poultry production systems.

Technical note: Antimicrobial susceptibility of Portuguese isolates of Staphylococcus aureus and Staphylococcus epidermidis in subclinical bovine mastitis.

PubMed

Nunes, S F; Bexiga, R; Cavaco, L M; Vilela, C L

2007-07-01

To evaluate the antimicrobial resistance traits of staphylococci responsible for subclinical bovine mastitis in Portugal, the minimum inhibitory concentrations (MIC) of 7 antimicrobial agents, frequently administered for mastitis treatment, were determined for 30 Staphylococcus aureus and 31 Staphylococcus epidermidis field isolates. Beta-lactamase production was detected through the use of nitrocefin-impregnated discs. The MIC that inhibited 90% of the isolates tested (MIC90) of penicillin, oxacillin, cefazolin, gentamicin, sulfamethoxazole/trimethoprim, oxytetracycline, and enrofloxacin were, respectively, 4, 0.5, 1, 1, 0.25, 0.25, and 0.06 microg/mL for Staph. aureus and > or = 64, 8, 1, 32, > or = 64, > or = 64, and 0.06 microg/mL for Staph. epidermidis. All Staph. aureus isolates showed susceptibility to oxacillin, cefazolin, gentamicin, sulphamethoxazole/trimethoprim, and enrofloxacin. Beta-lactamase production was detected in 20 of these isolates (66.7%), all of which were resistant to penicillin. Of the 31 Staph. epidermidis tested, 24 (77.4%) were beta-lactamase positive. All isolates were susceptible to both cefazolin and enrofloxacin. Nine Staph. epidermidis isolates were resistant to oxacillin, with MIC values ranging from 4 to 8 microg/mL. The MIC values of 5 antimicrobial agents tested were higher than those reported in other countries. Enrofloxacin was the only exception, showing lower MIC values compared with other reports. Overall, the antimicrobial agents tested in our study, with the exception of penicillin, were active against the 61 isolates studied.

Frequency of colistin and fosfomycin resistance in carbapenem-resistant Enterobacteriaceae from a tertiary care hospital in Karachi.

PubMed

Qamar, Salima; Shaheen, Najma; Shakoor, Sadia; Farooqi, Joveria; Jabeen, Kauser; Hasan, Rumina

2017-01-01

Management of infections with carbapenem-resistant Enterobacteriaceae (CRE) is challenging. In recent times, agents such as colistin and fosfomycin have been used in combination with other antibiotics to treat such infections. In this study, we aim to seek frequency of colistin and fosfomycin resistance in CRE from Pakistan. This study was conducted at clinical laboratories, Aga Khan University Hospital. In total, 251 CRE were included in the study. Colistin minimum inhibitory concentrations (MICs) were performed using broth microdilution (BMD) method and VITEK ® 2 system, whereas fosfomycin susceptibility was performed using Kirby-Bauer method. MIC 50 and MIC 90 were calculated for colistin and agreement between VITEK and BMD was also calculated. Out of 251 strains colistin MIC of ≥4 µg/mL was seen in 40 (15.9%). Of these strains 20 (50%) were Klebsiella pneumoniae . Colistin MIC 50 and MIC 90 were found to be 0.5 and 16 µg/mL, respectively. BMD and VITEK 2 showed 100% categorical agreement. Essential agreement was 88.5% with kappa score 0.733 indicating strong agreement between VITEK and BMD. 31 out of 251 (12.3%) CREs were resistant to fosfomycin. Study shows frequency of colistin and fosfomycin resistance to be 15.9% and 12.3%, respectively. In countries where rate of CREs is high, emerging resistance against these last resort antibiotics is alarming as it leaves clinicians with almost no options to manage such multidrug resistant and extensively drug resistant infections.

Ecdysteroids in Sida tuberculata R.E. Fries (Malvaceae): chemical composition by LC-ESI-MS and selective anti-Candida krusei activity.

PubMed

da Rosa, Hemerson Silva; de Camargo, Vanessa Brum; Camargo, Graziela; Garcia, Cássia V; Fuentefria, Alexandre M; Mendez, Andreas S L

2015-09-01

Sida tuberculata is found in a region of South America and has traditionally been consumed as an infusion or tea. The chemical composition and antifungal activity of aqueous infusions from leaves and roots were investigated. LC-ESI-MS mass spectra were successfully obtained and used to identify four ecdysteroids: 20-hydroxyecdysone-3-O-β-D-glycopyranoside, 20-hydroxyecdysone, 20-hydroxyecdysone-3-O-β-D-xylose and a hydroxyecdysterone derivative. The in vitro antifungal activity was studied, and the minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) were established against Candida krusei isolates. The antibiofilm activity was evaluated by the determination of the biofilm removal efficiency in contaminated central venous catheter (CVC) coupons. The preparations exhibited antifungal activity against the species tested, with MICs ranging from 3.90 to 62.50 μg/ml. The infusion removed the C. krusei biofilm after 90 min of exposure. The observed bioactivity and composition of ecdysteroids will contribute to the future development of antifungal substances for clinical use or as food additives. Copyright © 2015 Elsevier Ltd. All rights reserved.

A Weibull model to describe antimicrobial kinetics of oregano and lemongrass essential oils against Salmonella Enteritidis in ground beef during refrigerated storage.

PubMed

de Oliveira, Thales Leandro Coutinho; Soares, Rodrigo de Araújo; Piccoli, Roberta Hilsdorf

2013-03-01

The antimicrobial effect of oregano (Origanum vulgare L.) and lemongrass (Cymbopogon citratus (DC.) Stapf.) essential oils (EOs) against Salmonella enterica serotype Enteritidis in in vitro experiments, and inoculated in ground bovine meat during refrigerated storage (4±2 °C) for 6 days was evaluated. The Weibull model was tested to fit survival/inactivation bacterial curves (estimating of p and δ parameters). The minimum inhibitory concentration (MIC) value for both EOs on S. Enteritidis was 3.90 μl/ml. The EO concentrations applied in the ground beef were 3.90, 7.80 and 15.60 μl/g, based on MIC levels and possible activity reduction by food constituents. Both evaluated EOs in all tested levels, showed antimicrobial effects, with microbial populations reducing (p≤0.05) along time storage. Evaluating fit-quality parameters (RSS and RSE) Weibull models are able to describe the inactivation curves of EOs against S. Enteritidis. The application of EOs in processed meats can be used to control pathogens during refrigerated shelf-life. Copyright © 2012 Elsevier Ltd. All rights reserved.

Comparison of Neisseria gonorrhoeae MICs Obtained by Etest and Agar Dilution for Ceftriaxone, Cefpodoxime, Cefixime and Azithromycin.

PubMed

Gose, Severin; Kong, Carol J; Lee, Yer; Samuel, Michael C; Bauer, Heidi M; Dixon, Paula; Soge, Olusegun O; Lei, John; Pandori, Mark

2013-10-24

We evaluated Neisseria gonorrhoeae Etest minimum inhibitory concentrations (MICs) relative to agar dilution MICs for 664 urethral isolates for ceftriaxone (CRO) and azithromycin (AZM), 351 isolates for cefpodoxime (CPD) and 315 isolates for cefixime (CFM). Etest accurately determined CPD, CFM and AZM MICs, but resulted in higher CRO MICs. © 2013. Published by Elsevier B.V. All rights reserved.

Antifungal efficacy of thymol, carvacrol, eugenol and menthol as alternative agents to control the growth of food-relevant fungi.

PubMed

Abbaszadeh, S; Sharifzadeh, A; Shokri, H; Khosravi, A R; Abbaszadeh, A

2014-06-01

This work is an attempt to examine the antifungal activity of thymol, carvacrol, eugenol and menthol against 11 food-decaying fungi. The susceptibility test for the compounds was carried out in terms of minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) using microdilution method in 96 multi-well microtiter plates. Results indicated that all compounds were effective to varying extents against various fungal isolates, with the highest efficacy displayed by carvacrol (mean MIC value: 154.5 μg/mL) (P<0.05). The incorporation of increased concentrations of all compounds to the media led to progressive and significant reduction in growth for all fungi. The most potent inhibitory activity of thymol, carvacrol, eugenol and menthol was found for Cladosporium spp. (MIC: 100 μg/mL), Aspergillus spp. (MIC: 100 μg/mL), Cladosporium spp. (MIC: 350 μg/mL), and Aspergillus spp. and Cladosporium spp. (MIC: 125 μg/mL), respectively. Thus, the application of these herbal components could be considered as a good alternatives to inhibit fungal growth and to reduce the use of synthetic fungicides. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

In vitro Effects of Lemongrass Extract on Candida albicans Biofilms, Human Cells Viability, and Denture Surface

PubMed Central

Madeira, Petrus L. B.; Carvalho, Letícia T.; Paschoal, Marco A. B.; de Sousa, Eduardo M.; Moffa, Eduardo B.; da Silva, Marcos A. dos Santos; Tavarez, Rudys de Jesus Rodolfo; Gonçalves, Letícia M.

2016-01-01

The purpose of this study was to investigate whether immersion of a denture surface in lemongrass extract (LGE) has effects on C. albicans biofilms, human cell viability and denture surface. Minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) were performed for LGE against C. albicans. For biofilm analysis, discs were fabricated using a denture acrylic resin with surface roughness standardization. C. albicans biofilms were developed on saliva-coated discs, and the effects of LGE at MIC, 5XMIC, and 10XMIC were investigated during biofilm formation and after biofilm maturation. Biofilms were investigated for cell counting, metabolic activity, and microscopic analysis. The cytotoxicity of different concentrations of LGE to peripheral blood mononuclear cells (PBMC) was analyzed using MTT. The effects of LGE on acrylic resin were verified by measuring changes in roughness, color and flexural strength after 28 days of immersion. Data were analyzed by ANOVA, followed by a Tukey test at a 5% significance level. The minimal concentration of LGE required to inhibit C. albicans growth was 0.625 mg/mL, while MFC was 2.5 mg/mL. The presence of LGE during biofilm development resulted in a reduction of cell counting (p < 0.05), which made the MIC sufficient to reduce approximately 90% of cells (p < 0.0001). The exposure of LGE after biofilm maturation also had a significant antifungal effect at all concentrations (p < 0.05). When compared to the control group, the exposure of PBMC to LGE at MIC resulted in similar viability (p > 0.05). There were no verified differences in color perception, roughness, or flexural strength after immersion in LGE at MIC compared to the control (p > 0.05). It could be concluded that immersion of the denture surface in LGE was effective in reducing C. albicans biofilms with no deleterious effects on acrylic properties at MIC. MIC was also an effective and safe concentration for use. PMID:27446818

In vitro Effects of Lemongrass Extract on Candida albicans Biofilms, Human Cells Viability, and Denture Surface.

PubMed

Madeira, Petrus L B; Carvalho, Letícia T; Paschoal, Marco A B; de Sousa, Eduardo M; Moffa, Eduardo B; da Silva, Marcos A Dos Santos; Tavarez, Rudys de Jesus Rodolfo; Gonçalves, Letícia M

2016-01-01

The purpose of this study was to investigate whether immersion of a denture surface in lemongrass extract (LGE) has effects on C. albicans biofilms, human cell viability and denture surface. Minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) were performed for LGE against C. albicans. For biofilm analysis, discs were fabricated using a denture acrylic resin with surface roughness standardization. C. albicans biofilms were developed on saliva-coated discs, and the effects of LGE at MIC, 5XMIC, and 10XMIC were investigated during biofilm formation and after biofilm maturation. Biofilms were investigated for cell counting, metabolic activity, and microscopic analysis. The cytotoxicity of different concentrations of LGE to peripheral blood mononuclear cells (PBMC) was analyzed using MTT. The effects of LGE on acrylic resin were verified by measuring changes in roughness, color and flexural strength after 28 days of immersion. Data were analyzed by ANOVA, followed by a Tukey test at a 5% significance level. The minimal concentration of LGE required to inhibit C. albicans growth was 0.625 mg/mL, while MFC was 2.5 mg/mL. The presence of LGE during biofilm development resulted in a reduction of cell counting (p < 0.05), which made the MIC sufficient to reduce approximately 90% of cells (p < 0.0001). The exposure of LGE after biofilm maturation also had a significant antifungal effect at all concentrations (p < 0.05). When compared to the control group, the exposure of PBMC to LGE at MIC resulted in similar viability (p > 0.05). There were no verified differences in color perception, roughness, or flexural strength after immersion in LGE at MIC compared to the control (p > 0.05). It could be concluded that immersion of the denture surface in LGE was effective in reducing C. albicans biofilms with no deleterious effects on acrylic properties at MIC. MIC was also an effective and safe concentration for use.

Linking minimum inhibitory concentrations to whole genome sequence-predicted drug resistance in Mycobacterium tuberculosis strains from Romania.

PubMed

Ruesen, Carolien; Riza, Anca Lelia; Florescu, Adriana; Chaidir, Lidya; Editoiu, Cornelia; Aalders, Nicole; Nicolosu, Dragos; Grecu, Victor; Ioana, Mihai; van Crevel, Reinout; van Ingen, Jakko

2018-06-26

Mycobacterium tuberculosis drug resistance poses a major threat to tuberculosis control. Current phenotypic tests for drug susceptibility are time-consuming, technically complex, and expensive. Whole genome sequencing is a promising alternative, though the impact of different drug resistance mutations on the minimum inhibitory concentration (MIC) remains to be investigated. We examined the genomes of 72 phenotypically drug-resistant Mycobacterium tuberculosis isolates from 72 Romanian patients for drug resistance mutations. MICs for first- and second-line drugs were determined using the MycoTB microdilution method. These MICs were compared to macrodilution critical concentration testing by the Mycobacterium Growth Indicator Tube (MGIT) platform and correlated to drug resistance mutations. Sixty-three (87.5%) isolates harboured drug resistance mutations; 48 (66.7%) were genotypically multidrug-resistant. Different drug resistance mutations were associated with different MIC ranges; katG S315T for isoniazid, and rpoB S450L for rifampicin were associated with high MICs. However, several mutations such as in rpoB, rrs and rpsL, or embB were associated with MIC ranges including the critical concentration for rifampicin, aminoglycosides or ethambutol, respectively. Different resistance mutations lead to distinct MICs, some of which may still be overcome by increased dosing. Whole genome sequencing can aid in the timely diagnosis of Mycobacterium tuberculosis drug resistance and guide clinical decision-making.

In vitro activity of flomoxef against rapidly growing mycobacteria.

PubMed

Tsai, Moan-Shane; Tang, Ya-Fen; Eng, Hock-Liew

2008-06-01

The aim of this study was to determine the in vitro sensitivity of rapidly growing mycobacteria (RGM) to flomoxef in respiratory secretions collected from 61 consecutive inpatients and outpatients at Chang Gung Memorial Hospital-Kaohsiung medical center between July and December, 2005. Minimal inhibitory concentrations (MIC) of flomoxef were determined by the broth dilution method for the 61 clinical isolates of RGMs. The MICs of flomoxef at which 90% of clinical isolates were inhibited was >128 microg/mL in 26 isolates of Mycobacterium abscessus and 4 microg/mL in 31 isolates of M. fortuitum. Three out of 4 clinical M. peregrinum isolates were inhibited by flomoxef at concentrations of 4 microg/mL or less. Although the numbers of the clinical isolates of RGMs were small, these preliminary in vitro results demonstrate the potential activity of flomoxef in the management of infections due to M. fortuitum, and probably M. peregrinum in humans.

In vitro antifungal activity of silver nanoparticles against ocular pathogenic filamentous fungi.

PubMed

Xu, Yan; Gao, Chuanwen; Li, Xiaohua; He, Yi; Zhou, Lutan; Pang, Guangren; Sun, Shengtao

2013-03-01

Fungal keratitis is emerging as a major cause of vision loss in a developing country such as China because of higher incidence and the unavailability of effective antifungals. It is urgent to explore broad-spectrum antifungals to effectively suppress ocular fungal pathogens, and to develop new antifungal eye drops to combat this vision-threatening infection. The aim of this study is to investigate the antifungal activity of silver nanoparticles (nano-Ag) in comparison with that of natamycin against ocular pathogenic filamentous fungi in vitro. Susceptibility tests were performed against 216 strains of fungi isolated from patients with fungal keratitis from the Henan Eye Institute in China by broth dilution antifungal susceptibility test of filamentous fungi approved by the Clinical and Laboratory Standards Institute M38-A document. The isolates included 112 Fusarium isolates (82 Fusarium solani species complex, 20 Fusarium verticillioides species complex, and 10 Fusarium oxysporum species complex), 94 Aspergillus isolates (61 Aspergillus flavus species complex, 11 Aspergillus fumigatus species complex, 12 Aspergillus versicolor species complex, and 10 Aspergillus niger species complex), and 10 Alternaria alternata isolates. The minimum inhibitory concentration (MIC) range and mode, the MIC for 50% of the strains tested (MIC50 value), and the MIC90 value were provided for the isolates with the SPSS statistical package. MIC50 value of nano-Ag were 1, 0.5, and 0.5 μg/mL for Fusarium spp., Aspergillus spp., and Al. alternata, respectively. MIC90 values of nano-Ag were 1, 1, and 1 μg/mL for Fusarium spp., Aspergillus spp., and Al. alternata, respectively. MIC50 values of natamycin were 4, 32, and 4 μg/mL for Fusarium spp., Aspergillus spp., and Al. alternata, respectively. MIC90 values of natamycin were 8, 32, and 4 μg/mL for Fusarium spp., Aspergillus spp., and Al. alternata, respectively. Nano-Ag, relative to natamycin, exhibits potent in vitro activity against ocular pathogenic filamentous fungi.

Quality assurance for antimicrobial susceptibility testing of Neisseria gonorrhoeae in Latin American and Caribbean countries, 2013-2015.

PubMed

Sawatzky, Pam; Martin, Irene; Galarza, Patricia; Carvallo, Marıa Elena Trigoso; Araya Rodriguez, Pamela; Cruz, Olga Marina Sanabria; Hernandez, Alina Llop; Martinez, Mario Fabian; Borthagaray, Graciela; Payares, Daisy; Moreno, José E; Chiappe, Marina; Corredor, Aura Helena; Thakur, Sidharath Dev; Dillon, Jo-Anne R

2018-04-19

A Neisseria gonorrhoeae antimicrobial susceptibility quality control comparison programme was re-established in Latin America and the Caribbean to ensure antimicrobial susceptibility data produced from the region are comparable nationally and internationally. Three panels, consisting of N. gonorrhoeae isolates comprising reference strains and other characterised isolates were sent to 11 participating laboratories between 2013 and 2015. Antimicrobial susceptibilities for these isolates were determined using agar dilution, Etest or disc diffusion methods. Modal minimum inhibitory concentrations (MICs) for each panel isolate/antibiotic combination were calculated. The guidelines of the Clinical and Laboratory Standards Institute were used for interpretations of antimicrobial susceptibility. The agreement of MICs with the modal MICs was determined for each of the participating laboratories as well as for each of the antibiotics tested. Five of 11 laboratories that participated in at least one panel had an overall average agreement between participants' MIC results and modal MICs of >90%. For other laboratories, agreements ranged from 60.0% to 82.4%. The proportion of agreement between interpretations for all the antibiotics, except penicillin and tetracycline, was >90%. The percentages of agreement between MIC results and their modes for erythromycin, spectinomycin, cefixime and azithromycin were >90%. Tetracycline, ceftriaxone and ciprofloxacin agreement ranged from 84.5% to 89.1%, while penicillin had 78.8% agreement between MICs and modal MICs. The participating laboratories had acceptable results, similar to other international quality assurance programmes. It is important to ensure continuation of the International Gonococcal Antimicrobial Susceptibility Quality Control Comparison Programme to ensure that participants can identify and correct any problems in antimicrobial susceptibility testing for N. gonorrhoeae as they arise and continue to generate reproducible and reliable data. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

[Determination of sensitivity of biofilm-positive forms of microorganisms to antibiotics].

PubMed

Holá, Veronika; Růzicka, Filip; Tejkalová, Renata; Votava, Miroslav

2004-10-01

Nosocomial infections caused by biofilm-positive microorganisms are a serious therapeutic problem. In the biofilm, microorganisms are protected against adverse effects of the external environment, including the action of antibiotics. It is well known that the values of minimum inhibitory concentrations (MIC) determined for planktonic forms do not correspond to the actual concentrations of antibiotics necessary for the eradication of bacteria in a biofilm. The purpose of the study was to propose a method of determining minimum biofilm inhibitory concentrations (MBIC) and minimum biofilm eradication concentrations (MBEC) and to compare these values with MIC values. Biofilm-positive strains of Staphylococcus epidermidis were cultured so as to form a biofilm layer on polystyrene pegs. The biofilm on the pegs was then exposed to the action of antibiotics and after 18 hours we determined the minimum biofilm inhibitory concentration (MBIC). The evaluation of minimum biofilm eradication concentrations was done colorimetrically from the metabolic activity of surviving cells. MBIC and MBEC values were many times higher than MIC values. We selected such a duration of the biofilms cultivation on the pegs of the plate, which ensured that the number of bacterial cells corresponded to standard MIC assessment. The MBEC values established in our study indicate that the currently used concentrations of tested antibiotics cannot be used in monotherapy for an efficacious eradication of a biofilm. The MBEC determination is a far more laborious and time-consuming method than the determination of MIC, but the use of plates with pegs facilitates the handling of biofilms. The advantage of our method is the possibility of standardization of the size of the inoculum and thus of the whole MBEC assessment.

Evaluation of medicinal plants and colloidal silver efficiency against Vibrio parahaemolyticus infection in Litopenaeus vannamei cultured at low salinity.

PubMed

Morales-Covarrubias, María Soledad; García-Aguilar, Noemí; Bolan-Mejía, María Del; Puello-Cruz, Ana Carmela

2016-11-22

In shrimp aquaculture, reduction in the use of synthetic antibiotics is a priority due to the high incidence of resistant bacteria (Vibrio) in the white shrimp Litopenaeus vannamei. An increasing number of studies show bactericidal activity of natural treatments in aquaculture. The effectiveness of neem (Azadirachta indica) and oregano (Lippia berlandieri) aqueous extracts and colloidal silver against V. parahaemolyticus were evaluated in low salinity shrimp culture. Results show that aqueous extracts of oregano and neem each present a minimum inhibitory concentration (MIC) of 62.50 mg ml-1 and inhibitory halos of 12.0 to 19.0 mm. Colloidal silver gave a MIC of 2 mg ml-1, and the inhibitory halos were found to be between 11.8 and 18.8 mm, depending on treatment concentrations. An in vivo challenge test was conducted on white shrimp postlarvae cultured at low salinity (5 practical salinity units, PSU), and a significant increase (p < 0.05) in survival was demonstrated in the presence of the aqueous extracts (oregano 64%, neem 76% and colloidal silver 90%), when compared to the control (0%) in the challenge test. However, no significant differences were observed between treatments, suggesting that they all act as alternative bactericidal source agents against V. parahaemolyticus infections for L. vannamei postlarvae when cultured at 5 PSU.

Pharmacokinetic behavior of enrofloxacin and its metabolite ciprofloxacin in urutu pit vipers (Bothrops alternatus) after intramuscular administration.

PubMed

Waxman, Samanta; Prados, Ana Paula; de Lucas, José Julio; San Andrés, Manuel Ignacion; Regner, Pablo; de Oliveira, Vanesa Costa; de Roodt, Adolfo; Rodríguez, Casilda

2014-03-01

Enrofloxacin is widely used in veterinary medicine and is an important alternative to treating bacterial infections, which play an important role as causes of disease and death in captive snakes. Its extralabel use in nontraditional species has been related to its excellent pharmacokinetic and antimicrobial characteristics. This can be demonstrated by its activity against gram-negative organisms implicated in serious infectious diseases of reptile species with a rapid and concentration-dependent bactericidal effect and a large volume of distribution. Pharmacokinetic parameters for enrofloxacin were investigated in seven urutu pit vipers (Bothrops alternatus), following intramuscular injections of 10 mg/kg. The plasma concentrations of enrofloxacin and its metabolite, ciprofloxacin, were measured using high-performance liquid chromatography. Blood samples were collected from the ventral coccygeal veins at 0.5, 1, 2, 4, 8, 12, 24, 36, 48, 72, 96, 108, and 168 hr. The kinetic behavior was characterized by a relatively slow absorption (time of maximal plasma concentration = 4.50 +/- 3.45 hr) with peak plasma concentration of 4.81 +/- 1.12 microg/ml. The long half-life during the terminal elimination phase (t1/2 lambda = 27.91 +/- 7.55 hr) of enrofloxacin after intramuscular administration, calculated in the present study, could suggest that the antibiotic is eliminated relatively slowly and/or the presence of a slow absorption in urutu pit vipers. Ciprofloxacin reached a peak plasma concentration of 0.35 microg/ml at 13.45 hr, and the fraction of enrofloxacin metabolized to ciprofloxacin was 13.06%. If enrofloxacin's minimum inhibitory concentration (MIC90) values of 0.5 microg/ml were used, the ratios AUC(e+c): MIC90 (276 +/- 67 hr) and Cmax(e+c): MIC90 (10 +/- 2) reach the proposed threshold values (125 hr and 10, respectively) for optimized efficacy and minimized resistance development when treating infections caused by Pseudomonas. The administration of 10 mg/kg of enrofloxacin by the i.m. route should be considered to be a judicious choice in urutu pit vipers against infections caused by microorganisms with MIC values < or = 0.5 microg/ml. For less susceptible bacteria, a dose increase and/or an interval reduction should be evaluated.

Sub-Inhibitory Concentration of Piperacillin-Tazobactam May be Related to Virulence Properties of Filamentous Escherichia coli.

PubMed

de Andrade, João Paulo Lopes; de Macêdo Farias, Luiz; Ferreira, João Fernando Gonçalves; Bruna-Romero, Oscar; da Glória de Souza, Daniele; de Carvalho, Maria Auxiliadora Roque; dos Santos, Kênia Valéria

2016-01-01

Sub-inhibitory concentrations of antibiotics are always generated as a consequence of antimicrobial therapy and the effects of such residual products in bacterial morphology are well documented, especially the filamentation generated by beta-lactams. The aim of this study was to investigate some morphological and pathological aspects (virulence factors) of Escherichia coli cultivated under half-minimum inhibitory concentration (1.0 µg/mL) of piperacillin-tazobactam (PTZ sub-MIC). PTZ sub-MIC promoted noticeable changes in the bacterial cells which reach the peak of morphological alterations (filamentation) and complexity at 16 h of antimicrobial exposure. Thereafter the filamentous cells and a control one, not treated with PTZ, were comparatively tested for growth curve; biochemical profile; oxidative stress tolerance; biofilm production and cell hydrophobicity; motility and pathogenicity in vivo. PTZ sub-MIC attenuated the E. coli growth rate, but without changes in carbohydrate fermentation or in traditional biochemical tests. Overall, the treatment of E. coli with sub-MIC of PTZ generated filamentous forms which were accompanied by the inhibition of virulence factors such as the oxidative stress response, biofilm formation, cell surface hydrophobicity, and motility. These results are consistent with the reduced pathogenicity observed for the filamentous E. coli in the murine model of intra-abdominal infection. In other words, the treatment of E. coli with sub-MIC of PTZ suggests a decrease in their virulence.

In vitro effects of Salvia officinalis L. essential oil on Candida albicans

PubMed Central

Sookto, Tularat; Srithavaj, Theerathavaj; Thaweboon, Sroisiri; Thaweboon, Boonyanit; Shrestha, Binit

2013-01-01

Objective To determine the anticandidal activities of Salvia officinalis L. (S. officinalis) essential oil against Candida albicans (C. albicans) and the inhibitory effects on the adhesion of C. albicans to polymethyl methacrylate (PMMA) resin surface. Methods Disc diffusion method was first used to test the anticandidal activities of the S. officinalis L. essential oil against the reference strain (ATCC 90028) and 2 clinical strains of C. albicans. Then the minimal inhibitory concentration (MIC) and minimal lethal concentration (MLC) were determined by modified membrane method. The adhesion of C. albicans to PMMA resin surface was assessed after immersion with S. officinalis L. essential oil at various concentrations of 1×MIC, 0.5×MIC and 0.25×MIC at room temperature for 30 min. One-way ANOVA was used to compare the Candida cell adhesion with the pretreatment agents and Tukey's test was used for multiple comparisons. Results S. officinalis L. essential oil exhibited anticandidal activity against all strains of C. albicans with inhibition zone ranging from 40.5 mm to 19.5 mm. The MIC and MLC of the oil were determined as 2.780 g/L against all test strains. According to the effects on C. albicans adhesion to PMMA resin surface, it was found that immersion in the essential oil at concentrations of 1×MIC (2.780 g/L), 0.5×MIC (1.390 g/L) and 0.25×MIC (0.695 g/L) for 30 min significantly reduced the adhesion of all 3 test strains to PMMA resin surface in a dose dependent manner (P<0.05). Conclusions S. officinalis L. essential oil exhibited anticandidal activities against C. albicans and had inhibitory effects on the adhesion of the cells to PMMA resin surface. With further testing and development, S. officinalis essential oil may be used as an antifungal denture cleanser to prevent candidal adhesion and thus reduce the risk of candida-associated denture stomatitis. PMID:23646301

Antibacterial activity of epigallocatechin-3-gallate (EGCG) and its synergism with β-lactam antibiotics sensitizing carbapenem-associated multidrug resistant clinical isolates of Acinetobacter baumannii.

PubMed

Lee, Spencer; Razqan, Ghaida Saleh Al; Kwon, Dong H

2017-01-15

Infections caused by Acinetobacter baumannii were responsive to conventional antibiotic therapy. However, recently, carbapenem-associated multidrug resistant isolates have been reported worldwide and present a major therapeutic challenge. Epigallocatechin-3-Gallate (EGCG) extracted from green tea exhibits antibacterial activity. We evaluated the antibacterial activity of EGCG and possible synergism with antibiotics in carbapenem-associated multidrug resistant A. baumannii. A potential mechanism for synergism was also explored. Seventy clinical isolates of A. baumannii collected from geographically different areas were analyzed by minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of EGCG. Checkerboard and time-killing assays were performed to exam the synergism between EGCG and antibiotics. The effects of EGCG on a multidrug efflux pump inhibitor (1-[1-naphthylmethyl] piperazine; NMP) and β-lactamase production were also examined in A. baumannii. Sixty-three of 70 clinical isolates of A. baumannii carried carbapenemase-encoding genes with carbapenem-associated multidrug resistance. Levels of MIC and MBC of EGCG ranged from 64 to 512µg/ml and from 128 to ≥1024µg/ml, respectively among the clinical isolates. MIC 90 and MBC 86 levels were 256µg/ml and 512µg/ml of EGCG, respectively. Subinhibitory concentration of EGCG in combination with all antibiotics tested, including carbapenem, sensitized (MICs fall≤1.0µg/ml) all carbapenem-associated multidrug resistant isolates. Checkerboard and time-killing assays showed synergism between EGCG and meropenem (or carbenicillin) counted as fractional inhibitory concentration of < 0.5 and cell numbers' decrease per ml of >2log10 within 12h, respectively. EGCG significantly increased the effect of NMP but was unrelated to β-lactamase production in A. baumannii, suggesting EGCG may be associated with inhibition of efflux pumps. Overall we suggest that EGCG-antibiotic combinations might provide an alternative approach to treat infections with A. baumannii regardless of antibiotic resistance. Copyright © 2016 Elsevier GmbH. All rights reserved.

Candida albicans Impairments Induced by Peppermint and Clove Oils at Sub-Inhibitory Concentrations

PubMed Central

Rajkowska, Katarzyna; Otlewska, Anna; Kunicka-Styczyńska, Alina; Krajewska, Agnieszka

2017-01-01

Members of Candida species cause significant health problems, inducing various types of superficial and deep-seated mycoses in humans. In order to prevent from Candida sp. development, essential oils are more and more frequently applied, due to their antifungal activity, low toxicity if used appropriately, and biodegrability. The aim of the study was to characterize the early alterations in Candida albicans metabolic properties in relation to proteins and chromosomal DNA profiles, after treatment with peppermint and clove oils at sub-inhibitory concentrations. The yeasts were affected by the oils even at a concentration of 0.0075% v/v, which resulted in changes in colony morphotypes and metabolic activities. Peppermint and clove oils at concentrations ranging from 0.015× MIC (minimal inhibitory concentration) to 0.5× MIC values substantially affected the enzymatic abilities of C. albicans, and these changes were primarily associated with the loss or decrease of activity of all 9 enzymes detected in the untreated yeast. Moreover, 29% isolates showed additional activity of N-acetyl-β-glucosaminidase and 14% isolates—α-fucosidase in comparison to the yeast grown without essential oils addition. In response to essential oils at 0.25–0.5× MIC, extensive changes in C. albicans whole-cell protein profiles were noted. However, the yeast biochemical profiles were intact with the sole exception of the isolate treated with clove oil at 0.5× MIC. The alterations were not attributed to gross chromosomal rearrangements in C. albicans karyotype. The predominantly observed decrease in protein fractions and the yeast enzymatic activity after treatment with the oils should be considered as a phenotypic response of C. albicans to the essential oils at their sub-inhibitory concentrations and may lead to the reduction of this yeast pathogenicity. PMID:28629195

Candida albicans Impairments Induced by Peppermint and Clove Oils at Sub-Inhibitory Concentrations.

PubMed

Rajkowska, Katarzyna; Otlewska, Anna; Kunicka-Styczyńska, Alina; Krajewska, Agnieszka

2017-06-19

Members of Candida species cause significant health problems, inducing various types of superficial and deep-seated mycoses in humans. In order to prevent from Candida sp. development, essential oils are more and more frequently applied, due to their antifungal activity, low toxicity if used appropriately, and biodegrability. The aim of the study was to characterize the early alterations in Candida albicans metabolic properties in relation to proteins and chromosomal DNA profiles, after treatment with peppermint and clove oils at sub-inhibitory concentrations. The yeasts were affected by the oils even at a concentration of 0.0075% v / v , which resulted in changes in colony morphotypes and metabolic activities. Peppermint and clove oils at concentrations ranging from 0.015× MIC (minimal inhibitory concentration) to 0.5× MIC values substantially affected the enzymatic abilities of C. albicans , and these changes were primarily associated with the loss or decrease of activity of all 9 enzymes detected in the untreated yeast. Moreover, 29% isolates showed additional activity of N -acetyl-β-glucosaminidase and 14% isolates-α-fucosidase in comparison to the yeast grown without essential oils addition. In response to essential oils at 0.25-0.5× MIC, extensive changes in C. albicans whole-cell protein profiles were noted. However, the yeast biochemical profiles were intact with the sole exception of the isolate treated with clove oil at 0.5× MIC. The alterations were not attributed to gross chromosomal rearrangements in C. albicans karyotype. The predominantly observed decrease in protein fractions and the yeast enzymatic activity after treatment with the oils should be considered as a phenotypic response of C. albicans to the essential oils at their sub-inhibitory concentrations and may lead to the reduction of this yeast pathogenicity.

In vitro susceptibility of contagious ovine digital dermatitis associated Treponema spp. isolates to antimicrobial agents in the UK.

PubMed

Angell, Joseph W; Clegg, Simon R; Sullivan, Leigh E; Duncan, Jennifer S; Grove-White, Dai H; Carter, Stuart D; Evans, Nicholas J

2015-12-01

Contagious ovine digital dermatitis (CODD) is an important cause of infectious lameness in sheep in the UK and Ireland and has a severe impact on the welfare of affected individuals. The three treponemal phylogroups Treponema medium/Treponema vincentii-like, Treponema phagedenis-like and Treponema pedis spirochaetes have been associated with clinical CODD lesions and are considered to be a necessary cause of disease. There are scant data on the antimicrobial susceptibility of the treponemes cultured from CODD lesions. The aim of this study was to determine in vitro the miniumum inhibitory concentration/ minimum bactericidal concentration (MIC/MBC) of antimicrobials used in the sheep industry for isolates of the three CODD associated treponeme phylogroups T. medium/T. vincentii-like, T. phagedenis-like and T. pedis. Twenty treponeme isolates; from 19 sheep with clinical CODD lesions. A microdilution method was used to determine in vitro the MIC/MBC of 10 antimicrobial agents for 20 treponeme isolates (five T. medium/T. vincentii-like, 10 T. phagedenis-like and five T. pedis). The antimicrobials tested were penicillin G, amoxicillin, oxytetracycline, tilmicosin, lincomycin, spectinomycin, tylosin, tildipirosin, tulathromycin and gamithromycin. The treponeme isolates tested showed low MICs and MBCs to all 10 antimicrobials tested. They were most susceptible to gamithromycin and tildipirosin (MIC90: 0.0469 mg/L), and were least susceptible to lincomycin, spectinomycin and oxytetracycline (MIC90: 48 mg/L, 24 mg/L and 3 mg/L, respectively). These data are comparable to in vitro antimicrobial susceptibility data for treponemes cultured from bovine digital dermatitis lesions. Dependent on local licensing, penicillin and tilmicosin appear to be the best candidates for future in vivo studies. © 2015 The Authors. Veterinary Dermatology published by John Wiley & Sons Ltd on behalf of the ESVD and ACVD.

Biofilm formation in Malassezia pachydermatis strains isolated from dogs decreases susceptibility to ketoconazole and itraconazole.

PubMed

Jerzsele, Akos; Gyetvai, Béla; Csere, István; Gálfi, Péter

2014-12-01

Malassezia pachydermatis is a commonly isolated yeast in veterinary dermatology that can produce biofilms in vitro and in vivo, lowering its susceptibility to antimicrobial drugs. The aim of this study was to determine and compare the in vitro susceptibility of planktonic cells and biofilms of M. pachydermatis isolates to ketoconazole and itraconazole. The presence of biofilm formation was confirmed by crystal violet staining and absorbance measurement at 595 nm wavelength, and by a scanning electron microscopy method. Cell viability was determined by the Celltiter 96 Aqueous One solution assay containing a water-soluble tetrazolium compound (MTS) with absorbance measurement at 490 nm. Planktonic cell minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) of ketoconazole and itraconazole were very low: MIC90 and MFC90 were 0.032 and 0.125 μg/ml for ketoconazole, while 0.063 and 0.25 μg/ml for itraconazole, respectively. Also, the half maximal effective concentrations (EC50) of itraconazole were higher for planktonic cells and biofilms compared to ketoconazole. The EC50 values of ketoconazole were 18-169 times higher and those of itraconazole 13-124 times higher for biofilms than for planktonic cells. Biofilm EC50 levels exceeded MICs 103-2060 times for ketoconazole and 84-1400 times for itraconazole. No significant difference was found between these values of the two substances. In conclusion, biofilms of all examined M. pachydermatis strains were much less susceptible to ketoconazole and itraconazole than their planktonic forms.

Activity of essential oil-based microemulsions against Staphylococcus aureus biofilms developed on stainless steel surface in different culture media and growth conditions.

PubMed

Campana, Raffaella; Casettari, Luca; Fagioli, Laura; Cespi, Marco; Bonacucina, Giulia; Baffone, Wally

2017-01-16

Food safety is a fundamental concern for both consumers and the food industry, especially as the numbers of reported cases of food-associated infections continue to increase. Industrial surfaces can provide a suitable substrate for the development and persistence of bacterial organized in biofilms that represent a potential source of food contamination. The negative consumer perception of chemical disinfectants has shifted the attention to natural substances, such as plant extracts. The aim of this study was to investigate the possibility of using the essential oils (EOs) in the fight against S. aureus biofilms. First, the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), Minimum Biofilm Inhibitory Concentration (MBIC), Minimum Biofilm Eradication Concentration (MBEC) of eleven EOs against S. aureus were determined. Cinnamomum cassia and Salvia officinalis EOs showed the greatest antibacterial properties with 1.25% MIC and MBC, 1.25% MBIC and 2.5% MBEC respectively. Gas Chromatography/Mass Spectrometry analysis revealed cinnamaldehyde (82.66%) and methoxy cinnamaldehyde (10.12%) as the most abundant substances of C. cassia, while cis-thujone (23.90%), camphor (19.22%) and 1.8-cineole (10.62%) of S. officinalis. Three different microemulsions, formulated with C. cassia, S. officinalis or both, were finally tested against S. aureus biofilms in different culture media and growth conditions, causing a >3 logarithmic reductions in S. aureus 24h-old biofilms and desiccated biofilms, and up to 68% of biofilm removal after 90min of exposure. The obtained data suggest the potential use of EOs, alone or in combination, for the formulation of sanitizers as alternative or in support in the disinfection of contaminated surfaces. Copyright © 2016 Elsevier B.V. All rights reserved.

[Cefazolin efficacy and antibiotic sensitivity against pathogenic bacteria in pediatric with acute upper urinary tract infection].

PubMed

Fuke, Toshiya; Abe, Yoshifusa; Hoshino, Akihiro; Oto, Hideyasu; Sakai, Naho; Murayama, Junichiro; Yoshida, Koichiro; Itabashi, Kazuo

2010-05-01

Acute upper urinary tract infection may cause sepsis, especially in neonates and infants, mandating the choice of appropriate, effective antibacterials minimizing increasing bacterial resistance. Frequently prescribing broad-spectrum cephalosporinin is one such example. Different antibacterial therapies are initiated clinically due to treatment protocol differences among institutions, disease severity, etc. We studied the efficacy of cefazolin (CEZ), a first-generation cephalosporin, as first-line parenteral treatment in acute upper urinary tract infection. We found that 88.9% of microbial infections have indications for CEZ. CEZ efficacy is 91.3%, and 97.2% of urine cultures show negative results. Escherichia coli sensitivity to antibacterial agents is 90.9% of the minimal inhibitory concentration (MIC) < 4 for CEZ, 93.9% of MIC < 1 for ceftazidime (CAZ), 63.6% of MIC < 4 for ampicillin, and 81.8% of MIC < 2 for gentamicin. CEZ thus has the same efficacy as CAZ and is more effective than other antibacterial agents against E. coli. We concluded that CEZ is an effective antibacterial in initial antibacterial pediatric therapy in acute upper urinary tract infection.

In vitro activity of novel anti-MRSA cephalosporins and comparator antimicrobial agents against staphylococci involved in prosthetic joint infections.

PubMed

Isnard, Christophe; Dhalluin, Anne; Malandain, Damasie; Bruey, Quentin; Auzou, Michel; Michon, Jocelyn; Giard, Jean-Christophe; Guérin, François; Cattoir, Vincent

2018-02-05

Ceftaroline and ceftobiprole are new parenteral cephalosporins with potent activity against methicillin-resistant (MR) staphylococci, which are the leading cause of prosthetic joint infections (PJIs). The aim of this study was to determine and compare the in vitro activities of both molecules against staphylococcal isolates recovered from clinically documented PJIs. A collection of 200 non-duplicate clinical isolates [100 Staphylococcus aureus and 100 coagulase-negative staphylococci (CoNS), including 19 and 27 MR isolates, respectively] was studied. Minimum inhibitory concentrations (MICs) of oxacillin, ceftaroline, ceftobiprole, vancomycin, teicoplanin, clindamycin, levofloxacin, linezolid and daptomycin were determined by the broth microdilution method. Bactericidal activity (at 4× MIC) of ceftaroline, ceftobiprole, vancomycin, teicoplanin, linezolid and daptomycin was assessed by time-kill assay. Among the S. aureus isolates, 100% were susceptible to ceftaroline (MIC 50/90 , 0.25/0.5μg/mL) and 98% were susceptible to ceftobiprole (MIC 50/90 , 0.5/1μg/mL), regardless of their methicillin resistance. The two ceftobiprole-non-susceptible strains (including one MRSA) showed MICs at 4mg/L. Against CoNS isolates, ceftaroline and ceftobiprole exhibited in vitro potency with MIC 50/90 values at 0.06/0.25μg/mL and 0.25/1μg/mL, respectively. At 4× MIC, ceftaroline and ceftobiprole showed rapid and marked bactericidal activity against both S. aureus and CoNS (after 24/12h and 12/6h of incubation, respectively), whilst none of the other molecules tested had a bactericidal effect by 24h. This study showed that ceftaroline and ceftobiprole have excellent in vitro activity against clinical isolates of staphylococci involved in PJIs. These molecules may therefore represent promising alternatives for the treatment of such infections. Copyright © 2018 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

Glutathione may have implications in the design of 3-bromopyruvate treatment protocols for both fungal and algal infections as well as multiple myeloma

PubMed Central

Niedźwiecka, Katarzyna; Augustyniak, Daria; Majkowska-Skrobek, Grażyna; Cal-Bąkowska, Magdalena; Ko, Young H.; Pedersen, Peter L.; Goffeau, Andre

2016-01-01

In different fungal and algal species, the intracellular concentration of reduced glutathione (GSH) correlates closely with their susceptibility to killing by the small molecule alkylating agent 3-bromopyruvate (3BP). Additionally, in the case of Cryptococcus neoformans cells 3BP exhibits a synergistic effect with buthionine sulfoximine (BSO), a known GSH depletion agent. This effect was observed when 3BP and BSO were used together at concentrations respectively of 4-5 and almost 8 times lower than their Minimal Inhibitory Concentration (MIC). Finally, at different concentrations of 3BP (equal to the half-MIC, MIC and double-MIC in a case of fungi, 1 mM and 2.5 mM for microalgae and 25, 50, 100 μM for human multiple myeloma (MM) cells), a significant decrease in GSH concentration is observed inside microorganisms as well as tumor cells. In contrast to the GSH concentration decrease, the presence of 3BP at concentrations corresponding to sub-MIC values or half maximal inhibitory concentration (IC50) clearly results in increasing the expression of genes encoding enzymes involved in the synthesis of GSH in Cryptococcus neoformans and MM cells. Moreover, as shown for the first time in the MM cell model, the drastic decrease in the ATP level and GSH concentration and the increase in the amount of ROS caused by 3BP ultimately results in cell death. PMID:27582536

Glutathione may have implications in the design of 3-bromopyruvate treatment protocols for both fungal and algal infections as well as multiple myeloma.

PubMed

Niedźwiecka, Katarzyna; Dyląg, Mariusz; Augustyniak, Daria; Majkowska-Skrobek, Grażyna; Cal-Bąkowska, Magdalena; Ko, Young H; Pedersen, Peter L; Goffeau, Andre; Ułaszewski, Stanisław

2016-10-04

In different fungal and algal species, the intracellular concentration of reduced glutathione (GSH) correlates closely with their susceptibility to killing by the small molecule alkylating agent 3-bromopyruvate (3BP). Additionally, in the case of Cryptococcus neoformans cells 3BP exhibits a synergistic effect with buthionine sulfoximine (BSO), a known GSH depletion agent. This effect was observed when 3BP and BSO were used together at concentrations respectively of 4-5 and almost 8 times lower than their Minimal Inhibitory Concentration (MIC). Finally, at different concentrations of 3BP (equal to the half-MIC, MIC and double-MIC in a case of fungi, 1 mM and 2.5 mM for microalgae and 25, 50, 100 μM for human multiple myeloma (MM) cells), a significant decrease in GSH concentration is observed inside microorganisms as well as tumor cells. In contrast to the GSH concentration decrease, the presence of 3BP at concentrations corresponding to sub-MIC values or half maximal inhibitory concentration (IC50) clearly results in increasing the expression of genes encoding enzymes involved in the synthesis of GSH in Cryptococcus neoformans and MM cells. Moreover, as shown for the first time in the MM cell model, the drastic decrease in the ATP level and GSH concentration and the increase in the amount of ROS caused by 3BP ultimately results in cell death.

In vitro susceptibility of Candida spp. to fluconazole, itraconazole and voriconazole and the correlation between triazoles susceptibility: Results from a five-year study.

PubMed

Lei, J; Xu, J; Wang, T

2018-06-01

Candida spp. is a common cause of invasive fungal disease. The aim of this study was to examine the susceptibility of Candida spp. to fluconazole, itraconazole and voriconazole and explore the correlation between triazoles susceptibility. The antifungal susceptibility in the present study was measured by ATB Fungus 3 method, and the potential relationship was examined by obtaining the correlation of measured minimal inhibitory concentrations (MICs) of Candida spp. isolates. A total of 2099 clinical isolates of Candida spp. from 1441 patients were analyzed. The organisms included 1435 isolates of Candida albicans, 207 isolates of Candida glabrata, 65 isolates of Candida parapsilosis, 31 isolates of Candida krusei, 268 isolates of Candida tropicalis. Voriconazole and itraconazole were more active than fluconazole and against Candida spp. in vitro. The fluconazole, itraconazole and voriconazole MIC 90 (MIC for 90% of the isolates) for all Candida spp. isolates was 4mg/L, 1mg/L and 0.25mg/L, respectively. There was a moderate correlation between the fluconazole MIC s for Candida spp. isolates and this for voriconazole (R 2 =0.475; P<0.01) and itraconazole (R 2 =0.431; P<0.01). Voriconazole MICs for the Candida spp. isolates also correlated with those for itraconazole (R 2 =0.401; P<0.01). These observations suggest that the in vitro susceptibility of Candida spp. to fluconazole, itraconazole and voriconazole exhibits a moderate correlation. Published by Elsevier Masson SAS.

Habituation of enterotoxigenic Staphylococcus aureus to Origanum vulgare L. essential oil does not induce direct-tolerance and cross-tolerance to salts and organic acids

PubMed Central

Tavares, Adassa Gama; do Monte, Daniel Farias Marinho; Albuquerque, Allan dos Reis; Sampaio, Fábio Correia; Magnani, Marciane; de Siqueira, José Pinto; de Souza, Evandro Leite

2015-01-01

Enterotoxigenic Staphylococcus aureus strains that were isolated from foods were investigated for their ability to develop direct-tolerance and cross-tolerance to sodium chloride (NaCl), potassium chloride (KCl), lactic acid (LA) and acetic acid (AA) after habituation in sublethal amounts (1/2 of the minimum inhibitory concentration - 1/2 MIC and 1/4 of the minimum inhibitory concentration - 1/4 MIC) of Origanum vulgare L. essential oil (OVEO). The habituation of S. aureus to 1/2 MIC and 1/4 MIC of OVEO did not induce direct-tolerance or cross-tolerance in the tested strains, as assessed by modulation of MIC values. Otherwise, exposing the strains to OVEO at sublethal concentrations maintained or increased the sensitivity of the cells to the tested stressing agents because the MIC values of OVEO, NaCl, KCl, LA and AA against the cells that were previously habituated to OVEO remained the same or decreased when compared with non-habituated cells. These data indicate that OVEO does not have an inductive effect on the acquisition of direct-tolerance or cross-tolerance in the tested enterotoxigenic strains of S. aureus to antimicrobial agents that are typically used in food preservation. PMID:26413067

CHEMICAL CHARACTERIZATION AND EVALUATION OF ANTIBACTERIAL, ANTIFUNGAL, ANTIMYCOBACTERIAL, AND CYTOTOXIC ACTIVITIES OF Talinum paniculatum

PubMed Central

REIS, Luis F.C. DOS; CERDEIRA, Cláudio D.; PAULA, Bruno F. DE; da SILVA, Jeferson J.; COELHO, Luiz F.L.; SILVA, Marcelo A.; MARQUES, Vanessa B.B.; CHAVASCO, Jorge K.; ALVES-DA-SILVA, Geraldo

2015-01-01

SUMMARY In this study, the bioactivity of Talinum paniculatum was evaluated, a plant widely used in folk medicine. The extract from the T. paniculatum leaves (LE) was obtained by percolation with ethanol-water and then subjecting it to liquid-liquid partitions, yielding hexane (HX), ethyl acetate (EtOAc), butanol (BuOH), and aqueous (Aq) fractions. Screening for antimicrobial activity of the LE and its fractions was evaluated in vitro through broth microdilution method, against thirteen pathogenic and non-pathogenic microorganisms, and the antimycobacterial activity was performed through agar diffusion assay. The cytotoxic concentrations (CC90) for LE, HX, and EtOAc were obtained on BHK-21 cells by using MTT reduction assay. The LE showed activity against Serratia marcescens and Staphylococcus aureus, with Minimum Inhibitory Concentration (MIC) values of 250 and 500 µg/mL, respectively. Furthermore, HX demonstrated outstanding activity against Micrococcus luteusand Candida albicans with a MIC of 31.2 µg/mL in both cases. The MIC for EtOAc also was 31.2 µg/mL against Escherichia coli. Conversely, BuOH and Aq were inactive against all tested microorganisms and LE proved inactive against Mycobacterium tuberculosis and Mycobacterium bovis as well. Campesterol, stigmasterol, and sitosterol were the proposed structures as main compounds present in the EF and HX/EtOAc fractions, evidenced by mass spectrometry. Therefore, LE, HX, and EtOAc from T. paniculatum showed potential as possible sources of antimicrobial compounds, mainly HX, for presenting low toxicity on BHK-21 cells with excellent Selectivity Index (SI = CC90/MIC) of 17.72 against C. albicans. PMID:26603226

Antimicrobial susceptibility pattern of clinical isolates of Burkholderia pseudomallei in Bangladesh.

PubMed

Dutta, Subarna; Haq, Sabah; Hasan, Mohammad Rokibul; Haq, Jalaluddin Ashraful

2017-07-20

Melioidosis an infectious disease, caused by a Gram negative bacterium called Burkholderia pseudomallei, is endemic in Bangladesh. This organism is sensitive to limited number of antimicrobial agents and need prolonged treatment. There is no comprehensive data on the antimicrobial susceptibility profile of B. pseudomallei isolated in Bangladesh over last several years. The present study aimed to determine the antimicrobial susceptibility pattern of B. pseudomallei isolated in a tertiary care hospital of Dhaka city from 2009 to 2015. All B. pseudomallei isolated from melioidosis patients over a period of 7 years (2009-2015) in the Department of Microbiology of a 725-bed tertiary care referral hospital in Dhaka city, Bangladesh were included in the study. B. pseudomallei was identified by Gram stain, culture, specific biochemical tests, serology and PCR using specific primers constructed from 16s rRNA region of B. pseudomallei. Antimicrobial susceptibility to specific agents was determined by disk diffusion and minimum inhibitory concentration methods. A total of 20 isolates of B. pseudomallei which were isolated from patients coming from different geographic locations of Bangladesh were included in the study. All the isolates were uniformly sensitive (100%) to ceftazidime, imipenem, piperacillin-tazobactam, amoxicillin-clavulanic acid and tetracycline by both disk diffusion and MIC methods. Two strains were resistant to trimethoprim-sulfamethoxazole by disk diffusion method but were sensitive by MIC method. The MIC 50 and MIC 90 values of the above antimicrobial agents were almost similar. All the isolates were resistant to amikacin by both MIC and disk diffusion methods. The results of the study suggest that B. pseudomallei prevalent in Bangladesh were still susceptible to all recommended antimicrobial agents used for the treatment of melioidosis. However, regular monitoring is needed to detect any emergence of resistance and shifting of MIC 50 and MIC 90 values.

Chemical composition and in vitro antibacterial activity of Pistacia terebinthus essential oils derived from wild populations in Kosovo.

PubMed

Pulaj, Bledar; Mustafa, Behxhet; Nelson, Kate; Quave, Cassandra L; Hajdari, Avni

2016-05-26

Plant material from different organs of Pistacia terebinthus L., (Anacardiaceae) were collected in Kosovo with aim to analyze the chemical variability of the essential oils among native populations and to test them for potential antibacterial activity against Staphylococcus aureus. Essential oils obtained from leaves, pedicels, fruits and galls were analyzed by GC-FID and GC/MS. Minimum inhibitory concentration (MIC) against three clinically relevant strains of S. aureus (NRS385, LAC and UAMS-1) were used to evaluate the antibacterial activity of essential oils. In total, 33 different compounds were identified. The main constituents were α-pinene (12.58-66.29 %), D-limonene (13.95-46.29 %), β-ocimene (0.03-40.49 %), β-pinene (2.63-20.47 %), sabinene (0.00-5.61 %) and (Z)-β-ocimene (0.00-44.85 %). Antibacterial testing of the essential oils against three clinical isolates of S. aureus revealed that seven of the eight samples had some activity at the concentration range tested (0.04-0.512 % v/v). The gall tissues from both sites produced the highest yield of essential oil (3.24 and 6 %), and both exhibited growth inhibitory activity against S. aureus. The most bioactive essential oils, which exhibited MIC90 values ranging from 0.032-0.128 % v/v, obtained from the fruits of the Ura e Shejtë collection site. Likewise, the leaf and pedicel essential oil from the same site was highly active with MIC90 values of 0.064-0.128 and 0.032-0.256 % v/v, respectively. Principle Component Analyses demonstrated that there is a variation in the chemical composition of essential oil depending on the plant organs from which essential oil are obtained and the geographical origin of the plant populations. The highest variability regarding the chemical composition of essential oil was found between oils obtained from different organs originating from the Prizren site. The MIC90 activity of Pistacia terebinthus was on par or superior compared with Tea Tree Oil control (0.128 % v/v), suggesting that essential oils from this species may have some potential for development as an antibacterial agent for S. aureus infections.

Evaluation of the tannic acid inhibitory effect against the NorA efflux pump of Staphylococcus aureus.

PubMed

Tintino, Saulo R; Oliveira-Tintino, Cícera D M; Campina, Fábia F; Silva, Raimundo L P; Costa, Maria do S; Menezes, Irwin R A; Calixto-Júnior, João T; Siqueira-Junior, José P; Coutinho, Henrique D M; Leal-Balbino, Tereza C; Balbino, Valdir Q

2016-08-01

During the early periods of antibiotic usage, bacterial infections were considered tamed. However, widespread antibiotic use has promoted the emergence of antibiotic-resistant pathogens, including multidrug resistant strains. Active efflux is a mechanism for bacterial resistance to inhibitory substances, known simply as drug efflux pumps. The bacterium Staphylococcus aureus is an important pathogenic bacterium responsible for an array of infections. The NorA efflux pump has been shown to be responsible for moderate fluoroquinolone resistance of S. aureus. The inhibition of the efflux pump was assayed using a sub-inhibitory concentration of standard efflux pump inhibitors and tannic acid (MIC/8), where its capacity to decrease the MIC of Ethidium bromide (EtBr) and antibiotics due to the possible inhibitory effect of these substances was observed. The MICs of EtBr and antibiotics were significantly reduced in the presence of tannic acid, indicating the inhibitory effect of this agent against the efflux pumps of both strains causing a three-fold reduction of the MIC when compared with the control. These results indicate the possible usage of tannic acid as an adjuvant in antibiotic therapy against multidrug resistant bacteria (MDR). Copyright © 2016 Elsevier Ltd. All rights reserved.

Group a streptococcus antibiotic resistance in southern Brazil: a 17-year surveillance study.

PubMed

Torres, Rosângela Stadnick Lauth de Almeida; Torres, Renato Pedro de Almeida; Smeesters, Pierre Robert; Palmeiro, Jussara Kasuko; de Messias-Reason, Iara José; Dalla-Costa, Libera M

2011-06-01

Scarce data are available about the antimicrobial resistance of Group A Streptococcus in South America. This study evaluated the antimicrobial susceptibility profile of 1,112 isolates of Group A Streptococcus during the period from 1993 to 2009 in Curitiba city, Brazil. Macrolide-resistant isolates were characterized by emm typing and pulsed-field gel electrophoresis. All isolates were susceptible to penicillin, vancomycin, and tigecycline. On the contrary, 18.6% of the isolates were resistant to tetracycline, presenting a minimum inhibitory concentration (MIC)(50)/MIC(90) of 32/64 mg/L. Erythromycin resistance rose from 1.9% before 2000 to 4% after 2000 and was associated with a marked increased of MIC levels. Simultaneously, both the phenotype and genotype of macrolide resistance were modified as the M phenotypes (mef(A) genotype) were replaced by the cMLS(B) phenotypes (erm(B) genotype). This polyclonal spreading of cMLS(B) macrolide resistance has not been previously observed in South America and should stimulate further epidemiological surveillance in this part of the world.

Association of macrophage inhibitory cytokine-1 with nutritional status, body composition and bone mineral density in patients with anorexia nervosa: the influence of partial realimentation.

PubMed

Dostálová, Ivana; Kaválková, Petra; Papežová, Hana; Domluvilová, Daniela; Zikán, Vít; Haluzík, Martin

2010-04-23

Macrophage inhibitory cytokine-1 (MIC-1) is a key inducer of cancer-related anorexia and weight loss. However, its possible role in the etiopathogenesis of nutritional disorders of other etiology such as anorexia nervosa (AN) is currently unknown. We measured fasting serum concentrations of MIC-1 in patients with AN before and after 2-month nutritional treatment and explored its relationship with nutritional status, metabolic and biochemical parameters. Sixteen previously untreated women with AN and twenty-five normal-weight age-matched control women participated in the study. We measured serum concentrations of MIC-1 and leptin by ELISA, free fatty acids by enzymatic colorimetric assay, and biochemical parameters by standard laboratory methods; determined resting energy expenditure by indirect calorimetry; and assessed bone mineral density and body fat content by dual-energy X-ray absorptiometry. ANOVA, unpaired t-test or Mann-Whitney test were used for groups comparison as appropriate. The comparisons of serum MIC-1 levels and other studied parameters in patients with AN before and after partial realimentation were assessed by paired t-test or Wilcoxon Signed Rank Test as appropriate. At baseline, fasting serum MIC-1 concentrations were significantly higher in patients with AN relative to controls. Partial realimentation significantly reduced serum MIC-1 concentrations in patients with AN but it still remained significantly higher compared to control group. In AN group, serum MIC-1 was inversely related to Buzby nutritional risk index, serum insulin-like growth factor-1, serum glucose, serum total protein, serum albumin, and lumbar bone mineral density and it significantly positively correlated with the duration of AN and age. MIC-1 concentrations in AN patients are significantly higher relative to healthy women. Partial realimentation significantly decreased MIC-1 concentration in AN group. Clinical significance of these findings needs to be further clarified.

Surveillance of iclaprim activity: In vitro susceptibility of gram-positive pathogens collected from 2012 to 2014 from the United States, Asia Pacific, Latin American and Europe.

PubMed

Huang, David B; File, Thomas M; Dryden, Matthew; Corey, G Ralph; Torres, Antoni; Wilcox, Mark H

2018-04-01

Iclaprim is a diaminopyrimidine, which inhibits bacterial dihydrofolate reductase, and it is highly active against Gram-positive pathogens including emerging drug-resistant pathogens. In vitro activity of iclaprim and comparators against 2814 Gram-positive clinical isolates from the United States, Asia Pacific, Latin American and Europe collected between 2012 and 2014 were tested. Susceptibility testing was performed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Minimum inhibitory concentration (MIC) interpretations were based on CLSI and European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. MIC 50 /MIC 90 for all S. aureus, methicillin susceptible S. aureus, methicillin resistant S. aureus, beta-hemolytic streptococci, and Streptococcus pneumoniae were 0.06/0.12, 0.06/0.12, 0.06/0.5, 0.06/0.25, and 0.06/2μg/mL, respectively. Iclaprim was 8 to 32-fold more potent than trimethoprim, the only FDA approved dihydrofolate reductase inhibitor, against all Gram-positive isolates including resistant phenotypes. The MIC 90 of iclaprim was also lower than most of the comparators including linezolid and vancomycin against Gram-positive pathogens. Iclaprim demonstrated potent activity against a contemporary collection (2012-2014) of Gram-positive clinical isolates from the United States, Asia Pacific, Latin America and Europe. Copyright © 2017 Elsevier Inc. All rights reserved.

Fragment Discovery for the Design of Nitrogen Heterocycles as Mycobacterium tuberculosis Dihydrofolate Reductase Inhibitors.

PubMed

Shelke, Rupesh U; Degani, Mariam S; Raju, Archana; Ray, Mukti Kanta; Rajan, Mysore G R

2016-08-01

Fragment-based drug design was used to identify Mycobacterium tuberculosis (Mtb) dihydrofolate reductase (DHFR) inhibitors. Screening of ligands against the Mtb DHFR enzyme resulted in the identification of multiple fragment hits with IC50 values in the range of 38-90 μM versus Mtb DHFR and minimum inhibitory concentration (MIC) values in the range of 31.5-125 μg/mL. These fragment scaffolds would be useful for anti-tubercular drug design. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antibiotic susceptibility of periodontal Streptococcus constellatus and Streptococcus intermedius clinical isolates.

PubMed

Rams, Thomas E; Feik, Diane; Mortensen, Joel E; Degener, John E; van Winkelhoff, Arie J

2014-12-01

Streptococcus constellatus and Streptococcus intermedius in subgingival dental plaque biofilms may contribute to forms of periodontitis that resist treatment with conventional mechanical root debridement/surgical procedures and may additionally participate in some extraoral infections. Because systemic antibiotics are often used in these clinical situations, and little is known of the antibiotic susceptibility of subgingival isolates of these two bacterial species, this study determined the in vitro susceptibility to six antibiotics of fresh S. constellatus and S. intermedius clinical isolates from human periodontitis lesions. A total of 33 S. constellatus and 17 S. intermedius subgingival strains, each recovered from separate patients with severe chronic periodontitis (n = 50) before treatment, were subjected to antibiotic gradient strip susceptibility testing with amoxicillin, azithromycin, clindamycin, ciprofloxacin, and doxycycline on blood-supplemented Mueller-Hinton agar and to the inhibitory effects of metronidazole at 16 mg/L in an enriched Brucella blood agar dilution assay. Clinical and Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing interpretative standards were used to assess the results. Clindamycin was the most active antibiotic against S. constellatus (minimum inhibitory concentration at 90% [MIC90] 0.25 mg/L), and amoxicillin was most active against S. intermedius (MIC90 0.125 mg/L). A total of 30% of the S. constellatus and S. intermedius clinical isolates were resistant in vitro to doxycycline, 98% were only intermediate in susceptibility to ciprofloxacin, and 90% were resistant to metronidazole at 16 mg/L. Subgingival S. constellatus and S. intermedius exhibited variable antibiotic susceptibility profiles, potentially complicating empirical selection of periodontitis antibiotic therapy in patients who are species positive.

Relevance of liver failure for anti-infective agents: from pharmacokinetic alterations to dosage adjustments

PubMed Central

Büdingen, Fiona V.; Gonzalez, Daniel; Tucker, Amelia N.

2014-01-01

The liver is a complex organ with great ability to influence drug pharmacokinetics (PK). Due to its wide array of function, its impairment has the potential to affect bioavailability, enterohepatic circulation, drug distribution, metabolism, clearance, and biliary elimination. These alterations differ widely depending on the cause of the liver failure, if it is acute or chronic in nature, the extent of impairment, and comorbid conditions. In addition, the effects on liver functions do not occur in a proportional or predictable manner for escalating degrees of liver impairment. The ability of hepatic alterations to influence PK is also dependent on drug characteristics, such as administration route, chemical properties, protein binding, and extraction ratio, among others. This complexity makes it difficult to predict what effects these changes will have on a particular drug. Unlike certain classes of agents, efficacy of anti-infectives is most often dependent on fulfilling PK/pharmacodynamic targets, such as maximum concentration/minimum inhibitory concentration (Cmax/MIC), area under the curve/minimum inhibitory concentration (AUC/MIC), time above MIC (T>MIC), half-maximal inhibitory concentration (IC50) or half-maximal effective concentration (EC50), or the time above the concentration which inhibits viral replication by 95% (T>EC95). Loss of efficacy and/or an increased risk of toxicity may occur in certain circumstances of liver injury. Although it is important to consider these potential alterations and their effects on specific anti-infectives, many lack data to constitute specific dosing adjustments, making it important to monitor patients for effectiveness and toxicities of therapy. PMID:24949199

[Comparative evaluation of the sensitivity of Acinetobacter to colistin, using the prediffusion and minimum inhibitory concentration methods: detection of heteroresistant isolates].

PubMed

Herrera, Melina E; Mobilia, Liliana N; Posse, Graciela R

2011-01-01

The objective of this study is to perform a comparative evaluation of the prediffusion and minimum inhibitory concentration (MIC) methods for the detection of sensitivity to colistin, and to detect Acinetobacter baumanii-calcoaceticus complex (ABC) heteroresistant isolates to colistin. We studied 75 isolates of ABC recovered from clinically significant samples obtained from various centers. Sensitivity to colistin was determined by prediffusion as well as by MIC. All the isolates were sensitive to colistin, with MIC = 2µg/ml. The results were analyzed by dispersion graph and linear regression analysis, revealing that the prediffusion method did not correlate with the MIC values for isolates sensitive to colistin (r² = 0.2017). Detection of heteroresistance to colistin was determined by plaque efficiency of all the isolates with the same initial MICs of 2, 1, and 0.5 µg/ml, which resulted in 14 of them with a greater than 8-fold increase in the MIC in some cases. When the sensitivity of these resistant colonies was determined by prediffusion, the resulting dispersion graph and linear regression analysis yielded an r² = 0.604, which revealed a correlation between the methodologies used.

Comparison of automated and traditional minimum inhibitory concentration procedures for microbiological cosmetic preservatives.

PubMed

Lenczewski, M E; McGavin, S T; VanDyke, K

1996-01-01

Minimum inhibitory concentration (MIC) is used to test resistance of microorganisms against antibiotics and to test cosmetic preservatives. This research expanded traditional MIC with automation and application of colorimetric endpoint MIC. All experiments included common cosmetic preservatives and microorganisms used in testing preservative efficacy. An autodilutor using three 96-well microtiter plates processed 6 preservatives against 1 microorganism in 15 min. The unique tip design made it possible to accurately deliver viscous test materials that cannot be dispensed accurately with vacuum or fluid-filled systems. Tetrazolium violet, a redox indicator, provided a visual color change from clear to purple at the MIC. Optimum concentration of tetrazolium violet was 0.01% with addition of 0.2% glucose to Mueller-Hinton broth for both gram-positive and gram-negative bacteria. The colorimetric endpoint was evident after 24 h from previously cryogenically stored organisms that were thawed before use and after 4 h for 18-24 h broth cultures subcultured from agar plates. The autodilutor accurately pipetted viscous cosmetic products such as hand lotion and shampoo, which cannot be pipetted with a traditional micropipetter.

Postantibiotic effect and postantibiotic sub-minimum inhibitory concentration effect of valnemulin against Staphylococcus aureus isolates from swine and chickens.

PubMed

Zhao, D H; Yu, Y; Zhou, Y F; Shi, W; Deng, H; Liu, Y H

2014-02-01

The postantibiotic effect (PAE) and postantibiotic sub-minimum inhibitory concentration (MIC) effect (PA-SME) of valnemulin against Staphylococcus aureus were investigated in vitro using a spectrophotometric technique and classic viable count method. A standard curve was constructed by regression analysis of the number of colonies and the corresponding optical density (OD) at 630 nm of the inoculum. After exposure to valnemulin at different concentrations for an hour, the antibiotic was removed by centrifuging and washing. The PA-SMEs were measured after initial exposure to valnemulin at 4 × the MIC, and then, valnemulin was added to reach corresponding desired concentrations in the resuspended culture. Samples were collected hourly until the culture became turbid. The results were calculated by converting the OD values into the counts of bacteria in accordance with the curve. The MIC of valnemulin against eight strains was identically 0.125 μg ml(-1) . The mean PAEs were 2.12 h (1 × MIC) and 5.06 h (4 × MIC), and the mean PA-SMEs were 6.85 h (0.1 × MIC), 9.12 h (0.2 × MIC) and 10.8 h (0.3 × MIC). The results showed that the strains with identical MICs exhibited different PAEs and PA-SMEs. Valnemulin produced prolonged PAE and PA-SME periods for Staph. aureus, supporting a longer dosing interval while formulating a daily administration dosage. In this study, valnemulin demonstrated prolonged postantibiotic effects and postantibiotic sub-MIC effects on strains of Staphylococcus aureus. The strains with identical MICs of valnemulin exhibited different PAEs and PA-SMEs. Staphylococcus aureus isolated from different species has little impact on the postantibiotic effect of valnemulin. The result suggests a longer dosing interval while formulating a daily administration dosage, and it may play a valuable role of valnemulin in treating Staph. aureus infections in animals. © 2013 The Society for Applied Microbiology.

Sub-inhibitory concentrations of penicillin G induce biofilm formation by field isolates of Actinobacillus pleuropneumoniae.

PubMed

Hathroubi, S; Fontaine-Gosselin, S-È; Tremblay, Y D N; Labrie, J; Jacques, M

2015-09-30

Actinobacillus pleuropneumoniae is a Gram-negative bacterium and causative agent of porcine pleuropneumonia. This is a highly contagious disease that causes important economic losses to the swine industry worldwide. Penicillins are extensively used in swine production and these antibiotics are associated with high systemic clearance and low oral bioavailability. This may expose A. pleuropneumoniae to sub-inhibitory concentrations of penicillin G when the antibiotic is administered orally. Our goal was to evaluate the effect of sub-minimum inhibitory concentration (MIC) of penicillin G on the biofilm formation of A. pleuropneumoniae. Biofilm production of 13 field isolates from serotypes 1, 5a, 7 and 15 was tested in the presence of sub-MIC of penicillin G using a polystyrene microtiter plate assay. Using microscopy techniques and enzymatic digestion, biofilm architecture and composition were also characterized after exposure to sub-MIC of penicillin G. Sub-MIC of penicillin G significantly induced biofilm formation of nine isolates. The penicillin G-induced biofilms contained more poly-N-acetyl-D-glucosamine (PGA), extracellular DNA and proteins when compared to control biofilms grown without penicillin G. Additionally, penicillin G-induced biofilms were sensitive to DNase which was not observed with the untreated controls. Furthermore, sub-MIC of penicillin G up-regulated the expression of pgaA, which encodes a protein involved in PGA synthesis, and the genes encoding the envelope-stress sensing two-component regulatory system CpxRA. In conclusion, sub-MICs of penicillin G significantly induce biofilm formation and this is likely the result of a cell envelope stress sensed by the CpxRA system resulting in an increased production of PGA and other matrix components. Copyright © 2015 Elsevier B.V. All rights reserved.

Antibiotic susceptibility of Legionella strains isolated from public water sources in Macau and Guangzhou.

PubMed

Xiong, Lina; Yan, He; Shi, Lei; Mo, Ziyao

2016-12-01

The purpose of this study was to investigate the susceptibility of waterborne strains of Legionella to eight antimicrobials commonly used in legionellosis therapy. The minimum inhibitory concentrations (MICs) of 66 environmental Legionella strains, isolated from fountains and cooling towers of public facilities (hotels, schools, and shopping malls) in Macau and Guangzhou, were tested using the microdilution method in buffered yeast extract broth. The MIC 50 /MIC 90 values for erythromycin, cefotaxime (CTX), doxycycline (DOC), minocycline (MIN), azithromycin, ciprofloxacin, levofloxacin (LEV), and moxifloxacin were 0.125/0.5 mg/L, 4/8 mg/L, 8/16 mg/L, 4/8 mg/L, 0.125/0.5 mg/L, 0.031/0.031 mg/L, 0.031/0.031 mg/L, and 0.031/0.062 mg/L, respectively. Legionella isolates were inhibited by either low concentrations of macrolides and fluoroquinolones, or high concentrations of CTX and tetracycline drugs. LEV was the most effective drug against different Legionella species and serogroups of L. pneumophila isolates. The latter were inhibited in decreasing order by MIN > CTX >DOC, while non-L. pneumophila isolates were inhibited by CTX> MIN >DOC. In this study, we evaluated drug resistance of pathogenic bacteria from the environment. This may help predict the emergence of drug resistance, improve patient outcomes, and reduce hospitalization costs.

Pharmacokinetics of imipenem after intravenous, intramuscular and subcutaneous administration to cats.

PubMed

Albarellos, Gabriela A; Denamiel, Graciela A; Montoya, Laura; Quaine, Pamela C; Lupi, Martín P; Landoni, María F

2013-06-01

The study describes the pharmacokinetics and predicted efficacy of imipenem after intravenous (IV), intramuscular (IM) and subcutaneous (SC) administration to five adult cats at a dose of 5 mg/kg. Susceptibility to imipenem [minimum inhibitory concentration (MIC)] was determined for antimicrobial resistant Escherichia coli (n = 13) and staphylococci (n = 3) isolated from domestic cat infections (urinary system, skin and conjunctiva). Maximum plasma concentrations of imipenem were 13.45 µg/ml (IV), 6.47 µg/ml (IM) and 3.83 µg/ml (SC). Bioavailability was 93.18% (IM) and 107.90% (SC). Elimination half-lives for IV, IM and SC administration were 1.17, 1.44 and 1.55 h, respectively. All tested bacteria were susceptible to imipenem; MIC values were 0.03 µg/ml for Staphylococcus species and <0.25-0.5 µg/ml for E coli. Mean imipenem concentrations remained above a MIC of 0.5 µg/ml for approximately 4 h (IV and IM) and 9 h (SC). Imipenem would be predicted to be effective for the treatment of antimicrobial resistant bacterial infections in cats at a dosage of 5 mg/kg every 6-8 h (IV, IM), or longer for the SC route. However, clinical trials are mandatory to establish its efficacy and proper dosing.

Anti-Salmonella activity of medicinal plants from Cameroon.

PubMed

Nkuo-Akenji, T; Ndip, R; McThomas, A; Fru, E C

2001-06-01

To evaluate the effects of herbal extracts derived from plants commonly prescribed by traditional practitioners for the treatment of typhoid fever. A cross sectional study. Departments of Life Sciences and Chemistry, University of Buea, Cameroon. Methanol extracts of plant parts commonly used in Cameroon for the treatment of typhoid fever. Antimicrobial activity was tested using the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) assays. Methanol extracts of plant parts commonly used in Cameroon for the treatment of typhoid fever were tested for antibacterial activity against Salmonella typhi, S. paratyphi and S. typhimurium. The formulations used were: 1) Formulation A comprising Cymbogogon citratus leaves, Carica papaya leaves, and Zea mays silk. 2) Formulation B comprising C. papaya roots, Mangifera indica leaves, Citrus limon fruit and C. citratus leaves. 3) C. papaya leaves. 4) Emilia coccinea whole plant. 5) Comelina bengalensis leaves. 6) Telfaria occidentalis leaves. 7) Gossypium arboreum whole plant. Antimicrobial activity was tested using the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) assays. Generally, Formulation A elicited inhibitory activity at a lower range of 0.02 to 0.06 mg/ml. Similarly, Formulation B elicited bacterial activity at the lowest range of 0.06 to 0.25 mg/ml. C. bengalensis leaves on the other hand, showed the lowest activity with a concentration range of 0.132 to 2.0 mg/ml and 1 to 4 mg/ml in MIC and MBC assays respectively. S. paratyphi was most sensitive to the formulations (concentration range of 0.02 to 1 mg/ml in both MIC and MBC assays) while S. typhimurium was the least sensitive and concentrations of up to 4 mg/ml were required to be bactericidal. It is concluded that plant extracts with low MIC and MBC values (1 mg/ml and lower) may contain compounds with therapeutic activity.

Liquid and vapour-phase antifungal activities of essential oils against Candida albicans and non-albicans Candida.

PubMed

Mandras, Narcisa; Nostro, Antonia; Roana, Janira; Scalas, Daniela; Banche, Giuliana; Ghisetti, Valeria; Del Re, Simonetta; Fucale, Giacomo; Cuffini, Anna Maria; Tullio, Vivian

2016-08-30

The management of Candida infections faces many problems, such as a limited number of antifungal drugs, toxicity, resistance of Candida to commonly antifungal drugs, relapse of Candida infections, and the high cost of antifungal drugs. Though azole antifungal agents and derivatives continue to dominate as drugs of choice against Candida infections, there are many available data referring to the anticandidal activity of essential oils. Since we have previous observed a good antimicrobial activity of some essential oils against filamentous fungi, the aim of this study was to extend the research to evaluate the activity of the same oils on Candida albicans, C.glabrata and C.tropicalis clinical strains, as well as the effects of related components. Essential oils selection was based both on ethnomedicinal use and on proved antibacterial and/or antifungal activity of some of these oils. Fluconazole and voriconazole were used as reference drugs. The minimum inhibitory concentration (MIC) and the minimal fungicidal concentration (MFC) of essential oils (thyme red, fennel, clove, pine, sage, lemon balm, and lavender) and their major components were investigated by the broth microdilution method (BM) and the vapour contact assay (VC). Using BM, pine oil showed the best activity against all strains tested, though C.albicans was more susceptible than C.glabrata and C.tropicalis (MIC50-MIC90 = 0.06 %, v/v). On the contrary, sage oil displayed a weak activity (MIC50-MIC90 = 1 %, v/v). Thyme red oil (MIC50-MIC90 ≤ 0.0038 %, v/v for C.albicans and C.tropicalis, and 0.0078- < 0.015 %, v/v for C.glabrata), followed by lemon balm, lavender and sage were the most effective by VC. Carvacrol and thymol showed the highest activity, whereas linalyl acetate showed the lowest activity both by two methods. α-pinene displayed a better activity by BM than VC. Results show a good activity of essential oils, mainly thymus red and pine oils, and their components carvacrol, thymol and α-pinene against Candida spp., including fluconazole/voriconazole resistant strains. These data encourage adequately controlled and randomized clinical investigations. The use in vapour phase could have additional advantages without requiring direct contact, resulting in easy of environmental application such as in hospital, and/or in school.

Determination of Optimal Amikacin Dosing Regimens for Pediatric Patients With Burn Wound Sepsis.

PubMed

Yu, Tian; Stockmann, Chris; Healy, Daniel P; Olson, Jared; Wead, Stephanie; Neely, Alice N; Kagan, Richard J; Spigarelli, Michael G; Sherwin, Catherine M T

2015-01-01

This study aimed to develop optimal amikacin dosing regimens for the empirical treatment of Gram-negative bacterial sepsis in pediatric patients with burn injuries. A pharmacodynamic (PD) target in which the peak concentration (Cmax) is ≥8 times the minimum inhibitory concentration (MIC) (Cmax/MIC ≥ 8) is reflective of optimal bactericidal activity and has been used to predict clinical outcomes. Population pharmacokinetic modeling was performed in NONMEM 7.2 for pediatric patients with and without burn injuries. Amikacin pharmacokinetic parameters were compared between the two groups and multiple dosing regimens were simulated using MATLAB to achieve the PD target in ≥90% of patients with burn injuries. The pharmacokinetic analysis included 282 amikacin concentrations from 70 pediatric patients with burn injuries and 99 concentrations from 32 pediatric patients without burns. A one-compartment model with first-order elimination described amikacin pharmacokinetics well for both groups. Clearance (CL) was significantly higher in patients with burn injuries than in patients without (7.22 vs 5.36 L/h, P < .001). The volume of distribution (V) was also significantly increased in patients with burn injuries (22.7 vs 18.7 L, P < .01). Weight significantly influenced amikacin CL (P < .001) and V (P < .001) for both groups. Model-based simulations showed that a higher amikacin dose (≥25 mg/kg) achieved a Cmax/MIC ≥8 in ≥90% of patients with assumed infections of organisms with an MIC = 8 mg/L. Amikacin pharmacokinetics are altered in patients with burn injuries, including a significant increase in CL and V. In simulations, increased doses (≥25 mg/kg) led to improved PD target attainment rates. Further clinical evaluation of this proposed dosing regimen is warranted to assess clinical and microbiological outcomes in pediatric patients with burn wound sepsis.

Effective concentration-based serum pharmacodynamics for antifungal azoles in a murine model of disseminated Candida albicans infection.

PubMed

Maki, Katsuyuki; Kaneko, Shuji

2013-12-01

An assessment of the effective in vivo concentrations of antifungal drugs is important in determining their pharmacodynamics, and therefore, their optimal dosage regimen. Here we establish the effective in vivo concentration-based pharmacodynamics of three azole antifungal drugs (fluconazole, itraconazole, and ketoconazole) in a murine model of disseminated Candida albicans infection. A key feature of this study was the use of a measure of mycelial (m) growth rather than of yeast growth, and pooled mouse sera rather than synthetic media as a growth medium, for determining the minimum inhibitory concentrations (MICs) of azoles for C. albicans (denoted serum mMICs). The serum mMIC assay was then used to measure antifungal concentrations and effects as serum antifungal titers in the serum of treated mice. Both serum mMIC and sub-mMIC values reflected the effective in vivo serum concentrations. Supra-mMIC and mMIC effects exhibited equivalent efficacies and were concentration-independent, while the sub-mMIC effect was concentration-dependent. Following administration of the minimum drug dosage that inhibited an increase in mouse kidney fungal burden, the duration periods of these effects were similar for all drugs tested. The average duration of either the mMIC effect including the supra-mMIC effect, the sub-mMIC effect, or the post-antifungal effect (PAFE) were 6.9, 6.5 and 10.6 h, respectively. Our study suggests that the area under the curve for serum drug concentration versus time, between the serum mMIC and the sub-mMIC, and exposure time above the serum sub-mMIC after the mMIC effect, are major pharmacodynamic parameters. These findings have important implications for effective concentration-based pharmacodynamics of fungal infections treated with azoles.

In vitro susceptibility of Borrelia burgdorferi isolates to three antibiotics commonly used for treating equine Lyme disease.

PubMed

Caol, Sanjie; Divers, Thomas; Crisman, Mark; Chang, Yung-Fu

2017-09-29

Lyme disease in humans is predominantly treated with tetracycline, macrolides or beta lactam antibiotics that have low minimum inhibitory concentrations (MIC) against Borrelia burgdorferi. Horses with Lyme disease may require long-term treatment making frequent intravenous or intramuscular treatment difficult and when administered orally those drugs may have either a high incidence of side effects or have poor bioavailability. The aim of the present study was to determine the in vitro susceptibility of three B. burgdorferi isolates to three antibiotics of different classes that are commonly used in practice for treating Borrelia infections in horses. Broth microdilution assays were used to determine minimum inhibitory concentration of three antibiotics (ceftiofur sodium, minocycline and metronidazole), for three Borrelia burgdorferi isolates. Barbour-Stoner-Kelly (BSK K + R) medium with a final inoculum of 10 6 Borrelia cells/mL and incubation periods of 72 h were used in the determination of MICs. Observed MICs indicated that all isolates had similar susceptibility to each drug but susceptibility to the tested antimicrobial agents varied; ceftiofur sodium (MIC = 0.08 μg/ml), minocycline hydrochloride (MIC = 0.8 μg/ml) and metronidazole (MIC = 50 μg/ml). The MIC against B. burgorferi varied among the three antibiotics with ceftiofur having the lowest MIC and metronidazole the highest MIC. The MIC values observed for ceftiofur in the study fall within the range of reported serum and tissue concentrations for the drug metabolite following ceftiofur sodium administration as crystalline-free acid. Minocycline and metronidazole treatments, as currently used in equine practice, could fall short of attaining MIC concentrations for B. burgdorferi.

Minimum inhibitory concentrations of medicinal plants used in Northern Peru as antibacterial remedies

PubMed Central

Malca-García, G.; Glenn, A.; Sharon, D.; Chait, G.; Díaz, D.; Pourmand, K.; Jonat, B.; Somogy, S.; Guardado, G.; Aguirre, C.; Chan, R.; Meyer, K.; Kuhlman, A.; Townesmith, A.; Effio-Carbajal, J.; Frías-Fernandez, F.; Benito, M.

2010-01-01

Aim The plant species reported here are traditionally used in Northern Peru to treat bacterial infections, often addressed by the local healers as “inflammation”. The aim of this study was to evaluate the Minimum Inhibitory Concentration (MIC) of their antibacterial properties against Gram-positive and Gram-negative bacteria. Materials and methods The antimicrobial activity of ethanolic and water extracts of 141 plant species was determined using a deep-well broth microdilution method on commercially available bacterial strains. Results The ethanolic extracts of 51 species inhibited Escherichia coli, and 114 ethanolic extracts inhibited Staphylococcus aureus. In contrast, only 30 aqueous extracts showed activity against E. coli and 38 extracts against S. aureus. The MIC concentrations were mostly very high and ranged from 0.008 to 256mg/ml, with only 36 species showing inhibitory concentrations of <4mg/ml. The ethanolic extracts exhibited stronger activity and a much broader spectrum of action than the aqueous extracts. Hypericum laricifolium, Hura crepitans, Caesalpinia paipai, Cassia fistula, Hyptis sidifolia, Salvia sp., Banisteriopsis caapi, Miconia salicifolia and Polygonum hydropiperoides showed the lowest MIC values and would be interesting candidates for future research. Conclusions The presence of antibacterial activity could be confirmed in most species used in traditional medicine in Peru which were assayed in this study. However, the MIC for the species employed showed a very large range, and were mostly very high. Nevertheless, traditional knowledge might provide some leads to elucidate potential candidates for future development of new antibiotic agents. PMID:20678568

Minimum inhibitory concentrations of medicinal plants used in Northern Peru as antibacterial remedies.

PubMed

Bussmann, R W; Malca-García, G; Glenn, A; Sharon, D; Chait, G; Díaz, D; Pourmand, K; Jonat, B; Somogy, S; Guardado, G; Aguirre, C; Chan, R; Meyer, K; Kuhlman, A; Townesmith, A; Effio-Carbajal, J; Frías-Fernandez, F; Benito, M

2010-10-28

The plant species reported here are traditionally used in Northern Peru to treat bacterial infections, often addressed by the local healers as "inflammation". The aim of this study was to evaluate the minimum inhibitory concentration (MIC) of their antibacterial properties against gram-positive and gram-negative bacteria. The antimicrobial activity of ethanolic and water extracts of 141 plant species was determined using a deep-well broth microdilution method on commercially available bacterial strains. The ethanolic extracts of 51 species inhibited Escherichia coli, and 114 ethanolic extracts inhibited Staphylococcus aureus. In contrast, only 30 aqueous extracts showed activity against Escherichia coli and 38 extracts against Staphylococcus aureus. The MIC concentrations were mostly very high and ranged from 0.008 to 256 mg/ml, with only 36 species showing inhibitory concentrations of <4 mg/ml. The ethanolic extracts exhibited stronger activity and a much broader spectrum of action than the aqueous extracts. Hypericum laricifolium, Hura crepitans, Caesalpinia paipai, Cassia fistula, Hyptis sidifolia, Salvia sp., Banisteriopsis caapi, Miconia salicifolia and Polygonum hydropiperoides showed the lowest MIC values and would be interesting candidates for future research. The presence of antibacterial activity could be confirmed in most species used in traditional medicine in Peru which were assayed in this study. However, the MIC for the species employed showed a very large range, and were mostly very high. Nevertheless, traditional knowledge might provide some leads to elucidate potential candidates for future development of new antibiotic agents. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Characterization of carbapenem-resistant Gram-negative bacteria from Tamil Nadu.

PubMed

Nachimuthu, Ramesh; Subramani, Ramkumar; Maray, Suresh; Gothandam, K M; Sivamangala, Karthikeyan; Manohar, Prasanth; Bozdogan, Bülent

2016-10-01

Carbapenem resistance is disseminating worldwide among Gram-negative bacteria. The aim of this study was to identify carbapenem-resistance level and to determine the mechanism of carbapenem resistance among clinical isolates from two centres in Tamil Nadu. In the present study, a total of 93 Gram-negative isolates, which is found to be resistant to carbapenem by disk diffusion test in two centres, were included. All isolates are identified at species level by 16S rRNA sequencing. Minimal inhibitory concentrations (MICs) of isolates for Meropenem were tested by agar dilution method. Presence of blaOXA, blaNDM, blaVIM, blaIMP and blaKPC genes was tested by PCR in all isolates. Amplicons were sequenced for confirmation of the genes. Among 93 isolates, 48 (%52) were Escherichia coli, 10 (%11) Klebsiella pneumoniae, nine (%10) Pseudomonas aeruginosa. Minimal inhibitory concentration results showed that of 93 suspected carbapenem-resistant isolates, 27 had meropenem MICs ≥ 2 μg/ml. The MIC range, MIC50 and MIC90 were < 0.06 to >128 μg/ml, 0.12 and 16 μg/ml, respectively. Fig. 1 . Among meropenem-resistant isolates, E. coli were the most common (9/48, 22%), followed by K. pneumoniae (7/9, 77%), P. aeruginosa (6/10, 60%), Acinetobacter baumannii (2/2, 100%), Enterobacter hormaechei (2/3, 67%) and one Providencia rettgeri (1/1, 100%). PCR results showed that 16 of 93 carried blaNDM, three oxa181, and one imp4. Among blaNDM carriers, nine were E. coli, four Klebsiella pneumoniae, two E. hormaechei and one P. rettgeri. Three K. pneumoniae were OXA-181 carriers. The only imp4 carrier was P. aeruginosa. A total of seven carbapenem-resistant isolates were negatives by PCR for the genes studied. All carbapenem-resistance gene-positive isolates had meropenem MICs >2 μg/ml. Our results confirm the dissemination of NDM and emergence of OXA-181 beta-lactamase among Gram-negative bacteria in South India. This study showed the emergence of NDM producer in clinical isolates of E. hormaechei and P. rettgeri in India.

Positive interaction of thyme (red) essential oil with human polymorphonuclear granulocytes in eradicating intracellular Candida albicans.

PubMed

Tullio, Vivian; Mandras, Narcisa; Allizond, Valeria; Nostro, Antonia; Roana, Janira; Merlino, Chiara; Banche, Giuliana; Scalas, Daniela; Cuffini, Anna Maria

2012-10-01

The essential oils have started to be recognized for their potential antimicrobial role only in recent years. Clinical experience showed that the efficacy of antimicrobial agents depends not only on their direct effect on a given microorganism but also on the functional activity of the host immune system. Since data on the effects of essential oils on the innate immune system are scanty and fragmentary, the aim of this study was to evaluate the influence of thyme (red) essential oil (EO), at subinhibitory/inhibitory concentrations, on intracellular killing activity by human polymorphonuclear granulocytes (PMNs) against Candida albicans. In order to provide a frame of reference for the activity of this EO, its in vitro killing activity in the absence of PMNs was also evaluated.Results showed that EO at subminimal inhibitory (subMIC)/minimal inhibitory (MIC) concentrations significantly enhanced intracellular killing of C. albicans in comparison with EO-free controls and was comparable to the positive control (fluconazole). In in vitro killing assays without PMNs, we observed progressive growth of the yeast cells in the presence of EO subMIC/MIC concentrations. A positive antifungal interaction with phagocytes could explain why this EO, which appeared to be only fungistatic in time-kill assays, had efficacy in killing yeast cells once incubated with PMNs. Georg Thieme Verlag KG Stuttgart · New York.

Susceptibility screening of hyphae-forming fungi with a new, easy, and fast inoculum preparation method.

PubMed

Schmalreck, Arno; Willinger, Birgit; Czaika, Viktor; Fegeler, Wolfgang; Becker, Karsten; Blum, Gerhard; Lass-Flörl, Cornelia

2012-12-01

In vitro susceptibility testing of clinically important fungi becomes more and more essential due to the rising number of fungal infections in patients with impaired immune system. Existing standardized microbroth dilution methods for in vitro testing of molds (CLSI, EUCAST) are not intended for routine testing. These methods are very time-consuming and dependent on sporulating of hyphomycetes. In this multicentre study, a new (independent of sporulation) inoculum preparation method (containing a mixture of vegetative cells, hyphae, and conidia) was evaluated. Minimal inhibitory concentrations (MIC) of amphotericin B, posaconazole, and voriconazole of 180 molds were determined with two different culture media (YST and RPMI 1640) according to the DIN (Deutsches Institut für Normung) microdilution assay. 24 and 48 h MIC of quality control strains, tested per each test run, prepared with the new inoculum method were in the range of DIN. YST and RPMI 1640 media showed similar MIC distributions for all molds tested. MIC readings at 48 versus 24 h yield 1 log(2) higher MIC values and more than 90 % of the MICs read at 24 and 48 h were within ± 2 log(2) dilution. MIC end point reading (log(2 MIC-RPMI 1640)-log(2 MIC-YST)) of both media demonstrated a tendency to slightly lower MICs with RPMI 1640 medium. This study reports the results of a new, time-saving, and easy-to-perform method for inoculum preparation for routine susceptibility testing that can be applied for all types of spore-/non-spore and hyphae-forming fungi.

Pharmacokinetic/pharmacodynamic evaluation of marbofloxacin as a single injection for Pasteurellaceae respiratory infections in cattle using population pharmacokinetics and Monte Carlo simulations.

PubMed

Paulin, A; Schneider, M; Dron, F; Woehrle, F

2018-02-01

Population pharmacokinetic of marbofloxacin was investigated with 52 plasma concentration-time profiles obtained after intramuscular administration of Forcyl® in cattle. Animal's status, pre-ruminant, ruminant, or dairy cow, was retained as a relevant covariate for clearance. Monte Carlo simulations were performed using a stratification by status, and 1000 virtual disposition curves were generated in each bovine subpopulation for the recommended dosage regimen of 10 mg/kg as a single injection. The probability of target attainment (PTA) of pharmacokinetic/pharmacodynamic (PK/PD) ratios associated with clinical efficacy and prevention of resistance was determined in each simulated subpopulation. The cumulative fraction of response (CFR) of animals achieving a PK/PD ratio predictive of positive clinical outcome was then calculated for the simulated dosage regimen, taking into account the minimum inhibitory concentration (MIC) distribution of Pasteurella multocida, Mannheimia haemolytica, and Histophilus somni. When considering a ratio of AUC 0-24 hr /MIC (area under the curve/minimum inhibitory concentration) greater than 125 hr, CFRs ranging from 85% to 100% against the three Pasteurellaceae in each bovine subpopulation were achieved. The PTA of the PK/PD threshold reflecting the prevention of resistances was greater than 90% up to MPC (mutant prevention concentration) values of 1 μg/ml in pre-ruminants and ruminants and 0.5 μg/ml in dairy cows. © 2017 The Authors. Journal of Veterinary Pharmacology and Therapeutics Published by John Wiley & Sons Ltd.

The transforming growth factor-ss superfamily cytokine macrophage inhibitory cytokine-1 is present in high concentrations in the serum of pregnant women.

PubMed

Moore, A G; Brown, D A; Fairlie, W D; Bauskin, A R; Brown, P K; Munier, M L; Russell, P K; Salamonsen, L A; Wallace, E M; Breit, S N

2000-12-01

Macrophage inhibitory cytokine-1 (MIC-1) is a recently described divergent member of the transforming growth factor-ss superfamily. MIC-1 transcription up-regulation is associated with macrophage activation, and this observation led to its cloning. Northern blots indicate that MIC-1 is also present in human placenta. A sensitive sandwich enzyme-linked immunosorbent assay for the quantification of MIC-1 was developed and used to examine the role of this cytokine in pregnancy. High levels of MIC-1 are present in the sera of pregnant women. The level rises substantially with progress of gestation. MIC-1 can also be detected, in large amounts, in amniotic fluid and placental extracts. In addition, the BeWo placental trophoblastic cell line was found to constitutively express the MIC-1 transcript and secrete large amounts of MIC-1. These findings suggest that the placental trophoblast is a major source of the MIC-1 present in maternal serum and amniotic fluid. We suggest that MIC-1 may promote fetal survival by suppressing the production of maternally derived proinflammatory cytokines within the uterus.

A multicentre study of meticillin-resistant Staphylococcus aureus in acute bacterial skin and skin-structure infections in China: susceptibility to ceftaroline and molecular epidemiology.

PubMed

Zhang, Hui; Xiao, Meng; Kong, Fanrong; O'Sullivan, Matthew V N; Mao, Lei-Li; Zhao, Hao-Ran; Zhao, Ying; Wang, He; Xu, Ying-Chun

2015-04-01

Ceftaroline is a novel cephalosporin with activity against Gram-positive organisms, including meticillin-resistant Staphylococcus aureus (MRSA). The objective of this study was to investigate the susceptibility to ceftaroline of hospital-associated MRSA (HA-MRSA) isolates causing acute bacterial skin and skin-structure infections (ABSSSIs) in China and to examine their relationship by genotyping. A total of 251 HA-MRSA isolates causing ABSSSIs were collected from a multicentre study involving 56 hospitals in 38 large cities across 26 provinces in mainland China. All isolates were characterised by multilocus sequence typing (MLST), staphylococcal cassette chromosome mec (SCCmec) typing, spa typing and detection of the Panton-Valentine leukocidin locus (lukS-PV and lukF-PV). Minimum inhibitory concentrations (MICs) of 14 antimicrobial agents, including ceftaroline, were determined by broth microdilution and were interpreted using Clinical and Laboratory Standards Institute breakpoints. The ceftaroline MIC50 and MIC90 values (MICs that inhibit 50% and 90% of the isolates, respectively) were 1 μg/mL and 2 μg/mL, respectively; 33.5% (n=84) of the isolates studied were ceftaroline-non-susceptible, with MICs of 2 μg/mL, but no isolate exhibited ceftaroline resistance (MIC>2 μg/mL). All of the ceftaroline-non-susceptible isolates belonged to the predominant HA-MRSA clones: 95.2% (n=80) from MLST clonal complex 8 (CC8), with the remaining 4.8% (n=4) from CC5. The high rate of non-susceptibility to ceftaroline amongst HA-MRSA causing ABSSSIs in China is concerning. Copyright © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Disinfection efficiencies of sage and spearmint essential oils against planktonic and biofilm Staphylococcus aureus cells in comparison with sodium hypochlorite.

PubMed

Vetas, Dimitrios; Dimitropoulou, Eleni; Mitropoulou, Gregoria; Kourkoutas, Yiannis; Giaouris, Efstathios

2017-09-18

Staphylococcus aureus causes human infections and foodborne intoxications. This study explored the potential antibacterial actions of sage and spearmint essential oils (EOs) against both its planktonic and biofilm cells, in comparison with sodium hypochlorite (NaOCl), a commonly applied chemical sanitizer. Initially, the minimum inhibitory and bactericidal concentrations (MICs, MBCs) of each plant mixture were determined against planktonic cultures, following growth at 30°C for 24h. Stationary phase planktonic bacteria were then individually exposed for 6min to either each EO (applied at 1-2×MBC; 2.5-5%), or NaOCl (250-450ppm). These were also left to form biofilms on 96-well polystyrene microplates, at 30°C for 96h, with medium renewal at 48h, in the presence of 10 different concentrations of each EO, expanding from sub- to super-inhibitory for planktonic growth, and the minimum biofilm inhibitory concentrations (MBICs; >90% inhibition) of each plant mixture were calculated. Formed biofilms were finally exposed for 6min to either each EO (applied at 2-6×MBC; 5-15%), or NaOCl (7500-25,000ppm; applied either alone or in combination with each EO at 5%). Results showed that both EOs presented MIC and MBC equal to 1.25 and 2.5%, respectively. As expected, their application at their MIC and above significantly inhibited biofilm formation, while spearmint EO was still able to cause this at ½ of its MIC, with MBICs equal to 1.25 and 0.63% for sage and spearmint EOs, respectively. Alarmingly, the application of both EOs at 1/8 to 1/16 of their MIC further increased biofilm formation. Regarding biofilm disinfection experiments, the individual application of each EO against the pre-established sessile communities resulted in log decrease ranges of 0.8-3logCFU/cm 2 , while in the case of NaOCl application (either alone or combined with each EO), the observed reductions never exceeded 1.7logCFU/cm 2 . These last results highlight the great antimicrobial recalcitrance of biofilm communities, found here to be ca. 100 times more resistant to NaOCl compared to planktonic ones, and stress the urgent need for further research on alternative, adequate and safe disinfection strategies to control them in food processing and other environments. Copyright © 2017 Elsevier B.V. All rights reserved.

In vitro activity of Tedizolid phosphate against multidrug-resistant Streptococcus pneumoniae isolates from Asian countries.

PubMed

Baek, Jin Yang; Kang, Cheol-In; Kim, So Hyun; Ko, Kwan Soo; Chung, Doo Ryeon; Peck, Kyong Ran; Hsueh, Po-Ren; Thamlikitkul, Visanu; So, Thomas Man-Kit; Lee, Nam Yong; Song, Jae-Hoon

2016-06-01

Tedizolid phosphate is a second-generation oxazolidinone prodrug that is potential activity against a wide range of Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus, penicillin-resistant streptococci, and vancomycin-resistant enterococci. The in vitro activity of tedizolid and other comparator agents against multidrug-resistant (MDR) pneumococci from various Asian countries were evaluated. Of the S. pneumoniae clinical pneumonia isolates collected during 2008 and 2009 from 8 Asian countries (Korea, Taiwan, Thailand, Hong Kong, Vietnam, Malaysia, Philippines, and Sri Lanka), 104 isolates of MDR pneumococci were included in this study. Antimicrobial susceptibility testing for 18 antimicrobial agents was performed by broth microdilution method. Tedizolid was highly active against pneumococci. All isolates tested were inhibited at a tedizolid minimum inhibitory concentration (MIC) value of ≤0.25μg/ml (ranged from ≤0.03μg/ml to 0.25μg/ml). The MIC50 and MIC90 of tedizolid against MDR pneumococci were both 0.12μg/ml, while MIC50 and MIC90 of linezolid were 0.5μg/ml and 1μg/ml, respectively. In addition, tedizolid maintained the activity against S. pneumoniae regardless of the extensively drug-resistant (XDR) phenotype of the isolates. The activity of tedizolid was excellent against all types of MDR pneumococci, exhibiting and maintaining at least 4-fold-greater potency compared to linezolid, regardless of resistance phenotypes to other commonly utilized agents. Tedizolid has the potential to be an agent to treat infections caused by MDR pneumococci in the Asia. Copyright © 2016 Elsevier Inc. All rights reserved.

Susceptibility profile and epidemiological cut-off values of Cryptococcus neoformans species complex from Argentina.

PubMed

Córdoba, Susana; Isla, Maria G; Szusz, Wanda; Vivot, Walter; Altamirano, Rodrigo; Davel, Graciela

2016-06-01

Epidemiological cut-off values (ECVs) based on minimal inhibitory concentration (MIC) distribution have been recently proposed for some antifungal drug/Cryptococcus neoformans combinations. However, these ECVs vary according to the species studied, being serotypes and the geographical origin of strains, variables to be considered. The aims were to define the wild-type (WT) population of the C. neoformans species complex (C. neoformans) isolated from patients living in Argentina, and to propose ECVs for six antifungal drugs. A total of 707 unique C. neoformans isolates obtained from HIV patients suffering cryptococcal meningitis were studied. The MIC of amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole and posaconazole was determined according to the EDef 7.2 (EUCAST) reference document. The MIC distribution, MIC50 , MIC90 and ECV for each of these drugs were calculated. The highest ECV, which included ≥95% of the WT population modelled, was observed for flucytosine and fluconazole (32 μg ml(-1) each). For amphotericin B, itraconazole, voriconazole and posaconazole, the ECVs were: 0.5, 0.5, 0.5 and 0.06 μg ml(-1) respectively. The ECVs determined in this study may aid in identifying the C. neoformans strains circulating in Argentina with decreased susceptibility to the antifungal drugs tested. © 2016 Blackwell Verlag GmbH.

The effects of subinhibitory concentrations of costus oil on virulence factor production in Staphylococcus aureus.

PubMed

Qiu, J; Wang, J; Luo, H; Du, X; Li, H; Luo, M; Dong, J; Chen, Z; Deng, X

2011-01-01

To determine the antimicrobial activity of costus (Saussurea lappa) oil against Staphylococcus aureus, and to evaluate the influence of subinhibitory concentrations of costus oil on virulence-related exoprotein production in staph. aureus. Minimal inhibitory concentrations (MICs) were determined using a broth microdilution method, and the MICs of costus oil against 32 Staph. aureus strains ranged from 0.15 to 0.6 μl ml(-1) . The MIC(50) and MIC(90) were 0.3 and 0.6 μl ml(-1) , respectively. Western blot, haemolytic, tumour necrosis factor (TNF) release and real-time RT-PCR assays were performed to evaluate the effects of subinhibitory concentrations of costus oil on virulence-associated exoprotein production in Staph. aureus. The data presented here show that costus oil dose dependently decreased the production of α-toxin, toxic shock syndrome toxin 1 (TSST-1) and enterotoxins A and B in both methicillin-sensitive Staph. aureus (MSSA) and methicillin-resistant Staph. aureus (MRSA). Costus oil has potent antimicrobial activity against Staph. aureus, and the production of α-toxin, TSST-1 and enterotoxins A and B in Staph. aureus was decreased by costus oil. The data suggest that costus oil may deserve further investigation for its potential therapeutic value in treating Staph. aureus infections. Furthermore, costus oil could be rationally applied in food products as a novel food preservative both to inhibit the growth of Staph. aureus and to repress the production of exotoxins, particularly staphylococcal enterotoxins. © 2010 The Authors. Journal of Applied Microbiology © 2010 The Society for Applied Microbiology.

Effect of hydrogen peroxide on antibacterial activities of Canadian honeys.

PubMed

Brudzynski, Katrina

2006-12-01

Honey is recognized as an efficacious topical antimicrobial agent in the treatment of burns and wounds. The antimicrobial activity in some honeys depends on the endogenous hydrogen peroxide content. This study was aimed to determine whether honey's hydrogen peroxide level could serve as a honey-specific, activity-associated biomarker that would allow predicting and assessing the therapeutic effects of honey. Using a broth microdilution assay, I analyzed antibacterial activities of 42 Canadian honeys against two bacterial strains: Escherichia coli (ATCC 14948) and Bacillus subtilis (ATCC 6633). The MIC90 and MIC50 were established from the dose-response relationship between antibacterial activities and honey concentrations. The impact of H2O2 on antibacterial activity was determined (i) by measuring the levels of H2O2 before and after its removal by catalase and (ii) by correlating the results with levels of antibacterial activities. Canadian honeys demonstrated moderate to high antibacterial activity against both bacterial species. Both MIC90 and MIC50 revealed that the honeys exhibited a selective growth inhibitory activity against E. coli, and this activity was strongly influenced by endogenous H2O2 concentrations. Bacillus subtilis activity was marginally significantly correlated with H2O2 content. The removal of H2O2 by catalase reduced the honeys' antibacterial activity, but the enzyme was unable to completely decompose endogenous H2O2. The 25%-30% H2O2 "leftover" was significantly correlated with the honeys' residual antibacterial activity against E. coli. These data indicate that all Canadian honeys exhibited antibacterial activity, with higher selectivity against E. coli than B. subtilis, and that these antibacterial activities were correlated with hydrogen peroxide production in honeys. Hydrogen peroxide levels in honey, therefore, is a strong predictor of the honey's antibacterial activity.

Evaluation of the efficacy of four weak acids as antifungal preservatives in low-acid intermediate moisture model food systems.

PubMed

Huang, Yang; Wilson, Mark; Chapman, Belinda; Hocking, Ailsa D

2010-02-01

The potential efficacy of four weak acids as preservatives in low-acid intermediate moisture foods was assessed using a glycerol based agar medium. The minimum inhibitory concentrations (MIC, % wt./wt.) of each acid was determined at two pH values (pH 5.0, pH 6.0) and two a(w) values (0.85, 0.90) for five food spoilage fungi, Eurotium herbariorum, Eurotium rubrum, Aspergillus niger, Aspergillus flavus and Penicillium roqueforti. Sorbic acid, a preservative commonly used to control fungal growth in low-acid intermediate moisture foods, was included as a reference. The MIC values of the four acids were lower at pH 5.0 than pH 6.0 at equivalent a(w) values, and lower at 0.85 a(w) than 0.90 a(w) at equivalent pH values. By comparison with the MIC values of sorbic acid, those of caprylic acid and dehydroacetic acid were generally lower, whereas those for caproic acid were generally higher. No general observation could be made in the case of capric acid. The antifungal activities of all five weak acids appeared related not only to the undissociated form, but also the dissociated form, of each acid.

PK-PD Analysis of Marbofloxacin against Streptococcus suis in Pigs.

PubMed

Lei, Zhixin; Liu, Qianying; Yang, Bing; Khaliq, Haseeb; Cao, Jiyue; He, Qigai

2017-01-01

Marbofloxacin is a fluoroquinolone antibiotic and highly effective treatment for respiratory diseases. Here we aimed to evaluate the ex vivo activity of marbofloxacin against Streptococcus suis in pig serum, as well as the optimal dosages scheme for avoiding the fluoroquinolone resistance development. A single dose of 8 mg/kg body weight (bw) was administrated orally to healthy pigs and serum samples were collected during the next 72 h. Serum marbofloxacin content was determined by high-performance liquid chromatography. We estimated the C max (6.28 μg/ml), AUC 0-24 h (60.30 μg.h/ml), AUC 0-∞ (88.94 μg.h/ml), T 1/2ke, (12.48 h), T max (0.75 h) and Cl b (0.104 L/h) of marbofloxacin in pigs, as well as the bioavailability of marbofloxacin (94.21%) after a single 8 mg/kg oral administration. We also determined the pharmacodynamic of marbofloxacin against 134 Streptococcus suis strains isolated from Chinese cities in TSB and serum. These isolated strains had a MIC 90 of 1 μg/ml. HB2, a virulent, serotype 2 isolate of SS , was selected for having antibacterial activity in TSB and serum to marbofloxacin. We determined the minimum inhibitory concentration (MIC, 1 μg/ml in TSB, 2 μg/ml in serum), minimum bactericidal concentration (MBC, 4 μg/ml in TSB, 4 μg/ml in serum), and mutant prevention concentration (2.56 μg/ml in TSB) for marbofloxacin against Streptococcus suis (HB2). In serum, by inhibitory sigmoid E max modeling, the AUC 0-24h /MIC values for marbofloxacin against HB2 were 25.23 (bacteriostatic), 35.64 (bactericidal), and 39.71 (elimination) h. Based on Monte Carlo simulations, the predicted optimal oral doses of marbofloxacin curing Streptococcus suis were 5.88 (bacteriostatic), 8.34 (bactericidal), and 9.36 (elimination) mg/kg.bw for a 50% target attainment ratio, and 8.16 (bacteriostatic), 11.31 (bactericidal), and 12.35 (elimination) mg/kg.bw for a 90% target attainment ratio. The data presented here provides optimized dosage information for clinical use; however, these predicted dosages should also be validated in clinical practice.

[Pharmacokinetic effects of antibiotics on the development of bacterial resistance particularly in reference to azithromycin].

PubMed

Wenisch, C

2000-01-01

Antibiotics reduce the mortality from infectious diseases but not the prevalence of these diseases. Use, and often abuse, of antimicrobial agents encourages the evolution of bacteria toward resistance, often resulting in therapeutic failure. There are two factors which influence potential utility of a drug in a specific clinical situation. The first is the measure of potency of the antibiotic for the pathogen in question (minimal inhibitory concentration [MIC], minimal bactericidal concentration [MBC]). The second is whichever relationship between the concentration-time profile and potency of the antibiotic linked most robustly to clinical outcome (time above MIC or MBC [T > MIC or T > MBC]; Peak/MIC or MBC; area under the curve [AUC]/MIC or AUC/MBC). Herein the effects of pharmacokinetics of antimicrobials on the evolution of antimicrobial resistance with particular reference to azithromycin are considered.

Cefazolin potency against methicillin-resistant Staphylococcus aureus: a microbiologic assessment in support of a novel drug delivery system for skin and skin structure infections.

PubMed

Nicolau, David P; Silberg, Barry N

2017-01-01

Despite aggressive medical and surgical management, the resolution of skin and skin structure infections is often difficult due to insufficient host response, reduced drug penetration, and a high prevalence of resistance organisms such as methicillin-resistant Staphylococcus aureus (MRSA). As a result of these factors, conventional management often consists of prolonged broad-spectrum systemic antimicrobials. An alternative therapy in development, ultrasonic drug dispersion (UDD), uses a subcutaneous injection followed by external trans-cutaneous ultrasound to deliver high tissue concentrations of cefazolin with limited systemic exposure. While it is postulated that these high concentrations may be suitable to treat more resistant organisms such as MRSA, the cefazolin minimum inhibitory concentration (MIC) distribution for this organism is currently unknown. We assessed the potency of cefazolin against a collection of 1,239 MRSA from 42 US hospitals using Clinical Laboratory Standard Institute-defined broth micro-dilution methodology. The cefazolin MIC inhibiting 50% of the isolates was 64 mg/L; 81% had MICs ≤128 and nearly all (99.9%) had MICs ≤512 mg/L. The overwhelming majority of MRSA had cefazolin MICs that were considerably lower than achievable tissue concentrations (≥1,000 mg/L) using this novel drug delivery system. While the currently defined cefazolin MRSA phenotypic profile precludes the use of parenteral administration, techniques that deliver local exposures in excess of these inhibitory concentrations may provide a novel treatment strategy for skin and skin structure infections.

Isolated cell behavior drives the evolution of antibiotic resistance

PubMed Central

Artemova, Tatiana; Gerardin, Ylaine; Dudley, Carmel; Vega, Nicole M; Gore, Jeff

2015-01-01

Bacterial antibiotic resistance is typically quantified by the minimum inhibitory concentration (MIC), which is defined as the minimal concentration of antibiotic that inhibits bacterial growth starting from a standard cell density. However, when antibiotic resistance is mediated by degradation, the collective inactivation of antibiotic by the bacterial population can cause the measured MIC to depend strongly on the initial cell density. In cases where this inoculum effect is strong, the relationship between MIC and bacterial fitness in the antibiotic is not well defined. Here, we demonstrate that the resistance of a single, isolated cell—which we call the single-cell MIC (scMIC)—provides a superior metric for quantifying antibiotic resistance. Unlike the MIC, we find that the scMIC predicts the direction of selection and also specifies the antibiotic concentration at which selection begins to favor new mutants. Understanding the cooperative nature of bacterial growth in antibiotics is therefore essential in predicting the evolution of antibiotic resistance. PMID:26227664

Antibacterial Effect of Curcuma longa (Turmeric) Against Staphylococcus aureus and Escherichia coli.

PubMed

Afrose, R; Saha, S K; Banu, L A; Ahmed, A U; Shahidullah, A S; Gani, A; Sultana, S; Kabir, M R; Ali, M Y

2015-07-01

This observational study was conducted during the period from July 2010 to June 2011 in the Department of Pharmacology in the collaboration of Department of Microbiology, Mymensingh Medical College, Mymensingh to determine the profile of antibacterial effect of Crude Turmeric paste aqueous turmeric extract, and standard antibiotic Amikacin against Staphylococcus aureus and Escherichia coli. Three separate experiments were done e.g. (Expt- I) Inhibitory effect of Crude Turmeric paste incorporated into nutrient agar (NA) media, (Expt- II) Minimum inhibitory concentration of (a) Aqueous Turmeric extract and (b) Amikacin by broth dilution technique and (Expt-III) their subculture study in nutrient agar (NA) media for confirmation of respective results of previous experiments. Inhibitory effects were observed against the growth of Staph Aureus and Esch coli at 10% and 30% respectively of Crude Turmeric paste incorporated into NA media. The broth dilution technique was followed to determine the MIC of Aqueous Turmeric extract and Amikacin. The MIC of Aqueous Turmeric extract was 800 μg/ml against Staph aureus and that against Esch coli was 2000 μg/ml and the MIC of Amikacin was 10 μg/ml for both the bacteria. The MIC of Amikacin was the lowest in comparison to MIC of Aqueous Turmeric extract for complete inhibition of growth of Staph aureus and Esch coli. The subculture study showed similar results with that of previous experiments in terms of inhibitory effects of Crude Turmeric paste and MIC of Aqueous Turmeric extract and Amikacin against all of the organisms studied.

Minimum inhibitory concentration distribution in environmental Legionella spp. isolates.

PubMed

Sandalakis, Vassilios; Chochlakis, Dimosthenis; Goniotakis, Ioannis; Tselentis, Yannis; Psaroulaki, Anna

2014-12-01

In Greece standard tests are performed in the watering and cooling systems of hotels' units either as part of the surveillance scheme or following human infection. The purpose of this study was to establish the minimum inhibitory concentration (MIC) distributions of environmental Legionella isolates for six antimicrobials commonly used for the treatment of Legionella infections, by MIC-test methodology. Water samples were collected from 2004 to 2011 from 124 hotels from the four prefectures of Crete (Greece). Sixty-eight (68) Legionella isolates, comprising L. pneumophila serogroups 1, 2, 3, 5, 6, 8, 12, 13, 15, L. anisa, L. rubrilucens, L. maceachernii, L. quinlivanii, L. oakridgensis, and L. taurinensis, were included in the study. MIC-tests were performed on buffered charcoal yeast extract with α-ketoglutarate, L-cysteine, and ferric pyrophosphate. The MICs were read after 2 days of incubation at 36 ± 1 °C at 2.5% CO2. A large distribution in MICs was recorded for each species and each antibiotic tested. Rifampicin proved to be the most potent antibiotic regardless of the Legionella spp.; tetracycline appeared to have the least activity on our environmental isolates. The MIC-test approach is an easy, although not so cost-effective, way to determine MICs in Legionella spp. These data should be kept in mind especially since these Legionella species may cause human disease.

Optimal Clinical Doses of Faropenem, Linezolid, and Moxifloxacin in Children With Disseminated Tuberculosis: Goldilocks

PubMed Central

Srivastava, Shashikant; Deshpande, Devyani; Pasipanodya, Jotam; Nuermberger, Eric; Swaminathan, Soumya; Gumbo, Tawanda

2016-01-01

Background. When treated with the same antibiotic dose, children achieve different 0- to 24-hour area under the concentration-time curves (AUC0–24) because of maturation and between-child physiological variability on drug clearance. Children are also infected by Mycobacterium tuberculosis isolates with different antibiotic minimum inhibitory concentrations (MICs). Thus, each child will achieve different AUC0–24/MIC ratios when treated with the same dose. Methods. We used 10 000-subject Monte Carlo experiments to identify the oral doses of linezolid, moxifloxacin, and faropenem that would achieve optimal target exposures associated with optimal efficacy in children with disseminated tuberculosis. The linezolid and moxifloxacin exposure targets were AUC0–24/MIC ratios of 62 and 122, and a faropenem percentage of time above MIC >60%, in combination therapy. A linezolid AUC0–24 of 93.4 mg × hour/L was target for toxicity. Population pharmacokinetic parameters of each drug and between-child variability, as well as MIC distribution, were used, and the cumulative fraction of response (CFR) was calculated. We also considered drug penetration indices into meninges, bone, and peritoneum. Results. The linezolid dose of 15 mg/kg in full-term neonates and infants aged up to 3 months and 10 mg/kg in toddlers, administered once daily, achieved CFR ≥ 90%, with <10% achieving linezolid AUC0–24 associated with toxicity. The moxifloxacin dose of 25 mg/kg/day achieved a CFR > 90% in infants, but the optimal dose was 20 mg/kg/day in older children. The faropenem medoxomil optimal dosage was 30 mg/kg 3–4 times daily. Conclusions. The regimen and doses of linezolid, moxifloxacin, and faropenem identified are proposed to be adequate for all disseminated tuberculosis syndromes, whether drug-resistant or -susceptible. PMID:27742641

Antimicrobial susceptibility and serotypes of Actinobacillus (Haemophilus) pleuropneumoniae recovered from Missouri swine.

PubMed

Fales, W H; Morehouse, L G; Mittal, K R; Bean-Knudsen, C; Nelson, S L; Kintner, L D; Turk, J R; Turk, M A; Brown, T P; Shaw, D P

1989-01-01

The antimicrobial susceptibility of 73 Actinobacillus (Haemophilus) pleuropneumoniae isolates from swine in Missouri was determined with a microdilution minimal inhibitory concentration test system. Serotyping was accomplished by means of co-agglutination. Serotype 1 (39/73) and serotype 5 (30/73) were commonly found, whereas serotype 7 (4/73) was infrequently encountered. Most isolates (MIC90) were found susceptible to ampicillin (amoxicillin), cephalothin, penicillin, erythromycin, gentamicin, and kanamycin. Marked resistance was found with oxytetracycline, tylosin, and sulfadimethoxine. The data indicate that use of ampicillin (amoxicillin) or penicillin may correlate well with the favorable outcome of treatment.

Inhibition of Listeria monocytogenes by food antimicrobials applied singly and in combination.

PubMed

Brandt, Alex L; Castillo, Alejandro; Harris, Kerri B; Keeton, Jimmy T; Hardin, Margaret D; Taylor, Thomas M

2010-01-01

Combining food antimicrobials can enhance inhibition of Listeria monocytogenes in ready-to-eat (RTE) meats. A broth dilution assay was used to compare the inhibition of L. monocytogenes resulting from exposure to nisin, acidic calcium sulfate, ε-poly-L-lysine, and lauric arginate ester applied singly and in combination. Minimum inhibitory concentrations (MICs) were the lowest concentrations of single antimicrobials producing inhibition following 24 h incubation at 35 °C. Minimum bactericidal concentrations (MBCs) were the lowest concentrations that decreased populations by ≥3.0 log(10) CFU/mL. Combinations of nisin with acidic calcium sulfate, nisin with lauric arginate ester, and ɛ-poly-L-lysine with acidic calcium sulfate were prepared using a checkerboard assay to determine optimal inhibitory combinations (OICs). Fractional inhibitory concentrations (FICs) were calculated from OICs and were used to create FIC indices (FIC(I)s) and isobolograms to classify combinations as synergistic (FIC(I) < 1.00), additive/indifferent (FIC(I)= 1.00), or antagonistic (FIC(I) > 1.00). MIC values for nisin ranged from 3.13 to 6.25 μg/g with MBC values at 6.25 μg/g for all strains except for Natl. Animal Disease Center (NADC) 2045. MIC values for ε-poly-L-lysine ranged from 6.25 to 12.50 μg/g with MBCs from 12.50 to 25.00 μg/g. Lauric arginate ester at 12.50 μg/g was the MIC and MBC for all strains; 12.50 mL/L was the MIC and MBC for acidic calcium sulfate. Combining nisin with acidic calcium sulfate synergistically inhibited L. monocytogenes; nisin with lauric arginate ester produced additive-type inhibition, while ε-poly-L-lysine with acidic calcium sulfate produced antagonistic-type inhibition. Applying nisin along with acidic calcium sulfate should be further investigated for efficacy on RTE meat surfaces. © 2010 Institute of Food Technologists®

In vitro comparison of the activity of various antibiotics and drugs against new Taiwan isolates and standard strains of avian mycoplasma.

PubMed

Lin, M Y

1987-01-01

Twenty-nine antibiotics or drugs were incorporated individually into mycoplasma agar to evaluate their inhibitory activity against avian mycoplasmas: 100 recent Taiwan isolates of 7 serotypes and 10 standard strains of 7 serotypes were tested. All of the standard strains were very sensitive to erythromycin, chlorotetracycline, doxycycline, minocycline, and tetracycline, but the local isolates were highly resistant to these antibiotics. The drugs or antibiotics that possessed an MIC90 of 50 micrograms/ml or less against the local isolates were tiamulin (less than 0.4 micrograms/ml), lincospectin (2.7), josamycin (2.7), lincomycin (3.0), spectinomycin (4.8), tylosin (6.0), kanamycin (6.0), chloramphenicol (6.0), gentamicin (7.5), apramycin (24.5), doxycycline (27.4), minocycline (29.0), spiramycin (30.0), colistin (44.3), leucomycin (45.0), and streptomycin (50.0). The MIC90 of the other antibiotics or drugs was greater than 50 micrograms/ml. None of the isolates or strains were sensitive to nalidixic acid, ronidazole, penicillin, ampicillin, cephalexin, carbadox, or four sulfa drugs at a concentration about 5 times the therapeutic level.

Discrepancy in Vancomycin AUC/MIC Ratio Targeted Attainment Based upon the Susceptibility Testing in Staphylococcus aureus.

PubMed

Eum, Seenae; Bergsbaken, Robert L; Harvey, Craig L; Warren, J Bryan; Rotschafer, John C

2016-09-27

This study demonstrated a statistically significant difference in vancomycin minimum inhibitory concentration (MIC) for Staphylococcus aureus between a common automated system (Vitek 2) and the E-test method in patients with S. aureus bloodstream infections. At an area under the serum concentration time curve (AUC) threshold of 400 mg∙h/L, we would have reached the current Infectious Diseases Society of America (IDSA)/American Society of Health System Pharmacists (ASHP)/Society of Infectious Diseases Pharmacists (SIDP) guideline suggested AUC/MIC target in almost 100% of patients while using the Vitek 2 MIC data; however, we could only generate 40% target attainment while using E-test MIC data ( p < 0.0001). An AUC of 450 mg∙h/L or greater was required to achieve 100% target attainment using either Vitek 2 or E-test MIC results.

[Molecular epidemiology and antifungal susceptibility of Candida species isolated from urine samples of patients in intensive care unit].

PubMed

Yüksekkaya, Serife; Fındık, Duygu; Arslan, Uğur

2011-01-01

The aims of this study were to analyse the amphotericin B and fluconazole susceptibility and molecular epidemiology of Candida strains (Candida albicans, Candida tropicalis and Candida glabrata) isolated from the urine samples of patients hospitalized in the intensive care unit. Identification of the isolates was done according to microscopic morphology (chlamydospor, blastospor, pseudohyphae and true hyphae) on cornmeal agar, germ tube formation and carbohydrate assimilation patterns (API ID 32C bioMérieux, France). Antifungal susceptibilities of the isolates were determined by in vitro broth microdilution method recommended by Clinical and Laboratory Standards Institute (CLSI). To investigate the clonal relationship of the isolates, randomly amplified polymorphic DNA (RAPD) analysis was performed by using Cnd3 primer. Of the 56 Candida isolates minimum inhibitory concentration (MIC) ranges, MIC50 and MIC90 values for amphotericin B were 0.125-1 µg/ml, 0.125 and 0.5 µg/ml for C.albicans, 0.125-1 µg/ml, 0.25 and 1 µg/ml for C.tropicalis and 0.125-1 µg/ml, 0.25 and 1 µg/ml for C.glabrata, respectively. Fluconazole MIC ranges, MIC50 and MIC90 values were 0.25-4 µg/ml, 0.25 and 0.5 µg/ml for C.albicans, 0.25-16 µg/ml, 0.5 and 1 µg/ml for C.tropicalis and 0.5-64 µg/ml, 8 and 16 µg/ml for C.glabrata, respectively. For amphotericin B, none of the isolates had high MIC values (MIC > 1 µg/ml). While one of the C.glabrata isolates was resistant to fluconazole (MIC ≥ 64 µg/ml), one C.tropicalis and two C.glabrata isolates were dose-dependent susceptible (MIC: 16-32 µg/ml). The results of RAPD analysis indicated an exogenous spread from two clones for C.albicans, one clone for C.glabrata and one clone for C.tropicalis. This study underlines the importance of molecular epidemiological analysis of clinical samples together with hospital environmental samples in terms of Candida spp. To determine the exogenous origin for the related strains and to prevent nosocomial Candida infections.

Pharmacokinetics, milk penetration and PK/PD analysis by Monte Carlo simulation of marbofloxacin, after intravenous and intramuscular administration to lactating goats.

PubMed

Lorenzutti, A M; Litterio, N J; Himelfarb, M A; Zarazaga, M D P; San Andrés, M I; De Lucas, J J

2017-12-01

The main objectives of this study were (i) to evaluate the serum pharmacokinetic behaviour and milk penetration of marbofloxacin (MFX; 5 mg/kg), after intravenous (IV) and intramuscular (IM) administration in lactating goats and simulate a multidose regimen on steady-state conditions, (ii) to determine the minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) of coagulase negative staphylococci (CNS) isolated from caprine mastitis in Córdoba, Argentina and (iii) to make a PK/PD analysis by Monte Carlo simulation from steady-state pharmacokinetic parameters of MFX by IV and IM routes to evaluate the efficacy and risk of the emergence of resistance. The study was carried out with six healthy, female, adult Anglo Nubian lactating goats. Marbofloxacin was administered at 5 mg/kg bw by IV and IM route. Serum and milk concentrations of MFX were determined with HPLC/uv. From 106 regional strains of CNS isolated from caprine mastitis in herds from Córdoba, Argentina, MICs and MPCs were determined. MIC 90 and MPC 90 were 0.4 and 6.4 μg/ml, respectively. MIC and MPC-based PK/PD analysis by Monte Carlo simulation indicates that IV and IM administration of MFX in lactating goats may not be adequate to recommend it as an empirical therapy against CNS, because the most exigent endpoints were not reached. Moreover, this dose regimen could increase the probability of selecting mutants and resulting in emergence of resistance. Based on the results of Monte Carlo simulation, the optimal dose of MFX to achieve an adequate antimicrobial efficacy should be 10 mg/kg, but it is important take into account that fluoroquinolones are substrates of efflux pumps, and this fact may determine that assumption of linear pharmacokinetics at high doses of MFX may be incorrect. © 2017 John Wiley & Sons Ltd.

Anti-glycation and anti-oxidation properties of Capsicum frutescens and Curcuma longa fruits: possible role in prevention of diabetic complication.

PubMed

Khan, Ibrar; Ahmad, Haroon; Ahmad, Bashir

2014-09-01

The accumulation of advanced glycationend products (AGE's) in the body, due to the non-enzymatic glycation of proteins is associated with several pathological conditions like aging and diabetes mellitus. Hence a plant having anti-glycation and anti-oxidation potentials may serve as therapeutic agent for diabetic complications and aging. In this study the anti-glycation and anti-oxidation properties of crude methanolic extracts of fruits of Capsicum frutescens and Curcuma longa were investigated. Among the two C. frutescens had more anti-glycation ability with a minimum inhibitory concentration (MIC50) of 90βg/mLas compared to 324βg/mL MIC50 of C. longa. Curcuma longa had the more anti-oxidation potential i.e. 35.01, 30.83 and 28.08% at 0.5mg, 0.25mg and 0.125mg respectively.

Direct detection by real-time PCR of ftsI gene mutations affecting MICs of β-lactam agents for Haemophilus influenzae isolates from meningitis.

PubMed

Kishii, Kozue; Morozumi, Miyuki; Chiba, Naoko; Ono, Akiko; Ubukata, Kimiko

2011-10-01

One resistance mechanism of Haemophilus influenzae to ampicillin involves decreased affinity of penicillin-binding protein (PBP) 3 for β-lactam antibiotics reflecting amino acid substitutions in PBP3 encoded by the ftsI gene. Three amino acid substitutions, Ser385Thr, Arg517His, and Asn526Lys, are especially responsible for β-lactam resistance. We constructed a new real-time polymerase chain reaction (PCR) to directly detect these substitutions in addition to 16S ribosomal RNA (rRNA), cap, and bla(TEM) genes. Our real-time PCR was evaluated using 206 clinical H. influenzae strains isolated from pediatric patients with meningitis. Relative sensitivities and specificities of real-time PCR were 90.5-100% and 96.3-100% for all resistance classes compared with our previously reported conventional PCR. In addition, real-time PCR shortened time required from 3 h by conventional PCR to 1.5 h. When correlations between combinations of amino acid substitutions in the ftsI gene detected by real-time PCR and minimum inhibitory concentrations (MICs) of β-lactam antibiotics were evaluated, MIC(90)s of ampicillin for β-lactamase-nonproducing ampicillin-intermediate-resistant strains with Asn526Lys, β-lactamase-nonproducing, ampicillin-resistant strains with Ser385Thr, and β-lactamase-nonproducing ampicillin-resistant strains with both Asn526Lys and Ser385Thr, respectively, were two, four, and eight times higher than those for sensitive strains. Similarly, MIC(90)s of cephalosporins for these strains, respectively, were two, 16-32, and 16-32 times higher than those for sensitive strains. Thus, real-time PCR can guide antibiotic use.

Tris-EDTA significantly enhances antibiotic efficacy against multidrug-resistant Pseudomonas aeruginosa in vitro.

PubMed

Buckley, Laura M; McEwan, Neil A; Nuttall, Tim

2013-10-01

Multidrug-resistant Pseudomonas aeruginosa commonly complicates chronic bacterial otitis in dogs. The aim of this in vitro study was to determine the effect of ethylenediaminetetraacetic acid-tromethamine (Tris-EDTA) on the minimal bactericidal concentrations (MBCs) and minimal inhibitory concentrations (MICs) of marbofloxacin and gentamicin for multidrug-resistant P. aeruginosa isolates from cases of canine otitis. Eleven isolates were identified as multidrug resistant on disc diffusion; 10 were resistant to marbofloxacin and two were resistant to gentamicin. Isolates were incubated for 90 min with each antibiotic alone and in combination with Tris-EDTA at concentrations of 0.075 μg/mL to 5 mg/mL for marbofloxacin, 0.001 μg/mL to 10 mg/mL for gentamicin and 17.8:4.7 to 0.14:0.04 mg/mL for Tris-EDTA. Positive and negative controls were included. Aliquots of each antibiotic and/or Tris-EDTA concentration were subsequently transferred to sheep blood agar to determine the MBCs, and tryptone soy broth was added to the remaining suspensions to determine the MICs. Tris-EDTA alone was bacteriostatic but not bactericidal at any concentration. The addition of Tris-EDTA significantly reduced the median MBC (from 625 to 468.8 μg/mL; P < 0.001) and MIC (from 29.3 to 2.4 μg/mL; P = 0.008) of marbofloxacin, and the median MBC (from 625 to 39.1 μg/mL) and MIC (from 19.5 to 1.2 μg/mL) of gentamicin (both P < 0.001). Tris-EDTA significantly reduced the MBCs and MICs of marbofloxacin and gentamicin for multidrug-resistant P. aeruginosa in vitro. This may be of use to clinicians managing these infections in dogs. © 2013 ESVD and ACVD.

Balancing vancomycin efficacy and nephrotoxicity: should we be aiming for trough or AUC/MIC?

PubMed

Patel, Karisma; Crumby, Ashley S; Maples, Holly D

2015-04-01

Sixty years later, the question that still remains is how to appropriately utilize vancomycin in the pediatric population. The Infectious Diseases Society of America published guidelines in 2011 that provide guidance for dosing and monitoring of vancomycin in adults and pediatrics. However, goal vancomycin trough concentrations of 15-20 μg/mL for invasive infections caused by methicillin-resistant Staphylococcus aureus were based primarily on adult pharmacokinetic and pharmacodynamic data that achieved an area under the curve to minimum inhibitory concentration ratio (AUC/MIC) of ≥400. Recent pediatric literature shows that vancomycin trough concentrations needed to achieve the target AUC/MIC are different than the adult goal troughs cited in the guidelines. This paper addresses several thoughts, including the role of vancomycin AUC/MIC in dosing strategies and safety monitoring, consistency in laboratory reporting, and future directions for calculating AUC/MIC in pediatrics.

Tolerance response of multidrug-resistant Salmonella enterica strains to habituation to Origanum vulgare L. essential oil

PubMed Central

Monte, Daniel F. M.; Tavares, Adassa G.; Albuquerque, Allan R.; Sampaio, Fábio C.; Oliveira, Tereza C. R. M.; Franco, Octavio L.; Souza, Evandro L.; Magnani, Marciane

2014-01-01

Multidrug-resistant Salmonella enterica isolates from human outbreaks or from poultry origin were investigated for their ability to develop direct-tolerance or cross-tolerance to sodium chloride, potassium chloride, lactic acid, acetic acid, and ciprofloxacin after habituation in subinhibitory amounts ( of the minimum inhibitory concentration – (MIC) and of the minimum inhibitory concentration – MIC) of Origanum vulgare L. essential oil (OVEO) at different time intervals. The habituation of S. enterica to OVEO did not induce direct-tolerance or cross-tolerance in the tested strains, as assessed by the modulation of MIC values. However, cells habituated to OVEO maintained or increased susceptibility to the tested antimicrobials agents, with up to fourfold double dilution decrease from previously determined MIC values. This study reports for the first time the non-inductive effect of OVEO on the acquisition of direct-tolerance or cross-tolerance in multidrug-resistant S. enterica strains to antimicrobial agents that are largely used in food preservation, as well as to CIP, the therapeutic drug of salmonellosis. PMID:25566231

Antifungal Activity of Commercial Essential Oils and Biocides against Candida Albicans.

PubMed

Serra, Elisa; Hidalgo-Bastida, Lilia Araida; Verran, Joanna; Williams, David; Malic, Sladjana

2018-01-25

Management of oral candidosis, most frequently caused by Candida albicans , is limited due to the relatively low number of antifungal drugs and the emergence of antifungal tolerance. In this study, the antifungal activity of a range of commercial essential oils, two terpenes, chlorhexidine and triclosan was evaluated against C. albicans in planktonic and biofilm form. In addition, cytotoxicity of the most promising compounds was assessed using murine fibroblasts and expressed as half maximal inhibitory concentrations (IC50). Antifungal activity was determined using a broth microdilution assay. The minimum inhibitory concentration (MIC) was established against planktonic cells cultured in a range of concentrations of the test agents. The minimal biofilm eradication concentration (MBEC) was determined by measuring re-growth of cells after pre-formed biofilm was treated for 24 h with the test agents. All tested commercial essential oils demonstrated anticandidal activity (MICs from 0.06% ( v / v ) to 0.4% ( v / v )) against planktonic cultures, with a noticeable increase in resistance exhibited by biofilms (MBECs > 1.5% ( v / v )). The IC50s of the commercial essential oils were lower than the MICs, while a one hour application of chlorhexidine was not cytotoxic at concentrations lower than the MIC. In conclusion, the tested commercial essential oils exhibit potential as therapeutic agents against C. albicans , although host cell cytotoxicity is a consideration when developing these new treatments.

Evaluation of enrofloxacin use in koalas (Phascolarctos cinereus) via population pharmacokinetics and Monte Carlo simulation.

PubMed

Black, L A; Landersdorfer, C B; Bulitta, J B; Griffith, J E; Govendir, M

2014-06-01

Clinically normal koalas (n = 6) received a single dose of intravenous enrofloxacin (10 mg/kg). Serial plasma samples were collected over 24 h, and enrofloxacin concentrations were determined via high-performance liquid chromatography. Population pharmacokinetic modeling was performed in S-ADAPT. The probability of target attainment (PTA) was predicted via Monte Carlo simulations (MCS) using relevant target values (30-300) based on the unbound area under the curve over 24 h divided by the minimum inhibitory concentration (MIC) (fAUC0-24 /MIC), and published subcutaneous data were incorporated (Griffith et al., 2010). A two-compartment disposition model with allometrically scaled clearances (exponent: 0.75) and volumes of distribution (exponent: 1.0) adequately described the disposition of enrofloxacin. For 5.4 kg koalas (average weight), point estimates for total clearance (SE%) were 2.58 L/h (15%), central volume of distribution 0.249 L (14%), and peripheral volume 2.77 L (20%). MCS using a target fAUC0-24 /MIC of 40 predicted highest treatable MICs of 0.0625 mg/L for intravenous dosing and 0.0313 mg/L for subcutaneous dosing of 10 mg/kg enrofloxacin every 24 h. Thus, the frequently used dosage of 10 mg/kg enrofloxacin every 24 h subcutaneously may be appropriate against gram-positive bacteria with MICs ≤ 0.03 mg/L (PTA > 90%), but appears inadequate against gram-negative bacteria and Chlamydiae in koalas. © 2013 John Wiley & Sons Ltd.

Cefazolin potency against methicillin-resistant Staphylococcus aureus: a microbiologic assessment in support of a novel drug delivery system for skin and skin structure infections

PubMed Central

Nicolau, David P; Silberg, Barry N

2017-01-01

Introduction Despite aggressive medical and surgical management, the resolution of skin and skin structure infections is often difficult due to insufficient host response, reduced drug penetration, and a high prevalence of resistance organisms such as methicillin-resistant Staphylococcus aureus (MRSA). As a result of these factors, conventional management often consists of prolonged broad-spectrum systemic antimicrobials. An alternative therapy in development, ultrasonic drug dispersion (UDD), uses a subcutaneous injection followed by external trans-cutaneous ultrasound to deliver high tissue concentrations of cefazolin with limited systemic exposure. While it is postulated that these high concentrations may be suitable to treat more resistant organisms such as MRSA, the cefazolin minimum inhibitory concentration (MIC) distribution for this organism is currently unknown. Materials and methods We assessed the potency of cefazolin against a collection of 1,239 MRSA from 42 US hospitals using Clinical Laboratory Standard Institute-defined broth micro-dilution methodology. Results The cefazolin MIC inhibiting 50% of the isolates was 64 mg/L; 81% had MICs ≤128 and nearly all (99.9%) had MICs ≤512 mg/L. Conclusion The overwhelming majority of MRSA had cefazolin MICs that were considerably lower than achievable tissue concentrations (≥1,000 mg/L) using this novel drug delivery system. While the currently defined cefazolin MRSA phenotypic profile precludes the use of parenteral administration, techniques that deliver local exposures in excess of these inhibitory concentrations may provide a novel treatment strategy for skin and skin structure infections. PMID:28794647

Comparative antimicrobial characterization of LBM415 (NVP PDF-713), a new peptide deformylase inhibitor of clinical importance.

PubMed

Fritsche, Thomas R; Sader, Helio S; Cleeland, Roy; Jones, Ronald N

2005-04-01

LBM415 (NVP PDF-713) is the first member of the peptide deformylase (PDF) inhibitor class being developed for clinical trials as a parenteral and oral agent for treatment of community-acquired respiratory tract disease and serious infections caused by antimicrobial-resistant gram-positive cocci. In this study susceptibility testing results from 1,306 recent clinical isolates selected to over-represent resistance trends among the species were summarized. All staphylococci (153 strains; MIC at which 90% of isolates were inhibited [MIC90], 2 microg/ml), Streptococcus pneumoniae (170 strains; MIC90, 1 microg/ml), other streptococci (150 strains; MIC90, 1 microg/ml), enterococci (104 strains; MIC90, 4 microg/ml), Moraxella catarrhalis (103 strains; MIC90, 0.5 microg/ml), and Legionella pneumophila (50 strains; MIC90, 0.12 microg/ml) were inhibited at < or = 8 microg of LBM415/ml, as were 97% of Haemophilus influenzae isolates (300 strains; MIC90, 4 to 8 microg/ml). Among other bacterial groups, 100% of gram-positive and -negative anaerobes, including 22 Bacteroides spp. strains (31 strains total; MIC90, 1 microg/ml), were inhibited by < or = 4 microg/ml, whereas Enterobacteriaceae (112 strains) and most nonfermentative bacilli (107 strains) were not inhibited at readily achievable concentrations. The compound was found to have a dominantly bacteriostatic action, and spontaneous single-step mutational rates occurred at low levels (10(-6) to <10(-8)). Drug interaction studies failed to identify any class-specific synergistic interactions, nor were antagonistic interactions observed. Variations in broth and agar MIC test conditions demonstrated that, whereas the agar-based method trended towards a 1-log2 dilution-higher MIC than the broth method and was inoculum dependent, other variations in incubation environment, medium supplements, pH, or calcium concentration had little influence on LBM415 MIC results. Use of the efflux inhibitor phe-arg-beta-naphthylamide showed an average of 1 log2 dilution decrease in H. influenzae MICs, demonstrating the contribution of efflux pumps in influencing susceptibility to PDF inhibitors. The in vitro activity of LBM415 against targeted bacterial species, including resistant subsets, and other laboratory characteristics of this novel compound demonstrate the potential of PDF inhibitors as a new class of antimicrobial agents.

A randomized pharmacokinetic and pharmacodynamic evaluation of every 8-hour and 12-hour dosing strategies of vancomycin and cefepime in neurocritically-ill patients.

PubMed

Kassel, Lynn E; Van Matre, Edward T; Foster, Charles J; Fish, Douglas N; Mueller, Scott W; Sherman, Deb S; Wempe, Michael F; MacLaren, Robert; Neumann, Robert T; Kiser, Tyree H

2018-06-15

Neurocritically-ill patients have clinically significant alterations in pharmacokinetic parameters of renally-eliminated medications, which may result in subtherapeutic plasma and cerebrospinal fluid antibiotic concentrations. Prospective, randomized, open-label study of adult neurocritically-ill patients treated with vancomycin and cefepime. Vancomycin 15 mg/kg and cefepime 2 g were dosed at every 8 or 12-hour intervals. The primary outcomes were the achievement of pharmacodynamic targets related to time of unbound drug above minimum inhibitory concentrations (MIC) for 60% or more of the dosing interval (fT>MIC ≥60%) for β-lactams and ratio of 24-hour area under the curve (AUC):MIC of 400 or greater for vancomycin. Twenty patients were included in the study. Patients were divided equally between the every 12-hour (n=10) and every 8-hour (n=10) dosing groups. Patients (mean age of 51.8 ± 11 years) were primarily male (60%) and Caucasian (95%), and the majority had an admission diagnosis of intracranial hemorrhage (80%). Compared to the every 12-hour group, the every 8-hour vancomycin group achieved target trough concentrations (>15 μg/ml) significantly more frequently at initial measurement (0% vs 80%, p<0.01) and at 7 to 10 days (0% vs 90%, p=0.045) and achieved pharmacodynamic targets more frequently at increasing MICs. Similarly, compared to every 12-hour dosing, the every 8-hour cefepime dosing strategy significantly increased pharmacodynamic target attainment (fT>MIC ≥60%) at an MIC of 8 μg/ml (20% vs 70%, p=0.02). This study demonstrated that more frequent dosing of vancomycin and cefepime is required to achieve optimal pharmacodynamic targets in adult neurocritically-ill patients. The need for increased total daily doses is potentially secondary to the development of augmented renal clearance. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

The Effect of Polyherbal Medicines Used for the Treatment of Tuberculosis on Other Opportunistic Organisms of Humans Infected with Tuberculosis.

PubMed

Famewo, Elizabeth Bosede; Clarke, Anna Maria; Afolayan, Anthony Jide

2017-10-01

In many immunocompromised patients, opportunistic bacterial and fungal infections are common. Polyherbal medicines examined in this study are used by the indigenous people of South Africa for the treatment of tuberculosis (TB) and other opportunistic infections associated with TB. To evaluate the antibacterial and antifungal activity of nine polyherbal remedies against four Gram-positive and Gram-negative bacteria respectively and three fungi. Agar dilution method was used to determine the minimum inhibitory concentration (MIC) of the remedies against the organisms. The inhibitory activity of the polyherbal medicines based on the overall MIC revealed that HBfs and FB remedies were the most active remedies against the bacterial isolates at the concentration of 2.5 mg/mL, followed by HBts remedy at 5.0 mg/mL. However, the MIC valves of KWTa, KWTb, KWTc, HBss, EL and AL remedies were higher than 5.0 mg/mL which was the highest concentration used. Only KWTa remedy showed activity against Aspergillus niger and Aspergillus fumigatus with the MIC value of 2.5 mg/mL. While KWTc and HBts had the highest activity at 1.25 mg/mL against Candida albicans , the remaining remedies were active at 2.5 mg/mL. This study revealed that some of these polyherbal formulations have activities against some of the opportunistic bacterial and fungal isolates associated with TB patients. The capability of these remedies to inhibit the organisms is an indication that they are a potential broad-spectrum antimicrobial agent. However, the remedies that are inactive might contain stimulant effects on the immune system. In the Eastern Cape Province of South Africa, no study has been reported on the effect of polyherbal remedies used for the treatment of TB on the opportunistic pathogen. This study therefore revealed that some of the polyherbal medicines possess activity against bacterial and fungal pathogens. Abbreviations used: TB: Tuberculosis; MIC: Minimum Inhibitory Concentration; CFU/ML: Colony Forming Unit Per Mill.

Effects of sub-minimum inhibitory concentrations of antimicrobial agents on Streptococcus mutans biofilm formation.

PubMed

Dong, Liping; Tong, Zhongchun; Linghu, Dake; Lin, Yuan; Tao, Rui; Liu, Jun; Tian, Yu; Ni, Longxing

2012-05-01

Many studies have demonstrated that sub-minimum inhibitory concentrations (sub-MICs) of antimicrobial agents can inhibit bacterial biofilm formation. However, the mechanisms by which antimicrobial agents at sub-MICs inhibit biofilm formation remain unclear. At present, most studies are focused on Gram-negative bacteria; however, the effects of sub-MICs of antimicrobial agents on Gram-positive bacteria may be more complex. Streptococcus mutans is a major cariogenic bacterium. In this study, the S. mutans growth curve as well as the expression of genes related to S. mutans biofilm formation were evaluated following treatment with 0.5× MIC of chlorhexidine (CHX), tea polyphenols and sodium fluoride (NaF), which are common anticaries agents. The BioFlux system was employed to generate a biofilm under a controlled flow. Morphological changes of the S. mutans biofilm were observed and analysed using field emission scanning electron microscopy and confocal laser scanning microscopy. The results indicated that these three common anticaries agents could significantly upregulate expression of the genes related to S. mutans biofilm formation, and S. mutans exhibited a dense biofilm with an extensive extracellular matrix following treatment with sub-MICs of NaF and CHX. These findings suggest that sub-MICs of anticaries agents favour S. mutans biofilm formation, which might encourage dental caries progression. Copyright © 2012 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Observations of resistance through minimum inhibitory concentrations trends for respiratory specimens of commonly isolated organisms.

PubMed

Gillard, Christopher J; Al-Dahir, Sara; Brakta, Fatima

2016-03-01

The objective of this study was to determine minimum inhibitory concentration (MIC) trends among common bacterial organisms found in respiratory isolates in the trauma intensive care unit setting. In this retrospective observational study, MIC data was reviewed over a three year period from January 2009 to December 2011 for the three most frequently identified organisms isolated from respiratory specimens in a trauma intensive care unit along with corresponding hospital data. The most frequently isolated bacterial species identified were Staphylococcus aureus (229 isolates), Pseudomonas aeruginosa (129 isolates), and Acinetobacter species (87 isolates) in the analysis within our institution from 2009-2011. There was considerable variability among the MIC trends for the analyzed organisms. For Pseudomonas isolates, observed sensitivities were as high as 100% for antibiotics ciprofloxacin and imipenem in 2009, but decreased over the next two years in 2010 and 2011. There was considerable variability among the MIC trends for Acinetobacter over the three year period for the antibiotics tested. The MIC data for most Staphylococcus aureus isolates over the three years were sensitive to vancomycin with little change in the observed MIC data. The data reported is observational and indicates the need for future studies to establish a valid relationship of the MIC data over time in our institution particularly among our gram negative organisms, to monitor patterns of antimicrobial resistance. Copyright © 2016 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

The pharmacokinetic-pharmacodynamic modeling and cut-off values of tildipirosin against Haemophilus parasuis

PubMed Central

Lei, Zhixin; Liu, Qianying; Yang, Bing; Ahmed, Saeed; Cao, Jiyue; He, Qigai

2018-01-01

The goal of this study was to establish the epidemiological, pharmacodynamic cut-off values, optimal dose regimens for tildipirosin against Haemophilus parasuis. The minimum inhibitory concentrations (MIC) of 164 HPS isolates were determined and SH0165 whose MIC (2 μg/ml ) were selected for PD analysis. The ex vivo MIC in plasma of SH0165 was 0.25 μg/ml which was 8 times lower than that in TSB. The bacteriostatic, bactericidal and elimination activity (AUC24h/MIC) in serum were 26.35, 52.27 and 73.29 h based on the inhibitory sigmoid Emax modeling. The present study demonstrates that 97.9% of the wild-type (WT) isolates were covered when the epidemiological cut-off value (ECV) was set at 8 μg/ml. The parameters including AUC24h, AUC, T1/2, Cmax, CLb and MRT in PELF were 19.56, 60.41, 2.32, 4.02, 56.6, and 2.63 times than those in plasma, respectively. Regarding the Monte Carlo simulation, the COPD was defined as 0.5 μg/ml in vitro, and the optimal doses to achieve bacteriostatic, bactericidal and elimination effect were 1.85, 3.67 and 5.16 mg/kg for 50% target, respectively, and 2.07, 4.17 and 5.78 mg/kg for 90% target, respectively. The results of this study offer a more optimised alternative for clinical use and demonstrated that 4.17 mg/kg of tildipirosin by intramuscular injection could have an effect on bactericidal activity against HPS. These values are of great significance for the effective treatment of HPS infections, but it also be deserved to be validated in clinical practice in the future research. PMID:29416722

Minimum inhibitory (MIC) and minimum microbicidal concentration (MMC) of polihexanide and triclosan against antibiotic sensitive and resistant Staphylococcus aureus and Escherichia coli strains

PubMed Central

Assadian, Ojan; Wehse, Katrin; Hübner, Nils-Olaf; Koburger, Torsten; Bagel, Simone; Jethon, Frank; Kramer, Axel

2011-01-01

Background: An in-vitro study was conducted investigating the antimicrobial efficacy of polihexanide and triclosan against clinical isolates and reference laboratory strains of Staphylococcus aureus and Escherichia coli. Methods: The minimal inhibitory concentration (MIC) and the minimal microbicidal concentration (MMC) were determined following DIN 58940-81 using a micro-dilution assay and a quantitative suspension test following EN 1040. Polihexanide was tested in polyethylene glycol 4000, triclosan in aqueous solutions. Results: Against all tested strains the MIC of polihexanide ranged between 1–2 µg/mL. For triclosan the MICs varied depending on strains ranging between 0.5 µg/mL for the reference strains and 64 µg/mL for two clinical isolates. A logRF >5 without and logRF >3 with 0.2% albumin burden was achieved at 0.6 µg/mL triclosan. One exception was S. aureus strain H-5-24, where a triclosan concentration of 0.6 µg/mL required 1 minute without and 10 minutes with albumin burden to achieve the same logRFs. Polihexanide achieved a logRF >5 without and logRF >3 with albumin burden at a concentration of 0.6 µg/mL within 30 sec. The exception was the North-German epidemic MRSA strain, were an application time of 5 minutes was required. Conclusion: The clinical isolates of E. coli generally showed higher MICs against triclosan, both in the micro-dilution assay as well in the quantitative suspension test than comparable reference laboratory strains. For polihexanide and triclosan strain dependant susceptibility was shown. However, both antimicrobial compounds are effective when used in concentrations common in practice. PMID:22242087

Effects of Total Alkaloids of Sophora alopecuroides on Biofilm Formation in Staphylococcus epidermidis

PubMed Central

Li, Xue; Guan, Cuiping; He, Yulong; Wang, Yujiong

2016-01-01

Staphylococcus epidermidis (S. epidermidis) is an opportunistic pathogen with low pathogenicity and a cause of the repeated outbreak of bovine mastitis in veterinary clinical settings. In this report, a biofilm model of S. epidermidis was generated and the minimal inhibitory concentration (MIC) and sub-MIC (SMIC) on bacterial cultures were assessed for the following agents: total alkaloids of Sophora alopecuroides (TASA), ciprofloxacin (CIP), and erythromycin (ERY). The formation and characteristic parameters of biofilm were analyzed in terms of XTT assay, silver staining, and confocal laser scanning microscope (CLSM). Results showed that a sub-MIC of TASA could inhibit 50% biofilm of bacterial activity, while 250-fold MIC of CIP and ERY MICs only inhibited 50% and 47% of biofilm formation, respectively. All three agents could inhibit the biofilm formation at an early stage, but TASA showed a better inhibitory effect on the late stage of biofilm thickening. A morphological analysis using CLSM further confirmed the destruction of biofilm by these agents. These results thus suggest that TASA has an inhibitory effect on biofilm formation of clinic S. epidermidis, which may be a potential agent warranted for further study on the treatment prevention of infection related to S. epidermidis in veterinary clinic. PMID:27413745

In Vivo Pharmacokinetics/Pharmacodynamics of Cefquinome in an Experimental Mouse Model of Staphylococcus Aureus Mastitis following Intramammary Infusion

PubMed Central

Yu, Yang; Zhou, Yu-Feng; Chen, Mei-Ren; Li, Xiao; Qiao, Gui-Lin; Sun, Jian; Liao, Xiao-Ping; Liu, Ya-Hong

2016-01-01

Staphylococcus aureus remains the major cause of morbidity of bovine mastitis worldwide leading to massive economic losses. Cefquinome is a fourth generation cephalosporin, which preserves susceptibility and antibacterial activity against S. aureus. This work aims to study the pharmacokinetic (PK) and pharmacodynamic (PD) modeling following intramammary administration of cefquinome against S. aureus mastitis. The mouse model of S. aureus mastitis was developed for the PK/PD experiments. The plasma PK characteristics after intramammary injection of cefquinome at various single doses of 25, 50, 100, 200, 400 μg per gland (both fourth pairs of glands: L4 and R4) were calculated using one-compartment and first-order absorption model. PD study was investigated based on twenty-one intermittent dosing regimens, of which total daily dose ranged from 25 to 4800 μg per mouse and dosage intervals included 8, 12 or 24 h. The sigmoid Emax model of inhibitory effect was employed for PK/PD modeling. The results of PK/PD integration of cefquinome against S. aureus suggested that the percentage of duration that drug concentration exceeded the minimal inhibitory concentration (%T>MIC) and the ratio of area under time-concentration curve over MIC (AUC/MIC) are important indexes to evaluate the antibacterial activity. The PK/PD parameters of %T>MIC and AUC0-24/MIC were 35.98% and 137.43 h to obtain a 1.8 logCFU/gland reduction of bacterial colony counts in vivo, against S. aureus strains with cefquinome MIC of 0.5μg/ml. PMID:27218674

In Vivo Pharmacokinetics/Pharmacodynamics of Cefquinome in an Experimental Mouse Model of Staphylococcus Aureus Mastitis following Intramammary Infusion.

PubMed

Yu, Yang; Zhou, Yu-Feng; Chen, Mei-Ren; Li, Xiao; Qiao, Gui-Lin; Sun, Jian; Liao, Xiao-Ping; Liu, Ya-Hong

2016-01-01

Staphylococcus aureus remains the major cause of morbidity of bovine mastitis worldwide leading to massive economic losses. Cefquinome is a fourth generation cephalosporin, which preserves susceptibility and antibacterial activity against S. aureus. This work aims to study the pharmacokinetic (PK) and pharmacodynamic (PD) modeling following intramammary administration of cefquinome against S. aureus mastitis. The mouse model of S. aureus mastitis was developed for the PK/PD experiments. The plasma PK characteristics after intramammary injection of cefquinome at various single doses of 25, 50, 100, 200, 400 μg per gland (both fourth pairs of glands: L4 and R4) were calculated using one-compartment and first-order absorption model. PD study was investigated based on twenty-one intermittent dosing regimens, of which total daily dose ranged from 25 to 4800 μg per mouse and dosage intervals included 8, 12 or 24 h. The sigmoid Emax model of inhibitory effect was employed for PK/PD modeling. The results of PK/PD integration of cefquinome against S. aureus suggested that the percentage of duration that drug concentration exceeded the minimal inhibitory concentration (%T>MIC) and the ratio of area under time-concentration curve over MIC (AUC/MIC) are important indexes to evaluate the antibacterial activity. The PK/PD parameters of %T>MIC and AUC0-24/MIC were 35.98% and 137.43 h to obtain a 1.8 logCFU/gland reduction of bacterial colony counts in vivo, against S. aureus strains with cefquinome MIC of 0.5μg/ml.

Comparative in vitro study of the antimicrobial activities of different commercial antibiotic products of vancomycin

PubMed Central

2011-01-01

Background One of the most critical problems about antimicrobial therapy is the increasing resistance to antibiotics. Previous studies have shown that there is a direct relation between erroneous prescription, dosage, route, duration of the therapy and the antibiotics resistance. Other important point is the uncertainty about the quality of the prescribed medicines. Some physicians believe that generic drugs are not as effective as innovator ones, so it is very important to have evidence that shows that all commercialized drugs are suitable for therapeutic use. Methods Microbial assays were used to establish the potency, the Minimal Inhibitory Concentrations (MICs), the Minimal Bactericidal Concentration (MBCs), the critical concentrations, and the production of spontaneous mutants that are resistant to vancomycin. Results The microbial assay was validated in order to determine the Vancomycin potency of the tasted samples. All the products showed that have potency values between 90 - 115% (USP requirement). The products behave similarly because the MICs, The MBCs, the critical concentrations, the critical concentrations ratios between standard and samples, and the production of spontaneous mutants don't have significant differences. Conclusions All products analyzed by microbiological tests, show that both trademarks and generics do not have statistical variability and the answer of antimicrobial activity Show also that they are pharmaceutical equivalents. PMID:21777438

Comparative in vitro study of the antimicrobial activities of different commercial antibiotic products of vancomycin.

PubMed

Diaz, Jorge A; Silva, Edelberto; Arias, Maria J; Garzón, María

2011-07-21

One of the most critical problems about antimicrobial therapy is the increasing resistance to antibiotics. Previous studies have shown that there is a direct relation between erroneous prescription, dosage, route, duration of the therapy and the antibiotics resistance. Other important point is the uncertainty about the quality of the prescribed medicines. Some physicians believe that generic drugs are not as effective as innovator ones, so it is very important to have evidence that shows that all commercialized drugs are suitable for therapeutic use. Microbial assays were used to establish the potency, the Minimal Inhibitory Concentrations (MICs), the Minimal Bactericidal Concentration (MBCs), the critical concentrations, and the production of spontaneous mutants that are resistant to vancomycin. The microbial assay was validated in order to determine the Vancomycin potency of the tasted samples. All the products showed that have potency values between 90 - 115% (USP requirement). The products behave similarly because the MICs, The MBCs, the critical concentrations, the critical concentrations ratios between standard and samples, and the production of spontaneous mutants don't have significant differences. All products analyzed by microbiological tests, show that both trademarks and generics do not have statistical variability and the answer of antimicrobial activity Show also that they are pharmaceutical equivalents.

IN VITRO EFFICACY OF EXTRACTS FROM PLANTS USED BY SMALL-HOLDER FARMERS IN THE TREATMENT OF DERMATOPHILOSIS IN CATTLE.

PubMed

Ndhlovu, Daud N; Masika, Patrick J

2017-01-01

Bovine dermatophilosis, an important skin disease of cattle caused by Dermatophilus congolensis , negatively impacts the livelihoods of small-holder farmers in Zimbabwe. This impact is through, morbidity, loss of draught animal power, costs incurred to manage the disease, losses associated with devalued damaged hides and the resultant culling of some of the affected cattle. Due to the inaccessibility of conventional drugs to manage bovine dermatophilosis, farmers have been reported to use local medicinal plants to manage the disease. The aim of the study was to evaluate the in vitro antimicrobial activities of three plants that small-holder farmers in Zimbabwe used to manage bovine dermatophilosis. Dried plant materials were ground into powder and extracted individually using, water, 80 % acetone and 80 % methanol. The antimicrobial properties of the plants were evaluated against two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and one Gram-positive (Staphylococcus aureus) reference bacterial strains. They were further evaluated against a field isolate of Dermatophilus congolensis . The assays used were the disc diffusion, minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). Acetone and methanol extracts had superior inhibitory activities than did those of water. Pterocarpus angolensis DC extracts had better inhibitory properties with absolute MIC values of 0.156 - 5 mg/ml, Cissus Quadrangularis L had MIC values in the range 0.156 - 5 mg/ml while that of Catunaregam spinosa Thunb, Terveng was 0.156 - 10 mg/ml. Dermatophilus congolensis was more sensitive to Pterocarpus angolensis DC average MIC = 0.63 mg/ml than to Cissus quadrangularis L average MIC = 1.25 mg/ml and Catunaregam. spinosa Thunb, Terveng average MIC = 2.08 mg/ml. These results suggest the potential antibacterial activities of extracts of the three plants and hence farmers are, in a way, justified in using the plants. Better results (lower MIC) could be obtained by extracting and evaluating pure active compounds of the plants.

Comparison of methods to detect the in vitro activity of silver nanoparticles (AgNP) against multidrug resistant bacteria.

PubMed

Cavassin, Emerson Danguy; de Figueiredo, Luiz Francisco Poli; Otoch, José Pinhata; Seckler, Marcelo Martins; de Oliveira, Roberto Angelo; Franco, Fabiane Fantinelli; Marangoni, Valeria Spolon; Zucolotto, Valtencir; Levin, Anna Sara Shafferman; Costa, Silvia Figueiredo

2015-10-05

Multidrug resistant microorganisms are a growing challenge and new substances that can be useful to treat infections due to these microorganisms are needed. Silver nanoparticle may be a future option for treatment of these infections, however, the methods described in vitro to evaluate the inhibitory effect are controversial. This study evaluated the in vitro activity of silver nanoparticles against 36 susceptible and 54 multidrug resistant Gram-positive and Gram-negative bacteria from clinical sources. The multidrug resistant bacteria were oxacilin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus spp., carbapenem- and polymyxin B-resistant A. baumannii, carbapenem-resistant P. aeruginosa and carbapenem-resistant Enterobacteriaceae. We analyzed silver nanoparticles stabilized with citrate, chitosan and polyvinyl alcohol and commercial silver nanoparticle. Silver sulfadiazine and silver nitrate were used as control. Different methods were used: agar diffusion, minimum inhibitory concentration, minimum bactericidal concentration and time-kill. The activity of AgNPs using diffusion in solid media and the MIC methods showed similar effect against MDR and antimicrobial-susceptible isolates, with a higher effect against Gram-negative isolates. The better results were achieved with citrate and chitosan silver nanoparticle, both with MIC90 of 6.75 μg mL(-1), which can be due the lower stability of these particles and, consequently, release of Ag(+) ions as revealed by X-ray diffraction (XRD). The bactericidal effect was higher against antimicrobial-susceptible bacteria. It seems that agar diffusion method can be used as screening test, minimum inhibitory concentration/minimum bactericidal concentration and time kill showed to be useful methods. The activity of commercial silver nanoparticle and silver controls did not exceed the activity of the citrate and chitosan silver nanoparticles. The in vitro inhibitory effect was stronger against Gram-negative than Gram-positive, and similar against multidrug resistant and susceptible bacteria, with best result achieved using citrate and chitosan silver nanoparticles. The bactericidal effect of silver nanoparticle may, in the future, be translated into important therapeutic and clinical options, especially considering the shortage of new antimicrobials against the emerging antimicrobial resistant microorganisms, in particular against Gram-negative bacteria.

In vitro activity of bergamot natural essence and furocoumarin-free and distilled extracts, and their associations with boric acid, against clinical yeast isolates.

PubMed

Romano, L; Battaglia, F; Masucci, L; Sanguinetti, M; Posteraro, B; Plotti, G; Zanetti, S; Fadda, G

2005-01-01

There is very little information, to date, on the antifungal activity of bergamot oil. In this study, we investigated the in vitro activity of three bergamot oils (natural essence, furocoumarin-free extract and distilled extract) against clinically relevant Candida species. We studied the two derivatives, components of Italian pharmaceutical products, that are supposed to be less toxic than the essential oil. In vitro susceptibility of 40 clinical isolates of Candida spp. (Candida albicans, n=20; Candida glabrata, n=13; Candida krusei, n=4; Candida tropicalis, n=2; Candida parapsilosis, n=1), associated with symptomatic and asymptomatic vulvovaginal candidiasis, was determined using a modification of the NCCLS M27-A2 broth microdilution method. MICs were evaluated for each of the oils alone and combined with sub-inhibitory concentrations of the well-known antiseptic, boric acid. To boric acid, all isolates had MIC values ranging from 0.094% to 0.187% (w/v). At 24 h readings, the MIC(90 )s (for all isolates) were (v/v): 5% for natural essence of bergamot, 2.5% for the furocoumarin-free extract, and 1.25% for the distilled extract. At the 48 h reading, these values increased to >10%, 5% and 2.5%, respectively. At both readings, MIC(90 )s for all oil+boric acid combinations were significantly lower than corresponding values for the oils alone (P <0.05). These data indicate that bergamot oils are active in vitro against Candida spp., suggesting their potential role for the topical treatment of Candida infections.

Slime production and proteinase activity of Candida species isolated from blood samples and the comparison of these activities with minimum inhibitory concentration values of antifungal agents.

PubMed

Ozkan, Semiha; Kaynak, Fatma; Kalkanci, Ayse; Abbasoglu, Ufuk; Kustimur, Semra

2005-05-01

Slime and proteinase activity of 54 strains consisting of 19 Candida parapsilosis and 35 C. albicans strains isolated from blood samples were investigated in this study. Ketoconazole, amphothericin B, and fluconazole susceptibility of Candida species were compared with slime production and proteinase activity of these species. For both Candida species, no correlation was detected between the slime activity and minimum inhibitory concentration (MIC) values of the three antifungal agents. For both Candida species no correlation was detected between the proteinase activity and the MIC values of amphothericin B, and fluconazole however, statistically significant difference, was determined between the proteinase activity and MIC values of ketoconazole (p = 0.007). Slime production was determined by using modified Christensen macrotube method and proteinase activity was measured by the method of Staib. Antifungal susceptibility was determined through the guidelines of National Committee for Laboratory Standards (NCCLS M27-A).

Antimicrobial Effect of Jasminum grandiflorum L. and Hibiscus rosa-sinensis L. Extracts Against Pathogenic Oral Microorganisms--An In Vitro Comparative Study.

PubMed

Nagarajappa, Ramesh; Batra, Mehak; Sharda, Archana J; Asawa, Kailash; Sanadhya, Sudhanshu; Daryani, Hemasha; Ramesh, Gayathri

2015-01-01

To assess and compare the antimicrobial potential and determine the minimum inhibitory concentration (MIC) of Jasminum grandiflorum and Hibiscus rosa-sinensis extracts as potential anti-pathogenic agents in dental caries. Aqueous and ethanol (cold and hot) extracts prepared from leaves of Jasminum grandiflorum and Hibiscus rosa-sinensis were screened for in vitro antimicrobial activity against Streptococcus mutans and Lactobacillus acidophilus using the agar well diffusion method. The lowest concentration of every extract considered as the minimum inhibitory concentration (MIC) was determined for both test organisms. Statistical analysis was performed with one-way analysis of variance (ANOVA). At lower concentrations, hot ethanol Jasminum grandiflorum (10 μg/ml) and Hibiscus rosa-sinensis (25 μg/ml) extracts were found to have statistically significant (P≤0.05) antimicrobial activity against S. mutans and L. acidophilus with MIC values of 6.25 μg/ml and 25 μg/ml, respectively. A proportional increase in their antimicrobial activity (zone of inhibition) was observed. Both extracts were found to be antimicrobially active and contain compounds with therapeutic potential. Nevertheless, clinical trials on the effect of these plants are essential before advocating large-scale therapy.

Oxyresveratrol, a Stilbene Compound from Morus alba L. Twig Extract Active Against Trichophyton rubrum.

PubMed

Lu, Hai-Peng; Jia, Ya-Nan; Peng, Ya-Lin; Yu, Yan; Sun, Si-Long; Yue, Meng-Ting; Pan, Min-Hui; Zeng, Ling-Shu; Xu, Li

2017-12-01

Morus alba L. (mulberry) twig is known to have an inhibitory effect on pathogens in traditional Chinese medicine. In the present study, the dermophytic fungus, Trichophyton rubrum, was used to evaluate the inhibitory effect of total M. alba twig extract and extracts obtained using solvents with different polarities by the method of 96-well MTT colorimetry. The main active substance was isolated and identified by tracking its activity. In addition, the inhibitory effects of active extracts and a single active substance were investigated in combination with miconazole nitrate. Our data indicated that ethyl acetate extracts of mulberry twig (TEE) exhibited a desired inhibitory activity on T. rubrum with the minimum inhibitory concentration (MIC) of 1.000 mg/mL. With activity tracking, the main substance showing antimicrobial activity was oxyresveratrol (OXY), which was isolated from TEE. Its MIC for inhibiting the growth of T. rubrum was 0.500 mg/mL. The combined use of miconazole nitrate and OXY showed a synergistic inhibitory effect, as shown by a significant decrease in the MIC of both components. Based on the OXY content in TEE, the contribution rate of OXY to the inhibitory effect of TEE on T. rubrum was 80.52%, so it was determined to be the main antimicrobial substance in M. alba twig. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Effects of Intracanal Irrigant MTAD Combined with Nisin at Sub-Minimum Inhibitory Concentration Levels on Enterococcus faecalis Growth and the Expression of Pathogenic Genes

PubMed Central

Ling, Junqi; Mao, Xueli; Ning, Yang; Deng, Dongmei

2014-01-01

Exposure to antibiotics is considered to be the major driver in the selection of antibiotic-resistant bacteria and may induce diverse biological responses in bacteria. MTAD is a common intracanal irrigant, but its bactericidal activity remains to be improved. Previous studies have indicated that the antimicrobial peptide nisin can significantly improve the bactericidal activity of MTAD against Enterococcus faecalis. However, the effects of MTAD and its modification at sub-minimum inhibitory concentration (sub-MIC) levels on Enterococcus faecalis growth and the expression of pathogenic genes still need to be explored. In this study, the results of post-antibiotic effects (PAE) and post-antibiotic sub-MIC effects (PASME) showed that MTADN (nisin in combination with MTAD) had the best post-antibiotic effect. E. faecalis after challenge with MTAD was less sensitive to alkaline solutions compared with MTAN (nisin in place of doxycycline in MTAD) and MTADN. E. faecalis induced with sub-MIC of MTAD generated resistance to the higher concentration, but induction of E. faecalis with MTAN did not cause resistance to higher concentrations. Furthermore, real-time polymerase chain reaction (RT-PCR) showed that the stress caused by sub-MIC exposure to MTAD, MTAN, or MTADN resulted in up- or down-regulation of nine stress genes and four virulence-associated genes in E. faecalis and resulted in different stress states. These findings suggested that nisin improved the post-antibacterial effect of MTAD at sub-MIC levels and has considerable potential for use as a modification of MTAD. PMID:24603760

Three-component, one-pot synthesis of anthranilamide Schiff bases bearing 4-aminoquinoline moiety as Mycobacterium tuberculosis gyrase inhibitors.

PubMed

Salve, Preeti S; Alegaon, Shankar G; Sriram, Dharmarajan

2017-04-15

An efficient three-component, one-pot protocol is described for the synthesis of biologically interesting 2-(benzylideneamino)-N-(7-chloroquinolin-4-yl)benzohydrazide derivatives from isatoic anhydride, 7-chloro-4-hydrazinylquinoline and aromatic and/or hetero aromatic aldehydes under catalyst free condensation by using water as reaction media. All synthesized compounds were evaluated for their antimycobacterial activity against Mycobacterium tuberculosis (MTB) and cytotoxicity activity against normal VERO cell lines. The synthesized compounds exhibited minimum inhibitory concentration (MIC) ranging from 0.78 to 25μM. Among the tested compounds 4c, 4o, 4r, and 4u exhibited promising inhibitory activity (MIC=3.12μM). Compounds 4h and 4i stand out, showing MIC values of 0.78 and 1.56μM respectively. Both compounds were further screened for their Mycobacterium tuberculosis DNA gyrase inhibitory assay which suggested that these compounds have a great potential for further optimization and development as antitubercular agents. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pharmacodynamics of oxytetracycline administered alone and in combination with carprofen in calves.

PubMed

Brentnall, C; Cheng, Z; McKellar, Q A; Lees, P

2012-09-15

The pharmacodynamics (PD) of oxytetracycline was investigated against a strain of Mannheimia haemolytica. In vitro measurements, comprising minimum inhibitory concentration (MIC), minimum bactericidal concentration and time-kill curves, were conducted in five matrices; Mueller Hinton Broth (MHB), cation-adjusted MHB (CAMHB) and calf serum, exudate and transudate. MICs were much higher in the biological fluids than in MHB and CAMHB. Ratios of MIC were, serum: CAMHB 19 : 1; exudate:CAMHB 16.1; transudate:CAMHB 14 : 1. Ex vivo data, generated in the tissue cage model of inflammation, demonstrated that oxytetracycline, administered to calves intramuscularly at a dose rate of 20 mg/kg, did not inhibit the growth of M haemolytica in serum, exudate and transudate, even at peak concentration. However, using in vitro susceptibility in CAMHB and in vivo-determined pharmacokinetic (PK) variables, average and minimum oxytetracycline concentrations relative to MIC (C(av)/MIC and C(min)/MIC) predicted achievement of efficacy for approximately 48 hours after dosing. Similar C(av)/MIC and C(min)/MIC data were obtained when oxytetracycline was administered in the presence of carprofen. PK-PD integration of data for oxytetracycline, based on MICs determined in the three biological fluids, suggests that it possesses, at most, limited direct killing activity against M haemolytica. These data raise questions concerning the mechanism(s) of action of oxytetracycline, when administered at clinically recommended dose rates.

Simulated comparison of the pharmacodynamics of ciprofloxacin and levofloxacin against Pseudomonas aeruginosa using pharmacokinetic data from healthy volunteers and 2002 minimum inhibitory concentration data.

PubMed

Burgess, David S; Hall, Ronald G

2007-07-01

Until the 2002 approval of levofloxacin 750 mg QD, ciprofloxacin was the fluoroquinolone of choice against Pseudomonas aeruginosa infections. This study evaluated the AUC:MIC ratios for ciprofloxacin 400 mg BID and TID and levofloxacin 750 mg QD, all administered intravenously, against P. aeruginosa using a Monte Carlo simulation. Pharmacokinetic data for ciprofloxacin and levofloxacin and 2002 MIC distributions against P. aeruginosa were obtained from studies in healthy volunteers published in the peer-reviewed literature. Pharmacokinetic studies of each agent were identified by separate MEDLINE searches combining the MeSH heading pharmacokinetics with the generic name of the antimicrobial. Only human studies published in English between 1990 and 2001 were included. Included studies also had to meet 3 minimum criteria: evaluation of clinically relevant dosing regimens, use of rigorous study methods, and provision of mean (SD) values for the pharmacokinetic parameters of interest. When multiple studies met these criteria, a single study was selected for each antimicrobial regimen. Pharmacodynamic analysis was performed using a Monte Carlo simulation of 10,000 patients by integrating the pharmacokinetic parameters, their variability, and 2002 MIC distributions for each antimicrobial regimen. The probability of target attainment was determined for each regimen for an AUC:MIC ratio from 0 to 300. A > or =90% probability of target attainment was considered satisfactory. For ciprofloxacin 400 mg TID and levofloxacin 750 mg QD, the AUC:MIC ratio at the corresponding 2002 Clinical Laboratory Standards Institute break points of 1 and 2 microg/mL were 33 and 34, respectively. The probabilities of target attainment for a free AUC:MIC ratio >90 (equivalent to a total AUC:MIC ratio > or =125) were 47% for ciprofloxacin 400 mg BID, 54% for ciprofloxacin 400 mg TID, and 48% for levofloxacin 750 mg QD. When pharmacokinetic data from healthy volunteers and 2002 MIC data were used, none of the simulated fluoroquinolone regimens achieved a high likelihood of target attainment against P. aeruginosa.

RpoS Plays a Central Role in the SOS Induction by Sub-Lethal Aminoglycoside Concentrations in Vibrio cholerae

PubMed Central

Baharoglu, Zeynep; Krin, Evelyne; Mazel, Didier

2013-01-01

Bacteria encounter sub-inhibitory concentrations of antibiotics in various niches, where these low doses play a key role for antibiotic resistance selection. However, the physiological effects of these sub-lethal concentrations and their observed connection to the cellular mechanisms generating genetic diversification are still poorly understood. It is known that, unlike for the model bacterium Escherichia coli, sub-minimal inhibitory concentrations (sub-MIC) of aminoglycosides (AGs) induce the SOS response in Vibrio cholerae. SOS is induced upon DNA damage, and since AGs do not directly target DNA, we addressed two issues in this study: how sub-MIC AGs induce SOS in V. cholerae and why they do not do so in E. coli. We found that when bacteria are grown with tobramycin at a concentration 100-fold below the MIC, intracellular reactive oxygen species strongly increase in V. cholerae but not in E. coli. Using flow cytometry and gfp fusions with the SOS regulated promoter of intIA, we followed AG-dependent SOS induction. Testing the different mutation repair pathways, we found that over-expression of the base excision repair (BER) pathway protein MutY relieved this SOS induction in V. cholerae, suggesting a role for oxidized guanine in AG-mediated indirect DNA damage. As a corollary, we established that a BER pathway deficient E. coli strain induces SOS in response to sub-MIC AGs. We finally demonstrate that the RpoS general stress regulator prevents oxidative stress-mediated DNA damage formation in E. coli. We further show that AG-mediated SOS induction is conserved among the distantly related Gram negative pathogens Klebsiella pneumoniae and Photorhabdus luminescens, suggesting that E. coli is more of an exception than a paradigm for the physiological response to antibiotics sub-MIC. PMID:23613664

RpoS plays a central role in the SOS induction by sub-lethal aminoglycoside concentrations in Vibrio cholerae.

PubMed

Baharoglu, Zeynep; Krin, Evelyne; Mazel, Didier

2013-01-01

Bacteria encounter sub-inhibitory concentrations of antibiotics in various niches, where these low doses play a key role for antibiotic resistance selection. However, the physiological effects of these sub-lethal concentrations and their observed connection to the cellular mechanisms generating genetic diversification are still poorly understood. It is known that, unlike for the model bacterium Escherichia coli, sub-minimal inhibitory concentrations (sub-MIC) of aminoglycosides (AGs) induce the SOS response in Vibrio cholerae. SOS is induced upon DNA damage, and since AGs do not directly target DNA, we addressed two issues in this study: how sub-MIC AGs induce SOS in V. cholerae and why they do not do so in E. coli. We found that when bacteria are grown with tobramycin at a concentration 100-fold below the MIC, intracellular reactive oxygen species strongly increase in V. cholerae but not in E. coli. Using flow cytometry and gfp fusions with the SOS regulated promoter of intIA, we followed AG-dependent SOS induction. Testing the different mutation repair pathways, we found that over-expression of the base excision repair (BER) pathway protein MutY relieved this SOS induction in V. cholerae, suggesting a role for oxidized guanine in AG-mediated indirect DNA damage. As a corollary, we established that a BER pathway deficient E. coli strain induces SOS in response to sub-MIC AGs. We finally demonstrate that the RpoS general stress regulator prevents oxidative stress-mediated DNA damage formation in E. coli. We further show that AG-mediated SOS induction is conserved among the distantly related Gram negative pathogens Klebsiella pneumoniae and Photorhabdus luminescens, suggesting that E. coli is more of an exception than a paradigm for the physiological response to antibiotics sub-MIC.

The role of drug efflux pumps in Malassezia pachydermatis and Malassezia furfur defence against azoles.

PubMed

Iatta, Roberta; Puttilli, Maria Rita; Immediato, Davide; Otranto, Domenico; Cafarchia, Claudia

2017-03-01

This study aims to evaluate the effect of efflux pump modulators (EPMs) on the minimal inhibitory concentration (MIC) of fluconazole (FLZ) and voriconazole (VOR) in Malassezia furfur and Malassezia pachydermatis. The in vitro efficacy of azoles, in combination with EPMs (ie haloperidol-HAL, promethazine-PTZ and cyclosporine A-CYS), against 21 M. furfur from bloodstream infection patients and 14 M. pachydermatis from the skin of dogs with dermatitis, was assessed using a broth microdilution chequerboard analysis. Data were analysed using the model-fractional inhibitory concentration index (FICI) method. The MIC of FLZ and VOR of Malassezia spp. decreased in the presence of sub-inhibitory concentrations of HAL and/or PTZ. The synergic effect was observed only in strains with FLZ MIC≥128 μg/mL for M. furfur, FLZ MIC≥64 μg/mL for M. pachydermatis and VOR MIC≥4 μg/mL in both Malassezia spp. These results suggest that the drug efflux pumps are involved as defence mechanisms to azole drugs in Malassezia yeast. The synergism might be related to an increased expression of efflux pump genes, eventually resulting in azole resistance phenomena. Finally, the above FLZ and VOR MIC values might be considered the cut-off to discriminate susceptible and resistant strains. © 2016 Blackwell Verlag GmbH.

Revisiting the susceptibility testing of Mycobacterium tuberculosis to ethionamide in solid culture medium.

PubMed

Lakshmi, Rajagopalan; Ramachandran, Ranjani; Kumar, D Ravi; Sundar, A Syam; Radhika, G; Rahman, Fathima; Selvakumar, N; Kumar, Vanaja

2015-11-01

Increase in the isolation of drug resistant phenotypes of Mycobacterium tuberculosis necessitates accuracy in the testing methodology. Critical concentration defining resistance for ethionamide (ETO), needs re-evaluation in accordance with the current scenario. Thus, re-evaluation of conventional minimum inhibitory concentration (MIC) and proportion sensitivity testing (PST) methods for ETO was done to identify the ideal breakpoint concentration defining resistance. Isolates of M. tuberculosis (n=235) from new and treated patients were subjected to conventional MIC and PST methods for ETO following standard operating procedures. With breakpoint concentration set at 114 and 156 µg/ml, an increase in specificity was observed whereas sensitivity was high with 80 µg/ml as breakpoint concentration. Errors due to false resistant and susceptible isolates were least at 80 µg/ml concentration. Performance parameters at 80 µg/ml breakpoint concentration indicated significant association between PST and MIC methods.

In Vitro Drug Interaction Modeling of Combinations of Azoles with Terbinafine against Clinical Scedosporium prolificans Isolates

PubMed Central

Meletiadis, Joseph; Mouton, Johan W.; Meis, Jacques F. G. M.; Verweij, Paul E.

2003-01-01

The in vitro interaction between terbinafine and the azoles voriconazole, miconazole, and itraconazole against five clinical Scedosporium prolificans isolates after 48 and 72 h of incubation was tested by a microdilution checkerboard (eight-by-twelve) technique. The antifungal effects of the drugs alone and in combination on the fungal biomass as well as on the metabolic activity of fungi were measured using a spectrophotometric method and two colorimetric methods, based on the lowest drug concentrations showed 75 and 50% growth inhibition (MIC-1 and MIC-2, respectively). The nature and the intensity of the interactions were assessed using a nonparametric approach (fractional inhibitory concentration [FIC] index model) and a fully parametric response surface approach (Greco model) of the Loewe additivity (LA) no-interaction theory as well as a nonparametric (Prichard model) and a semiparametric response surface approaches of the Bliss independence (BI) no-interaction theory. Statistically significant synergy was found between each of the three azoles and terbinafine in all cases, although with different intensities. A 27- to 64-fold and 16- to 90-fold reduction of the geometric mean of the azole and terbinafine MICs, respectively, was observed when they were combined, resulting in FIC indices of <1 to 0.02. Using the MIC-1 higher levels of synergy were obtained, , which were more consistent between the two incubation periods than using the MIC-2. The strongest synergy among the azoles was found with miconazole using the BI-based models and with voriconazole using the LA-based models. The synergistic effects both on fungal growth and metabolic activity were more potent after 72 h of incubation. Fully parametric approaches in combination with the modified colorimetric method might prove useful for testing the in vitro interaction of antifungal drugs against filamentous fungi. PMID:12499177

Relationship of in vitro minimum inhibitory concentrations of tilmicosin against Mannheimia haemolytica and Pasteurella multocida and in vivo tilmicosin treatment outcome among calves with signs of bovine respiratory disease.

PubMed

McClary, David G; Loneragan, Guy H; Shryock, Thomas R; Carter, Brandon L; Guthrie, Carl A; Corbin, Marilyn J; Mechor, Gerald D

2011-07-01

To determine associations between in vitro minimum inhibitory concentrations (MICs) of tilmicosin against Mannheimia haemolytica and Pasteurella multocida and in vivo tilmicosin treatment outcome among calves with clinical signs of bovine respiratory disease (BRD). Observational, retrospective, cohort study. 976 feeder calves with clinical signs of BRD enrolled in 16 randomized clinical trials. Records of clinical trials from October 26, 1996, to November 15, 2004, were searched to identify calves with BRD from which a single isolate of M haemolytica or P multocida was identified via culture of deep nasal swab samples prior to treatment with tilmicosin (10 mg/kg [4.5 mg/lb], SC) and for which MICs of tilmicosin against the isolate were determined. The MICs of tilmicosin against recovered isolates and response to tilmicosin treatment were evaluated. Tilmicosin resistance among M haemolytica and P multocida isolates was uncommon (6/745 [0.8%] and 16/231 [6.9%], respectively). Treatment outcome, defined as success or failure after tilmicosin treatment, did not vary with the MIC of tilmicosin against recovered isolates. The proportion of treatment failures attributed to M haemolytica isolates categorized as resistant (MIC of tilmicosin, ≥ 32 μg/mL) or not susceptible (MIC of tilmicosin, ≥ 16 μg/mL), was 0.2% and 0.5%, respectively. Recovery of tilmicosin-resistant M haemolytica or P multocida isolates was rare, and no association was detected between MIC of tilmicosin and treatment response.

In vitro antifungal activity of hydroxychavicol isolated from Piper betle L.

PubMed

Ali, Intzar; Khan, Farrah G; Suri, Krishan A; Gupta, Bishan D; Satti, Naresh K; Dutt, Prabhu; Afrin, Farhat; Qazi, Ghulam N; Khan, Inshad A

2010-02-03

Hydroxychavicol, isolated from the chloroform extraction of the aqueous leaf extract of Piper betle L., (Piperaceae) was investigated for its antifungal activity against 124 strains of selected fungi. The leaves of this plant have been long in use tropical countries for the preparation of traditional herbal remedies. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of hydroxychavicol were determined by using broth microdilution method following CLSI guidelines. Time kill curve studies, post-antifungal effects and mutation prevention concentrations were determined against Candida species and Aspergillus species "respectively". Hydroxychavicol was also tested for its potential to inhibit and reduce the formation of Candida albicans biofilms. The membrane permeability was measured by the uptake of propidium iodide. Hydroxychavicol exhibited inhibitory effect on fungal species of clinical significance, with the MICs ranging from 15.62 to 500 microg/ml for yeasts, 125 to 500 microg/ml for Aspergillus species, and 7.81 to 62.5 microg/ml for dermatophytes where as the MFCs were found to be similar or two fold greater than the MICs. There was concentration-dependent killing of Candida albicans and Candida glabrata up to 8 x MIC. Hydroxychavicol also exhibited an extended post antifungal effect of 6.25 to 8.70 h at 4 x MIC for Candida species and suppressed the emergence of mutants of the fungal species tested at 2 x to 8 x MIC concentration. Furthermore, it also inhibited the growth of biofilm generated by C. albicans and reduced the preformed biofilms. There was increased uptake of propidium iodide by C. albicans cells when exposed to hydroxychavicol thus indicating that the membrane disruption could be the probable mode of action of hydroxychavicol. The antifungal activity exhibited by this compound warrants its use as an antifungal agent particularly for treating topical infections, as well as gargle mouthwash against oral Candida infections.

In vitro antifungal activity of hydroxychavicol isolated from Piper betle L

PubMed Central

2010-01-01

Background Hydroxychavicol, isolated from the chloroform extraction of the aqueous leaf extract of Piper betle L., (Piperaceae) was investigated for its antifungal activity against 124 strains of selected fungi. The leaves of this plant have been long in use tropical countries for the preparation of traditional herbal remedies. Methods The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of hydroxychavicol were determined by using broth microdilution method following CLSI guidelines. Time kill curve studies, post-antifungal effects and mutation prevention concentrations were determined against Candida species and Aspergillus species "respectively". Hydroxychavicol was also tested for its potential to inhibit and reduce the formation of Candida albicans biofilms. The membrane permeability was measured by the uptake of propidium iodide. Results Hydroxychavicol exhibited inhibitory effect on fungal species of clinical significance, with the MICs ranging from 15.62 to 500 μg/ml for yeasts, 125 to 500 μg/ml for Aspergillus species, and 7.81 to 62.5 μg/ml for dermatophytes where as the MFCs were found to be similar or two fold greater than the MICs. There was concentration-dependent killing of Candida albicans and Candida glabrata up to 8 × MIC. Hydroxychavicol also exhibited an extended post antifungal effect of 6.25 to 8.70 h at 4 × MIC for Candida species and suppressed the emergence of mutants of the fungal species tested at 2 × to 8 × MIC concentration. Furthermore, it also inhibited the growth of biofilm generated by C. albicans and reduced the preformed biofilms. There was increased uptake of propidium iodide by C. albicans cells when exposed to hydroxychavicol thus indicating that the membrane disruption could be the probable mode of action of hydroxychavicol. Conclusions The antifungal activity exhibited by this compound warrants its use as an antifungal agent particularly for treating topical infections, as well as gargle mouthwash against oral Candida infections. PMID:20128889

Phenolic content, antibacterial and antioxidant activities of Erica herbacea L.

PubMed

Vucić, Dragana M; Petković, Miroslav R; Rodić-Grabovac, Branka B; Stefanović, Olgica D; Vasić, Sava M; Comić, Ljiljana R

2013-01-01

Antibacterial and antioxidant activity, total phenolic and flavonoid concentrations of aqueous, ethanol and ethyl acetate extracts from the leaves and flowers of Erica herbacea L. were studied. In vitro antibacterial activity of the extracts was determined by macrodilution method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) have been determined. Testing was performed on 30 clinical isolates, including different strains of Escherichia coli, Enterococcus faecalis and Proteus vulgaris. The values for MIC were in the range from 2.5 mg/mL to 40 mg/mL. The most sensitive bacterial strains were Proteus vulgaris strains. The aqueous extract from E. herbacea was found the most active. The total phenolic content was determined using Folin-Ciocalteu reagent and ranged between 14.98 and 119.88 mg GA/g. The concentration of flavonoids in extracts was determined using spectrophotometric method with aluminium chloride and obtained results varied from 16.19 to 26.90 mg RU/g. Antioxidant activity was monitored spectrophotometrically using DPPH reagent. The highest capacity to neutralize DPPH radicals was found in the aqueous extract from E. herbacea. The results of the total phenolic content determination of the examined extracts indicate that E. herbacea extracts are a rich source of phenolic compounds and also possess a significant antioxidant activity and moderate antibacterial activity.

Effect of nanoliposomes containing Zataria multiflora Boiss. essential oil on gene expression of Shiga toxin 2 in Escherichia coli O157:H7.

PubMed

Khatibi, S A; Misaghi, A; Moosavy, M H; Akhondzadeh Basti, A; Mohamadian, S; Khanjari, A

2018-02-01

Enterohaemorrhagic Escherichia coli serotype O157:H7 as a major human pathogen is responsible for food borne outbreaks, bloody diarrhoea, haemorrhagic colitis and haemolytic uraemic syndrome and even death. In this study, the antibacterial activity of the Zataria multiflora essential oil (ZMEO) and nanoliposome-encapsulated ZMEO was evaluated on the pathogenicity of E. coli O157:H7. The minimum inhibitory concentrations (MIC) of essential oil (EO) were determined against the bacterium before and after encapsulation into nanoliposome. Then, the effect of subinhibitory concentrations was evaluated on Shiga toxin 2 (Stx2) production. The effect of free and nanoliposomal EO was also studied on the gene expression of Stx2 by real-time PCR. It was found that inhibitory activity of EO was improved after incorporation into nanoliposomes (P < 0·05). The MIC of free EO against E. coli O157:H7 was 0·03% (v/v), while this value decreased to 0·015%, after encapsulation of EO into nanoliposomes. Furthermore, subinhibitory concentrations of liposomal EO (50 and 75% MIC) had significantly higher inhibitory effect on Stx2 titre than its free form (P < 0·05). Sub-MICs of nanoencapsulated EO also showed a better activity in reduction of Stx2A gene expression than free EO. Using 75% MIC of nanoliposomal EO, the relative transcriptional level of Stx2A gene was decreased from 0·721 to 0·646. The findings of present study suggest that application of nanoliposomes can improve the antibacterial effect of EOs like ZMEO. Due to the enhancement of antimicrobial activity, nanoencapsulation of plant EOs and extracts may increase their commercial application not only in food area but also in the pharmaceutics, cosmetics and health products. © 2017 The Society for Applied Microbiology.

Effect of Catechins, Green tea Extract and Methylxanthines in Combination with Gentamicin Against Staphylococcus aureus and Pseudomonas aeruginosa

PubMed Central

Fazly Bazzaz, Bibi Sedigheh; Sarabandi, Sahar; Khameneh, Bahman; Hosseinzadeh, Hossein

2016-01-01

Objectives: Bacterial resistant infections have become a global health challenge and threaten the society’s health. Thus, an urgent need exists to find ways to combat resistant pathogens. One promising approach to overcoming bacterial resistance is the use of herbal products. Green tea catechins, the major green tea polyphenols, show antimicrobial activity against resistant pathogens. The present study aimed to investigate the effect of catechins, green tea extract, and methylxanthines in combination with gentamicin against standard and clinical isolates of Staphylococcus aureus (S. aureus) and the standard strain of Pseudomonas aeruginosa (P. aeruginosa). Methods: The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) values of different agents against bacterial strains were determined. The interactions of green tea extract, epigallate catechin, epigallocatechin gallate, two types of methylxanthine, caffeine, and theophylline with gentamicin were studied in vitro by using a checkerboard method and calculating the fraction inhibitory concentration index (FICI). Results: The MICs of gentamicin against bacterial strains were in the range of 0.312 - 320 μg/mL. The MIC values of both types of catechins were 62.5 - 250 μg/ mL. Green tea extract showed insufficient antibacterial activity when used alone. Methylxanthines had no intrinsic inhibitory activity against any of the bacterial strains tested. When green tea extract and catechins were combined with gentamicin, the MIC values of gentamicin against the standard strains and a clinical isolate were reduced, and synergistic activities were observed (FICI < 1). A combination of caffeine with gentamicin did not alter the MIC values of gentamicin. Conclusion: The results of the present study revealed that green tea extract and catechins potentiated the antimicrobial action of gentamicin against some clinical isolates of S. aureus and standard P. aeruginosa strains. Therefore, combinations of gentamicin with these natural compounds might be a promising approach to combat microbial resistance. PMID:28097041

Application of Origanum majorana L. essential oil as an antimicrobial agent in sausage.

PubMed

Busatta, C; Vidal, R S; Popiolski, A S; Mossi, A J; Dariva, C; Rodrigues, M R A; Corazza, F C; Corazza, M L; Vladimir Oliveira, J; Cansian, R L

2008-02-01

This work reports on the antimicrobial activity in fresh sausage of marjoram (Origanum majorana L.) essential oil against several species of bacteria. The in vitro minimum inhibitory concentration (MIC) was determined for 10 selected aerobic heterotrophic bacterial species. The antimicrobial activity of distinct concentrations of the essential oil based on the highest MIC value was tested in a food system comprising fresh sausage. Batch food samples were also inoculated with a fixed concentration of Escherichia coli and the time course of the product was evaluated with respect to the action of the different concentrations of essential oil. Results showed that addition of marjoram essential oil to fresh sausage exerted a bacteriostatic effect at oil concentrations lower than the MIC, while a bactericidal effect was observed at higher oil concentrations which also caused alterations in the taste of the product.

Antitubercular activity and inhibitory effect on Epstein-Barr virus activation of sterols and polyisoprenepolyols from an edible mushroom, Hypsizigus marmoreus.

PubMed

Akihisa, Toshihiro; Franzblau, Scott Gary; Tokuda, Harukuni; Tagata, Masaaki; Ukiya, Motohiko; Matsuzawa, Tsunetomo; Metori, Koichi; Kimura, Yumiko; Suzuki, Takashi; Yasukawa, Ken

2005-06-01

Seven sterols (1-7) and eight polyisoprenepolyols (8-15), isolated from the non-saponifiable lipid fraction of the dichloromethane extract of an edible mushroom, Hypsizigus marmoreus (Buna-shimeji), were tested for their antitubercular activity against Mycobacterium tuberculosis strain H37Rv using the Microplate Alamar Blue Assay (MABA). Six sterols (2-7) and two polyisoprenepolyols (8, 12) showed a minimum inhibitory concentration (MIC) in the range of 1-51 microg/ml, while the others (1, 9-11, 13-15) were inactive (MIC>128 microg/ml). The seven sterols (1-7) and three polyisoprenepolyols (8, 10, 12) were further evaluated for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. Sterols 6 and 7 showed potent inhibitory effects while preserving the high viability of Raji cells.

Effects of temperature and antibiotics on persistence of antibiotic-resistant bacteria and antibiotic resistance genes in poultry litter

USDA-ARS?s Scientific Manuscript database

The effect of low, residual concentrations of antibiotics in manure and other environmental matrices is not well understood. It has been hypothesized that antibiotic concentrations below clinical MIC (minimal inhibitory concentrations) are still capable of selecting for resistance. The objective of ...

[The combination effects of antibacterial agents against clinical isolated multiple-drug resistant Pseudomonas aeruginosa].

PubMed

Maesaki, Shigefumi; Yamaguchi, Toshiyuki; Sasaki, Kazumasa; Hashikita, Giichi; Shibuya, Shunsuke; Watanabe, Masaharu; Takayama, Sadao; Kawakami, Sayoko; Nagasawa, Mitsuaki; Suzuki, Noriyasu; Uchida, Takashi; Okabe, Tadashi; Kobayashi, Sugako

2006-02-01

The effectiveness of antibacterial agents against 70 strains of clinically isolated multiple-drug resistant Pseudomonas aeruginosa (MDRP) was measured by the micro dilution method. Fifty of all strains (71%) produced metallo-beta-lactamase and the IMP-1 gene was detected by polymerase chain reaction (PCR). The MIC90 (the minimum inhibitory concentration of an antibiotic necessary to inhibit the growth of 90% of bacterial strains) values of biapenem (BIPM), meropenem (MEPM), tazobactam/piperacillin (TAZ/PIPC), sulbactam/ cefoperazone (SBT/CPZ), cefepime (CFPM), ciprofloxacin (CPFX), pazufloxacin (PZFX), amikacin (AMK) and aztreonam (AZT) were found to be 265, 512, 256, 512, 512, 64, 128, 128 and 128 microg/mL, respectively. The in vitro combination effects of antibacterial agents were examined against 62 strains of MDRP and the synergy or additive effects were evaluated by fractional inhibitory concentration (FIC) index calculated by the checkerboard method. The combination of AMK and AZT showed synergy effects on 15/59 (25.4%) strains of MDRP. The synergy and additive effects on the MDRP strains were also found by the other antibacterial agents combination such as TAZ/PIPC and AMK, CFPM and AMK, and SBT/CPZ and AZT. These results suggested the necessity of further investigation of clinical usefulness.

Impact of high-flux haemodialysis on the probability of target attainment for oral amoxicillin/clavulanic acid combination therapy.

PubMed

Hui, Katrina; Patel, Kashyap; Kong, David C M; Kirkpatrick, Carl M J

2017-07-01

Clearance of small molecules such as amoxicillin and clavulanic acid is expected to increase during high-flux haemodialysis, which may result in lower concentrations and thus reduced efficacy. To date, clearance of amoxicillin/clavulanic acid (AMC) during high-flux haemodialysis remains largely unexplored. Using published pharmacokinetic parameters, a two-compartment model with first-order input was simulated to investigate the impact of high-flux haemodialysis on the probability of target attainment (PTA) of orally administered AMC combination therapy. The following pharmacokinetic/pharmacodynamic targets were used to calculate the PTA. For amoxicillin, the time that the free concentration remains above the minimum inhibitory concentration (MIC) of ≥50% of the dosing period (≥50%ƒT >MIC ) was used. For clavulanic acid, the time that the free concentration was >0.1 mg/L of ≥45% of the dosing period (≥45%ƒT >0.1 mg/L ) was used. Dialysis clearance reported in low-flux haemodialysis for both compounds was doubled to represent the likely clearance during high-flux haemodialysis. Monte Carlo simulations were performed to produce concentration-time profiles over 10 days in 1000 virtual patients. Seven different regimens commonly seen in clinical practice were explored. When AMC was dosed twice daily, the PTA was mostly ≥90% for both compounds regardless of when haemodialysis commenced. When administered once daily, the PTA was 20-30% for clavulanic acid and ≥90% for amoxicillin. The simulations suggest that once-daily orally administered AMC in patients receiving high-flux haemodialysis may result in insufficient concentrations of clavulanic acid to effectively treat infections, especially on days when haemodialysis occurs. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Stem bark extract and fraction of Persea americana (Mill.) exhibits bactericidal activities against strains of bacillus cereus associated with food poisoning.

PubMed

Akinpelu, David A; Aiyegoro, Olayinka A; Akinpelu, Oluseun F; Okoh, Anthony I

2014-12-30

The study investigates the in vitro antibacterial potentials of stem bark extracts of Persea americana on strains of Bacillus cereus implicated in food poisoning. The crude stem bark extracts and butanolic fraction at a concentration of 25 mg/mL and 10 mg/mL, respectively, exhibited antibacterial activities against test isolates. The zones of inhibition exhibited by the crude extract and the fraction ranged between 10 mm and 26 mm, while the minimum inhibitory concentration values ranged between 0.78 and 5.00 mg/mL. The minimum bactericidal concentrations ranged between 3.12 mg/mL-12.5 mg/mL and 1.25-10 mg/mL for the extract and the fraction, respectively. The butanolic fraction killed 91.49% of the test isolates at a concentration of 2× MIC after 60 min of contact time, while a 100% killing was achieved after the test bacterial cells were exposed to the butanolic fraction at a concentration of 3× MIC after 90 min contact time. Intracellular protein and potassium ion leaked out of the test bacterial cells when exposed to certain concentrations of the fraction; this is an indication of bacterial cell wall disruptions by the extract's butanolic fraction and, thus, caused a biocidal effect on the cells, as evident in the killing rate test results.

Antimicrobial effects of citrus sinensis peel extracts against periodontopathic bacteria: an in vitro study.

PubMed

Hussain, Khaja Amjad; Tarakji, Bassel; Kandy, Binu Purushothaman Panar; John, Jacob; Mathews, Jacob; Ramphul, Vandana; Divakar, Darshan Devang

2015-01-01

Use of plant extracts and phytochemicals with known antimicrobial properties may have great significance in therapeutic treatments. To assess the in vitro antimicrobial potential and also determine the minimum inhibitory concentration (MIC) of Citrus sinensis peel extracts with a view of searching a novel extract as a remedy for periodontal pathogens. Aqueous and ethanol (cold and hot) extracts prepared from peel of Citrus sinensis were screened for in vitro antimicrobial activity against Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia, using agar well diffusion method. The lowest concentration of every extract considered as the minimal inhibitory concentration (MIC) values were determined for both test organisms. Confidence level and level of significance were set at 95% and 5% respectively. Prevotella intermedia and Porphyromonas gingivalis were resistant to aqueous extracts while Aggregatibacter actinomycetemcomitans was inhibited at very high cncentrations. Hot ethanolic extracts showed significantly higher zone of inhibition than cold ethanolic extract. Minimum inhibitory concentration of hot and cold ethanolic extracts of Citrus sinensis peel ranged between 12-15 mg/ml against all three periodontal pathogens. Both extracts were found sensitive and contain compounds with therapeutic potential. Nevertheless, clinical trials on the effect of these plants are essential before advocating large-scale therapy.

Mutant prevention concentration, pharmacokinetic-pharmacodynamic integration, and modeling of enrofloxacin data established in diseased buffalo calves.

PubMed

Ramalingam, B; Sidhu, P K; Kaur, G; Venkatachalam, D; Rampal, S

2015-12-01

The pharmacokinetic-pharmacodynamic (PK/PD) modeling of enrofloxacin data using mutant prevention concentration (MPC) of enrofloxacin was conducted in febrile buffalo calves to optimize dosage regimen and to prevent the emergence of antimicrobial resistance. The serum peak concentration (Cmax ), terminal half-life (t1/2 K10) , apparent volume of distribution (Vd(area) /F), and mean residence time (MRT) of enrofloxacin were 1.40 ± 0.27 μg/mL, 7.96 ± 0.86 h, 7.74 ± 1.26 L/kg, and 11.57 ± 1.01 h, respectively, following drug administration at dosage 12 mg/kg by intramuscular route. The minimum inhibitory concentration (MIC), minimum bactericidal concentration, and MPC of enrofloxacin against Pasteurella multocida were 0.055, 0.060, and 1.45 μg/mL, respectively. Modeling of ex vivo growth inhibition data to the sigmoid Emax equation provided AUC24 h /MIC values to produce effects of bacteriostatic (33 h), bactericidal (39 h), and bacterial eradication (41 h). The estimated daily dosage of enrofloxacin in febrile buffalo calves was 3.5 and 8.4 mg/kg against P. multocida/pathogens having MIC90 ≤0.125 and 0.30 μg/mL, respectively, based on the determined AUC24 h /MIC values by modeling PK/PD data. The lipopolysaccharide-induced fever had no direct effect on the antibacterial activity of the enrofloxacin and alterations in PK of the drug, and its metabolite will be beneficial for its use to treat infectious diseases caused by sensitive pathogens in buffalo species. In addition, in vitro MPC data in conjunction with in vivo PK data indicated that clinically it would be easier to eradicate less susceptible strains of P. multocida in diseased calves. © 2015 John Wiley & Sons Ltd.

In vitro antimicrobial susceptibility of Mycoplasma bovis isolated in Israel from local and imported cattle.

PubMed

Gerchman, Irena; Levisohn, Sharon; Mikula, Inna; Lysnyansky, Inna

2009-06-12

Monitoring of susceptibility to antibiotics in field isolates of pathogenic bovine mycoplasmas is important for appropriate choice of treatment. Our study compared in vitro susceptibility profiles of Mycoplasma bovis clinical strains, isolated during 2005-2007 from Israeli and imported calves. Minimal inhibitory concentration (MIC) values were determined for macrolides by the microbroth dilution test, for aminoglycosides by commercial Etest, and for fluoroquinolones and tetracyclines by both methods. Notably, although correlation between the methods was generally good, it was not possible to determine the MIC endpoint for enrofloxacin-resistant strains (MIC > or =2.5 microg/ml in the microtest) by Etest. Comparison of antibiotic susceptibility profiles between local and imported M. bovis strains revealed that local strains were significantly more resistant to macrolides than most isolates from imported animals, with MIC(50) of 128 microg/ml vs. 2 microg/ml for tilmicosin and 8 microg/ml vs. 1 microg/ml for tylosin, respectively. However, local strains were more susceptible than most imported strains to fluoroquinolones and spectinomycin. Difference in susceptibility to tetracycline, doxycycline and oxytetracycline between local and imported strains was expressed in MIC(90) values for imported strains in the susceptible range compared to intermediate susceptibility for local strains. The marked difference in susceptibility profiles of M. bovis strains isolated from different geographical regions seen in this study emphasizes the necessity for performing of the antimicrobial susceptibility testing periodically and on a regional basis.

Chemical Constituents and an Alternative Medicinal Veterinary Herbal Soap Made from Senna macranthera

PubMed Central

Inoue Andrade, Flávia; Purgato, Gislaine Aparecida; de Faria Maia, Thalita; Pais Siqueira, Raoni; Lima, Sâmia; Diaz, Marisa Alves Nogueira

2015-01-01

Upon undergoing biomonitoring, the most active dichloromethane extract retrieved from Senna macranthera roots led to the isolation of three main compounds: emodine, physione, and chrysophanol. In this sequence, these compounds revealed a potential antibacterial activity against Staphylococcus aureus strains isolated from animals with mastitis infections with minimum inhibitory concentration (MIC) values of 20, 90, and 90 μg mL−1, respectively. Therefore, an herbal soap was also produced from this same active extract. This soap was tested in vitro using gloves contaminated by animals with bovine mastitis that had been discarded after use by milkers and showed similar results to previously tested compounds. These results indicate the potential of this plant as an alternative veterinary medicine for the production of antibacterial soaps that aimed at controlling bovine mastitis infections in small Brazilian farms. PMID:25821480

Monoterpene isolated from the essential oil of Trachyspermum ammi is cytotoxic to multidrug-resistant Pseudomonas aeruginosa and Staphylococcus aureus strains.

PubMed

Hosseinkhani, Faride; Jabalameli, Fereshteh; Banar, Maryam; Abdellahi, Nafiseh; Taherikalani, Morovat; Leeuwen, Willem B van; Emaneini, Mohammad

2016-04-01

The aim of this study was to determine whether an herbal extract containing monoterpene exhibited activity against multidrug-resistant Staphylococcus aureus and Pseudomonas aeruginosa isolated from clinical infection samples. The essential oil of Trachyspermum ammi (L.) Sprague ex Turrill (Apiaceae) fruit was extracted by hydrodistillation. Fruit residues were treated with hydrochloric acid and re-hydrodistilled to obtain volatile compounds. Compounds in the distilled oil were identified using gas-chromatography (GC) and GC-mass spectrometry (MS). The antibiotic susceptibility of all bacterial isolates was analyzed using both the disc diffusion method and determination of the minimum inhibitory concentration (MIC). The sensitivity of antibiotic-resistant isolates to essential oil was also determined by using the disc diffusion method and MIC determination. Of 26 clinical isolates, 92% were multidrug-resistant (MDR). Aromatic monoterpenes (thymol, paracymene, and gamma-terpinene) were the major (90%) components of the oil. Growth of S. aureus strains was successfully inhibited by the oil, with an inhibitory zone diameter (IZD) between 30-60mm and MIC <0.02μL/mL. The oil had no antimicrobial activity against clinical isolates of P. aeruginosa; rather, it prevented pigment production in these isolates. This study revealed that the essential oil of Trachyspermum ammi, which contains monoterpene, has good antibacterial potency. Monoterpenes could thus be incorporated into antimicrobial ointment formulas in order to treat highly drug-resistant S. aureus infections. Our findings also underscore the utility of research on natural products in order to combat bacterial multidrug resistance.

Monitoring of antimicrobial susceptibility of Streptococcus suis in the Netherlands, 2013-2015.

PubMed

van Hout, Jobke; Heuvelink, Annet; Gonggrijp, Maaike

2016-10-15

The objective of the present study was to analyse the in vitro antimicrobial susceptibility of Streptococcus suis isolates from post-mortem samples from pigs in the Netherlands. S. suis isolates originated from diagnostic submissions of pigs sent to the Pathology Department of GD Animal Health, from April 2013 till June 2015. Minimal inhibitory concentrations (MICs) of in total 15 antimicrobials were assessed by broth microdilution following CLSI recommendations. MIC 50 and MIC 90 values were determined and MICs were interpreted as susceptible, intermediate and resistant using CLSI veterinary breakpoints (when available). Emergence of resistance among S. suis (n=1163) derived from clinical submissions of pigs appeared to be limited. Resistance to ampicillin, ceftiofur, clindamycin, enrofloxacin, florfenicol, penicillin, trimethoprim/sulfamethoxazole and tetracycline was 0.3%, 0.5%, 48.1%, 0.6%, 0.1%, 0.5%, 3.0%, and 78.4%, respectively. Cross-resistance between penicillin and ampicillin appeared to be incomplete. MIC values of erythromycin, clindamycin, neomycin, penicillin and tilmicosin for isolates originating from grower/finisher pigs were significantly more often lower than the MIC values of isolates from suckling/weaned piglets. It has to be kept in mind that these results represent only part of the Dutch pig population and it can be discussed whether this is a representative sample. Interpretation of the MIC results of (clinically relevant) antimicrobials tested for treatment of S. suis infection is strongly hampered by the lack of CLSI-defined veterinary clinical breakpoints that are animal species- and body site-specific. Therefore, and to conduct a clinically reliable monitoring of antimicrobial susceptibility of veterinary pathogens, more species- and organ-specific veterinary breakpoints are urgently needed. Copyright © 2016 Elsevier B.V. All rights reserved.

Isojacareubin from the Chinese Herb Hypericum japonicum: Potent Antibacterial and Synergistic Effects on Clinical Methicillin-Resistant Staphylococcus aureus (MRSA)

PubMed Central

Zuo, Guo-Ying; An, Jing; Han, Jun; Zhang, Yun-Ling; Wang, Gen-Chun; Hao, Xiao-Yan; Bian, Zhong-Qi

2012-01-01

Through bioassay-guided fractionation of the extracts from the aerial parts of the Chinese herb Hypericum japonicum Thunb. Murray, Isojacareubin (ISJ) was characterized as a potent antibacterial compound against the clinical methicillin-resistant Staphylococcus aureus (MRSA). The broth microdilution assay was used to determine the minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of ISJ alone. The results showed that its MICs/MBCs ranged from 4/16 to 16/64 μg/mL, with the concentrations required to inhibit or kill 50% of the strains (MIC50/MBC50) at 8/16 μg/mL. Synergistic evaluations of this compound with four conventional antibacterial agents representing different types were performed by the chequerboard and time-kill tests. The chequerboard method showed significant synergy effects when ISJ was combined with Ceftazidime (CAZ), Levofloxacin (LEV) and Ampicillin (AMP), with the values of 50% of the fractional inhibitory concentration indices (FICI50) at 0.25, 0.37 and 0.37, respectively. Combined bactericidal activities were also observed in the time-kill dynamic assay. The results showed the ability of ISJ to reduce MRSA viable counts by log10CFU/mL at 24 h of incubation at a concentration of 1 × MIC were 1.5 (LEV, additivity), 0.92 (CAZ, indifference) and 0.82 (AMP, indifference), respectively. These in vitro anti-MRSA activities of ISJ alone and its synergy with conventional antibacterial agents demonstrated that ISJ enhanced their efficacy, which is of potential use for single and combinatory therapy of patients infected with MRSA. PMID:22942699

Antifungal Activity of Thapsia villosa Essential Oil against Candida, Cryptococcus, Malassezia, Aspergillus and Dermatophyte Species.

PubMed

Pinto, Eugénia; Gonçalves, Maria-José; Cavaleiro, Carlos; Salgueiro, Lígia

2017-09-22

The composition of the essential oil (EO) of Thapsia villosa (Apiaceae), isolated by hydrodistillation from the plant's aerial parts, was analysed by GC and GC-MS. Antifungal activity of the EO and its main components, limonene (57.5%) and methyleugenol (35.9%), were evaluated against clinically relevant yeasts ( Candida spp., Cryptococcus neoformans and Malassezia furfur ) and moulds ( Aspergillus spp. and dermatophytes). Minimum inhibitory concentrations (MICs) were measured according to the broth macrodilution protocols by Clinical and Laboratory Standards Institute (CLSI). The EO, limonene and methyleugenol displayed low MIC and MFC (minimum fungicidal concentration) values against Candida spp., Cryptococcus neoformans , dermatophytes, and Aspergillus spp. Regarding Candida species, an inhibition of yeast-mycelium transition was demonstrated at sub-inhibitory concentrations of the EO (MIC/128; 0.01 μL/mL) and their major compounds in Candida albicans . Fluconazole does not show this activity, and the combination with low concentrations of EO could associate a supplementary target for the antifungal activity. The association of fluconazole with T. villosa oil does not show antagonism, but the combination limonene/fluconazole displays synergism. The fungistatic and fungicidal activities revealed by T. villosa EO and its main compounds, associated with their low haemolytic activity, confirm their potential antimicrobial interest against fungal species often associated with human mycoses.

Antibiotic resistance of lactic acid bacteria and Bifidobacterium spp. isolated from dairy and pharmaceutical products.

PubMed

D'Aimmo, Maria Rosaria; Modesto, Monica; Biavati, Bruno

2007-04-01

The outlines of antibiotic resistance of some probiotic microorganisms were studied. This study was conducted with the double purpose of verifying their ability to survive if they are taken simultaneously with an antibiotic therapy and to increase the selective properties of suitable media for the isolation of samples containing mixed bacterial populations. We isolated from commercial dairy and pharmaceutical products, 34 strains declared as probiotics, belonging to the genera Bifidobacterium and Lactobacillus, and 21 strains of starter culture bacteria. All the microorganisms have been compared by electrophoresis of the soluble proteins for the purpose of identifying them. A Multiplex-PCR with genus- and species-specific primers was used to detect for Bifidobacterium animalis subsp. lactis presence. All bifidobacteria were B. animalis subsp. lactis except one Bifidobacterium longum. Sometimes the identification showed that the used strain was not the one indicated on the label. The lactobacilli were Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus delbrueckii subsp. bulgaricus. The streptococci were all Streptococcus thermophilus. The minimal inhibitory concentration (MIC) of 24 common antibiotic substances has been valued by the broth microdilution method. All tested strains were susceptible to ampicillin, bacitracin, clindamycin, dicloxacillin, erytromycin, novobiocin, penicillin G, rifampicin (MIC(90) ranging from 0.01 to 4 microg/ml); resistant to aztreonam, cycloserin, kanamycin, nalidixic acid, polymyxin B and spectinomycin (MIC(90) ranging from 64 to >1000 microg/ml). The susceptibility to cephalothin, chloramphenicol, gentamicin, lincomycin, metronidazole, neomycin, paromomycin, streptomycin, tetracycline and vancomycin was variable and depending on the species.

The environmental source of emerging Apophysomyces variabilis infection in India.

PubMed

Prakash, Hariprasath; Ghosh, Anup Kumar; Rudramurthy, Shivaprakash Mandya; Paul, Raees Ahmad; Gupta, Sunita; Negi, Vishwanand; Chakrabarti, Arunaloke

2016-08-01

The rare mucoraceous fungus, Apophysomyces species complex ranks second after Rhizopus arrhizus causing mucormycosis in India. The source of this agent in the environment is not clearly known. We conducted an environmental study to find its presence in Indian soil. The soil samples from different geographical locations were analyzed for isolation of Mucorales. Rhizopus arrhizus (24.6%) was most commonly isolated from soil, followed by Lichtheimia spp. (23.2%), Cunninghamella spp. (21.7%), Rhizopus microsporus (14%) and Apophysomyces spp. (4.5%). The isolation of Apophysomyces species complex was significantly associated with low nitrogen content of the soil. Based on sequencing of internal transcribed spacer (ITS) and 28S (D1/D2) regions of ribosomal DNA, the Apophysomyces isolates were identified as Apophysomyces variabilis with 98 to 100% similarity to type strain A. variabilis (CBS658.93). The analysis of amplified fragment length polymorphism (AFLP) fingerprinting data demonstrated genomic diversity of A. variabilis isolates with multiple clades (similarity 40-90%). The minimum inhibitory concentrations (MIC), MIC50 and MIC90 for A. variabilis isolates were 1 and 4 μg/ml for amphotericin B, 0.25 and 0.5 μg/ml for itraconazole, 0.125 and 0.25 μg/ml for posaconazole, 0.06 and 0.12 μg/ml for terbinafine, respectively. The present study revealed abundant presence of A. variabilis in Indian soil with low nitrogen content, its genetic heterogeneity and relatively high MICs for amphotericin B. © The Author 2016. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A long journey from minimum inhibitory concentration testing to clinically predictive breakpoints: deterministic and probabilistic approaches in deriving breakpoints.

PubMed

Dalhoff, A; Ambrose, P G; Mouton, J W

2009-08-01

Since the origin of an "'International Collaborative Study on Antibiotic Sensitivity Testing'" in 1971, considerable advancement has been made to standardize clinical susceptibility testing procedures of antimicrobial agents. However, a consensus on the methods to be used and interpretive criteria was not reached, so the results of susceptibility testing were discrepant. Recently, the European Committee on Antimicrobial Susceptibility Testing achieved a harmonization of existing methods for susceptibility testing and now co-ordinates the process for setting breakpoints. Previously, breakpoints were set by adjusting the mean pharmacokinetic parameters derived from healthy volunteers to the susceptibilities of a population of potential pathogens expressed as the mean minimum inhibitory concentration (MIC) or MIC90%. Breakpoints derived by the deterministic approach tend to be too high, since this procedure does not take the variabilities of drug exposure and the susceptibility patterns into account. Therefore, first-step mutants or borderline susceptible bacteria may be considered as fully susceptible. As the drug exposure of such sub-populations is inadequate, resistance development will increase and eradication rates will decrease, resulting in clinical failure. The science of pharmacokinetics/pharmacodynamics integrates all possible drug exposures for standard dosage regimens and all MIC values likely to be found for the clinical isolates into the breakpoint definitions. Ideally, the data sets used originate from patients suffering from the disease to be treated. Probability density functions for both the pharmacokinetic and microbiological variables are determined, and a large number of MIC/drug exposure scenarios are calculated. Therefore, this method is defined as the probabilistic approach. The breakpoints thus derived are lower than the ones defined deterministically, as the entire range of probable drug exposures from low to high is modeled. Therefore, the amplification of drug-resistant sub-populations will be reduced. It has been a long journey since the first attempts in 1971 to define breakpoints. Clearly, this implies that none of the various approaches is right or wrong, and that the different approaches reflect different philosophies and mirror the tremendous progress made in the understanding of the pharmacodynamic properties of different classes of antimicrobials.

Sub-inhibitory concentrations of gentamicin triggers the expression of aac(6')Ie-aph(2″)Ia, chaperons and biofilm related genes in Lactobacillus plantarum MCC 3011.

PubMed

George, Jaimee; Halami, Prakash Motiram

2017-10-01

The study aimed to analyze the effects of sub-inhibitory concentrations of gentamicin on the expressions of high level aminoglycoside resistant (HLAR) bifunctional aac(6')Ie-aph(2″)Ia, biofilm and chaperone genes in Lactobacillus plantarum. The analysis of the biofilm formation in five isolates obtained from chicken sausages indicated their role in exhibiting phenotypic resistance based on the varied MIC values despite carrying the bifunctional gene. The biofilm formation significantly increased when L. plantarum MCC 3011 was grown in sub-inhibitory concentrations of gentamicin (4 μg/ml), kanamycin (8 μg/ml) and streptomycin (2 μg/ml). Thirty day gentamicin selection increased minimum inhibitory concentration (MIC) values from 4 to 64 and 2 to 256 fold for gentamicin and kanamycin, respectively when compared to the parental cultures. Expression studies revealed that constant exposure to gentamicin had induced chaperon [groEL] and the bifunctional gene, aac(6')Ie-aph(2″)Ia upto nine fold. Induction of groEL, groES and lamC genes in gentamicin (4 μg/ml) preincubated MCC 3011 indicated their significant role in aminoglycoside mediated response. Our study indicates that constant exposure to sub inhibitory concentrations of gentamicin allows L. plantarum to adapt against higher doses of aminoglycosides. This highlights the risks and food safety issues associated with the use of aminoglycosides in livestock and consumption of farm oriented fermented food products. Copyright © 2017 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Circulation of Highly Drug-Resistant Clostridium difficile Ribotypes 027 and 001 in Two Tertiary-Care Hospitals in Mexico.

PubMed

Martínez-Meléndez, Adrián; Tijerina-Rodríguez, Laura; Morfin-Otero, Rayo; Camacho-Ortíz, Adrián; Villarreal-Treviño, Licet; Sánchez-Alanís, Hugo; Rodríguez-Noriega, Eduardo; Baines, Simon D; Flores-Treviño, Samantha; Maldonado-Garza, Héctor Jesús; Garza-González, Elvira

2018-05-01

To assess drug susceptibility and characterize Clostridium difficile ribotypes in isolates from two tertiary-care hospitals in Mexico. Isolates were evaluated for genotyping, antimicrobial susceptibility testing and detection of mutations associated with drug resistance. PCR ribotyping was performed using a combination of gel-based and capillary electrophoresis-based approaches. MIC 50 and MIC 90 were ≥128 mg/L for ciprofloxacin, erythromycin, clindamycin, and rifampicin. There was no reduced susceptibility to metronidazole or tetracycline; however, reduced susceptibility to vancomycin (≥4 mg/L) and fidaxomicin (≥2 mg/L) was detected in 50 (40.3%) and 4 (3.2%) isolates, respectively. Furthermore, the rpoB Arg505Lys mutation was more frequently detected in isolates with high minimum inhibitory concentration (MIC) to rifampicin (≥32 mg/L) (OR = 52.5; 95% CI = 5.17-532.6; p < 0.000). Of the 124 C. difficile isolates recovered, 84 (66.7%) were of ribotype 027, 18 (14.5%) of ribotype 001, and the remainder were other ribotypes (353, 255, 220, 208, 176, 106, 076, 020, 019, 017, 014, 012, 003, and 002). Ribotypes 027 and 001 were the most frequent C. difficile isolates recovered in this study, and demonstrated higher MICs. Furthermore, we found four isolates with reduced susceptibility to fidaxomicin, raising a concern since this drug is currently unavailable in Mexican Hospitals.

Additive interaction of carbon dots extracted from soluble coffee and biogenic silver nanoparticles against bacteria

NASA Astrophysics Data System (ADS)

Andrade, Patricia F.; Nakazato, Gerson; Durán, Nelson

2017-06-01

It is known the presence of carbon dots (CDs) in carbohydrate based foods. CDs extracted from coffee grounds and instant coffee was also published. CDs from soluble coffee revealed an average size of 4.4 nm. CDs were well-dispersed in water, fluorescent and we have characterized by XPS, XRD analysis, fluorescence and by FTIR spectra. The MIC value by serial micro-dilution assays for CDs on S. aureus ATCC 25923 was 250 μg/mL and E. coli ATCC 25922 >1000 ug/mL. For silver nanoparticles biogenically synthesized was 6.7 μg/mL. Following the checkerboard assay with combining ½ MIC values of the MICs of 125 μg/mL of carbon dots and 3.4 μg/mL of silver nanoparticles, following the fractionated inhibitory concentration (FIC) index methodology, on S. aureus gave a fractionated inhibitory concentration (FIC) value of 1.0, meaning additive interaction. In general, the unfunctionalized CDs showed to be inefficient as antibacterial compounds, however the CDs extracted from Coffee powder and together silver nanoparticles appeared interesting as antibacterial association.

Potential Information Loss Due to Categorization of Minimum Inhibitory Concentration Frequency Distributions.

PubMed

Mazloom, Reza; Jaberi-Douraki, Majid; Comer, Jeffrey R; Volkova, Victoriya

2018-01-01

A bacterial isolate's susceptibility to antimicrobial is expressed as the lowest drug concentration inhibiting its visible growth, termed minimum inhibitory concentration (MIC). The susceptibilities of isolates from a host population at a particular time vary, with isolates with specific MICs present at different frequencies. Currently, for either clinical or monitoring purposes, an isolate is most often categorized as Susceptible, Intermediate, or Resistant to the antimicrobial by comparing its MIC to a breakpoint value. Such data categorizations are known in statistics to cause information loss compared to analyzing the underlying frequency distributions. The U.S. National Antimicrobial Resistance Monitoring System (NARMS) includes foodborne bacteria at the food animal processing and retail product points. The breakpoints used to interpret the MIC values for foodborne bacteria are those relevant to clinical treatments by the antimicrobials in humans in whom the isolates were to cause infection. However, conceptually different objectives arise when inference is sought concerning changes in susceptibility/resistance across isolates of a bacterial species in host populations among different sampling points or times. For the NARMS 1996-2013 data for animal processing and retail, we determined the fraction of comparisons of susceptibility/resistance to 44 antimicrobial drugs of twelve classes of a bacterial species in a given animal host or product population where there was a significant change in the MIC frequency distributions between consecutive years or the two sampling points, while the categorization-based analyses concluded no change. The categorization-based analyses missed significant changes in 54% of the year-to-year comparisons and in 71% of the slaughter-to-retail within-year comparisons. Hence, analyses using the breakpoint-based categorizations of the MIC data may miss significant developments in the resistance distributions between the sampling points or times. Methods considering the MIC frequency distributions in their entirety may be superior for epidemiological analyses of resistance dynamics in populations.

An investigation of vancomycin minimum inhibitory concentration creep among methicillin-resistant Staphylococcus aureus strains isolated from pediatric patients and healthy children in Northern Taiwan.

PubMed

Chang, Chia-Ning; Lo, Wen-Tsung; Chan, Ming-Chin; Yu, Ching-Mei; Wang, Chih-Chien

2017-06-01

The phenomenon of vancomycin minimum inhibitory concentration (MIC) creep is an increasingly serious problem in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. In this study, we investigated the vancomycin and daptomycin MIC values of MRSA strains isolated from pediatric patients and MRSA colonized healthy children. Then, we assessed whether there was evidence of clonal dissemination for strains with an MIC to vancomycin of ≥ 1.5 μg/mL. We collected clinical MRSA isolates from pediatric patients and from healthy children colonized with MRSA during 2008-2012 at a tertiary medical center in northern Taiwan and obtained vancomycin and daptomycin MIC values using the Etest method. Pulse-field gel electrophoresis (PFGE) and staphylococcal cassette chromosome (SCCmec) typing were used to assess clonal dissemination for strains with an MIC to vancomycin of ≥ 1.5 μg/mL. A total 195 MRSA strains were included in this study; 87 were isolated patients with a clinical MRSA infection, and the other 108 strains from nasally colonized healthy children. Vancomycin MIC≥1.5 μg/mL was seen in more clinical isolates (60/87, 69%) than colonized isolates (32/108, 29.6%), p < 0.001. The PFGE typing of both strains revealed multiple pulsotypes. Vancomycin MIC creeps existed in both clinical MRSA isolates and colonized MRSA strains. Great diversity of PFGE typing was in both strains collected. There was no association between the clinical and colonized MRSA isolates with vancomycin MIC creep. Copyright © 2016. Published by Elsevier B.V.

Evaluation of bioactivity of linalool-rich essential oils from Ocimum basilucum and Coriandrum sativum varieties.

PubMed

Duman, Ahmet D; Telci, Isa; Dayisoylu, Kenan S; Digrak, Metin; Demirtas, Ibrahim; Alma, Mehmet H

2010-06-01

Essential oils from Ocimum basilicum L. and Coriandrum sativum L. varieties originating from Turkey were investigated for their antimicrobial properties. The antimicrobial effects of the oil varieties were evaluated by the disc diffusion and minimum inhibitory concentration (MIC) methods against eight bacteria and three fungi. The compositions of the essential oils were analyzed and identified by GC and GC-MS. O. basilicum, C. sativum var. macrocarpum and var. microcarpum oils revealed the presence of linalool (54.4%), eugenol (9.6%), methyl eugenol (7.6%); linalool (78.8%), gamma-terpinene (6.0%), nerol acetate (3.5%); and linalool (90.6%), and nerol acetate (3.3%) as the major components, respectively. The oils exhibited antibacterial activity ranging from 1.25 to 10 microL disc(-1) against the test organisms with inhibition zones of 9.5-39.0 mm and minimal inhibitory concentrations values in the range 0.5- > or =1 microL/L. Linalool, eugenol, and methyl eugenol at 1.25 microL disc(-1) had antimicrobial effects on all microorganisms, giving inhibition zones ranging from 7 to 19 mm.

Antimicrobial effect of sour pomegranate sauce on Escherichia coli O157:H7 and Staphylococcus aureus.

PubMed

Kışla, Duygu; Karabıyıklı, Şeniz

2013-05-01

Pomegranate sauce is one of the most popular pomegranate products produced in Turkey. This study was conducted to determine the minimum inhibitory concentrations (MICs) of both traditional and commercial sour pomegranate sauce samples on Staphylococcus aureus (ATCC 25923) and Escherichia coli O157:H7 (ATCC 43895). The initial microflora of the pomegranate sauce samples was determined by performing the enumerations of total aerobic mesophilic bacteria, yeast and mold, S. aureus, E. coli, and the determination of Salmonella spp. MIC tests were applied to the neutralized and the original (unneutralized) sour pomegranate sauce samples in order to put forth the inhibition effect depending on low pH value. It was found that inhibitory effect of the traditional and the commercial samples, except one sample, on pathogens was not only due to the acidity of the products. The results of MIC tests indicated that although both traditional and commercial samples showed a considerable inhibitory effect on test microorganisms, the traditional pomegranate sauce samples were more effective than the commercial ones. © 2013 Institute of Food Technologists®

The use of minimum selectable concentrations (MSCs) for determining the selection of antimicrobial resistant bacteria.

PubMed

Khan, Sadia; Beattie, Tara K; Knapp, Charles W

2017-03-01

The use of antimicrobial compounds is indispensable in many industries, especially drinking water production, to eradicate microorganisms. However, bacterial growth is not unusual in the presence of disinfectant concentrations that would be typically lethal, as bacterial populations can develop resistance. The common metric of population resistance has been based on the Minimum Inhibitory Concentration (MIC), which is based on bacteria lethality. However, sub-lethal concentrations may also select for resistant bacteria due to the differences in bacterial growth rates. This study determined the Minimal Selective Concentrations (MSCs) of bacterial populations exposed to free chlorine and monochloramine, representing a metric that possibly better reflects the selective pressures occurring at lower disinfectant levels than MIC. Pairs of phylogenetically similar bacteria were challenged to a range of concentrations of disinfectants. The MSCs of free chlorine and monochloramine were found to range between 0.021 and 0.39 mg L -1 , which were concentrations 1/250 to 1/5 than the MICs of susceptible bacteria (MIC susc ). This study indicates that sub-lethal concentrations of disinfectants could result in the selection of resistant bacterial populations, and MSCs would be a more sensitive indicator of selective pressure, especially in environmental systems.

Influence of vancomycin minimum inhibitory concentration on the outcome of methicillin-susceptible Staphylococcus aureus left-sided infective endocarditis treated with antistaphylococcal β-lactam antibiotics: a prospective cohort study by the International Collaboration on Endocarditis⋆

PubMed Central

Pericàs, J.M.; Messina, J.A.; Garcia-de-la-Mària, C.; Park, L.; Sharma-Kuinkel, B.K.; Marco, F.; Wray, D.; Kanafani, Z.A.; Carugati, M.; Durante-Mangoni, E.; Tattevin, P.; Chu, V.H.; Moreno, A.; Fowler, V.G.; Miró, J.M.

2018-01-01

Objectives Left-sided methicillin-susceptible Staphylococcus aureus (MSSA) endocarditis treated with cloxacillin has a poorer prognosis when the vancomycin minimum inhibitory concentration (MIC) is ≥1.5 mg/L. We aimed to validate this using the International Collaboration on Endocarditis cohort and to analyse whether specific genetic characteristics were associated with a high vancomycin MIC (≥1.5 mg/L) phenotype. Methods All patients with left-sided MSSA infective endocarditis treated with antistaphylococcal β-lactam antibiotics between 2000 and 2006 with available isolates were included. Vancomycin MIC was determined by Etest as either high (≥1.5 mg/L) or low (<1.5 mg/L). Isolates underwent spa typing to infer clonal complexes and multiplex PCR for identifying virulence genes. Univariate analysis was performed to evaluate the association between in-hospital and 1-year mortality, and vancomycin MIC phenotype. Results Sixty-two cases met the inclusion criteria. Vancomycin MIC was low in 28 cases (45%) and high in 34 cases (55%). No significant differences in patient demographic data or characteristics of infection were observed between patients with infective endocarditis due to high and low vancomycin MIC isolates. Isolates with high and low vancomycin MIC had similar distributions of virulence genes and clonal lineages. In-hospital and 1-year mortality did not differ significantly between the two groups (32% (9/28) vs. 27% (9/34), p 0.780; and 43% (12/28) vs. 29% (10/34), p 0.298, for low and high vancomycin MIC respectively). Conclusions In this international cohort of patients with left-sided MSSA endocarditis treated with antistaphylococcal β-lactams, vancomycin MIC phenotype was not associated with patient demographics, clinical outcome or virulence gene repertoire. PMID:28159672

Influence of different susceptibility testing methods and media on determination of the relevant fluconazole minimum inhibitory concentrations for heavy trailing Candida isolates with low-high phenotype.

PubMed

Alp, Sehnaz; Sancak, Banu; Hascelik, Gulsen; Arikan, Sevtap

2010-11-01

We investigated the incidence of trailing growth with fluconazole in 101 clinical Candida isolates (49 C. albicans and 52 C. tropicalis) and tried to establish the convenient susceptibility testing method and medium for fluconazole minimum inhibitory concentration (MIC) determination. MICs were determined by CLSI M27-A2 broth microdilution (BMD) and Etest methods on RPMI-1640 agar supplemented with 2% glucose (RPG) and on Mueller-Hinton agar supplemented with 2% glucose and 0.5 μg ml(-1) methylene blue (GMB). BMD and Etest MICs were read at 24 and 48 h, and susceptibility categories were compared. All isolates were determined as susceptible with BMD, Etest-RPG and Etest-GMB at 24 h. While all isolates were interpreted as susceptible at 48 h on Etest-RPG and Etest-GMB, one C. albicans isolate was interpreted as susceptible-dose dependent (S-DD) and two C. tropicalis isolates were interpreted as resistant with BMD. On Etest-RPG, trailing growth caused widespread microcolonies within the inhibition zone and resulted in confusion in MIC determination. On Etest-GMB, because of the nearly absence of microcolonies within the zone of inhibition, MICs were evaluated more easily. We conclude that, for the determination of fluconazole MICs of trailing Candida isolates, the Etest method has an advantage over BMD and can be used along with this reference method. Moreover, GMB appears more beneficial than RPG for the fluconazole Etest. © 2009 Blackwell Verlag GmbH.

[Therapeutic efficacy of levofloxacin against a model of replicable Legionella pneumophila lung infection in DBA/2 mice].

PubMed

Kashimoto, Yoshinori; Kurosaka, Yuichi; Karibe, Yukie; Uoyama, Saori; Fujikawa, Katsuko; Namba, Kenji; Otani, Tsuyoshi; Yamaguchi, Keizo

2009-10-01

The in vitro and in vivo antibacterial activities of levofloxacin (LVFX), a quinolone antibacterial, against clinically isolated Legionella pneumophila were investigated in comparison with those of existing antimicrobial agents approved for legionnaires disease. The minimum inhibitory concentrations (MICs) of the agents against 42 strains of L. pneumophila isolated in Japan were determined using agar dilution methods with buffered starch yeast extract agar. MIC90 of LVFX was 0.03 microg/ml and this activity was similar to ciprofloxacin and pazufloxacin, and higher than telithromycin and minocycline. Therapeutic efficacy of LVFX was studied against a pneumonia model induced by intranasal of L. pneumophila strain suzuki serogoup 1 in DBA/2 mice. Therapeutic doses in mice were selected that would closely match human exposure profile, area under the concentration-time curve (AUC) for a human oral dose of LVFX at 500 mg once a day. LVFX decreased significantly the bacterial burden in the lungs from the next day of commencing treatment. These results, including in vitro antibacterial activity against clinical isolates and therapeutic efficacy of a humanized dosing regimen, provide good evidence to support the use of LVFX at 500 mg once a day for treating patient with legionnaires disease.

Boeravinone B, A Novel Dual Inhibitor of NorA Bacterial Efflux Pump of Staphylococcus aureus and Human P-Glycoprotein, Reduces the Biofilm Formation and Intracellular Invasion of Bacteria.

PubMed

Singh, Samsher; Kalia, Nitin P; Joshi, Prashant; Kumar, Ajay; Sharma, Parduman R; Kumar, Ashok; Bharate, Sandip B; Khan, Inshad A

2017-01-01

This study elucidated the role of boeravinone B, a NorA multidrug efflux pump inhibitor, in biofilm inhibition. The effects of boeravinone B plus ciprofloxacin, a NorA substrate, were evaluated in NorA-overexpressing, wild-type, and knocked-out Staphylococcus aureus (SA-1199B, SA-1199, and SA-K1758, respectively). The mechanism of action was confirmed using the ethidium bromide accumulation and efflux assay. The role of boeravinone B as a human P -glycoprotein ( P -gp) inhibitor was examined in the LS-180 (colon cancer) cell line. Moreover, its role in the inhibition of biofilm formation and intracellular invasion of S. aureus in macrophages was studied. Boeravinone B reduced the minimum inhibitory concentration (MIC) of ciprofloxacin against S. aureus and its methicillin-resistant strains; the effect was stronger in SA-1199B. Furthermore, time-kill kinetics revealed that boeravinone B plus ciprofloxacin, at subinhibitory concentration (0.25 × MIC), is as equipotent as that at the MIC level. This combination also had a reduced mutation prevention concentration. Boeravinone B reduced the efflux of ethidium bromide and increased the accumulation, thus strengthening the role as a NorA inhibitor. Biofilm formation was reduced by four-eightfold of the minimal biofilm inhibitory concentration of ciprofloxacin, effectively preventing bacterial entry into macrophages. Boeravinone B effectively inhibited P -gp with half maximal inhibitory concentration (IC 50 ) of 64.85 μM. The study concluded that boeravinone B not only inhibits the NorA-mediated efflux of fluoroquinolones but also considerably inhibits the biofilm formation of S. aureus. Its P -gp inhibition activity demonstrates its potential as a bioavailability and bioefficacy enhancer.

Boeravinone B, A Novel Dual Inhibitor of NorA Bacterial Efflux Pump of Staphylococcus aureus and Human P-Glycoprotein, Reduces the Biofilm Formation and Intracellular Invasion of Bacteria

PubMed Central

Singh, Samsher; Kalia, Nitin P.; Joshi, Prashant; Kumar, Ajay; Sharma, Parduman R.; Kumar, Ashok; Bharate, Sandip B.; Khan, Inshad A.

2017-01-01

This study elucidated the role of boeravinone B, a NorA multidrug efflux pump inhibitor, in biofilm inhibition. The effects of boeravinone B plus ciprofloxacin, a NorA substrate, were evaluated in NorA-overexpressing, wild-type, and knocked-out Staphylococcus aureus (SA-1199B, SA-1199, and SA-K1758, respectively). The mechanism of action was confirmed using the ethidium bromide accumulation and efflux assay. The role of boeravinone B as a human P-glycoprotein (P-gp) inhibitor was examined in the LS-180 (colon cancer) cell line. Moreover, its role in the inhibition of biofilm formation and intracellular invasion of S. aureus in macrophages was studied. Boeravinone B reduced the minimum inhibitory concentration (MIC) of ciprofloxacin against S. aureus and its methicillin-resistant strains; the effect was stronger in SA-1199B. Furthermore, time–kill kinetics revealed that boeravinone B plus ciprofloxacin, at subinhibitory concentration (0.25 × MIC), is as equipotent as that at the MIC level. This combination also had a reduced mutation prevention concentration. Boeravinone B reduced the efflux of ethidium bromide and increased the accumulation, thus strengthening the role as a NorA inhibitor. Biofilm formation was reduced by four–eightfold of the minimal biofilm inhibitory concentration of ciprofloxacin, effectively preventing bacterial entry into macrophages. Boeravinone B effectively inhibited P-gp with half maximal inhibitory concentration (IC50) of 64.85 μM. The study concluded that boeravinone B not only inhibits the NorA-mediated efflux of fluoroquinolones but also considerably inhibits the biofilm formation of S. aureus. Its P-gp inhibition activity demonstrates its potential as a bioavailability and bioefficacy enhancer. PMID:29046665

Concentration-Dependent Antagonism and Culture Conversion in Pulmonary Tuberculosis

PubMed Central

Pasipanodya, Jotam G.; Denti, Paolo; Sirgel, Frederick; Lesosky, Maia; Gumbo, Tawanda; Meintjes, Graeme; McIlleron, Helen; Wilkinson, Robert J.

2017-01-01

Abstract Background. There is scant evidence to support target drug exposures for optimal tuberculosis outcomes. We therefore assessed whether pharmacokinetic/pharmacodynamic (PK/PD) parameters could predict 2-month culture conversion. Methods. One hundred patients with pulmonary tuberculosis (65% human immunodeficiency virus coinfected) were intensively sampled to determine rifampicin, isoniazid, and pyrazinamide plasma concentrations after 7–8 weeks of therapy, and PK parameters determined using nonlinear mixed-effects models. Detailed clinical data and sputum for culture were collected at baseline, 2 months, and 5–6 months. Minimum inhibitory concentrations (MICs) were determined on baseline isolates. Multivariate logistic regression and the assumption-free multivariate adaptive regression splines (MARS) were used to identify clinical and PK/PD predictors of 2-month culture conversion. Potential PK/PD predictors included 0- to 24-hour area under the curve (AUC0-24), maximum concentration (Cmax), AUC0-24/MIC, Cmax/MIC, and percentage of time that concentrations persisted above the MIC (%TMIC). Results. Twenty-six percent of patients had Cmax of rifampicin <8 mg/L, pyrazinamide <35 mg/L, and isoniazid <3 mg/L. No relationship was found between PK exposures and 2-month culture conversion using multivariate logistic regression after adjusting for MIC. However, MARS identified negative interactions between isoniazid Cmax and rifampicin Cmax/MIC ratio on 2-month culture conversion. If isoniazid Cmax was <4.6 mg/L and rifampicin Cmax/MIC <28, the isoniazid concentration had an antagonistic effect on culture conversion. For patients with isoniazid Cmax >4.6 mg/L, higher isoniazid exposures were associated with improved rates of culture conversion. Conclusions. PK/PD analyses using MARS identified isoniazid Cmax and rifampicin Cmax/MIC thresholds below which there is concentration-dependent antagonism that reduces 2-month sputum culture conversion. PMID:28205671

NorA efflux pump inhibitory activity of coumarins from Mesua ferrea.

PubMed

Roy, Somendu K; Kumari, Neela; Pahwa, Sonika; Agrahari, Udai C; Bhutani, Kamlesh K; Jachak, Sanjay M; Nandanwar, Hemraj

2013-10-01

The purpose of this investigation was to study the modulator and efflux pump inhibitor activity of coumarins isolated from Mesua ferrea against clinical strains as well as NorA-over expressed strain of Staphylococcus aureus 1199B. Seven coumarins were tested for modulator activity using ethidium bromide (EtBr) as a substrate. Compounds 1, 4-7 modulated the MIC of EtBr by ≥ 2 fold against wild type clinical strains of S. aureus 1199 and S. aureus 1199B, whereas compounds 4-7 modulated the MIC of EtBr by ≥ 16 fold against MRSA 831. Compounds 1, 4-7 also reduced the MIC of norfloxacin by ≥ 8 fold against S. aureus 1199B, and 4-6 reduced the MIC of norfloxacin by ≥ 8 fold against MRSA 831 at half of their MICs. Inhibition of EtBr efflux by NorA-overproducing S. aureus 1199B and MRSA 831 confirmed the role of compounds 4-6 as NorA efflux pump inhibitors (EPI). Dose-dependent activity at sub-inhibitory concentration (6.25 μg/mL) suggested that compounds 4 and 5 are promising EPI compared to verapamil against 1199B and MRSA 831 strains. © 2013.

Comparative in vitro activity of carbapenems against major Gram-negative pathogens: results of Asia-Pacific surveillance from the COMPACT II study.

PubMed

Kiratisin, Pattarachai; Chongthaleong, Anan; Tan, Thean Yen; Lagamayo, Evelina; Roberts, Sally; Garcia, Jemelyn; Davies, Todd

2012-04-01

Resistance rates amongst Gram-negative pathogens are increasing in the Asia-Pacific region. The Comparative Activity of Carbapenem Testing (COMPACT) II study surveyed the carbapenem susceptibility and minimum inhibitory concentrations (MICs) of doripenem, imipenem and meropenem against 1260 major Gram-negative pathogens isolated from hospitalised patients at 20 centres in five Asia-Pacific countries (New Zealand, the Philippines, Singapore, Thailand and Vietnam) during 2010. Pseudomonas aeruginosa (n=625), Enterobacteriaceae (n=500), and other Gram-negative pathogens including Acinetobacter baumannii (n=135) were collected from patients with bloodstream infection (32.2%), nosocomial pneumonia including ventilator-associated pneumonia (58.1%), and complicated intra-abdominal infection (9.7%), with 36.7% being isolated from patients in an Intensive Care Unit. As high as 29.8% of P. aeruginosa and 73.0% of A. baumannii isolates were not susceptible to at least a carbapenem, whereas the majority of Enterobacteriaceae (97.2%) were susceptible to all carbapenems. Respective MIC(50)/MIC(90) values (MICs for 50% and 90% of the organisms, respectively) of doripenem, imipenem and meropenem were: 0.38/8, 1.5/32 and 0.38/16 mg/L for P. aeruginosa; 0.023/0.094, 0.25/0.5 and 0.032/0.094 mg/L for Enterobacteriaceae; and 32/64, 32/128 and 32/64 mg/L for A. baumannii. Doripenem and meropenem had comparable activity against P. aeruginosa, both being more active than imipenem. All carbapenems were highly potent against Enterobacteriaceae, although imipenem demonstrated higher MIC values than doripenem and meropenem. The three carbapenems showed less activity against A. baumannii. The high prevalence of carbapenem resistance amongst important nosocomial pathogens (P. aeruginosa and A. baumannii) warrants rigorous infection control measures and appropriate antimicrobial use in the Asia-Pacific region. Copyright © 2012 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

In vitro antibacterial activity of ceftobiprole against clinical isolates from French teaching hospitals: proposition of zone diameter breakpoints.

PubMed

Lascols, C; Legrand, P; Mérens, A; Leclercq, R; Muller-Serieys, C; Drugeon, H B; Kitzis, M D; Reverdy, M E; Roussel-Delvallez, M; Moubareck, C; Brémont, S; Miara, A; Gjoklaj, M; Soussy, C-J

2011-03-01

The aims of this study were to determine the in vitro activity profile of ceftobiprole, a pyrrolidinone cephalosporin, against a large number of bacterial pathogens and to propose zone diameter breakpoints for clinical categorisation according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) minimum inhibitory concentration (MIC) breakpoints. MICs of ceftobiprole were determined by broth microdilution against 1548 clinical isolates collected in eight French hospitals. Disk diffusion testing was performed using 30 μg disks according to the method of the Comité de l'Antibiogramme de la Société Française de Microbiologie (CA-SFM). The in vitro activity of ceftobiprole, expressed by MIC(50/90) (MICs for 50% and 90% of the organisms, respectively) (mg/L), was as follows: meticillin-susceptible Staphylococcus aureus, 0.25/0.5; meticillin-resistant S. aureus (MRSA), 1/2; meticillin-susceptible coagulase-negative staphylococci (CoNS), 0.12/0.5; meticillin-resistant CoNS, 1/2; penicillin-susceptible Streptococcus pneumoniae, ≤ 0.008/0.03; penicillin-resistant S. pneumoniae, 0.12/0.5; viridans group streptococci, 0.03/0.12; β-haemolytic streptococci, ≤ 0.008/0.016; Enterococcus faecalis, 0.25/1; Enterococcus faecium, 64/128; Enterobacteriaceae, 0.06/32; Pseudomonas aeruginosa, 4/16; Acinetobacter baumannii, 0.5/64; Haemophilus influenzae, 0.03/0.12; and Moraxella catarrhalis, 0.25/0.5. According to the regression curve, zone diameter breakpoints could be 28, 26, 24 and 22 mm for MICs of 0.5, 1, 2 and 4 mg/L respectively. In conclusion, this study confirms the potent in vitro activity of ceftobiprole against many Gram-positive bacteria, including MRSA but not E. faecium, whilst maintaining a Gram-negative spectrum similar to the advanced-generation cephalosporins such as cefepime. Thus ceftobiprole appears to be well suited for the empirical treatment of a variety of healthcare-associated infections. Copyright © 2011 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

[In vitro synergistic effect of moxifloxacin and amphotericin B combination against Candida strains].

PubMed

Yalçin, Burçe; Kalkanci, Ayşe; Gürelik, Feryal; Fidan, Işil; Kustimur, Semra; Ozdek, Sengül

2010-01-01

Contradictory results such as synergy or indifferent effect, have been reported about the interactions between quinolones and antifungal drugs in different studies. The aim of this study was to investigate the in vitro susceptibilities of Candida spp. to moxifloxacin (MOX) alone and MOX + amphotericin B (AmB) combination. A total of 20 strains were included to the study, of which 19 were clinical isolates (10 Candida albicans, 4 Candida glabrata, 2 Candida parapsilosis, 1 Candida tropicalis, 1 Candida pelliculosa ve 1 Candida sake) and 1 was a standard strain (C. albicans ATCC 90028). In vitro susceptibilities of the strains to MOX with AmB were investigated by broth microdilution method according to the recommendations of the Clinical and Laboratory Standards Institute (CLSI), and in vitro interaction of these drugs were determined by a chequerboard titration method. Minimal inhibitory concentration (MIC) values of Candida spp. for MOX were found > or = 400 microg/ml indicating that MOX, by itself has no antifungal activity. AmB MIC values were found 1 microg/ml in 11 of the clinical isolates, and < or = 0.5 microg/ml in the other 8 clinical isolates and 1 standard strain. The inhibitor activity of AmB was slightly enhanced when combined with MOX, there being a decrease of 1-4 fold dilutions in the AmB MICs against all isolates tested. Synergistic effect between MOX and AmB, defined as a fractional inhibitory concentration (FIC) index as < or = 0.5, was observed in 90% (18/20; all were clinical isolates) of the strains, whereas indifferent effect (FIC = 1) was detected in 10% (2/20; 1 was clinical and 1 was standard strain) of the strains. Antagonistic effect was not observed for this combination even at 48th hours. It was concluded that these preliminary results should be confirmed by large-scaled in vitro and in vivo studies to evaluate MOX + AmB combination as a therapeutic option for the treatment of Candida infections.

Antibacterial and phytochemical studies on Calotropis gigantia (L.) R. Br. latex against selected cariogenic bacteria

PubMed Central

Ishnava, Kalpesh B.; Chauhan, Jenabhai B.; Garg, Akanksha A.; Thakkar, Arpit M.

2011-01-01

In vitro antibacterial potential of the chloroform, ethyl acetate, hexane, methanol and aqueous extracts of Calotropis gigantia (L.) R. Br. was evaluated by using five cariogenic bacteria, Actinomyces viscosus, Lactobacillus acidophilus, Lactobacillus casei, Streptococcus mitis and Streptococcus mutans. Agar well diffusion method and minimum inhibitory concentration (MIC) were used for this purpose. The chloroform extracted fraction of latex showed inhibitory effect against S. mutans and L. acidophilus with MIC value of 0.032 and 0.52 mg/mL, respectively. Qualitative investigation on structure elucidation of bioactive compound using IR, NMR and GC–MS techniques revealed the presence of methyl nonanoate, a saturated fatty acid. PMID:23961166

Water Disinfection Byproducts Induce Antibiotic Resistance-Role of Environmental Pollutants in Resistance Phenomena.

PubMed

Li, Dan; Zeng, Siyu; He, Miao; Gu, April Z

2016-03-15

The spread of antibiotic resistance represents a global threat to public health, and has been traditionally attributed to extensive antibiotic uses in clinical and agricultural applications. As a result, researchers have mostly focused on clinically relevant high-level resistance enriched by antibiotics above the minimal inhibitory concentrations (MICs). Here, we report that two common water disinfection byproducts (chlorite and iodoacetic acid) had antibiotic-like effects that led to the evolution of resistant E. coli strains under both high (near MICs) and low (sub-MIC) exposure concentrations. The subinhibitory concentrations of DBPs selected strains with resistance higher than those evolved under above-MIC exposure concentrations. In addition, whole-genome analysis revealed distinct mutations in small sets of genes known to be involved in multiple drug and drug-specific resistance, as well as in genes not yet identified to play role in antibiotic resistance. The number and identities of genetic mutations were distinct for either the high versus low sub-MIC concentrations exposure scenarios. This study provides evidence and mechanistic insight into the sub-MIC selection of antibiotic resistance by antibiotic-like environmental pollutants such as disinfection byproducts in water, which may be important contributors to the spread of global antibiotic resistance. The results from this study open an intriguing and profound question on the roles of large amount and various environmental contaminants play in selecting and spreading the antibiotics resistance in the environment.

In vitro susceptibility of Helicobacter pullorum strains to different antimicrobial agents.

PubMed

Ceelen, Liesbeth; Decostere, Annemie; Devriese, Luc A; Ducatelle, Richard; Haesebrouck, Freddy

2005-01-01

The in vitro activity of 13 antimicrobial agents against 23 Helicobacter pullorum strains from poultry (21) and human (two) origin, and one human H. canadensis strain was tested by the agar dilution method. With the H. pullorum strains, monomodal distributions of Minimum Inhibitory Concentrations (MICs) were seen with lincomycin, doxycycline, gentamicin, tobramycin, erythromycin, tylosin, metronidazole, and enrofloxacin in concentration ranges considered as indicating susceptibility in other bacteria. The normal susceptibility level for nalidixic acid was situated at or slightly above the MIC breakpoints proposed for Campylobacteriaceae. Ampicillin, ceftriaxone, and sulphamethoxazole-trimethoprim showed poor activity against H. pullorum. For the H. canadensis strain, a similar susceptibility pattern was seen, except for nalidixic acid and enrofloxacin, whose MIC of >512 and 8 microg/ml, respectively, indicated resistance of this agent. With spectinomycin, a bimodal distribution of the MICs was noted for the tested strains; eight H. pullorum isolates originating from one flock showed acquired resistance (MIC>512 microg/ml).

Factors influencing the potency of marbofloxacin for pig pneumonia pathogens Actinobacillus pleuropneumoniae and Pasteurella multocida.

PubMed

Dorey, L; Hobson, S; Lees, P

2017-04-01

For the pig respiratory tract pathogens, Actinobacillus pleuropneumoniae and Pasteurella multocida, Minimum Inhibitory Concentration (MIC) of marbofloxacin was determined in recommended broths and pig serum at three inoculum strengths. MICs in both growth matrices increased progressively from low, through medium to high starting inoculum counts, 10 4 , 10 6 and 10 8 CFU/mL, respectively. P. multocida MIC ratios for high:low inocula were 14:4:1 for broth and 28.2:1 for serum. Corresponding MIC ratios for A. pleuropneumoniae were lower, 4.1:1 (broth) and 9.2:1 (serum). MIC high:low ratios were therefore both growth matrix and bacterial species dependent. The effect of alterations to the chemical composition of broths and serum on MIC were also investigated. Neither adjusting broth or serum pH in six increments over the range 7.0 to 8.0 nor increasing calcium and magnesium concentrations of broth in seven incremental steps significantly affected MICs for either organism. In time-kill studies, the killing action of marbofloxacin had the characteristics of concentration dependency against both organisms in both growth matrices. It is concluded that MIC and time-kill data for marbofloxacin, generated in serum, might be preferable to broth data, for predicting dosages of marbofloxacin for clinical use. Copyright © 2016 Elsevier Ltd. All rights reserved.

Antifungal activity and mode of action of thymol and its synergism with nystatin against Candida species involved with infections in the oral cavity: an in vitro study.

PubMed

de Castro, Ricardo Dias; de Souza, Trícia Murielly Pereira Andrade; Bezerra, Louise Morais Dornelas; Ferreira, Gabriela Lacet Silva; Costa, Edja Maria Melo de Brito; Cavalcanti, Alessandro Leite

2015-11-24

Limitations of antifungal agents used in the treatment of oral candidiasis, as the development of resistant strains, are known by the scientific community. In this context, the aim of this study was to evaluate the antifungal activity of thymol against Candida albicans, Candida tropicalis and Candida krusei strains and to determine its mode of action and synergistic effect when combined with the synthetic antifungal nystatin. The minimum inhibitory concentration (MIC) was determined using a microdilution technique, and the minimum fungicidal concentration (MFC) was determined via subculture sowing. The mode of action of thymol was established by verifying fungal growth in the presence of sorbitol or ergosterol. The fractional inhibitory concentration index (FIC) was determined using the checkerboard method. Thymol presented an antifungal effect, with MICs of 39 μg/mL for C. albicans and C. krusei and 78 μg/mL for C. tropicalis. The results of the antifungal test remained unchanged in the presence of sorbitol; however, the MIC value of thymol against C. albicans increased eight times (from 39.0 to 312.5 μg/mL) in presence of exogenous ergosterol. The combination of thymol and nystatin reduced the MIC values of both products by 87.4%, generating an FIC index of 0.25. Thymol was found to have a fungicidal effect on Candida species and a synergistic effect when combined with nystatin.

Activity of TDT 067 (terbinafine in Transfersome) against agents of onychomycosis, as determined by minimum inhibitory and fungicidal concentrations.

PubMed

Ghannoum, Mahmoud; Isham, Nancy; Herbert, Jacqueline; Henry, William; Yurdakul, Sam

2011-05-01

TDT 067 is a novel carrier-based dosage form (liquid spray) of 15 mg/ml of terbinafine in Transfersome that has been developed to deliver terbinafine to the nail bed to treat onychomycosis. In this study, we report the in vitro activities of TDT 067 against dermatophytes, compared with those of the Transfersome vehicle, naked terbinafine, and commercially available terbinafine (1%) spray. The MICs of TDT 067 and comparators against 25 clinical strains each of Trichophyton rubrum, T. mentagrophytes, and Epidermophyton floccosum were determined according to the CLSI M38-A2 susceptibility method (2008). Minimum fungicidal concentrations (MFCs) were determined by subculturing visibly clear wells from the MIC microtiter plates. TDT 067 demonstrated potent activity against the dermatophyte strains tested, with an MIC range of 0.00003 to 0.015 μg/ml. Overall, TDT 067 MIC(50) values (defined as the lowest concentrations to inhibit 50% of the strains tested) were 8-fold and 60-fold lower than those of naked terbinafine and terbinafine spray, respectively. The Transfersome vehicle showed minimal inhibitory activity. TDT 067 demonstrated lower MFC values for T. rubrum and E. floccosum than naked terbinafine and terbinafine spray. TDT 067 has more potent antifungal activity against dermatophytes that cause nail infection than conventional terbinafine preparations. The Transfersome vehicle appears to potentiate the antifungal activity of terbinafine. Clinical investigation of TDT 067 for the topical treatment of onychomycosis is warranted.

Bioactive endophytic fungi isolated from Caesalpinia echinata Lam. (Brazilwood) and identification of beauvericin as a trypanocidal metabolite from Fusarium sp.

PubMed

Campos, Fernanda Fraga; Sales Junior, Policarpo A; Romanha, Alvaro José; Araújo, Márcio S S; Siqueira, Ezequias P; Resende, Jarbas M; Alves, Tânia M A; Martins-Filho, Olindo A; Santos, Vera Lúcia dos; Rosa, Carlos A; Zani, Carlos L; Cota, Betania Barros

2015-02-01

Aiming to identify new sources of bioactive secondary metabolites, we isolated 82 endophytic fungi from stems and barks of the native Brazilian tree Caesalpinia echinata Lam. (Fabaceae). We tested their ethyl acetate extracts in several in vitro assays. The organic extracts from three isolates showed antibacterial activity against Staphylococcus aureus and Escherichia coli [minimal inhibitory concentration (MIC) 32-64 μg/mL]. One isolate inhibited the growth of Salmonella typhimurium (MIC 64 μg/mL) and two isolates inhibited the growth of Klebsiella oxytoca (MIC 64 μg/mL), Candida albicans and Candida tropicalis (MIC 64-128 μg/mL). Fourteen extracts at a concentration of 20 μg/mL showed antitumour activities against human breast cancer and human renal cancer cells, while two isolates showed anti-tumour activities against human melanoma cancer cells. Six extracts were able to reduce the proliferation of human peripheral blood mononuclear cells, indicating some degree of selective toxicity. Four isolates were able to inhibit Leishmania (Leishmania) amazonensis and one isolate inhibited Trypanosoma cruzi by at least 40% at 20 μg/mL. The trypanocidal extract obtained from Fusarium sp. [KF611679] culture was subjected to bioguided fractionation, which revealed beauvericin as the compound responsible for the observed toxicity of Fusarium sp. to T. cruzi. This depsipeptide showed a half maximal inhibitory concentration of 1.9 μg/mL (2.43 μM) in a T. cruzi cellular culture assay.

Antimicrobial activity and synergy of antibiotics with two biphenyl compounds, protosappanins A and B from Sappan Lignum against methicillin-resistant Staphylococcus aureus strains.

PubMed

Zuo, Guo-Ying; Han, Zong-Qi; Han, Jun; Hao, Xiao-Yan; Tang, Hua-Shu; Wang, Gen-Chun

2015-10-01

This study aims to investigate antimicrobial ingredients from Sappan Lignum and to evaluate their synergy on methicillin-resistant Staphylococcus aureus strains with antibiotics. Bioactivity-guided phytochemical procedures were used to screen the active compounds. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were assayed by broth microdilution. The synergy was evaluated through checkerboard microdilution and loss of viability assays. Protosappanins A (PsA) and B (PsB) were identified from Sappan Lignum extracts. They showed active against both S. aureus and MRSA with MIC or MIC50 at 64 (PsA) and 128 (PsB) mg/L alone. When they were used in combination with antibiotics, they showed best synergy with amikacin and gentamicin with MIC50 (mg/L) of amikacin reduced more significantly from 32 to four (with PsA) and eight (with PsB), and the fractional inhibitory concentration index (FICI) ranged between 0.078 and 0.500 (FICI50  = 0.375). Moreover, the resistance of MRSA towards amikacin and gentamicin could be reversed by the Clinical and Laboratory Standards Institute criteria. The combined bactericidal mode could as well be synergy. PsA and PsB showed very low cytotoxicity in comparison with their promising activity against MRSA. Protosappanins A and B showed both alone activities and resistance reversal effects of amikacin and gentamicin against MRSA, which warrant further investigations for potential combinatory therapy of MRSA infection. © 2015 Royal Pharmaceutical Society.

In vitro activity of the siderophore monosulfactam BAL30072 against contemporary Gram-negative pathogens from New York City, including multidrug-resistant isolates.

PubMed

Landman, David; Singh, Manisha; El-Imad, Badiaa; Miller, Ezra; Win, Thida; Quale, John

2014-06-01

The in vitro activity of BAL30072 was assessed against clinical isolates from NYC hospitals, including isolates from a citywide surveillance study and a collection of isolates with well-characterised resistance mechanisms. BAL30072 was the most active β-lactam against Pseudomonas aeruginosa (MIC50/90, 0.25/1 μg/mL), Acinetobacter baumannii (MIC50/90, 4/>64 μg/mL) and KPC-possessing Klebsiella pneumoniae (MIC50/90, 4/>64 μg/mL). Combining BAL30072 with meropenem resulted in a ≥ 4-fold decrease in the BAL30072 MIC90 both for A. baumannii and K. pneumoniae. For isolates with a BAL30072 MIC>4 μg/mL, addition of a sub-MIC concentration of colistin resulted in a four-fold decrease in the BAL30072 MIC in 44% of P. aeruginosa, 82% of A. baumannii and 23% of K. pneumoniae. Using sub-MIC concentrations, BAL30072 plus colistin was bactericidal against 4 of 11 isolates in time-kill studies. BAL30072 MICs were frequently lower for P. aeruginosa and K. pneumoniae when tested using Mueller-Hinton agar versus Iso-Sensitest agar or Mueller-Hinton broth. Against the well-characterised isolates, reduced susceptibility to BAL30072 correlated with mexA and mexX expression (P. aeruginosa), adeB expression (A. baumannii) and presence of SHV-type ESBLs (A. baumannii and K. pneumoniae). BAL30072 shows promising activity against contemporary Gram-negatives, including MDR P. aeruginosa, A. baumannii and K. pneumoniae. Enhanced activity was often present when BAL30072 was combined with meropenem or colistin. BAL30072 MICs were influenced by the testing method, particularly for P. aeruginosa and K. pneumoniae. Further in vivo studies are warranted to determine the potential clinical utility of BAL30072 alone and combined with other agents. Copyright © 2014 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Determination of antifungal activities in serum samples from mice treated with different antifungal drugs allows detection of an active metabolite of itraconazole.

PubMed

Maki, Katsuyuki; Watabe, Etsuko; Iguchi, Yumi; Nakamura, Hideko; Tomishima, Masaki; Ohki, Hidenori; Yamada, Akira; Matsumoto, Satoru; Ikeda, Fumiaki; Tawara, Shuichi; Mutoh, Seitaro

2006-01-01

To establish an in vitro method of predicting in vivo efficacy of antifungal drugs against Candida albicans and Aspergillus fumigatus, the antifungal activities of fluconazole, itraconazole, and amphotericin B were determined in mouse serum. The minimum inhibitory concentration (MIC) of each drug was measured using mouse serum as a diluent. For C. albicans, the assay endpoint of azoles was defined as inhibition of mycelial extension (mMIC) and for A. fumigatus, as no growth (MIC). The MICs of amphotericin B for both pathogens were defined as the MIC at which no mycelial growth occurred. Serum MIC or mMIC determinations were then used to estimate the concentration of the drugs in serum of mice treated with antifungal drugs by multiplying the antifungal titer of the serum samples by the serum (m)MIC. The serum drug concentrations were also determined by HPLC. The serum concentrations estimated microbiologically showed good agreement with those determined by HPLC, except for itraconazole. Analysis of the serum samples from itraconazole-treated mice by a sensitive bioautography revealed the presence of additional spots, not seen in control samples of itraconazole. The bioautography assay demonstrated that the additional material detected in serum from mice treated with itraconazole was an active metabolite of itraconazole. The data showed that the apparent reduction in the itraconazole serum concentration as determined by HPLC was the result of the formation of an active metabolite, and that the use of a microbiological method to measure serum concentrations of drugs can provide a method for prediction of in vivo efficacy of antifungal drugs.

Combined application of origanum vulgare l. essential oil and acetic acid for controlling the growth of staphylococcus aureus in foods

PubMed Central

de Souza, Evandro Leite; de Barros, Jefferson Carneiro; da Conceição, Maria Lúcia; Neto, Nelson Justino Gomes; da Costa, Ana Caroliny Vieira

2009-01-01

This study evaluated the occurrence of an enhancing inhibitory effect of the combined application of Origanum vulgare L. essential oil and acetic acid against Staphylococcus aureus by the determination of Fractional Inhibitory Concentration (FIC) index and kill-time assay in nutrient broth, meat broth and in a food model (meat pieces). Acetic acid showed MIC and MFC of 0.6 and 1.25 μL.mL-1, respectively. For O. vulgare essential oil MIC and MBC were 1.25 and 2.5 μL.mL-1, respectively. FIC indexes of the mixture of essential oil and acetic acid at MIC x ½ were ≤ 1.0, showing an additive effect. No synergy was found at kill-time study. Anti-staphylococcal effect of the antimicrobials alone or in mixture (MIC x ½) was lower in meat than in nutrient and meat broths. The effective combination of essential oils and organic acids could appear as an attractive alternative for the food industry, as the doses to inhibit the microbial growth in foods can be lowered. PMID:24031377

An in vitro study of anticariogenic compounds incorporated into Bis-GMA/TEGDMA copolymer

NASA Astrophysics Data System (ADS)

Pilly Yadaiah, Vinay Kumar

Composite resins continue to evolve and are increasingly favoured by the people. However, drawbacks such as decreased longevity, secondary caries and costs make choosing composites a dilemma. This study evaluated drug release, inhibitory growth against Streptococcus mutans and drug stability of epigallocatechin-gallate (EGCg) incorporated into dental copolymer compared to resins containing chlorhexidine (CHX). Resin discs (5mm x 3mm) were prepared from 70 mol% Bis-GMA and 30 mol% TEGDMA comonomers containing: placebo, CHX and EGCg. Two corresponding concentrations in weight% of each drug for 0.5 and 1.0 x MIC were incorporated into paste resins and tested at time points: 24 hours, 7 days, 30 days, 60 days and 90 days. There is a significant difference in the 90 days drug delivery and bacterial inhibition among different drugs and drug ratios, which showed stability after 90 days. The results indicate that drug-based composites may reduce bacterial growth, which may improve its longevity.

Tilmicosin- and florfenicol-loaded hydrogenated castor oil-solid lipid nanoparticles to pigs: Combined antibacterial activities and pharmacokinetics.

PubMed

Ling, Z; Yonghong, L; Junfeng, L; Li, Z; Xianqiang, L

2018-04-01

The combined antibacterial effects of tilmicosin (TIL) and florfenicol (FF) against Actinobacillus pleuropneumoniae (APP) (n = 2), Streptococcus suis (S. suis) (n = 2), and Haemophilus parasuis (HPS) (n = 2) were evaluated by chekerboard test and time-kill assays. The pharmacokinetics (PKs) of TIL- and FF-loaded hydrogenated castor oil (HCO)-solid lipid nanoparticles (SLN) were performed in healthy pigs. The results indicated that TIL and FF showed synergistic or additive antibacterial activities against APP, S. suis and HPS with the fractional inhibitory concentration (FIC) ranging from 0.375 to 0.75. The time-kill assays showed that 1/2 minimum inhibitory concentration (MIC) TIL combined with 1/2 MIC FF had a stronger ability to inhibit the growth of APP, S. suis, and HPS than 1 MIC TIL or 1 MIC FF, respectively. After oral administration, plasma TIL and FF concentrations could maintain about 0.1 μg/ml for 192 and 176 hr. The SLN prolonged the last time point with detectable concentrations (T last ), area under the concentration-time curve (AUC 0-t ), elimination half-life (T ½ke ), and mean residence time (MRT) by 3.1, 5.6, 12.7, 3.4-fold of the active pharmaceutical ingredient (API) of TIL and 11.8, 16.5, 18.1, 12.1-fold of the API of FF, respectively. This study suggests that the TIL-FF-SLN could be a useful oral formulation for the treatment of APP, S. suis, and HPS infection in pigs. © 2017 John Wiley & Sons Ltd.

Systematic screening of plant extracts from the Brazilian Pantanal with antimicrobial activity against bacteria with cariogenic relevance.

PubMed

Brighenti, F L; Salvador, M J; Delbem, Alberto Carlos Botazzo; Delbem, Ádina Cleia Bottazzo; Oliveira, M A C; Soares, C P; Freitas, L S F; Koga-Ito, C Y

2014-01-01

This study proposes a bioprospection methodology regarding the antimicrobial potential of plant extracts against bacteria with cariogenic relevance. Sixty extracts were obtained from ten plants--(1) Jatropha weddelliana, (2) Attalea phalerata, (3) Buchenavia tomentosa, (4) Croton doctoris, (5) Mouriri elliptica, (6) Mascagnia benthamiana, (7) Senna aculeata, (8) Unonopsis guatterioides, (9) Allagoptera leucocalyx and (10) Bactris glaucescens--using different extraction methods - (A) 70° ethanol 72 h/25°C, (B) water 5 min/100°C, (C) water 1 h/55°C, (D) water 72 h/25°C, (E) hexane 72 h/25°C and (F) 90° ethanol 72 h/25°C. The plants were screened for antibacterial activity at 50 mg/ml using the agar well diffusion test against Actinomyces naeslundii ATCC 19039, Lactobacillus acidophilus ATCC 4356, Streptococcus gordonii ATCC 10558, Streptococcus mutans ATCC 35688, Streptococcus sanguinis ATCC 10556, Streptococcus sobrinus ATCC 33478 and Streptococcus mitis ATCC 9811. The active extracts were tested to determine their minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), cytotoxicity and chemical characterization. Forty-seven extracts (78%) were active against at least one microorganism. Extract 4A demonstrated the lowest MIC and MBC for all microorganisms except S. gordonii and the extract at MIC concentration was non-cytotoxic. The concentrated extracts were slightly cytotoxic. Electrospray ionization with tandem mass spectrometry analyses demonstrated that the extract constituents coincided with the mass of the terpenoids and phenolics. Overall, the best results were obtained for extraction methods A, B and C. The present work proved the antimicrobial activity of several plants. Particularly, extracts from C. doctoris were the most active against bacteria involved in dental caries disease. © 2014 S. Karger AG, Basel.

Could essential oils of green and black pepper be used as food preservatives?

PubMed

Nikolić, Miloš; Stojković, Dejan; Glamočlija, Jasmina; Ćirić, Ana; Marković, Tatjana; Smiljković, Marija; Soković, Marina

2015-10-01

Black and green pepper essential oils were used in this study in order to determine the chemical composition, in vitro antimicrobial activity against food spoilage microorganisms and in situ oils effect on food microorganism, after incorporation in chicken soup, by suggested methodology for calculation of Growth inhibition concentrations (GIC50). Chemical analysis revealed a total of 34 components. The major constituent of black pepper oil was trans-caryophyllene (30.33 %), followed by limonene (12.12 %), while β-pinene (24.42 %), δ(3)-carene (19.72 %), limonene (18.73 %) and α-pinene (10.39 %) were dominant compounds in green pepper oil. Antimicrobial activity was determined by microdilution technique and minimal inhibitory (MIC) and minimal bactericidal/fungicidal concentrations (MBC/MFC) were determined. Green pepper oil showed stronger antibacterial and antifungal activity (MIC 0.50-1.87; MBC 0.63-2.5 mg/ml; MIC 0.07-0.16; MFC 0.13-1.25 mg/ml) against black pepper oil (MIC 0.07-3.75; MBC 0.60-10.00 mg/ml; MIC 0.63-5.00; MFC 1.25-10.00 mg/ml. Oils successfully inhibited the growth of S. aureus in chicken soup in a dose dependent manner. GIC50 values were calculated after 24, 48 and 72 h and were in range of 0.156-0.689 mg/ml. The 50 % inhibitory concentrations (IC50) of EOs were 36.84 and 38.77 mg/ml with in 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay respectively. The obtained results revealed that black and green pepper volatiles are efficient in controlling the growth of known food-spoilage microorganisms.

Inhibitory effect of Zataria multiflora Boiss. essential oil, alone and in combination with monolaurin, on Listeria monocytogenes

PubMed Central

Raeisi, Mojtaba; Tajik, Hossein; Razavi Rohani, Seyed Mehdi; Tepe, Bektas; Kiani, Hossein; Khoshbakht, Rahem; Shirzad Aski, Hesamaddin; Tadrisi, Hamed

2016-01-01

Listeria monocytogenes is one of the major causes of infections in developing countries. In this study, chemical composition and anti-listerial effect of the essential oil of Zataria multiflora Boiss. alone and in combination with monolaurin were evaluated at different pH values (5, 6, and 7) and temperatures (5 ˚C and 30 ˚C). Chemical composition of Zataria multiflora Boiss. essential oil was evaluated by gas chromatography-mass spectrometry (GC-MS) analysis. Minimum inhibitory concentration (MIC) of the essential oil and monolaurin were determined using microbroth dilution method and the interactions of essential oil and monolaurin were determined by the evaluation of fractional inhibitory concentrations (FIC) index. Carvacrol (63.20%) and thymol (15.10%) were found as the main components of the essential oil. The MIC values of the oil and monolaurin at pH 7 and 30 ˚C were measured as 312.50 µg mL-1 and 125.00 µg mL-1, respectively. Combination of monolaurin and Z. multiflora essential oil were found to act synergistically (FIC index < 0.5) against L. monocytogenes under different pH and temperature conditions. Decrease in the pH and temperature values have increased the anti-listerial activity of monolaurin and the essential oil. The lowest MIC value of monolaurin and essential oil was observed at pH 5 and 5 ˚C. According to our results, the oil alone or in combination with monolaurin at low pH and temperature conditions showed a promising inhibitory effect on L. monocytogenes. PMID:27226881

Inhibitory effect of Zataria multiflora Boiss. essential oil, alone and in combination with monolaurin, on Listeria monocytogenes.

PubMed

Raeisi, Mojtaba; Tajik, Hossein; Razavi Rohani, Seyed Mehdi; Tepe, Bektas; Kiani, Hossein; Khoshbakht, Rahem; Shirzad Aski, Hesamaddin; Tadrisi, Hamed

2016-01-01

Listeria monocytogenes is one of the major causes of infections in developing countries. In this study, chemical composition and anti-listerial effect of the essential oil of Zataria multiflora Boiss. alone and in combination with monolaurin were evaluated at different pH values (5, 6, and 7) and temperatures (5 ˚C and 30 ˚C). Chemical composition of Zataria multiflora Boiss. essential oil was evaluated by gas chromatography-mass spectrometry (GC-MS) analysis. Minimum inhibitory concentration (MIC) of the essential oil and monolaurin were determined using microbroth dilution method and the interactions of essential oil and monolaurin were determined by the evaluation of fractional inhibitory concentrations (FIC) index. Carvacrol (63.20%) and thymol (15.10%) were found as the main components of the essential oil. The MIC values of the oil and monolaurin at pH 7 and 30 ˚C were measured as 312.50 µg mL(-1) and 125.00 µg mL(-1), respectively. Combination of monolaurin and Z. multiflora essential oil were found to act synergistically (FIC index < 0.5) against L. monocytogenes under different pH and temperature conditions. Decrease in the pH and temperature values have increased the anti-listerial activity of monolaurin and the essential oil. The lowest MIC value of monolaurin and essential oil was observed at pH 5 and 5 ˚C. According to our results, the oil alone or in combination with monolaurin at low pH and temperature conditions showed a promising inhibitory effect on L. monocytogenes.

Susceptibility of Legionella spp. to mycinamicin I and II and other macrolide antibiotics: effects of media composition and origin of organisms.

PubMed Central

Edelstein, P H; Pasiecznik, K A; Yasui, V K; Meyer, R D

1982-01-01

Thirty-three strains of Legionella spp., 29 of which were L. pneumophila, were tested for their susceptibilities to erythromycin (EM), rosaramicin, tylosin, mycinamicin I (Sch-27897), and mycinamicin II (Sch-27896). Testing was performed using an agar dilution method with two different types of media: buffered charcoal yeast extract medium supplemented with 0.1% alpha-ketoglutarate (BCYE alpha) and filter-sterilized yeast extract medium with 0.1% alpha-ketoglutarate (BYE alpha). The minimal inhibitory concentrations (MICs) of the drugs tested relative to the MICs of erythromycin were: rosaramicin, MIC approximately equal to 0.2 EM MIC; tylosin, MIC approximately equal to 2 EM MIC; mycinamicin I, MIC approximately equal to 0.5 EM MIC; and mycinamicin II, MIC approximately equal to EM MIC. Both types of media caused equivalent partial inactivation of the macrolides which was apparently due entirely to pH effect. MICs on BCYE alpha were one to five times more than those observed on BYE alpha; this may be due to poorer growth on BYE alpha. PMID:7125633

Antifungal Potential and Antioxidant Efficacy in the Shell Extract of Cocos nucifera (L.) (Arecaceae) against Pathogenic Dermal Mycosis

PubMed Central

Khalid Thebo, Nasreen; Ahmed Simair, Altaf; Sughra Mangrio, Ghulam; Ansari, Khalil Ahmed; Ali Bhutto, Aijaz; Lu, Changrui; Ali Sheikh, Wazir

2016-01-01

Background: Coconut is a tropical fruit well known for its essential oils that have been recognized for their biological activities since ancient times. There have been no previous investigations on the essential oils from coconut shells. Method: The shell extract of Cocos nucifera (L.) was prepared by the Soxhlet method and total phenolic content (TPC) in the extract was determined by Folin-Ciocalteu (FC) assay. The antioxidant potential of the coconut shell extract was evaluated by using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Minimum inhibitory concentration (MIC) of the extract was determined by the strip method against clinically isolated dermal mycosis of 20 infected patients. Result: Total antioxidant activity varied from 92.32% to 94.20% and total phenolic content was found at 5.33 ± 0.02 mg/g in the coconut shell extract. The extract was found to be most effective as an antifungal against human pathogenic fungi, including A. niger, A. flavus, T. rubrum, M. canis, M. gypseum, A. fumigates, T. mentagrophyte and T. vercossum. The crude shell extract was highly effective against all dermal mycosis tested with the MIC ranging from 62 mm to 90 mm, whereas all fungal samples showed good inhibitory effect. Conclusion: The results of the present study provide a potential cure for microbial infections. PMID:28930122

Antifungal activity of geldanamycin alone or in combination with fluconazole against Candida species.

PubMed

Zhang, Jinqing; Liu, Wei; Tan, Jingwen; Sun, Yi; Wan, Zhe; Li, Ruoyu

2013-04-01

A standardized broth microdilution method was used to test the antifungal activity of geldanamycin (GA), an inhibitor of heat shock protein 90 (Hsp90), alone or in combination with the antifungal agent fluconazole (FLC) against 32 clinical isolates of Candida spp. In addition, a disk diffusion test was also used to evaluate the antifungal effect of these two drugs against Candida spp. by measuring the inhibition zone diameters. We found that the range of minimal inhibitory concentrations (MICs) for GA alone against Candida spp. was 3.2-12.8 mg/L and the geometric mean of MICs was 6.54 mg/L. In addition, the combination of GA with FLC showed synergistic effects in vitro against 2 FLC-susceptible and 6 FLC-resistant isolates of C. albicans. As for the other isolates, indifference but no antagonism was observed. In the disk diffusion assay, the diameter of inhibition zones for FLC combined with GA against FLC-resistant C. albicans isolates was 30 mm, while no inhibition was observed with FLC alone. These results demonstrate that GA possesses antifungal activity against Candida spp., and the combination of GA with FLC shows in vitro synergistic activity against some C. albicans isolates, especially those resistant to FLC.

Gepotidacin (GSK2140944) In Vitro Activity against Gram-Positive and Gram-Negative Bacteria

PubMed Central

Farrell, D. J.; Rhomberg, P. R.; Scangarella-Oman, N. E.; Sader, H. S.

2017-01-01

ABSTRACT Gepotidacin is a first-in-class, novel triazaacenaphthylene antibiotic that inhibits bacterial DNA replication and has in vitro activity against susceptible and drug-resistant pathogens. Reference in vitro methods were used to investigate the MICs and minimum bactericidal concentrations (MBCs) of gepotidacin and comparator agents for Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli. Gepotidacin in vitro activity was also evaluated by using time-kill kinetics and broth microdilution checkerboard methods for synergy testing and for postantibiotic and subinhibitory effects. The MIC90 of gepotidacin for 50 S. aureus (including methicillin-resistant S. aureus [MRSA]) and 50 S. pneumoniae (including penicillin-nonsusceptible) isolates was 0.5 μg/ml, and for E. coli (n = 25 isolates), it was 4 μg/ml. Gepotidacin was bactericidal against S. aureus, S. pneumoniae, and E. coli, with MBC/MIC ratios of ≤4 against 98, 98, and 88% of the isolates tested, respectively. Time-kill curves indicated that the bactericidal activity of gepotidacin was observed at 4× or 10× MIC at 24 h for all of the isolates. S. aureus regrowth was observed in the presence of gepotidacin, and the resulting gepotidacin MICs were 2- to 128-fold higher than the baseline gepotidacin MICs. Checkerboard analysis of gepotidacin combined with other antimicrobials demonstrated no occurrences of antagonism with agents from multiple antimicrobial classes. The most common interaction when testing gepotidacin was indifference (fractional inhibitory concentration index of >0.5 to ≤4; 82.7% for Gram-positive isolates and 82.6% for Gram-negative isolates). The postantibiotic effect (PAE) of gepotidacin was short when it was tested against S. aureus (≤0.6 h against MRSA and MSSA), and the PAE–sub-MIC effect (SME) was extended (>8 h; three isolates at 0.5× MIC). The PAE of levofloxacin was modest (0.0 to 2.4 h), and the PAE-SME observed varied from 1.2 to >9 h at 0.5× MIC. These in vitro data indicate that gepotidacin is a bactericidal agent that exhibits a modest PAE and an extended PAE-SME against Gram-positive and -negative bacteria and merits further study for potential use in treating infections caused by these pathogens. PMID:28483959

The sub-inhibitory theory for antibiotic growth promoters.

PubMed

Broom, Leon J

2017-09-01

Antibiotics have played a critical role in the prevention, control, and treatment of bacterial diseases in humans and animals, and as growth promoters (AGPs) when used at sub-therapeutic concentrations in animal production. Numerous hypotheses have been proposed for the effectiveness of AGPs, which have largely centered on the beneficial modulation of the intestinal microbiota. However, these hypotheses have been doubted by some researchers, as AGPs are fed at concentrations that would typically be below minimum inhibitory concentrations (sub-MIC) for the antibiotic used. More recently, pro-inflammatory immune responses have been associated with poor growth performance, and this, along with reported direct, anti-inflammatory effects of some antibiotics, have led to suggestions that reducing the nutrient cost of (intestinal) inflammation may explain the growth promoting or permitting effect of AGPs. However, doubts about antibacterial effects of AGPs, and the search for alternative explanations, overlook the sub-MIC effects of antibiotics. This paper summarizes some of the reported sub-MIC effects of antibiotics and considers these in the context of helping to explain the mode of action of AGPs and effects seen in studies in vivo. This leads to suggestions for the features that alternatives to AGPs could exhibit to achieve similar performance efficacy as AGPs. © 2017 Poultry Science Association Inc.

Screening of commercial and pecan shell-extracted liquid smoke agents as natural antimicrobials against foodborne pathogens.

PubMed

Van Loo, Ellen J; Babu, D; Crandall, Philip G; Ricke, Steven C

2012-06-01

Liquid smoke extracts have traditionally been used as flavoring agents, are known to possess antioxidant properties, and serve as natural alternatives to conventional antimicrobials. The antimicrobial efficacies of commercial liquid smoke samples may vary depending on their source and composition and the methods used to extract and concentrate the smoke. We investigated the MICs of eight commercial liquid smoke samples against Salmonella Enteritidis, Staphylococcus aureus, and Escherichia coli . The commercial liquid smoke samples purchased were supplied by the manufacturer as water-based or concentrated extracts of smoke from different wood sources. The MICs of the commercial smokes to inhibit the growth of foodborne pathogens ranged from 0.5 to 6.0% for E. coli, 0.5 to 8.0% for Salmonella, and 0.38 to 6% for S. aureus. The MIC for each liquid smoke sample was similar in its effect on both E. coli and Salmonella. Solvent-extracted antimicrobials prepared using pecan shells displayed significant differences between their inhibitory concentrations depending on the type of solvent used for extraction. The results indicated that the liquid smoke samples tested in this study could serve as effective natural antimicrobials and that their inhibitory effects depended more on the solvents used for extraction than the wood source.

In vitro effectiveness of triterpenoids and their synergistic effect with antibiotics against Staphylococcus aureus strains.

PubMed

Hamza, Muhammad; Nadir, Maha; Mehmood, Nadir; Farooq, Adeel

2016-01-01

The aim of this study is to evaluate the effect of four triterpenoids such as oleanolic acid, ursolic acid, cycloastragenol, and beta-boswellic acid alone and in combination with antibiotics against Staphylococcus aureus strains. Sixteen clinical strains of S. aureus from infected wounds were isolated. Eight were methicillin-sensitive S. aureus (MSSA), and the other eight were methicillin-resistant S. aureus (MRSA). The activity was also seen in reference S. aureus American Type Culture Collection ™ strains. The activity of all the triterpenoids and antibiotics against S. aureus was evaluated by broth microdilution method. The effectiveness was judged by comparing the minimum inhibitory concentrations (MICs) of the compounds with antibiotics. The combination of antibiotics with compounds was evaluated by their fractional inhibitory concentrations (FIC). Against both clinical and reference MSSA strains, none of the compounds exhibited comparable activity to antibiotics vancomycin or cefradine except for ursolic acid (MIC 7.8 μg/ml). Against MRSA, all compounds (MIC 16-128 μg/ml) showed lesser activity than vancomycin (MIC 5.8 μg/ml). Among triterpenoid-antibiotic combinations, the most effective were ursolic acid and vancomycin against clinical strain MSSA (FIC S 0.17). However, overall, different combinations between triterpenoids and antibiotics showed 95%-46% ( P < 0.05) reduction in MICs of antibiotics compared to when antibiotics were used alone. Cefradine, a drug not suitable for treating MRSA (MIC = 45 μg/ml), showed a remarkable decrease in its MIC (87% P< 0.01) when it was used in combination with oleanolic acid or ursolic acid in both clinical and reference strains. The tested triterpenoids are relatively weaker than antibiotics. However, when used in combination with antibiotics, they showed remarkable synergistic effect and thus can help in prolonging the viability of these antibiotics against S. aureus infections. Furthermore, reduction in MIC of cefradine with oleanolic acid indicates their potential use against MRSA.

Inhibitory activity of reuterin, nisin, lysozyme and nitrite against vegetative cells and spores of dairy-related Clostridium species.

PubMed

Avila, Marta; Gómez-Torres, Natalia; Hernández, Marta; Garde, Sonia

2014-02-17

The butyric acid fermentation, responsible for late blowing of cheese, is caused by the outgrowth in cheese of some species of Clostridium, resulting in texture and flavor defects and economical losses. The aim of this study was to evaluate the effectiveness of different antimicrobial compounds against vegetative cells and spores of C. tyrobutyricum, C. butyricum, C. beijerinckii and C. sporogenes strains isolated from cheeses with late blowing defect. Minimal inhibitory concentration (MIC) for reuterin, nisin, lysozyme and sodium nitrite were determined against Clostridium strains in milk and modified RCM (mRCM) after 7d exposure. Although the sensitivity of Clostridium to the tested antimicrobials was strain-dependent, C. sporogenes and C. beijerinckii generally had higher MIC values than the rest of Clostridium species. The majority of Clostridium strains were more resistant to antimicrobials in milk than in mRCM, and vegetative cells exhibited higher sensitivity than spores. Reuterin (MIC values 0.51-32.5 mM) and nisin (MIC values 0.05-12.5 μg/ml) were able to inhibit the growth of vegetative cells and spores of all assayed Clostridium strains in milk and mRCM. Strains of C. tyrobutyricum exhibited the highest sensitivity to lysozyme (MIC values<0.20-400 μg/ml) and sodium nitrite (MIC values 18.75-150 μg/ml). These results suggest that reuterin and nisin, with a broad inhibitory activity spectrum against Clostridium spp. spores and vegetative cells, may be the best options to control Clostridium growth in dairy products and to prevent associated spoilage, such as late blowing defect of cheese. However, further studies in cheese would be necessary to validate this hypothesis. Copyright © 2013 Elsevier B.V. All rights reserved.

[Antimycoplasmal activities of ofloxacin and commonly used antimicrobial agents on Mycoplasma gallisepticum].

PubMed

Takahashi, I; Yoshida, T

1989-05-01

In vitro activities of ofloxacin (OFLX), a new quinolone derivative, against 29 strains of Mycoplasma gallisepticum was compared with those of 4 commonly used antimicrobial agents, doxycycline (DOXY), tylosin (TS), spectinomycin (SPCM) and thiamphenicol (TP). Antimycoplasmal activities of the drugs were evaluated on the MIC (final MIC) and MPC (minimum mycoplasmacidal concentration) values which were determined by a broth dilution procedure. The following results were obtained. 1. The MIC90s of OFLX and DOXY were both 0.20 micrograms/ml. The MICs of TS were distributed through a wide range (less than or equal to 0.006 - 0.78 micrograms/ml), and its MIC90 was 0.78 micrograms/ml. Of 29 M. gallisepticum strains, 27.6% were recognized as TS-resistant. The MIC90 values of SPCM and TP were 1.56 micrograms/ml and 3.13 micrograms/ml, respectively. The MIC90 of OFLX was equal to that of DOXY and 4- to 16-fold smaller than the values of the other 3 antibiotics. 2. The MPC of OFLX was the lowest among the antibiotics tested, its MPC90 value was 0.39 micrograms/ml and was followed by DOXY (1.56 micrograms/ml). The MPCs of TS were distributed in a wide range (0.012 - 3.13 micrograms/ml), and its MPC90 was 3.13 micrograms/ml. The MPC90 values of SPCM and TP were both 6.25 micrograms/ml. Therefore, the mycoplasmacidal activity of OFLX evaluated with MPC90 values was 4- to 16-fold greater than those of the other 4 antibiotics.

Growth Inhibition and Morphological Alteration of Fusarium sporotrichioides by Mentha piperita Essential Oil

PubMed Central

Rachitha, P.; Krupashree, K.; Jayashree, G. V.; Gopalan, Natarajan; Khanum, Farhath

2017-01-01

Objective: The aim of this study is to determine the phytochemical composition, antifungal activity of Mentha piperita essential oil (MPE) against Fusarium sporotrichioides. Methods: The phytochemical composition was conducted by gas chromatography mass spectrometry (GC MS) analysis and mycelia growth inhibition was determined by minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC), the morphological characterization was observed by scanning electron microscopy. Finally, the membrane permeability was determined by the release of extracellular constituents, pH, and total lipid content. Result: In GC MS analysis, 22 metabolites were identified such as menthol, l menthone, pulegone, piperitone, caryophyllene, menthol acetate, etc. The antifungal activity against targeted pathogen, with MIC and MFC 500 μg/mL and 1000 μg/mL, respectively. The MPE altered the morphology of F. sporotrichoides hyphae with the loss of cytoplasm content and contorted the mycelia. The increasing concentration of MPE showed increase in membrane permeability of F. sporotrichoides as evidenced by the release of extracellular constituents and pH with the disruption of cell membrane indicating decrease in lipid content of F. sporotrichoides. Conclusion: The observed results showed that MPE exhibited promising new antifungal agent against Fusarium sporotrichioides. SUMMARY F. sporotrichioides, filamentous fungi contaminate to corn and corn--based productsF. sporotrichioides mainly responsible for the production of T-2 toxinPhytochemical composition was conducted by gas chromatography--mass spectrometry analysisMentha piperita essential oil (MPE) is commonly known as peppermintThe F. sporotrichioides growth was inhibited by MPE (minimum inhibitory concentration, minimum fungicidal concentration)Morphological observation by scanning electron microscope. Abbreviations Used: Cfu: Colony forming unit; DMSO: Dimethyl sulfoxide, °C: Degree celsius; F. Sporotrichoides: Fusarium sporotrichioides; EOs: Essential oils; M: Molar, g: Gram/gravity, mg: Milligram; μg: Microgram, ml: Milliliter; mm: Millimeter, min: Minutes; M. piperita: Mentha piperita, MIC: Minimum inhibitory concentration; MFC: Minimum fungicidal concentration; MAE: Mentha arvensis essential oil; Na2SO4: Sodium sulfate; pH: Potential Hydrogen; PDB: Potato Dextrose Broth; SEM: Scanning electron microscope PMID:28250658

[Study on the inhibitory activity, in vitro, of baicalein and baicalin against skin fungi and bacteria].

PubMed

Yang, D; Hu, H; Huang, S; Chaumont, J P; Millet, J

2000-05-01

In this paper, we concentrated in examining, in vitro, the antiseptic activity of the baicalein and baicalin upon the seventeen pathogenic skin fungal and sixteen skin bacterial strains, these two flavonic compounds were known principally as the biosubstances of a traditional Chinese medicinal plant: Scutellaria baicalensis. In agar media, the baicalein possessed potent specific activity against the pathogenic yeasts with MICs of 70-100 micrograms/ml; But in the same condition, no inhibitory effect was observed upon dermatophytes and filamentous imperfect fungi for baicalein, and upon all used strains for baicalin. According to the antibacterial test of baicalein, a high efficacy was achieved against certain causative specie of axillary and foot's odour such as Micrococcus sedentarius, Staphylococcus epidermidis, S. hominis and C. xerosis with a MICs inferior to 250 micrograms/ml. The good inhibitory activity of baicalein could be linked to the group hydroxyl (-OH) in position seven of the molecule.

[Nationwide sensitivity surveillance of ciprofloxacin and various parenteral antibiotics against bacteria isolated from patients with severe infections--the first Ciproxan IV special investigation in 2001].

PubMed

Yamaguchi, Keizo; Ishii, Yoshikazu; Iinuma, Yoshitsugu; Yamanaka, Kiyoharu; Ichiyama, Satoshi; Watanabe, Naoki; Uehara, Nobuyuki; Kaku, Mitsuo; Kurokawa, Yukinori; Hayashi, Mutsumu; Hirakata, Yoichi

2003-12-01

The parenteral injection of ciprofloxacin (CPFX), a fluoroquinolone antimicrobial drug, was approved in September 2000 and a re-examination period of 6 years was set at that time. As a special investigation to apply for re-examination of this drug, it has been planned to conduct 3 nationwide surveillances during the re-examination period by collecting clinically isolated bacteria from patients with severe infections, to whom the drug was mainly indicated, and examining drug susceptibilities of the bacteria to various parenteral antimicrobial drugs including CPFX. This time, we determined the minimum inhibitory concentrations (MICs) of various parenteral antimicrobial drugs including CPFX against 1,220 strains isolated from patients with severe infections by the micro-liquid dilution method and compared susceptibilities of various clinically isolated bacteria to CPFX with those to other antimicrobial drugs. Gram-positive bacteria were less susceptible to CPFX than to carbapenems except 2 bacterial species, Enterococcus faecium and Enterococcus avium but susceptibilities of methicillin-susceptible Staphylococcus aureus (MSSA), Staphylococcus epidermidis and Enterococcus faecalis to CPFX were comparable to those to cefozopran. Susceptibility of Streptococcus pneumoniae to CPFX did not differ among ampicillin (ABPC)-susceptible Streptococcus pneumoniae (MIC of ABPC: < 0.25 microgram/ml), ABPC-intermediate S. pneumoniae (MIC of ABPC: 0.25-2 micrograms/ml) and ABPC-resistant S. pneumoniae (MIC of ABPC: > or = 4 micrograms/ml) MIC90 of CPFX: 1 microgram/ml) and a decrease in the antimicrobial activity seen among cephem and carbapenem antimicrobial drugs against penicillin-intermediate strains was not noted with CPFX. Gram-negative bacteria were susceptible to CPFX similarly to carbapenems and the MIC90 values of CPFX were in the range from < or = 0.063 to 2 micrograms/ml against strains except Stenotrophomonas maltophilia and Burkholderia cepacia. Pseudomonas aeruginosa was most susceptible to CPFX among the antibacterial drugs examined and the MIC90 was 2 micrograms/ml. CPFX also showed the lowest MIC90 value (0.5 microgram/ml) against beta-lactam-resistant P. aeruginosa among the drugs examined. When extended-spectrum beta-lactamase (ESBL) production and class B beta-lactamase production were examined in 439 strains of Enterobacteriaceae and 168 strains of glucose non-fermentative bacteria out of the Gram-negative bacteria collected this time, 3 strains (0.49%) producing ESBL and 7 strains (1.15%) producing class B beta-lactamase were found. The MIC range of CPFX to these 10 strains was between < or = 0.063 to 8 micrograms/ml and 5 strains among those showed susceptibilities (MIC of CPFX: 1 microgram/ml) based on the NCCLS breakpoint. CPFX also showed a satisfactory result concerning susceptibilities of major causal bacteria based on the report of the committee of Japan Society of Chemotherapy on the standard method for determination of susceptibility to antimicrobial agents, the breakpoint of pneumonia. Furthermore, susceptibilities of various bacteria isolated clinically from patients with severe infections this time did not differ much from the result of the nationwide surveillance which we conducted in 1997. Thus, it was concluded that the antimicrobial activity of CPFX was maintained in the post-marketing surveillance for its parenteral preparation.

Antibacterial activity of preservative-free topical anesthetic drops in current use in ophthalmology departments.

PubMed

Pelosini, Lucia; Treffene, Stephanie; Hollick, Emma J

2009-01-01

The antibacterial effect of topical anesthetics may lead to false-negative cultures from corneal specimens of bacterial keratitis. This in vitro study compared the antibacterial effect of 3 unpreserved topical anesthetics to indicate the most appropriate agent for corneal scrapes. Four bacterial strains (Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus pneumoniae) derived from the most frequently isolated microorganisms from corneal ulcers were cultured from stored control stocks and clinical specimens. These strains were used to determine the minimum inhibitory concentration (MIC) of 3 preservative-free anesthetic eyedrops: proxymetacaine 0.5%, oxybuprocaine 0.4%, and tetracaine 1%. There was no inhibition of growth seen with proxymetacaine 0.5% (5000 microg/mL) with any of the organisms except S. epidermidis, which demonstrated an MIC of 2500 microg/mL (equivalent to a dilution of (1/2)). Tetracaine 1% (10,000 microg/mL) produced an MIC ranging between 625 and 1250 microg/mL, inhibiting all 4 strains at the commercially available dilution. Oxybuprocaine 0.4% (4000 microg/mL) resulted to be the second most inhibitory preparation with an MIC ranging between 1000 and 2000 microg/mL. Currently used preservative-free topical anesthetics differ in bacterial growth inhibition. This in vitro study showed that proxymetacaine 0.5% is the least inhibitory on bacterial growth and therefore the most appropriate to be used before corneal scrapes.

Anti-MRSA cephalosporins Bristol-Myers Squibb.

PubMed

Johnson, A P

2001-02-01

BMS is investigating a series of cephalosporins for potential use in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infection [274213]. In vitro activity tests resulted in a minimum inhibitory concentration (MIC) of 1 to 8 microg/ml against MRSA 1274213]. A series of C(3) benzoyloxymethyl cephalosporins exhibited in vitro activity against MRSA and methicillin-susceptible Staphylococcus aureus (MSSA), with MIC values ranging from 0.007 to 2 microM, and improved in vivo stability in human plasma [258890].

Effect of essential oils prepared from Thai culinary herbs on sessile Candida albicans cultures.

PubMed

Hovijitra, Ray S; Choonharuangdej, Suwan; Srithavaj, Theerathavaj

2016-01-01

Although medicinal herbs with fungicidal effects have been ubiquitously employed in traditional medicine, such effects of culinary herbs and spices still have to be elucidated. Therefore, it is noteworthy to determine the antifungal efficacy of some edible herbs used in Thai cuisine against sessile Candida albicans cultures, and to inquire if they can be further utilized as naturally-derived antifungals. Fourteen essential oils extracted from Thai culinary herbs and spices were tested for their antifungal activity against C. albicans using the agar disk diffusion method followed by broth micro-dilution method for the determination of minimum inhibitory concentration (MIC) and minimum fungicidal concentration. The oils with potent antifungal effects against planktonic fungi were then assessed for their effect against sessile fungus (adherent organisms and established biofilm culture). MIC of the oils against sessile C. albicans was evaluated by 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide reduction assay. All selected culinary herbs and spices, except galangal, garlic, and turmeric, exhibited inhibitory effects on planktonic yeast cells. Cinnamon bark and sweet basil leaf essential oils exhibited potent fungicidal effect on planktonic and sessile fungus. Sessile MICs were 8-16 times higher than planktonic MICs. Consequently, both cinnamon bark and sweet basil leaf herbal oils seem to be highly effective anti-Candida choices. (J Oral Sci 58, 365-371, 2016).

Design, Synthesis, and Evaluation of Novel Tyrosine-Based DNA Gyrase B Inhibitors.

PubMed

Cotman, Andrej E; Trampuž, Marko; Brvar, Matjaž; Kikelj, Danijel; Ilaš, Janez; Peterlin-Mašič, Lucija; Montalvão, Sofia; Tammela, Päivi; Frlan, Rok

2017-08-01

The discovery and synthesis of new tyrosine-based inhibitors of DNA gyrase B (GyrB), which target its ATPase subunit, is reported. Twenty-four compounds were synthesized and evaluated for activity against DNA gyrase and DNA topoisomerase IV. The antibacterial properties of selected GyrB inhibitors were demonstrated by their activity against Staphylococcus aureus and Enterococcus faecalis in the low micromolar range. The most promising compounds, 8a and 13e, inhibited Escherichia coli and S. aureus GyrB with IC 50 values of 40 and 30 µM. The same compound also inhibited the growth of S. aureus and E. faecalis with minimal inhibitory concentrations (MIC 90 ) of 14 and 28 µg/mL, respectively. © 2017 Deutsche Pharmazeutische Gesellschaft.

In vitro activity and rodent efficacy of clinafloxacin for bovine and swine respiratory disease.

PubMed

Sweeney, Michael T; Quesnell, Rebecca; Tiwari, Raksha; Lemay, Mary; Watts, Jeffrey L

2013-01-01

Clinafloxacin is a broad-spectrum fluoroquinolone that was originally developed and subsequently abandoned in the late 1990s as a human health antibiotic for respiratory diseases. The purpose of this study was to investigate the activity of clinafloxacin as a possible treatment for respiratory disease in cattle and pigs. Minimum inhibitory concentration (MIC) values were determined using Clinical and Laboratory Standards Institute recommended procedures with recent strains from the Zoetis culture collection. Rodent efficacy was determined in CD-1 mice infected systemically or intranasally with bovine Mannheimia haemolytica or Pasteurella multocida, or swine Actinobacillus pleuropneumoniae, and administered clinafloxacin for determination of ED50 (efficacious dose-50%) values. The MIC90 values for clinafloxacin against bovine P. multocida, M. haemolytica, Histophilus somni, and M. bovis were 0.125, 0.5, 0.125, and 1 μg/ml, respectively, and the MIC90 values against swine P. multocida, A. pleuropneumoniae, S. suis, and M. hyopneumoniae were í0.03, í0.03, 0.125, and í0.008 μg/ml, respectively. Efficacy in mouse models showed average ED50 values of 0.019 mg/kg/dose in the bovine M. haemolytica systemic infection model, 0.55 mg/kg in the bovine P. multocida intranasal lung challenge model, 0.08 mg/kg/dose in the bovine P. multocida systemic infection model, and 0.7 mg/kg/dose in the swine A. pleuropneumoniae systemic infection model. Clinafloxacin shows good in vitro activity and efficacy in mouse models and may be a novel treatment alternative for the treatment of respiratory disease in cattle and pigs.

Modulation of quorum sensing-controlled virulence factors by Nymphaea tetragona (water lily) extract.

PubMed

Hossain, Md Akil; Lee, Seung-Jin; Park, Ji-Yong; Reza, Md Ahsanur; Kim, Tae-Hwan; Lee, Ki-Ja; Suh, Joo-Won; Park, Seung-Chun

2015-11-04

Nymphaea tetragona is a widely distributed ornamental species with ethnomedicinal uses in the treatment of diarrhea, dysentery, eruptive fevers, and infections. The anti-infectious activities of this herb have already been assessed to clarify its traditional use as a medicine. In this study, we aimed to verify the inhibitory effects of N. tetragona 50% methanol extract (NTME) on quorum sensing (QS)-controlled virulence factors of bacteria since QS and its virulence factors are novel targets for antimicrobial therapy. The antibacterial activity of this extract was evaluated against Chromobacterium violaceum and Pseudomonas aeruginosa. The inhibition of the violacein pigment of C. violaceum by NTME was determined qualitative and quantitative using standard methods. The effects of NTME on swarming motility, biofilm viability, pyocyanin production, and LasA protease activity were evaluated using P. aeruginosa. Finally, the in vitro and in vivo cytotoxicity of NTME were verified by MTT assay and oral administration to rats, respectively. The extract had concentration-dependent antibacterial activity against gram-negative bacteria. NTME at 1/2× minimum inhibitory concentration (MIC), 1× MIC and 2× MIC significantly lowered the levels of violacein of C. violaceum compared to that of the control. The swarming motility of P. aeruginosa was inhibited by ≥70% by treatment with 1/2× MIC of NTME. There were remarkable reductions in pyocyanin production and LasA protease activity in the overnight culture supernatant of P. aeruginosa supplemented with NTME when compared with that of the untreated control. The confocal micrographs of 24h biofilms of P. aeruginosa exposed to NTME exhibited a lower number of live cells than the control. No toxic effect was observed in in vitro and in vivo cytotoxicity assays of NTME. NTME was demonstrated to have significant concentration-dependent inhibitory effects on quorum sensing-mediated virulence factors of bacteria with non-toxic properties, and could thus be a prospective quorum sensing inhibitor. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Use of natural antimicrobials to increase antibiotic susceptibility of drug resistant bacteria.

PubMed

Palaniappan, Kavitha; Holley, Richard A

2010-06-15

Plant-derived antibacterial compounds may be of value as a novel means for controlling antibiotic resistant zoonotic pathogens which contaminate food animals and their products. Individual activity of natural antimicrobials (eugenol, thymol, carvacrol, cinnamaldehyde, allyl isothiocyanate (AIT)) and activity when paired with an antibiotic was studied using broth microdilution and checkerboard methods. In the latter assays, fractional inhibitory concentration (FIC) values were calculated to characterize interactions between the inhibitors. Bacteria tested were chosen because of their resistance to at least one antibiotic which had a known genetic basis. Substantial susceptibility of these bacteria toward the natural antimicrobials and a considerable reduction in the minimum inhibitory concentrations (MIC's) of the antibiotics were noted when paired combinations of antimicrobial and antibiotic were used. In the interaction study, thymol and carvacrol were found to be highly effective in reducing the resistance of Salmonella Typhimurium SGI 1 (tet A) to ampicillin, tetracycline, penicillin, bacitracin, erythromycin and novobiocin (FIC<0.4) and resistance of Streptococcus pyogenes ermB to erythromycin (FIC<0.5). With Escherichia coli N00 666, thymol and cinnamaldehyde were found to have a similar effect (FIC<0.4) in reducing the MIC's of ampicillin, tetracycline, penicillin, erythromycin and novobiocin. Carvacrol, thymol (FIC<0.3) and cinnamaldehyde (FIC<0.4) were effective against Staphylococcus aureus blaZ and in reducing the MIC's of ampicillin, penicillin and bacitracin. Allyl isothiocyanate (AIT) was effective in reducing the MIC of erythromycin (FIC<0.3) when tested against S. pyogenes. Fewer combinations were found to be synergistic when the decrease in viable population (log DP) was calculated. Together, fractional inhibitory concentrations < or = 0.5 and log DP<-1 indicated synergistic action between four natural antimicrobials and as many as three antibiotics to which these bacteria were normally resistant. Copyright 2010 Elsevier B.V. All rights reserved.

Effect of garlic and allium-derived products on the growth and metabolism of Spironucleus vortens.

PubMed

Millet, Coralie O M; Lloyd, David; Williams, Catrin; Williams, David; Evans, Gareth; Saunders, Robert A; Cable, Joanne

2011-02-01

Spironucleus is a genus of small, flagellated parasites, many of which can infect a wide range of vertebrates and are a significant problem in aquaculture. Following the ban on the use of metronidazole in food fish due to toxicity problems, no satisfactory chemotherapies for the treatment of spironucleosis are currently available. Using membrane inlet mass spectrometry and automated optical density monitoring of growth, we investigated in vitro the effect of Allium sativum (garlic), a herbal remedy known for its antimicrobial properties, on the growth and metabolism of Spironucleus vortens, a parasite of tropical fish and putative agent of hole-in-the-head disease. The allium-derived thiosulfinate compounds allicin and ajoene, as well as an ajoene-free mixture of thiosulfinates and vinyl-dithiins were also tested. Whole, freeze-dried garlic and allium-derived compounds had an inhibitory effect on gas metabolism, exponential growth rate and final growth yield of S. vortens in Keister's modified, TY-I-S33 culture medium. Of all the allium-derived compounds tested, the ajoene-free mixture of dithiins and thiosulfinates was the most effective with a minimum inhibitory concentration (MIC) of 107 μg ml(-1) and an inhibitory concentration at 50% (IC(50%)) of 58 μg ml(-1). It was followed by ajoene (MIC = 83 μg ml(-1), IC(50%) = 56 μg ml(-1)) and raw garlic (MIC >20 mg ml(-1), IC(50%) = 7.9 mg ml(-1)); allicin being significantly less potent with an MIC and IC(50%) above 160 μg ml(-1). All these concentrations are much higher than those reported to be required for the inhibition of most bacteria, protozoa and fungi previously investigated, indicating an unusual level of tolerance for allium-derived products in S. vortens. However, chemically synthesized derivatives of garlic constituents might prove a useful avenue for future research. Copyright © 2010 Elsevier Inc. All rights reserved.

Evaluation of Antimicrobial Activity of the Methanol Extracts from 8 Traditional Medicinal Plants

PubMed Central

Kang, Chang-Geun; Hah, Dae-Sik; Kim, Chung-Hui; Kim, Young-Hwan; Kim, Euikyung

2011-01-01

The methanol extract of 12 medicinal plants were evaluated for its antibacterial activity against Gram-positive (5 strains) and Gram-negative bacteria (10 strains) by assay for minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) . The antibacterial activity was determined by an agar dilution method (according to the guidelines of Clinical and Laboratory Standard Institute) . All the compounds (12 extracts) of the 8 medicinal plants (leaf or root) were active against both Gram-negative and Gram-positive bacteria. Gram-negative showed a more potent action than Gram positive bacteria. The MIC concentrations were various ranged from 0.6 μg/ml to 5000 μg/ml. The lowest MIC (0.6 μg/ml) and MBC (1.22 μg/ml) values were obtained with extract on 4 and 3 of the 15 microorganisms tested, respectively. PMID:24278548

Determination of antibacterial activity of green coffee bean extract on periodontogenic bacteria like Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans: An in vitro study.

PubMed

Bharath, Nagaraj; Sowmya, Nagur Karibasappa; Mehta, Dhoom Singh

2015-01-01

The aim of this study was to evaluate the antibacterial activity of pure green coffee bean extract on periodonto pathogenic bacteria Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Fusobacterium nucleatum (Fn) and Aggregatibacter actinomycetemcomitans (Aa). Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBC) were used to assess the antibacterial effect of pure green coffee bean extract against periodonto pathogenic bacteria by micro dilution method and culture method, respectively. MIC values of Pg, Pi and Aa were 0.2 μg/ml whereas Fn showed sensitive at concentration of 3.125 μg/ml. MBC values mirrors the values same as that of MIC. Antimicrobial activity of pure green coffee bean extract against Pg, Pi, Fn and Aa suggests that it could be recommended as an adjunct to mechanical therapy in the management of periodontal disease.

Stratifying low level Isoniazid resistance using additional intermediate drug concentration.

PubMed

Lakshmi, Rajagopalan; Ramachandran, Ranjani; Sundar, A Syam; Rahman, Fathima; Kumar, Vanaja

2014-06-01

Isoniazid (INH) susceptibility testing for 100 Mycobacterium tuberculosis performed by conventional minimum inhibitory concentration (MIC) method was stratified using additional drug concentrations. Introduction of additional drug concentrations did not greatly improve the discriminatory capacity, but can be used in specialized studies pertaining to cross resistance between structural analogues of INH. Copyright © 2014 Asian-African Society for Mycobacteriology. Published by Elsevier Ltd. All rights reserved.

Population PK Modeling and Target Attainment Simulations to Support Dosing of Ceftaroline Fosamil in Pediatric Patients With Acute Bacterial Skin and Skin Structure Infections and Community-Acquired Bacterial Pneumonia.

PubMed

Riccobene, Todd A; Khariton, Tatiana; Knebel, William; Das, Shampa; Li, James; Jandourek, Alena; Carrothers, Timothy J; Bradley, John S

2017-03-01

Ceftaroline, the active form of the prodrug ceftaroline fosamil, is approved for use in adults with community-acquired bacterial pneumonia (CABP) or acute bacterial skin and skin structure infections (ABSSSI) in the United States and for similar indications in Europe. Pharmacokinetic (PK) data from 5 pediatric (birth to <18 years) studies of ceftaroline fosamil were combined with PK data from adults to update a population PK model for ceftaroline and ceftaroline fosamil. This model, based on a data set including 305 children, was used to conduct simulations to estimate ceftaroline exposures and percentage of time that free drug concentrations were above the minimum inhibitory concentration (%fT>MIC) for pediatric dose regimens. With dose regimens of 8 mg/kg every 8 hours (q8h) in children aged 2 months to <2 years and 12 mg/kg (up to a maximum of 400 mg) q8h in children aged 2 years to <18 years or 600 mg q12h in children aged 12 to <18 years, >90% of children were predicted to achieve a target of 36% fT>MIC at an MIC of 2 mg/L, and >97% were predicted to achieve 44% fT>MIC at an MIC of 1 mg/L. Thus, high PK/pharmacodynamic target attainment would be maintained in children for targets associated with 1-log kill of Staphylococcus aureus and Streptococcus pneumoniae. The predicted ceftaroline exposures for these dose regimens were similar to those in adults given 600 mg q12h ceftaroline fosamil. This work contributed to the approval of dose regimens for children aged 2 months to <18 years by the FDA and EMA, which are presented. © 2016, The American College of Clinical Pharmacology.

In vitro antibacterial activity of poly (amidoamine)-G7 dendrimer.

PubMed

Gholami, Mitra; Mohammadi, Rashin; Arzanlou, Mohsen; Akbari Dourbash, Fakhraddin; Kouhsari, Ebrahim; Majidi, Gharib; Mohseni, Seyed Mohsen; Nazari, Shahram

2017-06-05

Nano-scale dendrimers are synthetic macromolecules that frequently used in medical and health field. Traditional anibiotics are induce bacterial resistence so there is an urgent need for novel antibacterial drug invention. In the present study seventh generation poly (amidoamine) (PAMAM-G7) dendrimer was synthesized and its antibacterial activities were evaluated against representative Gram- negative and Gram-positive bacteria. PAMAM-G7 was synthesized with divergent growth method. The structural and surface of PAMAM-G7 were investigated by transmission electron microscopy, scanning electron microscope and fourier transform infrared. Pseudomonas. aeruginosa (n = 15), E. coli (n = 15), Acinetobacter baumanni (n = 15), Shigella dysenteriae (n = 15), Klebsiella pneumoniae (n = 10), Proteus mirabilis (n = 15), Staphylococcus aureus (n = 15) and Bacillus subtilis (n = 10) have been used for antibacterial activity assay. Additionally, representative standard strains for each bacterium were included. Minimum Inhibitory Concentration (MIC) was determined using microdilution method. Subsequently, Minimum Bactericidal Concentration (MBC) was determined by sub-culturing each of the no growth wells onto Mueller Hinton agar medium. The cytotoxicity of PAMAM-G7 dendrimer were evaluated in HCT116 and NIH 3 T3 cells by MTT assay. The average size of each particle was approximately 20 nm. PAMAM-G7 was potentially to inhibit both Gram positive and gram negative growth. The MIC50 and MIC90 values were determined to be 2-4 μg/ml and 4-8 μg/ml, respectively. The MBC50 and MBC90 values were found to be 64-256 μg/ml and 128-256 μg/ml, respectively. The cytotoxity effect of dendrimer on HCT116 and NIH 3 T3 cells is dependent upon exposure time to and concentration of dendrimers. The most reduction (44.63 and 43%) in cell viability for HCT116 and NIH 3 T3 cells was observed at the highest concentration, 0.85 μM after 72 h treatmentm, respectively. This study we conclude that PAMAM-G7 dendrimer could be a potential candidate as a novel antibacterial agent.

Effectiveness of tilmicosin against Paenibacillus larvae, the causal agent of American Foulbrood disease of honeybees.

PubMed

Reynaldi, Francisco J; Albo, Graciela N; Alippi, Adriana M

2008-11-25

American Foulbrood (AFB) of honeybees (Apis mellifera L.), caused by the Gram-positive bacterium Paenibacillus larvae is one of the most serious diseases affecting the larval and pupal stages of honeybees (A. mellifera L.). The aim of the present work was to asses the response of 23 strains of P. larvae from diverse geographical origins to tilmicosin, a macrolide antibiotic developed for exclusive use in veterinary medicine, by means of the minimal inhibitory concentration (MIC) and the agar diffusion test (ADT). All the strains tested were highly susceptible to tilmicosin with MIC values ranging between 0.0625 and 0.5 microg ml(-1), and with MIC(50) and MIC(90) values of 0.250 microg ml(-1). The ADT tests results for 23 P. larvae strains tested showed that all were susceptible to tilmicosin with inhibition zones around 15 microg tilmicosin disks ranging between 21 and 50mm in diameter. Oral acute toxicity of tilmicosin was evaluated and the LD(50) values obtained demonstrated that it was virtually non-toxic for adult bees and also resulted non-toxic for larvae when compared with the normal brood mortality. Dosage of 1000 mg a.i. of tilmicosin applied in a 55 g candy resulted in a total suppression of AFB clinical signs in honeybee colonies 60 days after initial treatment. To our knowledge, this is the first report of the effectiveness of tilmicosin against P. larvae both in vitro and in vivo.

Inhibitory activity of Syzygium aromaticum and Cymbopogon citratus (DC.) Stapf. essential oils against Listeria monocytogenes inoculated in bovine ground meat

PubMed Central

de Oliveira, Thales Leandro Coutinho; das Graças Cardoso, Maria; de Araújo Soares, Rodrigo; Ramos, Eduardo Mendes; Piccoli, Roberta Hilsdorf; Tebaldi, Victor Maximiliano Reis

2013-01-01

This research evaluated the antimicrobial effect of the clove (Syzygium aromaticum) and lemongrass (Cymbopogon citratus (DC.) Stapf.) essential oils (EOs) against Listeria monocytogenes ATCC 19117 growth added to bovine ground meat stored under refrigeration (5 ± 2 °C) for three days. The EOs, extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), were tested in vitro using an agar well diffusion methodology for determination of Minimum Inhibitory Concentration (MIC). The MIC concentrations for both essential oils on culture tested of L. monocytogenes were 1.56%. The EOs concentrations applied in contaminated ground beef were 1.56, 3.125 and 6.25% (w/v) based on MIC levels and possible activity reductions by food constituents. The bacteria populations were significantly reduced (p ≤ 0.05) after one day of storage in ground meat samples treated with clove and lemongrass EOs at concentrations of 1.56%. There were no significant counts of L. monocytogenes in samples at the other concentrations of the two oils applied after the second day of storage. The sensory acceptability evaluation of the bovine ground meat samples treated with EOs showed that the addition at concentrations higher than 1.56% promote undesirable alterations of taste, odor and characteristic color. The application of EOs at low concentrations in food products can be used in combination with other preservation methods, such as refrigeration, to control pathogens and spoilage bacteria during shelf-life; which goes according to current market trends, where consumers are requesting natural products. PMID:24294222

Inhibitory activity of Syzygium aromaticum and Cymbopogon citratus (DC.) Stapf. essential oils against Listeria monocytogenes inoculated in bovine ground meat.

PubMed

de Oliveira, Thales Leandro Coutinho; das Graças Cardoso, Maria; de Araújo Soares, Rodrigo; Ramos, Eduardo Mendes; Piccoli, Roberta Hilsdorf; Tebaldi, Victor Maximiliano Reis

2013-01-01

This research evaluated the antimicrobial effect of the clove (Syzygium aromaticum) and lemongrass (Cymbopogon citratus (DC.) Stapf.) essential oils (EOs) against Listeria monocytogenes ATCC 19117 growth added to bovine ground meat stored under refrigeration (5 ± 2 °C) for three days. The EOs, extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), were tested in vitro using an agar well diffusion methodology for determination of Minimum Inhibitory Concentration (MIC). The MIC concentrations for both essential oils on culture tested of L. monocytogenes were 1.56%. The EOs concentrations applied in contaminated ground beef were 1.56, 3.125 and 6.25% (w/v) based on MIC levels and possible activity reductions by food constituents. The bacteria populations were significantly reduced (p ≤ 0.05) after one day of storage in ground meat samples treated with clove and lemongrass EOs at concentrations of 1.56%. There were no significant counts of L. monocytogenes in samples at the other concentrations of the two oils applied after the second day of storage. The sensory acceptability evaluation of the bovine ground meat samples treated with EOs showed that the addition at concentrations higher than 1.56% promote undesirable alterations of taste, odor and characteristic color. The application of EOs at low concentrations in food products can be used in combination with other preservation methods, such as refrigeration, to control pathogens and spoilage bacteria during shelf-life; which goes according to current market trends, where consumers are requesting natural products.

Anti-bacterial activity of synthetic N-heterocyclic oxidizing compounds.

PubMed

Babalola, G O

1998-01-01

Synthetic chlorochromate derivatives of pyridine and quinoline were active in vitro against type cultures of Escherichia coli (ATCC 128), Staphylococcus aureus (ATCC 14775), Pseudomonas aeruginosa (ATCC 10145) and Bacillus subtilis (NCTC 8236). The minimum inhibitory concentrations (MIC) were 125-250 micrograms ml-1 and 250-500 micrograms ml-1 for pyridinium chlorochromate and quinolinium chlorochromate, respectively. An established derivative of quinoline (Perfloxacin) had an MIC of 125-250 micrograms ml-1. The extinction time for 10(5) cfu in broth was 90 min for pyridinium chlorochromate and 120 min for quinolinium chlorochromate, except for B. subtilis which survived up to about 180 min and 360 min. A combination of the two compounds produced an antagonistic effect. The 50% lethal dose (LD50 toxicity) in mice was estimated at 76 micrograms g-1 and 33 micrograms g-1 body weight for the quinolinium and pyridinium chlorochromates. The compounds also exhibited some potential for suppressing a simulated staphylococcal infection in mice at the dosage levels of ca 22 micrograms g-1 for pyridinium chlorochromate and 45 micrograms g-1 for quinolinium chlorochromate.

Comparative in vitro activity of tigecycline against aerobic and facultative isolates recovered from hospitalized patients: an Argentinean multicenter study.

PubMed

Casellas, J M; Bantar, C; Duret, F

2007-10-01

Tigecycline, the 9-t-butylglycylamino derivative of minocycline is the first commercially available glycylcycline exhibiting an extended spectrum of antibacterial activity due to its capacity to evade the tetracycline ribosomal and efflux resistance mechanisms. We conducted a collaborative in vitro study determining the activity of tigecycline compared to 14 antimicrobials against clinically relevant isolates obtained from adult patients hospitalized in 9 Argentinean institutions. Minimum inhibitory concentrations (MICs) were determined by the reference broth microdilution method. The number of isolates and MICs 50/90 (mg/L) for tigecycline were the following: Acinetobacter spp. 132 (0.5/1); Escherichia coli 220 (0.12/0.25); Klebsiella spp. 220 (0.5/1), Enterobacter spp. 205 (0.5/1); Serratia spp. 84 (0.5/2); Haemophilus influenzae 96 (0.25/0.5); Staphylococcus aureus 223 (0.12/0.25); Streptococcus pneumoniae 98 (

In vitro activity of daptomycin against clinical isolates of Gram-positive bacteria.

PubMed

Piper, Kerryl E; Steckelberg, James M; Patel, Robin

2005-08-01

We determined the activity of daptomycin, a recently FDA-approved antimicrobial agent, against clinical isolates of Gram-positive bacteria, including viridans group streptococci (16 Streptococcus mitis species group, 12 S. mutans species group, 9 S. anginosus species group, 8 S. sanguinis species group, 5 S. salivarius species group) from patients with infective endocarditis, 32 methicillin-resistant Staphylococcus aureus, 32 high-level penicillin-resistant Streptococcus pneumoniae, 38 vancomycin-resistant enterococci (including 1 linezolid-resistant isolate), and the following unusual Gram-positive bacteria: 3 Listeria monocytogenes, 4 Erysipelothrix rhusiopathiae, 9 Corynebacterium species, 10 Abiotrophia/Granulicatella species, 2 Rothia (Stomatococcus) mucilaginosus, and 4 Gemella morbillorum. Daptomycin minimum inhibitory concentration (MIC)(90) values for the viridans group streptococci, methicillin-resistant S. aureus, penicillin-resistant S. pneumoniae, and Enterococcus species were 0.5, 0.5, < or =0.125, and 4 microg/ml, respectively. The daptomycin MIC range for the unusual Gram-positive bacteria was < or =0.125-2 microg/ml. We conclude that daptomycin has in vitro activity against viridans group streptococci associated with endocarditis as well as against several types of unusual Gram-positive bacteria that can cause endocarditis.

In vitro and in vivo antibacterial activities of E1077, a novel parenteral cephalosporin with a broad antibacterial spectrum.

PubMed Central

Hata, K; Otsuki, M; Nishino, T

1992-01-01

E1077 is a new injectable cephalosporin with a broad spectrum of antibacterial activity against gram-positive and gram-negative bacteria, including staphylococci and Pseudomonas aeruginosa. The in vitro activities of E1077 against clinical isolates of methicillin-susceptible Staphylococcus aureus (MIC of E1077 for 90% of the strains tested [MIC90], 0.78 microgram/ml) and methicillin-resistant S. aureus (MIC90, 50 micrograms/ml) were similar to those of cefpirome and flomoxef. Against Enterococcus faecalis (MIC90, 6.25 micrograms/ml), E1077 was the most active of the drugs tested and four times more active than cefpirome. The MIC90S of E1077 for streptococci, Haemophilus influenzae, and Neisseria gonorrhoeae ranged from 0.05 to 0.78 microgram/ml; E1077 was similar in activity to cefpirome. E1077 inhibited 90% of most species of the family Enterobacteriaceae at concentrations of less than or equal to 1.56 micrograms/ml, with the exception of Serratia marcescens and Proteus vulgaris (12.5 micrograms/ml). The activity of E1077 against P. aeruginosa (MIC90, 6.25 micrograms/ml) was comparable to that of ceftazidime. In vivo activity was evaluated with systemic infections in mice. E1077 showed a protective effect against systemic infections by gram-positive or gram-negative bacteria, as reflected by its in vitro activity. The protective effects of E1077 were higher than those of cefpirome against S. aureus and P. aeruginosa infections and similar to those of cefpirome against other bacterial infections. Morphological studies using differential interference and phase-contrast microscopy showed that low concentrations of E1077 caused swelling of S. aureus and spheroplast and bulge formation in P. aeruginosa. In general, the antibacterial profile of E1077 is similar to that of cefpirome. Images PMID:1416879

Inhibitory efficacy of geraniol on biofilm formation and development of adaptive resistance in Staphylococcus epidermidis RP62A.

PubMed

Kannappan, Arunachalam; Sivaranjani, Murugesan; Srinivasan, Ramanathan; Rathna, Janarthanam; Pandian, Shunmugiah Karutha; Ravi, Arumugam Veera

2017-10-01

The current study has been designed to delineate the efficacy of geraniol (GE) on biofilm formation in Staphylococcus epidermidis as well as the effect of subinhibitory concentrations of GE on the development of adaptive resistance. Biofilm biomass quantification assay was performed to evaluate the antibiofilm activity of GE against S. epidermidis. Microscopic observation of biofilms and extracellular polymeric substance (EPS), slime and cell surface hydrophobicity (CSH) production were also studied to support the antibiofilm potential of GE. In addition, S. epidermidis was examined for its adaptive resistance development upon continuous exposure of GE at its subinhibitory concentrations.Results/Key findings. The MIC of GE against S. epidermidis was 512 µg ml -1 . Without hampering the growth of the pathogen, GE at its sub-MICs (50, 100, 150 and 200 µg ml -1 ) exhibited a dose-dependent increase in antibiofilm activity. The minimal biofilm inhibitory concentration (MBIC) of GE was found to be 200 µg ml -1 with a maximum biofilm inhibition of 85 %. Disintegrated biofilm architecture, reduced EPS, slime and CSH production validated the antibiofilm efficacy of GE. Although the action of GE on preformed biofilm is limited, a 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction assay and live/dead cell staining method revealed reduction in the viability (47 %) of biofilm inhabitants at 2×MIC concentration. Sequential exposure of S. epidermidis to the sub-MICs of GE resulted in poor development of adaptive resistance with diminished biofilm formation. The present study highlights the potential of GE as a suitable candidate for the control of biofilm-mediated S. epidermidis infections.

Implementing Electric Potential Difference as a New Practical Parameter for Rapid and Specific Measurement of Minimum Inhibitory Concentration of Antibiotics.

PubMed

Mobasheri, Nasrin; Karimi, Mehrdad; Hamedi, Javad

2018-06-05

New methods to determine antimicrobial susceptibility of bacterial pathogens especially the minimum inhibitory concentration (MIC) of antibiotics have great importance in pharmaceutical industry and treatment procedures. In the present study, the MIC of several antibiotics was determined against some pathogenic bacteria using macrodilution test. In order to accelerate and increase the efficiency of culture-based method to determine antimicrobial susceptibility, the possible relationship between the changes in some physico-chemical parameters including conductivity, electrical potential difference (EPD), pH and total number of test strains was investigated during the logarithmic phase of bacterial growth in presence of antibiotics. The correlation between changes in these physico-chemical parameters and growth of bacteria was statistically evaluated using linear and non-linear regression models. Finally, the calculated MIC values in new proposed method were compared with the MIC derived from macrodilution test. The results represent significant association between the changes in EPD and pH values and growth of the tested bacteria during the exponential phase of bacterial growth. It has been assumed that the proliferation of bacteria can cause the significant changes in EPD values. The MIC values in both conventional and new method were consistent to each other. In conclusion, cost and time effective antimicrobial susceptibility test can be developed based on monitoring the changes in EPD values. The new proposed strategy also can be used in high throughput screening of biocompounds for their antimicrobial activity in a relatively shorter time (6-8 h) in comparison with the conventional methods.

Concentrations of antibiotics predicted to select for resistant bacteria: Proposed limits for environmental regulation.

PubMed

Bengtsson-Palme, Johan; Larsson, D G Joakim

2016-01-01

There are concerns that selection pressure from antibiotics in the environment may accelerate the evolution and dissemination of antibiotic-resistant pathogens. Nevertheless, there is currently no regulatory system that takes such risks into account. In part, this is due to limited knowledge of environmental concentrations that might exert selection for resistant bacteria. To experimentally determine minimal selective concentrations in complex microbial ecosystems for all antibiotics would involve considerable effort. In this work, our aim was to estimate upper boundaries for selective concentrations for all common antibiotics, based on the assumption that selective concentrations a priori need to be lower than those completely inhibiting growth. Data on Minimal Inhibitory Concentrations (MICs) were obtained for 111 antibiotics from the public EUCAST database. The 1% lowest observed MICs were identified, and to compensate for limited species coverage, predicted lowest MICs adjusted for the number of tested species were extrapolated through modeling. Predicted No Effect Concentrations (PNECs) for resistance selection were then assessed using an assessment factor of 10 to account for differences between MICs and minimal selective concentrations. The resulting PNECs ranged from 8 ng/L to 64 μg/L. Furthermore, the link between taxonomic similarity between species and lowest MIC was weak. This work provides estimated upper boundaries for selective concentrations (lowest MICs) and PNECs for resistance selection for all common antibiotics. In most cases, PNECs for selection of resistance were below available PNECs for ecotoxicological effects. The generated PNECs can guide implementation of compound-specific emission limits that take into account risks for resistance promotion. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

A Meta-Analysis of Genome-Wide Association Studies of Growth Differentiation Factor-15 Concentration in Blood

PubMed Central

Jiang, Jiyang; Thalamuthu, Anbupalam; Ho, Jennifer E.; Mahajan, Anubha; Ek, Weronica E.; Brown, David A.; Breit, Samuel N.; Wang, Thomas J.; Gyllensten, Ulf; Chen, Ming-Huei; Enroth, Stefan; Januzzi, James L.; Lind, Lars; Armstrong, Nicola J.; Kwok, John B.; Schofield, Peter R.; Wen, Wei; Trollor, Julian N.; Johansson, Åsa; Morris, Andrew P.; Vasan, Ramachandran S.; Sachdev, Perminder S.; Mather, Karen A.

2018-01-01

Blood levels of growth differentiation factor-15 (GDF-15), also known as macrophage inhibitory cytokine-1 (MIC-1), have been associated with various pathological processes and diseases, including cardiovascular disease and cancer. Prior studies suggest genetic factors play a role in regulating blood MIC-1/GDF-15 concentration. In the current study, we conducted the largest genome-wide association study (GWAS) to date using a sample of ∼5,400 community-based Caucasian participants, to determine the genetic variants associated with MIC-1/GDF-15 blood concentration. Conditional and joint (COJO), gene-based association, and gene-set enrichment analyses were also carried out to identify novel loci, genes, and pathways. Consistent with prior results, a locus on chromosome 19, which includes nine single nucleotide polymorphisms (SNPs) (top SNP, rs888663, p = 1.690 × 10-35), was significantly associated with blood MIC-1/GDF-15 concentration, and explained 21.47% of its variance. COJO analysis showed evidence for two independent signals within this locus. Gene-based analysis confirmed the chromosome 19 locus association and in addition, a putative locus on chromosome 1. Gene-set enrichment analyses showed that the“COPI-mediated anterograde transport” gene-set was associated with MIC-1/GDF15 blood concentration with marginal significance after FDR correction (p = 0.067). In conclusion, a locus on chromosome 19 was associated with MIC-1/GDF-15 blood concentration with genome-wide significance, with evidence for a new locus (chromosome 1). Future studies using independent cohorts are needed to confirm the observed associations especially for the chromosomes 1 locus, and to further investigate and identify the causal SNPs that contribute to MIC-1/GDF-15 levels. PMID:29628937

A Meta-Analysis of Genome-Wide Association Studies of Growth Differentiation Factor-15 Concentration in Blood.

PubMed

Jiang, Jiyang; Thalamuthu, Anbupalam; Ho, Jennifer E; Mahajan, Anubha; Ek, Weronica E; Brown, David A; Breit, Samuel N; Wang, Thomas J; Gyllensten, Ulf; Chen, Ming-Huei; Enroth, Stefan; Januzzi, James L; Lind, Lars; Armstrong, Nicola J; Kwok, John B; Schofield, Peter R; Wen, Wei; Trollor, Julian N; Johansson, Åsa; Morris, Andrew P; Vasan, Ramachandran S; Sachdev, Perminder S; Mather, Karen A

2018-01-01

Blood levels of growth differentiation factor-15 (GDF-15), also known as macrophage inhibitory cytokine-1 (MIC-1), have been associated with various pathological processes and diseases, including cardiovascular disease and cancer. Prior studies suggest genetic factors play a role in regulating blood MIC-1/GDF-15 concentration. In the current study, we conducted the largest genome-wide association study (GWAS) to date using a sample of ∼5,400 community-based Caucasian participants, to determine the genetic variants associated with MIC-1/GDF-15 blood concentration. Conditional and joint (COJO), gene-based association, and gene-set enrichment analyses were also carried out to identify novel loci, genes, and pathways. Consistent with prior results, a locus on chromosome 19, which includes nine single nucleotide polymorphisms (SNPs) (top SNP, rs888663, p = 1.690 × 10 -35 ), was significantly associated with blood MIC-1/GDF-15 concentration, and explained 21.47% of its variance. COJO analysis showed evidence for two independent signals within this locus. Gene-based analysis confirmed the chromosome 19 locus association and in addition, a putative locus on chromosome 1. Gene-set enrichment analyses showed that the"COPI-mediated anterograde transport" gene-set was associated with MIC-1/GDF15 blood concentration with marginal significance after FDR correction ( p = 0.067). In conclusion, a locus on chromosome 19 was associated with MIC-1/GDF-15 blood concentration with genome-wide significance, with evidence for a new locus (chromosome 1). Future studies using independent cohorts are needed to confirm the observed associations especially for the chromosomes 1 locus, and to further investigate and identify the causal SNPs that contribute to MIC-1/GDF-15 levels.

In vitro susceptibility of Trichophyton rubrum isolates to griseofulvin and tioconazole. Induction and isolation of a resistant mutant to both antimycotic drugs. Mutant of Trichophyton rubrum resistant to griseofulvin and tioconazole.

PubMed

Fachin, A L; Maffei, C M; Martinez-Rossi, N M

1996-01-01

The in vitro susceptibility of three clinical Trichophyton rubrum isolates to griseofulvin and tioconazole, determined by the minimal inhibitory concentration (MIC), was 2 and 0.5 to 1.0 micrograms/ml, respectively. One mutant (gril) obtained after mutagenic treatment of one of these isolates was selected and showed simultaneous resistance to griseofulvin (MIC > 2000 micrograms/ml) and tioconazole (MIC = 1.0 microgram/ml). The clinical importance and the possibility of a multidrug resistance (MDR)-type mechanism being involved in this event is discussed.

Bioactive endophytic fungi isolated from Caesalpinia echinata Lam. (Brazilwood) and identification of beauvericin as a trypanocidal metabolite from Fusarium sp.

PubMed Central

Campos, Fernanda Fraga; Sales, Policarpo A; Romanha, Alvaro José; Araújo, Márcio SS; Siqueira, Ezequias P; Resende, Jarbas M; Alves, Tânia MA; Martins-Filho, Olindo A; dos Santos, Vera Lúcia; Rosa, Carlos A; Zani, Carlos L; Cota, Betania Barros

2015-01-01

Aiming to identify new sources of bioactive secondary metabolites, we isolated 82 endophytic fungi from stems and barks of the native Brazilian tree Caesalpinia echinata Lam. (Fabaceae). We tested their ethyl acetate extracts in several in vitro assays. The organic extracts from three isolates showed antibacterial activity against Staphylococcus aureus and Escherichia coli [minimal inhibitory concentration (MIC) 32-64 μg/mL]. One isolate inhibited the growth of Salmonella typhimurium (MIC 64 μg/mL) and two isolates inhibited the growth of Klebsiella oxytoca (MIC 64 μg/mL), Candida albicans and Candida tropicalis (MIC 64-128 μg/mL). Fourteen extracts at a concentration of 20 μg/mL showed antitumour activities against human breast cancer and human renal cancer cells, while two isolates showed anti-tumour activities against human melanoma cancer cells. Six extracts were able to reduce the proliferation of human peripheral blood mononuclear cells, indicating some degree of selective toxicity. Four isolates were able to inhibit Leishmania (Leishmania) amazonensis and one isolate inhibited Trypanosoma cruzi by at least 40% at 20 μg/mL. The trypanocidal extract obtained from Fusarium sp. [KF611679] culture was subjected to bioguided fractionation, which revealed beauvericin as the compound responsible for the observed toxicity of Fusarium sp. to T. cruzi. This depsipeptide showed a half maximal inhibitory concentration of 1.9 μg/mL (2.43 μM) in a T. cruzi cellular culture assay. PMID:25742265

Antimicrobial and enhancement of the antibiotic activity by phenolic compounds: Gallic acid, caffeic acid and pyrogallol.

PubMed

Lima, Valéria N; Oliveira-Tintino, Cícera D M; Santos, Enaide S; Morais, Luís P; Tintino, Saulo R; Freitas, Thiago S; Geraldo, Yuri S; Pereira, Raimundo L S; Cruz, Rafael P; Menezes, Irwin R A; Coutinho, Henrique D M

2016-10-01

The indiscriminate use of antimicrobial drugs has increased the spectrum of exposure of these organisms. In our studies, these phenolic compounds were evaluated: gallic acid, caffeic acid and pyrogallol. The antibacterial, antifungal and modulatory of antibiotic activities of these compounds were assayed using microdilution method of Minimum Inhibitory Concentration (MIC) to bacteria and Minimum Fungicide Concentration (MFC) to fungi. The modulation was made by comparisons of the MIC and MFC of the compounds alone and combined with drugs against bacteria and fungi respectively, using a sub-inhibitory concentration of 128 μg/mL of substances (MIC/8). All substances not demonstrated clinically relevant antibacterial activity with a MIC above ≥1024 μg/mL. As a result, we observed that the caffeic acid presented a potentiating antibacterial effect over the 3 groups of bacteria studied. Pyrogallol showed a synergistic effect with two of the antibiotics tested, but only against Staphylococcus aureus. In general, caffeic acid was the substance that presented with the greatest number of antibiotics and with the greatest number of bacteria. In relation to the antifungal activity of all the compounds, the verified results were ≥1024 μg/mL, not demonstrating significant activity. Regarding potentiation of the effect of fluconazole, was observed synergistic effect only when assayed against Candida tropicalis, with all substances. Therefore, as can be seen, the compounds presented as substances that can be promising potentiating agents of antimicrobial drugs, even though they do not have direct antibacterial and antifungal action. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation of the antibacterial activity of the methylene chloride extract of Miconia ligustroides, isolated triterpene acids, and ursolic acid derivatives.

PubMed

Cunha, Wilson R; de Matos, Geilton X; Souza, Maria Goreti M; Tozatti, Marcos G; Andrade e Silva, Márcio L; Martins, Carlos H G; da Silva, Rosangela; Da Silva Filho, Ademar A

2010-02-01

The methylene chloride extract of Miconia ligustroides (DC.) Naudin (Melastomataceae), the isolated compounds ursolic and oleanolic acids and a mixture of these acids, and ursolic acid derivatives were evaluated against the following microorganisms: Bacillus cereus (ATCC 14579), Vibrio cholerae (ATCC 9458), Salmonella choleraesuis (ATCC 10708), Klebsiella pneumoniae (ATCC 10031), and Streptococcus pneumoniae (ATCC 6305). The microdilution method was used for determination of the minimum inhibitory concentration (MIC) during evaluation of the antibacterial activity. The methylene chloride extract showed no activity against the selected microorganisms. Ursolic acid was active against B. cereus, showing a MIC value of 20 microg/mL. Oleanolic acid was effective against B. cereus and S. pneumoniae with a MIC of 80 microg/mL in both cases. The mixture of triterpenes, ursolic and oleanolic acids, did not enhance the antimicrobial activity. However, the acetyl and methyl ester derivatives, prepared from ursolic acid, increased the inhibitory activity for S. pneumoniae.

Artepillin C and phenolic compounds responsible for antimicrobial and antioxidant activity of green propolis and Baccharis dracunculifolia DC.

PubMed

Veiga, R S; De Mendonça, S; Mendes, P B; Paulino, N; Mimica, M J; Lagareiro Netto, A A; Lira, I S; López, B G-C; Negrão, V; Marcucci, M C

2017-04-01

This study investigates the antimicrobial activity in Staphylococcus aureus isolates (methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA)) and antioxidant activity of green propolis, Baccharis dracunculifolia DC extracts and Artepillin C™. The amount of Artepillin C in different extracts was determined by high performance liquid chromatography analysis. Minimum inhibitory concentration 90 (MIC90) was determined using 40 isolates of S. aureus inoculated in Müeller-Hinton agar culture medium containing the green propolis and B. dracunculifolia DC extracts. PVEE (green propolis ethanolic extract) and BDEH (B. dracunculifolia hexanic extract) showed the greatest antimicrobial activity with MIC90 values of 246·3 and 295·5 μg ml -1 respectively. Green propolis ethanolic and hexanic extracts (PVEE and PVEH respectively) showed the greatest antioxidant activity assessed by DPPH (1,1-diphenyl-2-picryl hydrazyl radical) with IC 50 values of 13·09 and 95·86 μg ml -1 respectively. Green propolis ethanolic displays better antimicrobial and antioxidant activities compared to other extracts. These activities may be related to the presence of Artepillin C in synergism with the other constituents of the extracts. In this study, the antimicrobial activity of the extracts of green propolis and B. dracunculifolia DC demonstrated in MRSA and MSSA clinical isolates indicated that they can be important tools to treat infections caused by these bacteria. © 2017 The Society for Applied Microbiology.

Antimicrobial Susceptibility of Escherichia coli Strains Isolated from Alouatta spp. Feces to Essential Oils

PubMed Central

Carregaro, Adriano Bonfim; Santurio, Deise Flores; de Sá, Mariangela Facco; Santurio, Janio Moraes; Alves, Sydney Hartz

2016-01-01

This study evaluated the in vitro antibacterial activity of essential oils from Lippia graveolens (Mexican oregano), Origanum vulgaris (oregano), Thymus vulgaris (thyme), Rosmarinus officinalis (rosemary), Cymbopogon nardus (citronella), Cymbopogon citratus (lemongrass), and Eucalyptus citriodora (eucalyptus) against Escherichia coli (n = 22) strains isolated from Alouatta spp. feces. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for each isolate using the broth microdilution technique. Essential oils of Mexican oregano (MIC mean = 1818 μg mL−1; MBC mean = 2618 μg mL−1), thyme (MIC mean = 2618 μg mL−1; MBC mean = 2909 μg mL−1), and oregano (MIC mean = 3418 μg mL−1; MBC mean = 4800 μg mL−1) showed the best antibacterial activity, while essential oils of eucalyptus, rosemary, citronella, and lemongrass displayed no antibacterial activity at concentrations greater than or equal to 6400 μg mL−1. Our results confirm the antimicrobial potential of some essential oils, which deserve further research. PMID:27313638

Antifungal activity of Malaysian honey and propolis extracts against pathogens implicated in denture stomatitis

NASA Astrophysics Data System (ADS)

Yusoff, Nik Yusliyana Nik; Mohamad, Suharni; Abdullah, Haswati@Nurhayati; Rahman, Nurhayu Ab

2016-12-01

Malaysian honey and propolis extracts were investigated for their antifungal properties against pathogens implicated in denture stomatitis. Each of the honey and aqueous extracts propolis at net preparation, 1:1 and 1:2 dilutions was evaluated by using agar well diffusion assay and further investigated by minimum inhibitory concentration (MIC) within the range of 500 mg/mL to 62.5 mg/mL against oral fungi. The findings indicated that there was no effect of propolis on Candida spp for both types of propolis based on no inhibition zones was recorded. Meanwhile, for antifungal activity of honey, only honey from Trigona spp has shown activity at net preparation against C. albicans (10.47 ± 0.23 mm), C. tropicalis (12.29 ± 0.23 mm) and C. glabrata (8.69 ± 0.53 mm). For minimum inhibitory concentration, the data indicates that both propolis have shown inhibitory effect at 500 mg/mL. As for honey, Trigona spp was the effective honey that give MIC value at 250 mg/mL against Candida spp. Apis dorsata honey has shown MIC value at 500 mg/mL while Apis mellifera honey had inhibited C.albicans and C.glabrata at 500 mg/mL except for C.tropicalis at 250 mg/mL. It can be concluded that both propolis has shown weaker antifungal activity against oral fungi while only honey produced from Trigona spp had strong antifungal activity compare to other honey against oral fungi implicated in denture stomatitis.

Synergistic Interactions of Eugenol-tosylate and Its Congeners with Fluconazole against Candida albicans.

PubMed

Ahmad, Aijaz; Wani, Mohmmad Younus; Khan, Amber; Manzoor, Nikhat; Molepo, Julitha

2015-01-01

We previously reported the antifungal properties of a monoterpene phenol "Eugenol" against different Candida strains and have observed that the addition of methyl group to eugenol drastically increased its antimicrobial potency. Based on the results and the importance of medicinal synthetic chemistry, we synthesized eugenol-tosylate and its congeners (E1-E6) and tested their antifungal activity against different clinical fluconazole (FLC)- susceptible and FLC- resistant C. albicans isolates alone and in combination with FLC by determining fractional inhibitory concentration indices (FICIs) and isobolograms calculated from microdilution assays. Minimum inhibitory concentration (MIC) results confirmed that all the tested C. albicans strains were variably susceptible to the semi-synthetic derivatives E1-E6, with MIC values ranging from 1-62 μg/ml. The test compounds in combination with FLC exhibited either synergy (36%), additive (41%) or indifferent (23%) interactions, however, no antagonistic interactions were observed. The MICs of FLC decreased 2-9 fold when used in combination with the test compounds. Like their precursor eugenol, all the derivatives showed significant impairment of ergosterol biosynthesis in all C. albicans strains coupled with down regulation of the important ergosterol biosynthesis pathway gene-ERG11. The results were further validated by docking studies, which revealed that the inhibitors snugly fitting the active site of the target enzyme, mimicking fluconazole, may well explain their excellent inhibitory activity. Our results suggest that these compounds have a great potential as antifungals, which can be used as chemosensitizing agents with the known antifungal drugs.

In Vitro Antibacterial and Antibiofilm Activities of Chlorogenic Acid against Clinical Isolates of Stenotrophomonas maltophilia including the Trimethoprim/Sulfamethoxazole Resistant Strain

PubMed Central

Karunanidhi, Arunkumar; Thomas, Renjan; van Belkum, Alex; Neela, Vasanthakumari

2013-01-01

The in vitro antibacterial and antibiofilm activity of chlorogenic acid against clinical isolates of Stenotrophomonas maltophilia was investigated through disk diffusion, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), time-kill and biofilm assays. A total of 9 clinical S. maltophilia isolates including one isolate resistant to trimethoprim/sulfamethoxazole (TMP/SMX) were tested. The inhibition zone sizes for the isolates ranged from 17 to 29 mm, while the MIC and MBC values ranged from 8 to 16 μg mL−1 and 16 to 32 μg mL−1. Chlorogenic acid appeared to be strongly bactericidal at 4x MIC, with a 2-log reduction in viable bacteria at 10 h. In vitro antibiofilm testing showed a 4-fold reduction in biofilm viability at 4x MIC compared to 1x MIC values (0.085 < 0.397 A 490 nm) of chlorogenic acid. The data from this study support the notion that the chlorogenic acid has promising in vitro antibacterial and antibiofilm activities against S. maltophilia. PMID:23509719

Aqueous Humor Penetration and Biological Activity of Moxifloxacin 0.5% Ophthalmic Solution Alone or with Dexamethasone 0.1.

PubMed

Gomes, Rachel L R; Viana, Rodrigo Galvão; Melo, Luiz Alberto S; Cruz, Alessandro Carvalho; Suenaga, Eunice Mayumi; Kenyon, Kenneth R; Campos, Mauro

2017-03-01

To compare aqueous humor concentrations of topically applied moxifloxacin 0.5% ophthalmic solution alone or in combination with dexamethasone 0.1% and to correlate these concentrations with the minimum inhibitory concentrations (MICs) for common endophthalmitis-causing organisms. Sixty-eight patients undergoing routine phacoemulsification with intraocular lens implantation received either moxifloxacin 0.5% alone or moxifloxacin 0.5% combined with dexamethasone. For both groups, 1 drop of the test solution was instilled 4 times daily 1 day preoperatively and 1 drop 1 h preoperatively. An aqueous humor sample obtained immediately before paracentesis was submitted to high-performance liquid chromatography-tandem mass spectrometry to determine the moxifloxacin concentration. The mean concentrations of moxifloxacin were 986.6 ng/mL in the moxifloxacin with dexamethasone group and 741.3 ng/mL in the moxifloxacin group (P = 0.13). Moxifloxacin concentrations of all samples exceeded the MICs for Staphylococcus epidermidis, S. aureus, and Streptococcus pneumoniae. All samples in the moxifloxacin with dexamethasone group and 94% in the moxifloxacin group achieved the MIC for Enterococcus species. For quinolone-resistant S. aureus, the MIC was achieved in 29% in the moxifloxacin with dexamethasone group and 9% in the moxifloxacin group (P = 0.06). Aqueous humor moxifloxacin concentrations were higher when topically administrated in combination with dexamethasone compared to the moxifloxacin alone. However, this difference was not statistically significant. Nevertheless, the MICs of the most common pathogens associated with endophthalmitis were exceeded in both study groups.

Combination of Origanum vulgare L. essential oil and lactic acid to inhibit Staphylococcus aureus in meat broth and meat model

PubMed Central

de Barros, Jefferson C.; da Conceição, Maria Lúcia; Neto, Nelson Justino Gomes; da Costa, Ana Caroliny Vieira; de Souza, Evandro Leite

2012-01-01

This study assessed the occurrence of an enhancing inhibitory effect of the combined application of Origanum vulgare L. essential oil and lactic acid against Staphylococcus aureus by the determination of Fractional Inhibitory Concentration (FIC) index and cell viability in meat broth and meat model. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the oil was 0.6 and 1.25 µL.mL-1, respectively. Lactic acid showed MIC and MBC of 2.5 and 5µL.mL-1, respectively. FIC indices of the combined application of the oil and lactic acid were 0.5 showing a synergic interaction. The essential oil and lactic acid showed similar (p>0.05) anti-S. aureus effect in meat broth over 96 h of exposure. Treatment with essential oil or lactic acid presented a smaller anti-staphylococcal effect in meat in comparison to meat broth. No significant difference (p>0.05) was found for the microbial counts in meat treated with each antimicrobial alone or in mixture. These results could arise as an interesting approach for the improvement of food preservation using more natural procedures, considering the current demand of consumer and sensory quality of foods. PMID:24031936

Antibacterial activities of Origanum vulgare alone and in combination with different antimicrobials against clinical isolates of Salmonella typhi

PubMed Central

Bharti, Veni; Vasudeva, Neeru; Sharma, Sunil; Duhan, Joginder Singh

2013-01-01

Background: Typhoid fever continues to remain a major public health problem especially in the areas where there is problem of sanitation and hygiene. The emergence of multidrug resistance of Salmonella typhi, the bacteria responsible for Typhoid to ampicillin, chloramphenicol, and cotrimoxazole has further complicated the treatment and management of enteric fever. One strategy for the treatment of the multidrug resistant bacteria is to use herbs in combination with conventional drugs. The present study was done to find out the interaction effect of phenolic, nonphenolic fractions, and volatile oil of Origanum vulgare with ciprofloxacin. Materials and Methods: The minimum inhibitory concentration (MIC) by microdilution method for individual phytoconstituents and in combination with ciprofloxacin was compared for clinically isolated bacteria from patients infected with S. typhi. Fractional inhibitory concentration (FIC) and Fractional inhibitory concentration index (FICI) were also calculated. Results: The MIC declined to a significant level indicating synergistic relationship between ciprofloxacin and phenolic, nonphenolic fractions and volatile oil in vitro. The FICI exhibits synergistic effect for all the three samples while indifferent and antagonistic for samples and for phenolic and nonphenolic fractions. Conclusions: Present study shows that not only the formulation using O. vulgare and ciprofloxacin can overcome multidrug resistance but also will reduce the toxic effects of ciprofloxacin. PMID:24991069

The Prevalence of Vancomycin-Intermediate Staphylococcus aureus and Heterogeneous VISA Among Methicillin-Resistant Strains Isolated from Pediatric Population in a Turkish University Hospital.

PubMed

Mirza, Hasan Cenk; Sancak, Banu; Gür, Deniz

2015-10-01

There are limited data regarding the prevalence of vancomycin-intermediate Staphylococcus aureus (VISA)/heterogeneous VISA (hVISA) among pediatric population. Our objective was to determine the distribution of vancomycin and daptomycin minimum inhibitory concentrations (MICs) and explore the phenomenon of vancomycin MIC creep and the VISA/hVISA prevalence among the methicillin-resistant Staphylococcus aureus (MRSA) strains belonging to pediatric population by population analysis profile-area under the curve (PAP-AUC) and Etest macromethod. Vancomycin and daptomycin susceptibilities of 94 pediatric isolates of MRSA were tested by broth microdilution (BMD) and Etest methods. To determine the prevalence of VISA/hVISA, Etest macromethod and PAP-AUC was performed on all isolates. All isolates were susceptible to vancomycin and daptomycin by both BMD and Etest methods. Twenty-eight (29.8%) isolates had vancomycin MICs of 2 μg/ml by BMD. No increase in vancomycin MICs was observed over time. There were no VISA among 94 MRSA tested but 20 (21.3%) hVISA isolates were identified by PAP-AUC. Results of Etest macromethod were compared to PAP-AUC. Etest macromethod was 60.0% sensitive and 90.5% specific. The hVISA isolates represented 53.6% of isolates with vancomycin MICs of 2 μg/ml. Also, 75% of hVISA isolates had vancomycin MICs of 2 μg/ml. To our knowledge, this is the first study investigating the prevalence of VISA/hVISA among MRSA isolated from pediatric patients by PAP-AUC method. Based on our findings, MRSA isolates, which have vancomycin MIC of 2 μg/ml can be investigated for the presence of hVISA. In this study, daptomycin showed potent activity against all isolates and may represent a therapeutic option for MRSA infections.

Antioxidant and antimicrobial activities of solvent fractions of Vernonia cinerea (L.) Less leaf extract.

PubMed

Sonibare, Mubo A; Aremu, Oluwafunmilola T; Okorie, Patricia N

2016-06-01

Vernonia cinerea (L.) Less is used in folk medicine as a remedy for various diseases. The present study reports antioxidant and antimicrobial activities of solvent fractions of Vernonia cinerea. The antioxidant properties of solvent fractions of V. cinerea were evaluated by determining radicals scavenging activity, total flavonoid and phenolic contents measured with the 2,2-diphenyl-1-picryl hydrazyl (DPPH) test, the aluminum chloride and the Folin-ciocalteau methods, respectively. Antimicrobial activities were tested against human pathogenic microorganisms using agar diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of each active extract were determined. The ethyl acetate fraction having the IC50 value of 6.50 µg/mL demonstrated comparable DPPH radical-scavenging activity with standard antioxidants, gallic acid and quercetin included in the study. All fractions displayed moderate antimicrobial potential against the tested pathogens with the zone of inhibition that ranged from 9.0 to 13.5 mm. The MIC (1.56 mg/mL) and MBC (3.13 mg/mL) indicated highest susceptibility of Candida albicans in all fractions. The results of this study showed that the solvent fractions of V. cinerea possess antioxidant and antimicrobial activities, hence justifying the folkloric use of the plant for the treatment of various ailments in traditional medicine.

In vitro anti-mycobacterial activity of nine medicinal plants used by ethnic groups in Sonora, Mexico.

PubMed

Robles-Zepeda, Ramón Enrique; Coronado-Aceves, Enrique Wenceslao; Velázquez-Contreras, Carlos Arturo; Ruiz-Bustos, Eduardo; Navarro-Navarro, Moisés; Garibay-Escobar, Adriana

2013-11-25

Sonoran ethnic groups (Yaquis, Mayos, Seris, Guarijíos, Pimas, Kikapúes and Pápagos) use mainly herbal based preparations as their first line of medicinal treatment. Among the plants used are those with anti-tuberculosis properties; however, no formal research is available. Organic extracts were obtained from nine medicinal plants traditionally used by Sonoran ethnic groups to treat different kinds of diseases; three of them are mainly used to treat tuberculosis. All of the extracts were tested against Mycobacterium tuberculosis H37Rv using the Alamar Blue redox bioassay. Methanolic extracts from Ambrosia confertiflora, Ambrosia ambrosioides and Guaiacum coulteri showed minimal inhibitory concentration (MIC) values of 200, 790 and 1000 μg/mL, respectively, whereas no effect was observed with the rest of the methanolic extracts at the concentrations tested. Chloroform, dichloromethane, and ethyl acetate extracts from Ambrosia confertiflora showed a MIC of 90, 120 and 160 μg/mL, respectively. A. confertiflora and A. ambrosioides showed the best anti-mycobacterial activity in vitro. The activity of Guaiacum coulteri is consistent with the traditional use by Sonoran ethnic groups as anti-tuberculosis agent.For these reasons, it is important to investigate a broader spectrum of medicinal plants in order to find compounds active against Mycobacterium tuberculosis.

Comparative effect of propolis of honey bee and some herbal extracts on Candida albicans.

PubMed

Gavanji, Shahin; Larki, Behrouz

2017-03-01

To determine the effect of propolis on Candida albicans and to compare it with the effects of some other herbal extracts and antibiotics on this pathogenic fungi. The extracts of propolis, Thymus vulgaris, Caryophillium aromaticus, Echinophora platyloba, Allium cepa and Cinnamomum zeylanicum were prepared and the antifungi effects of the extracts were examined on Candida albicans ATCC10231 using disc-diffusion assay and micro-broth dilution. The minimum fungicidal concentration (MFC) and minimum inhibitory concentrations (MIC) as well as inhibition zone were evaluated and the anti fungi effects of herbal extracts were compared with amphotricin B and nystatin at the times of 24, 48 and 72 h. Data analysis was performed using t test. Obtained results showed that propolis extract with MIC 90 and MFC equal to 39 and 65 μg/mL, respectively, possess the highest antifungal activity when compared with other studied extracts. The extracts of Allium cepa and Thymus vulgaris, with MFC of 169 and 137 μg/mL, respectively, showed the lowest effects on the fungi. Also nystatin and amphotricin B yielded better effects on the tested fungi compared with the effects of all studied extracts on Candida albicans. Propolis extract is effective in controlling Candida albicans. However, the issue requires further investigation on samples in animals and performing toxicological examinations.

Effect of subinhibitory concentrations of chlorogenic acid on reducing the virulence factor production by Staphylococcus aureus.

PubMed

Li, Guanghui; Qiao, Mingyu; Guo, Yan; Wang, Xin; Xu, Yunfeng; Xia, Xiaodong

2014-09-01

Chlorogenic acid (CA) has been reported to inhibit several pathogens, but the influence of subinhibitory concentrations of CA on virulence expression of pathogens has not been fully elucidated. The aim of this study was to explore the effect of CA on the virulence factor production of Staphylococcus aureus. The minimum inhibitory concentration (MIC) of CA against S. aureus was determined using a broth microdilution method. Hemolysin assays, coagulase titer assays, adherence to solid-phase fibrinogen assays, Western blot, and real-time reverse transcriptase-polymerase chain reaction were performed to evaluate the effect of subinhibitory concentrations of CA on the virulence factors of S. aureus. MIC of CA against S. aureus ATCC29213 was found to be 2.56 mg/mL. At subinhibitory concentrations, CA significantly inhibited the hemolysis and dose-dependently decreased coagulase titer. Reduced binding to fibrinogen and decreased production of SEA were observed with treatment of CA at concentrations ranging from 1/16MIC to 1/2MIC. CA markedly inhibited the expression of hla, sea, and agr genes in S. aureus. These data demonstrate that the virulence expression of S. aureus could be reduced by CA and suggest that CA could be potentially developed as a supplemental strategy to control S. aureus infection and to prevent staphylococcal food poisoning.

In vitro susceptibilities of Leptospira spp. and Borrelia burgdorferi isolates to amoxicillin, tilmicosin, and enrofloxacin

PubMed Central

Kim, Doo; Kordick, Dorsey; Divers, Thomas

2006-01-01

Antimicrobial susceptibility testing was conducted with 6 different spirochetal strains (4 strains of Leptospira spp. and 2 strains of Borrelia burgdorferi) against 3 antimicrobial agents, commonly used in equine and bovine practice. The ranges of MIC and MBC of amoxicillin against Leptospira spp. were 0.05-6.25 µg/ml and 6.25-25.0 µg/ml, respectively. And the ranges of minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of amoxicillin against B. burgdorferi were 0.05-0.39 µg/ml and 0.20-0.78 µg/ml, respectively. The ranges of MIC and MBC of enrofloxacin against Leptospira spp. were 0.05-0.39 µg/ml and 0.05-0.39 µg/ml, respectively. Two strains of B. burgdorferi were resistant to enrofloxacin at the highest concentration tested for MBC (≥100 µg/ml). Therefore, the potential role of tilmicosin in the treatment of leptospirosis and borreliosis should be further evaluated in animal models to understand whether the in vivo studies will confirm in vitro results. All spirochetal isolates were inhibited (MIC) and were killed (MBC) by tilmicosin at concentrations below the limit of testing (≤0.01 µg/ml). PMID:17106227

In vitro susceptibilities of Leptospira spp. and Borrelia burgdorferi isolates to amoxicillin, tilmicosin, and enrofloxacin.

PubMed

Kim, Doo; Kordick, Dorsey; Divers, Thomas; Chang, Yung Fu

2006-12-01

Antimicrobial susceptibility testing was conducted with 6 different spirochetal strains (4 strains of Leptospira spp. and 2 strains of Borrelia burgdorferi) against 3 antimicrobial agents, commonly used in equine and bovine practice. The ranges of MIC and MBC of amoxicillin against Leptospira spp. were 0.05 - 6.25 microgram/ml and 6.25 - 25.0 microgram/ml, respectively. And the ranges of minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of amoxicillin against B. burgdorferi were 0.05 - 0.39 microgram/ml and 0.20 - 0.78 microgram/ml, respectively. The ranges of MIC and MBC of enrofloxacin against Leptospira spp. were 0.05 - 0.39 microgram/ml and 0.05 - 0.39 microgram/ml, respectively. Two strains of B. burgdorferi were resistant to enrofloxacin at the highest concentration tested for MBC (>or=100 microgram/ml). Therefore, the potential role of tilmicosin in the treatment of leptospirosis and borreliosis should be further evaluated in animal models to understand whether the in vivo studies will confirm in vitro results. All spirochetal isolates were inhibited (MIC) and were killed (MBC) by tilmicosin at concentrations below the limit of testing (

Subinhibitory concentrations of cell wall synthesis inhibitors promote biofilm formation of Enterococcus faecalis

NASA Astrophysics Data System (ADS)

Yu, Wen; Hallinen, Kelsey; Wood, Kevin

Enterococcus faecalis are commonly associated with hospital acquired infections, because they readily form biofilms on instruments and medical devices. Biofilms are inherently more resistant to killing by antibiotics compared to planktonic bacteria, in part because of their heterogeneous spatial structure. Surprisingly, however, subminimal inhibitory concentrations (sub-MICs) of some antibiotics can actually promote biofilm formation. Unfortunately, much is still unknown about how low drug doses affect the composition and spatial structure of the biofilm. In this work, we investigate the effects of sub-MICs of ampicillin on the formation of E. faecalis biofilms. First, we quantified biofilm mass using crystal violet staining in polystyrene microtiter plates. We found that total biofilm mass is increased over a narrow range of ampicillin concentrations before ultimately declining at higher concentrations. Second, we show that sub-MICs of ampicillin can increase mass of E. faecalis biofilms while simultaneously increasing extracellular DNA/RNA and changing total number of viable cells under confocal microscopy. Further, we use RNA-seq to identify genes differentially expressed under sub-MICs of ampicillin. Finally, we show a mathematical model to explain this phenomenon. This work was funded by The Hartwell Foundation Individual Biomedical Research Award and NSF CAREER 1553208 to KBW.

Studies on Antifungal Potential, Primary Characterization and Mode of Action of a De Novo Cytoplasmic Protein (EAF) from Human Commensal Escherichia coli Against Aspergillus spp.

PubMed

Balhara, Meenakshi; Ruhil, Sonam; Dhankhar, Sandeep; Chhillar, Anil K

2015-01-01

A de novo protein named as EAF (Escherichia antifungal protein) from the cytoplasmic pool of an Escherichia coli strain (MTCC 1652), has been purified to homogeneity using anion exchange (Q-XL Sepharose) and cation exchange (SP-Sepharose) chromatography. The MIC (minimum inhibitory concentration) values of purified protein against A. fumigatus (the major pathogenic species) were found to be comparable with standard drugs i.e. 3.90 µg/ml, 3.90 µg/ml and 1.25 µg/disc via microbroth dilution assay (MDA), percentage spore germination inhibition (PSGI) and disc diffusion assay (DDA) respectively. Toxicity results confirmed that it causes no haemolysis against human RBCs upto a concentration of 1000.0 µg/ml as compared to Amphotericin B (conventional antifungal drug) that causes hundred percent haemolysis at a concentration of 37.50 µg/ml only.The purified protein demonstrated a molecular mass of 28 kDa on SDS-PAGE which was further authenticated by MALDI-TOF. Proteomic and bioinformatics studies deciphered its significant homology (72 %) with chain A-D-ribose binding protein (cluster 2 sugar binding periplasmic proteins; sequence homologues of transcription regulatory proteins) from E. coli. Single dimensional page analysis of A. fumigatusproteins with due effect of EAF (at MIC50) revealed the inhibition of two major proteins; a heat shock protein 70-Hsp70 (68 kDa); having role in protein folding and functioning andphenylanalyl-t RNA synthetase PodG subunit protein (74 kDa); involved in growth polarity in fungi. Scanning electron microscopic studies depicted homologous results. We suggest that EAF most likely belongs to a new group of proteins with potent antifungal characteristics, negligible toxicity and targeting vital proteins of fungal metabolism.

Effect of tannic and gallic acids alone or in combination with carbenicillin or tetracycline on Chromobacterium violaceum CV026 growth, motility, and biofilm formation.

PubMed

Dusane, Devendra H; O'May, Che; Tufenkji, Nathalie

2015-07-01

Chromobacterium violaceum is an opportunistic pathogen that causes infections that are difficult to treat. The goal of this research was to evaluate the effect of selected tannins (tannic acid (TA) and gallic acid (GA)) on bacterial growth, motility, antibiotic (carbenicillin, tetracycline) susceptibility, and biofilm formation. Both tannins, particularly TA, impaired bacterial growth levels and swimming motilities at sub-minimum inhibitory concentrations (sub-MICs). In combination with tannins, antibiotics showed increased MICs, suggesting that tannins interfered with antibacterial activity. Sub-MICs of tetracycline or TA alone enhanced biofilm formation of C. violaceum; however, in combination, these compounds inhibited biofilm formation. In contrast, carbenicillin at sub-MICs was effective in inhibiting C. violaceum biofilm formation; however, in combination with lower concentrations of TA or GA, biofilms were enhanced. These results provide insights into the effects of tannins on C. violaceum growth and their varying interaction with antibiotics used to target C. violaceum infections.

The Relationship Between Vancomycin Trough Concentrations and AUC/MIC Ratios in Pediatric Patients: A Qualitative Systematic Review.

PubMed

Tkachuk, Stacey; Collins, Kyle; Ensom, Mary H H

2018-04-01

In adults, the area under the concentration-time curve (AUC) divided by the minimum inhibitory concentration (MIC) is associated with better clinical and bacteriological response to vancomycin in patients with methicillin-resistant Staphylococcus aureus who achieve target AUC/MIC ≥ 400. This target is often extrapolated to pediatric patients despite the lack of similar evidence. The impracticalities of calculating the AUC in practice means vancomycin trough concentrations are used to predict the AUC/MIC. This review aimed to determine the relationship between vancomycin trough concentrations and AUC/MIC in pediatric patients. We searched the MEDLINE and Embase databases, the Cochrane Database of Systematic Reviews, and the Cochrane Central Register of Controlled Trials using the medical subject heading (MeSH) terms vancomycin and AUC and pediatric* or paediatric*. Articles were included if they were published in English and reported a relationship between vancomycin trough concentrations and AUC/MIC. Of 122 articles retrieved, 11 met the inclusion criteria. One trial reported a relationship between vancomycin trough concentrations, AUC/MIC, and clinical outcomes but was likely underpowered. Five studies found troughs 6-10 mg/l were sufficient to attain an AUC/MIC > 400 in most general hospitalized pediatric patients. One study in patients undergoing cardiothoracic surgery found a trough of 18.4 mg/l achieved an AUC/MIC > 400. Two oncology studies reported troughs ≥ 15 mg/l likely attained an AUC/MIC ≥ 400. In critical care patients: one study found a trough of 9 mg/l did not attain the AUC/MIC target; another found 7 mg/l corresponded to an AUC/MIC of 400. Potential vancomycin targets varied based on the population studied but, for general hospitalized pediatric patients, troughs of 6-10 mg/l are likely sufficient to achieve AUC/MIC ≥ 400. For MIC ≥ 2 mg/l, higher troughs are likely necessary to achieve an AUC/MIC ≥ 400. More research is needed to determine the relationships between vancomycin trough concentrations, AUC/MIC, and clinical outcomes.

Exopolysaccharide matrix of developed Candida albicans biofilms after exposure to antifungal agents.

PubMed

da Silva, Wander José; Gonçalves, Letícia Machado; Seneviratne, Jayampath; Parahitiyawa, Nipuna; Samaranayake, Lakshman Perera; Del Bel Cury, Altair Antoninha

2012-01-01

This study aimed to evaluate the effects of fluconazole or nystatin exposure on developed Candida albicans biofilms regarding their exopolysaccharide matrix. The minimal inhibitory concentration (MIC) against fluconazole or nystatin was determined for C. albicans reference strain (ATCC 90028). Poly(methlymethacrylate) resin (PMMA) specimens were fabricated according to the manufacturer's instructions and had their surface roughness measured. Biofilms were developed on specimens surfaces for 48 h and after that were exposed during 24 h to fluconazole or nystatin prepared in a medium at MIC, 10 x MIC or 100 x MIC. Metabolic activity was evaluated using an XTT assay. Production of soluble and insoluble exopolysaccharide and intracellular polysaccharides was evaluated by the phenol-sulfuric method. Confocal laser scanning microscope was used to evaluate biofilm architecture and percentage of dead/live cells. Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. The presence of fluconazole or nystatin at concentrations higher than MIC results in a great reduction of metabolic activity (p<0.001). At MIC or 10 x MIC, fluconazole showed high amounts of intracellular polysaccharides (p<0.05), but did not affect the exopolysaccharide matrix (p>0.05). The exposure to nystatin also did not alter the exopolysaccharide matrix at all the tested concentrations (p>0.05). Biofilm architecture was not affected by either of the antifungal agents (p>0.05). Nystatin promoted higher proportion of dead cells (p<0.05). It may be concluded that fluconazole and nystatin above the MIC concentration reduced the metabolic activity of C. albicans biofilms; however, they were not able to alter the exopolysaccharide matrix and biofilm architecture.

Evaluation of the antibacterial activity of Piperaceae extracts and nisin on Alicyclobacillus acidoterrestris.

PubMed

Ruiz, Suelen P; Anjos, Márcia Maria Dos; Carrara, Vanessa S; Delima, Juliana N; Cortez, Diógenes Aparício G; Nakamura, Tânia U; Nakamura, Celso V; de Abreu Filho, Benício A

2013-11-01

Alicyclobacillus acidoterrestris is a gram-positive aerobic bacterium. This bacterium resists pasteurization temperatures and low pH and is usually involved in the spoilage of juices and acidic drinks. The objective of this study was to evaluate the antibacterial activities of nisin and the species Piper (Piperaceae) on A. acidoterrestris. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined by the broth microdilution method. The species Piper aduncum had the lowest MIC and an MBC of 15.6 μg/mL and was selected for fractionation. Six fractions were obtained, and the dichloromethane fraction (F.3) had the lowest MIC/MBC (7.81 μg/mL). The dichloromethane fraction was again fractionized, and a spectral analysis revealed that the compound was prenylated chromene (F.3.7). The checkerboard method demonstrated that the crude extract (CE) of P. aduncum plus nisin had a synergistic interaction (fractional inhibitory concentration [FIC] = 0.24). The bactericidal activity of (F.3.7) was confirmed by the time-kill curve. P. aduncum, nisin, and prenylated chromene exhibited strong antibacterial activity against the spores and vegetative cells of A. acidoterrestris. The results of this study suggest that extracts of the genus Piper may provide an alternative to the use of thermal processing for controlling A. spoilage. © 2013 Institute of Food Technologists®

Anticancer, antioxidant, and antibacterial activities of low molecular weight bioactive subfractions isolated from cultures of wood degrading fungus Cerrena unicolor

PubMed Central

Jaszek, Magdalena; Stefaniuk, Dawid; Ciszewski, Tomasz; Matuszewski, Łukasz

2018-01-01

The aim of this study is to investigate in vitro the anticancer, antioxidant, and antibacterial activities of three low molecular weight subfractions I, II and III isolated from secondary metabolites produced by the wood degrading fungus Cerrena unicolor. The present study demonstrated that the low molecular weight subfractions III exhibited the strongest inhibitory activity towards breast carcinoma cells MDA-MB-231, prostatic carcinoma cells PC3, and breast cancer cells MCF7 with the half-maximal inhibitory concentration (IC50) value of 52,25 μg/mL, 60,66 μg/mL, and 54,92 μg/mL, respectively. The highest percentage of inhibition was noted at a concentration of 300 μg/mL in all the examined tumor lines. A significant percentage (59.08%) of ex-LMSIII inhibition of the MDA-MB-231 tumor line was reached at a concentration of 15 μg/ml, while the concentration applied did not affect normal human fibroblast cells. The low molecular weight subfraction III was the most effective and additionally showed the highest free radical 1,1-diphenyl-2-picryl-hydrazyl scavenging activity (IC50 20.39 μg/mL) followed by the low molecular weight subfraction I (IC50 64.14 μg/mL) and II (IC50 49.22 μg/mL). The antibacterial activity of the tested preparations was evaluated against three microorganisms: Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. The MIC minimal inhibitory concentration (MIC) values for the low molecular weight subfraction I, II, and III showed a stronger inhibition effect on S. aureus than on B. subtilis and E. coli cells. The MIC values for the low molecular weight subfraction II against S. aureus, B. subtilis, and E. coli were 6.25, 12.5, and 100 mg/mL, respectively. PMID:29874240

Antibacterial Activity of Anthraquinone from Aloe on Spiced Pig Head

NASA Astrophysics Data System (ADS)

Xu, Lingyi; Li, Xiao; Cui, Yuqian; Pang, Meixia; Wang, Fang; Qi, Jinghua

2017-12-01

[Objective] To optimize the extraction of anthraquinone from Aloe by ultrasonic extraction and its antibacterialactivity. [Method]The influences of different extraction time and ethanol concentration, on anthraquinone contentwere evaluated by asingle factor experiment. And anthraquinone content was determined by ultraviolet spectrophotometry. The bacteriostasis of anthraquinone on spiced pig head’s common putrefying bacteria: Staphylococcus, Serratieae, Bacillus, Proteus and the minimal inhibitory concentration (MIC) were studied by oxford plate assay system. [Result]The best extraction time was 30 minutes and the best ethanol concentration was 80%. The antibacterial activity of the Aloe anthraquinone on Staphylococcus Aureus, Bacillus Proteus is obviously, the minimum inhibitory concentrations were 0.0625 g/mL, 0.05 g/mL, 0.125 g/mL respectively and no inhibitory effect on Serratieae. [Conclusions] The anthraquinones from Aloe can inhibit a part Of spoilage bacteria inspiced pig heads.

Novel Bacterial Topoisomerase Inhibitors with Potent Broad-Spectrum Activity against Drug-Resistant Bacteria.

PubMed

Charrier, Cédric; Salisbury, Anne-Marie; Savage, Victoria J; Duffy, Thomas; Moyo, Emmanuel; Chaffer-Malam, Nathan; Ooi, Nicola; Newman, Rebecca; Cheung, Jonathan; Metzger, Richard; McGarry, David; Pichowicz, Mark; Sigerson, Ralph; Cooper, Ian R; Nelson, Gary; Butler, Hayley S; Craighead, Mark; Ratcliffe, Andrew J; Best, Stuart A; Stokes, Neil R

2017-05-01

The novel bacterial topoisomerase inhibitor class is an investigational type of antibacterial inhibitor of DNA gyrase and topoisomerase IV that does not have cross-resistance with the quinolones. Here, we report the evaluation of the in vitro properties of a new series of this type of small molecule. Exemplar compounds selectively and potently inhibited the catalytic activities of Escherichia coli DNA gyrase and topoisomerase IV but did not block the DNA breakage-reunion step. Compounds showed broad-spectrum inhibitory activity against a wide range of Gram-positive and Gram-negative pathogens, including biodefence microorganisms and Mycobacterium tuberculosis No cross-resistance with fluoroquinolone-resistant Staphylococcus aureus and E. coli isolates was observed. Measured MIC 90 values were 4 and 8 μg/ml against a panel of contemporary multidrug-resistant isolates of Acinetobacter baumannii and E. coli , respectively. In addition, representative compounds exhibited greater antibacterial potency than the quinolones against obligate anaerobic species. Spontaneous mutation rates were low, with frequencies of resistance typically <10 -8 against E. coli and A. baumannii at concentrations equivalent to 4-fold the MIC. Compound-resistant E. coli mutants that were isolated following serial passage were characterized by whole-genome sequencing and carried a single Arg38Leu amino acid substitution in the GyrA subunit of DNA gyrase. Preliminary in vitro safety data indicate that the series shows a promising therapeutic index and potential for low human ether-a-go-go-related gene (hERG) inhibition (50% inhibitory concentration [IC 50 ], >100 μM). In summary, the compounds' distinct mechanism of action relative to the fluoroquinolones, whole-cell potency, low potential for resistance development, and favorable in vitro safety profile warrant their continued investigation as potential broad-spectrum antibacterial agents. Copyright © 2017 American Society for Microbiology.

Is Vancomycine Still a Choice for Chronic Osteomyelitis Empirical Therapy in Iran?

PubMed Central

Izadi, Morteza; Zamani, Mohammad Mahdi; Mousavi, Seyed Ahmad; Sadat, Seyed Mir Mostafa; Siami, Zeinab; Vais Ahmadi, Noushin; Jonaidi Jafari, Nematollah; Shirvani, Shahram; Majidi Fard, Mojgan; Imani Fooladi, Abbas Ali

2012-01-01

Background Pyogenic bacteria and especially Staphylococcus aurous (S. aurous) are the most common cause of chronic osteomyelitis. Not only treatment protocol of chronic osteomyelitis occasionally is amiss but also this malady responds to treatment difficultly. Objectives This study investigates antibiotic resistance pattern of S. aurous isolated from Iranian patients who suffer from chronic osteomyelitis by two methods: disk diffusion (Kirby bauyer) and E-test (Epsilometer test) to find Vancomycin susceptibility and MIC (Minimum inhibitory concentration). Patients and Methods One hundred and thirty one patients who suffer from chronic osteomyelitis which have been referred to both governmental and private hospitals at 2010 were tried out for culturing of osteomyelitis site (sites). Antibiotic susceptibility and MIC of isolated bacteria were investigated by Kirby bauyer and E-test respectively. Results Samples were collected from bone (73.4%), surrounding tissue (14.6%) and wound discharge (12%). S. aureus was isolated from 49.6% of the samples. According to disc diffusion, methicillin resistance S. aureus (MRSA) was 75% and Vancomycin resistance S. aurous (VRSA) was 0% and based on MIC, MRSA was 68.5% and VRSA was 0%. According to MIC experiments, maximum sensitivity was against to Vancomycin (90.2%) and ciprofloxacin (54.4%) respectively but based on disc diffusion, maximum sensitivity was against to Vancomycin (97.7%) and ciprofloxacin (43.2%), respectively (P = 0.001). E-test (9.8%) in comparison with Disc diffusion (2.3%) showed higher percent of intermediate susceptibility to Vancomycin (P = 0.017). Conclusions Comparison of antibiograms and MICs showed that Kirby bauyer technique especially for detection of VISA strains is not reliable comparison with E-test. Already VRSA strains have not detected in Iranian chronic osteomyelitis, Thus Vancomycin is the first choice for chronic osteomyelitis empirical therapy in Iran yet. PMID:23483042

Molecular resistance mechanisms of Mycoplasma agalactiae to macrolides and lincomycin.

PubMed

Prats-van der Ham, Miranda; Tatay-Dualde, Juan; de la Fe, Christian; Paterna, Ana; Sánchez, Antonio; Corrales, Juan Carlos; Contreras, Antonio; Gómez-Martín, Ángel

2017-11-01

The extensive use of antimicrobials for disease control has caused a remarkable decrease in antimicrobial susceptibility of different animal mycoplasma species, including Mycoplasma agalactiae (M. agalactiae), the main causative agent of contagious agalactia. However, the molecular mechanisms behind M. agalactiae resistance to macrolides and lincomycin have not yet been elucidated. The aim of the present study was to investigate the association between minimum inhibitory concentration (MIC) values of different antimicrobials and mutations in the 23S rRNA gene and ribosomal proteins L4 and L22, analysing both field isolates (n=50) and in vitro selected resistant mutants of M. agalactiae. The obtained MIC results of the studied field isolates demonstrate an increasing development of tylosin resistance in this bacterium, in comparison to previous studies. Interestingly, predicted amino acid changes in L22 (Ser89Leu and Gln90Lys/His) were the first variations observed when MICs of M. agalactiae started to increase (tylosin MIC ≥0.8μg/ml), whereas mutations at positions 2058 or 2059 of domain V of the 23S rRNA gene appeared from MIC values of 1.6μg/ml. These results were consistent in both field isolates and in vitro selected mutants of M. agalactiae. Thus, although in other mycoplasma species resistance to macrolides and lincosamides had been mainly related to mutations in the 23S rRNA gene, this work demonstrates the role of alterations in ribosomal protein L22 in decreased susceptibility of M. agalactiae. Moreover, these mutations can be used as molecular markers to set an interpretative breakpoint of antimicrobial resistance for M. agalactiae. Copyright © 2017 Elsevier B.V. All rights reserved.

In vitro antibacterial activity of doripenem against clinical isolates from French teaching hospitals: proposition of zone diameter breakpoints.

PubMed

Lascols, C; Legrand, P; Mérens, A; Leclercq, R; Armand-Lefevre, L; Drugeon, H B; Kitzis, M D; Muller-Serieys, C; Reverdy, M E; Roussel-Delvallez, M; Moubareck, C; Lemire, A; Miara, A; Gjoklaj, M; Soussy, C-J

2011-04-01

The aims of the study were to determine the in vitro activity of doripenem, a new carbapenem, against a large number of bacterial pathogens and to propose zone diameter breakpoints for clinical categorization in France according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) minimum inhibitory concentration (MIC) breakpoints. The MICs of doripenem were determined by the broth microdilution method against 1,547 clinical isolates from eight French hospitals. The disk diffusion test was performed (10-μg discs) according to the Comité de l'Antibiogramme de la Société Française de Microbiologie (CASFM) method. The MIC(50/90) (mg/L) values were as follows: methicillin-susceptible Staphylococcus aureus (MSSA) (0.03/0.25), methicillin-resistant Staphylococcus aureus (MRSA) (1/2), methicillin-susceptible coagulase-negative staphylococci (MSCoNS) (0.03/0.12), methicillin-resistant coagulase-negative staphylococci (MRCoNS) (2/8), Streptococcus pneumoniae (0.016/0.25), viridans group streptococci (0.016/2), β-hemolytic streptococci (≤0.008/≤0.008), Enterococcus faecalis (2/4), Enterococcus faecium (128/>128), Enterobacteriaceae (0.06/0.25), Pseudomonas aeruginosa (0.5/8), Acinetobacter baumannii (0.25/2), Haemophilus influenzae (0.12/0.25), and Moraxella catarrhalis (0.03/0.06). According to the regression curve, the zone diameter breakpoints were 24 and 19 mm for MICs of 1 and 4 mg/L, respectively. This study confirms the potent in vitro activity of doripenem against Pseudomonas aeruginosa, Acinetobacter, Enterobacteriaceae, MSSA, MSCoNS, and respiratory pathogens. According to the EUCAST MIC breakpoints (mg/L) ≤1/>4 for Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter, and ≤1/>1 for streptococci, pneumococci, and Haemophilus, the zone diameter breakpoints could be (mm) ≥24/<19 and ≥24/<24, respectively.

A novel interpretation of the Fractional Inhibitory Concentration Index: The case Origanum vulgare L. and Leptospermum scoparium J. R. et G. Forst essential oils against Staphylococcus aureus strains.

PubMed

Fratini, Filippo; Mancini, Simone; Turchi, Barbara; Friscia, Elisabetta; Pistelli, Luisa; Giusti, Giulia; Cerri, Domenico

2017-01-01

Origanum vulgare (oregano) and Leptospermum scoparium (manuka) were traditionally employed as natural remedies for infected wounds and skin injuries where Staphylococcus aureus is mainly involved. The first aim of this study was to investigate oregano and manuka essential oils (EOs) chemical compositions and evaluate their antibacterial activity (MIC, Minimum Inhibitory Concentration) against fourteen S. aureus wild strains. The second aim was to evaluate the antibacterial activities of oregano and manuka EOs mixed in different combination (FIC, Fractional Inhibitory Concentration) with an improved chequerboard technique. This allowed to avoid the usual uncertainty in the determination of MIC and FIC values and to obtain a more precise interpretation of FIC indexes (FICIs). Moreover, FICIs were discussed on the basis of a novel interpretation method to evaluate the synergistic/antagonistic effect of EOs mixtures. The most representative compounds in oregano EO were Carvacrol (65.93%), p-Cymene (9.33%) and γ-Terpinene (5.25%), while in manuka EO were Leptospermone (31.65%), cis-Calamenene (15.93%) and Flavesone (6.92%). EOs presented MIC values ranging from 1:2048 to 1:4096 v/v and FIC values ranging from 0.125 to 1. According to our interpretation, a synergistic effect (34.68%), a commutative effect (15.32%) and an indifferent effect (50.00%) and no antagonistic effect were observed. Conversely, according to two previously proposed FICI interpretation models, 1.80% synergistic effect could be observed and, respectively, 98.20% indifferent effect or 48.20% additive effect and 50.00% indifferent effect. As practical results, oregano and manuka EOs may be an effective alternative to chemotherapic drugs in staphylococcal infections and useful tools to enhance food security. Copyright © 2016 Elsevier GmbH. All rights reserved.

In vitro and in vivo anti-MRSA activities of nosokomycins.

PubMed

Uchida, Ryuji; Hanaki, Hideaki; Matsui, Hidenori; Hamamoto, Hiroshi; Sekimizu, Kazuhisa; Iwatsuki, Masato; Kim, Yong Pil; Tomoda, Hiroshi

2014-12-01

The anti-methicillin-resistant Staphylococcus aureus (MRSA) activity of nosokomycins A to D discovered in the silkworm-MRSA infection screening was investigated. The minimum inhibitory concentration (MIC) values of nosokomycins for authentic MRSA and S. aureus strains were calculated to be 0.06 to 2.0 μg/mL. They also showed potent inhibitory activity against 54 clinically isolated MRSA strains. Furthermore, nosokomycin A proved effective in the mouse-MRSA infection model.

Voriconazole, a safe alternative for treating infections caused by the Chrysosporium anamorph of Nannizziopsis vriesii in bearded dragons (Pogona vitticeps).

PubMed

Van Waeyenberghe, L; Baert, K; Pasmans, F; van Rooij, P; Hellebuyck, T; Beernaert, L; de Backer, P; Haesebrouck, F; Martel, A

2010-09-01

Dermal and systemic infections caused by the Chrysosporium anamorph of Nannizziopsis vriesii (CANV) are highly prevalent in reptiles and may result in severe disease and high mortality. Due to the high incidence of therapeutic failures, optimizing treatment is required. We first determined in this study the minimal inhibitory concentrations (MIC) of itraconazole, voriconazole, amphotericin B and terbinafine against 32 CANV isolates. For voriconazole, amphotericin B and terbinafine a monomodal MIC distribution was seen, whereas a bimodal MIC distribution was present for itraconazole, indicating acquired resistance in one isolate. Fourteen naturally-infected bearded dragons (Pogona vitticeps), from the same owner, were treated orally with either itraconazole (5 mg/kg q24h) or voriconazole (10 mg/kg q24h). The clinical condition, drug plasma concentrations and the presence of CANV in skin samples were followed. The animals were treated until complete clearance of the fungus. The plasma concentrations of voriconazole and itraconazole exceeded the minimal inhibitory concentrations of the CANV isolates. Elimination of CANV was achieved on average after 27 and 47 days of treatment with itraconazole and voriconazole, respectively. Whereas only 2 out of 7 survived after itraconazole treatment, only a single animal died in the voriconazole treated group. In conclusion, based on a limited number of animals, voriconazole applied at a regimen of 10 mg/kg bodyweight (BW) q24h seems to be a safe and effective antimycotic drug to eliminate CANV infections in bearded dragons.

Chemical composition and evaluation of modulatory of the antibiotic activity from extract and essential oil of Myracrodruon urundeuva.

PubMed

Figueredo, Fernando G; Lucena, Bruno F F; Tintino, Saulo R; Matias, Edinardo F F; Leite, Nadghia F; Andrade, Jacqueline C; Nogueira, Lavouisier F B; Morais, Edson C; Costa, José G M; Coutinho, Henrique D M; Rodrigues, Fabiola F G

2014-05-01

The combination of antibiotics with natural products has demonstrated promising synergistic effects in several therapeutic studies. The aim of this study was to determine the effect of a combination of an ethanol extract of Myracrodruon urundeuva Fr. All. (Anacardiaceae) (aroeira plant) and its essential oil with six antimicrobial drugs against multiresistant strains of Staphylococcus aureus and Escherichia coli from clinical isolates. After identification of the chemical components by GC-MS, the antibacterial activity of the natural products and antibiotics was assessed by determining the minimal inhibitory concentration (MIC) using the microdilution method and concentrations ranging 8-512 μg/mL and 0.0012-2.5 mg/mL, respectively. Assays were performed to test for a possible synergistic action between the plant products and the antimicrobials, using the extract and the oil at a sub-inhibitory concentration (128 μg/mL) and antibiotic at concentrations varying between 8 and 512 μg/mL. The GC-MS analysis identified the main compound as δ-carene (80.41%). The MIC of the natural products was >1024 μg/mL, except against S. aureus ATCC25923. Only the combinations of the natural products with gentamicin, amikacin and clindamycin were effective against S. aureus 358, enhancing the antibiotic activity by reducing the MIC. The extract from aroeira showed a higher antibacterial activity and the oil was more effective in potentiating the activity of conventional antibiotics.

Pharmacokinetic-pharmacodynamic integration and modelling of oxytetracycline administered alone and in combination with carprofen in calves.

PubMed

Brentnall, C; Cheng, Z; McKellar, Q A; Lees, P

2013-06-01

The pharmacokinetic (PK) and pharmacodynamic (PD) profiles of oxytetracycline were investigated, when administered both alone and in the presence of carprofen, in healthy calves. The study comprised a four treatment, four sequences, and four period cross-over design and used a tissue cage model, which permitted the collection of serum, inflamed tissue cage fluid (exudate) and non-inflamed tissue cage fluid (transudate). There were no clinically relevant differences in the PK profile of oxytetracycline when administered alone and when administered with carprofen. PK-PD integration was undertaken for a pathogenic strain of Mannheimia haemolytic (A1 76/1), by correlating in vitro minimum inhibitory concentration (MIC) and time-kill data with in vivo PK data obtained in the cross-over study. Based on in vitro susceptibility in cation adjusted Mueller Hinton Broth (CAMHB) and in vivo determined PK variables, ratios of maximum concentration (Cmax) and area under curve (AUC) to MIC and time for which concentration exceeded MIC (T>MIC) were determined. The CAMHB MIC data satisfied integrated PK/PD relationships predicted to achieve efficacy for approximately 48 h after dosing; mean values for serum were 5.13 (Cmax/MIC), 49.3 h (T>MIC) and 126.6 h (AUC(96h)/MIC). Similar findings were obtained when oxytetracycline was administered in the presence of carprofen, with PK-PD indices based on MIC determined in CAMHB. However, PK-PD integration of data, based on oxytetracycline MICs determined in the biological fluids, serum, exudate and transudate, suggest that it possesses, at most, limited direct killing activity against the M. haemolytica strain A1 76/1; mean values for serum were 0.277 (Cmax/MIC), 0 h (T>MIC) and 6.84 h (AUC(96h)/MIC). The data suggest that the beneficial therapeutic effects of oxytetracycline may depend, at least in part, on actions other than direct inhibition of bacterial growth. Copyright © 2013 Elsevier Ltd. All rights reserved.

In vitro susceptibility of rabbit strains of Clostridium spiroforme to antimicrobial agents.

PubMed

Carman, R J; Wilkins, T D

1991-08-30

Using an agar dilution method we measured the minimum inhibitory concentration (MIC) of 12 antimicrobial agents against 11 strains of iota-toxigenic strains of Clostridium spiroforme. Each strain was isolated from a separate outbreak of toxic diarrhoea of rabbits. Vancomycin and bacitracin, both agents used to treat intestinal clostridioses of humans and other animals, had a relatively high MIC (8 micrograms/ml or more). Metronidazole was uniformly active against C. spiroforme. With MIC of 8 micrograms/ml or more, both lincomycin (11 strains) and erythromycin (9 strains) were relatively inactive against C. spiroforme, conversely, penicillin G was active (MIC for 8 strains was 0.5 micrograms/ml or less). Exposure to any one of these drugs has been implicated as a predisposing factor for C. spiroforme mediated diarrhoea of rabbits. The greatest variation in MIC was seen for erythromycin (8-fold), penicillin G (8-fold) and tetracycline (16-fold).

Antibacterial activity of Thai herbal extracts on acne involved microorganism.

PubMed

Niyomkam, P; Kaewbumrung, S; Kaewnpparat, S; Panichayupakaranant, P

2010-04-01

Ethyl acetate and methanol extracts of 18 Thai medicinal plants were investigated for their antibacterial activity against Propionibacterium acnes, Stapylococcus aureus, and S. epidermidis. Thirteen plant extracts were capable of inhibiting the growth of P. acnes and S. epidermidis, while 14 plant extracts exhibited an inhibitory effect on S. aureus. Based on the broth dilution method, the ethyl acetate extract of Alpinia galanga (L.) Wild. (Zingiberaceae) rhizome showed the strongest antibacterial effect against P. acnes, with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 156.0 and 312.0 microg/mL, respectively. On the basis of bioassay-guided purification, the ethyl acetate extract was isolated to afford the antibacterial active compound, which was identified as 1'-acetoxychavicol acetate (1'-ACA). 1'-ACA had a strong inhibitory effect on P. acnes with MIC and MBC values of 62.0 and 250.0 microg/mL, respectively. Thus, 1'-ACA was used as an indicative marker for standardization of A. galanga extract using high performance liquid chromatography. These results suggest that A. galanga extract could be an interesting agent for further studies on an alternative treatment of acne.

Inhibitory effects of Caesalpinia sappan on growth and invasion of methicillin-resistant Staphylococcus aureus.

PubMed

Kim, Kang-Ju; Yu, Hyeon-Hee; Jeong, Seung-Il; Cha, Jung-Dan; Kim, Shin-Moo; You, Yong-Ouk

2004-03-01

In the present study, we investigated antimicrobial activity of Caesalpinia sappan against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and effect of Caesalpinia sappan extract on the invasion of MRSA to human mucosal fibroblasts (HMFs). Chloroform, n-butanol, methanol, and aqueous extracts of the Caesalpinia sappan showed antimicrobial activity against standard methicillin-sensitive Staphylococcus aureus (MSSA) as well as MRSA. Methanol extract of Caesalpinia sappan demonstrated a higher inhibitory activity than n-butanol, chloroform, and aqueous extracts. In the checkerboard dilution method, methanol extract of Caesalpinia sappan markedly lowered the minimal inhibitory concentrations (MICs) of ampicillin and oxacillin against MRSA. To determine whether methanol extract of Caesalpinia sappan inhibits the MRSA invasion to HMFs, the cells were treated with various sub-MIC concentrations of methanol extract and bacterial invasion was assayed. MRSA invasion was notably decreased in the presence of 20-80 microg/ml of Caesalpinia sappan extract compared to the control group. The effect of Caesalpinia sappan extract on MRSA invasion appeared dose-dependent. These results suggest that methanol extract of Caesalpinia sappan may have antimicrobial activity and the potential to restore the effectiveness of beta-lactam antibiotics against MRSA, and inhibit the MRSA invasion to HMFs.

Antifungal activity of geraniol and citronellol, two monoterpenes alcohols, against Trichophyton rubrum involves inhibition of ergosterol biosynthesis.

PubMed

Pereira, Fillipe de Oliveira; Mendes, Juliana Moura; Lima, Igara Oliveira; Mota, Kelly Samara de Lira; Oliveira, Wylly Araújo de; Lima, Edeltrudes de Oliveira

2015-02-01

Trichophyton rubrum is the most common fungus causing chronic dermatophytosis in humans. Antifungal activity of promising agents is of great interest. Geraniol and citronellol are monoterpenes with antimicrobial properties. This study aimed to investigate the inhibitory effects and possible mechanism of antifungal activity of geraniol and citronellol against strains of T. rubrum. The minimum inhibitory concentration (MIC) of each drug against 14 strains was determined by broth microdilution. The effects of the drugs on dry mycelial weight, conidial germination, infectivity on human nail fragments, and morphogenesis of T. rubrum were analyzed. The effects on the cell wall (test with sorbitol) and cell membrane (release of intracellular material and ergosterol biosynthesis) were investigated. MIC values of geraniol ranged between 16 and 256 µg/mL while citronellol showed MIC values from 8 to 1024 µg/mL. The drugs (MIC and 2 × MIC) inhibited the mycelial growth, conidia germination, and fungal growth on nail fragments. The drugs (half of MIC) induced the formation of wide, short, and crooked hyphae in T. rubrum morphology. With sorbitol, geraniol MIC was increased by 64-fold and citronellol by 32-fold. The drugs caused leakage of intracellular material and inhibited ergosterol biosynthesis. The results suggest that the drugs damage cell wall and cell membrane of T. rubrum through a mechanism that seems to involve the inhibition of the ergosterol biosynthesis. This study confirms that geraniol and citronellol can be regarded as potential drugs for controlling T. rubrum growth, with great potential against agents of dermatophytosis.

Antimicrobial Activity of Pomegranate and Green Tea Extract on Propionibacterium Acnes, Propionibacterium Granulosum, Staphylococcus Aureus and Staphylococcus Epidermidis.

PubMed

Li, Zhaoping; Summanen, Paula H; Downes, Julia; Corbett, Karen; Komoriya, Tomoe; Henning, Susanne M; Kim, Jenny; Finegold, Sydney M

2015-06-01

We used pomegranate extract (POMx), pomegranate juice (POM juice) and green tea extract (GT) to establish in vitro activities against bacteria implicated in the pathogenesis of acne. Minimum inhibitory concentrations (MIC) of 94 Propionibacterium acnes, Propionibacterium granulosum, Staphylococcus aureus, and Staphylococcus epidermidis strains were determined by Clinical and Laboratory Standards Institute-approved agar dilution technique. Total phenolics content of the phytochemicals was determined using the Folin-Ciocalteu method and the polyphenol composition by HPLC. Bacteria were identified by 16S rRNA sequence analysis. GT MIC of 400 μg/ml or less was obtained for 98% of the strains tested. 64% of P. acnes strains had POMx MICs at 50 μg/ml whereas 36% had MIC >400 μg/ml. POMx, POM juice, and GT showed inhibitory activity against all the P. granulosum strains at ≤100 μg/ml. POMx and GT inhibited all the S. aureus strains at 400 μg/ml or below, and POM juice had an MIC of 200 μg/ml against 17 S. aureus strains. POMx inhibited S. epidermidis strains at 25 μg/ml, whereas POM juice MICs were ≥200 μg/ml. The antibacterial properties of POMx and GT on the most common bacteria associated with the development and progression of acne suggest that these extracts may offer a better preventative/therapeutic regimen with fewer side effects than those currently available.

Activity of TDT 067 (Terbinafine in Transfersome) against Agents of Onychomycosis, as Determined by Minimum Inhibitory and Fungicidal Concentrations▿

PubMed Central

Ghannoum, Mahmoud; Isham, Nancy; Herbert, Jacqueline; Henry, William; Yurdakul, Sam

2011-01-01

TDT 067 is a novel carrier-based dosage form (liquid spray) of 15 mg/ml of terbinafine in Transfersome that has been developed to deliver terbinafine to the nail bed to treat onychomycosis. In this study, we report the in vitro activities of TDT 067 against dermatophytes, compared with those of the Transfersome vehicle, naked terbinafine, and commercially available terbinafine (1%) spray. The MICs of TDT 067 and comparators against 25 clinical strains each of Trichophyton rubrum, T. mentagrophytes, and Epidermophyton floccosum were determined according to the CLSI M38–A2 susceptibility method (2008). Minimum fungicidal concentrations (MFCs) were determined by subculturing visibly clear wells from the MIC microtiter plates. TDT 067 demonstrated potent activity against the dermatophyte strains tested, with an MIC range of 0.00003 to 0.015 μg/ml. Overall, TDT 067 MIC50 values (defined as the lowest concentrations to inhibit 50% of the strains tested) were 8-fold and 60-fold lower than those of naked terbinafine and terbinafine spray, respectively. The Transfersome vehicle showed minimal inhibitory activity. TDT 067 demonstrated lower MFC values for T. rubrum and E. floccosum than naked terbinafine and terbinafine spray. TDT 067 has more potent antifungal activity against dermatophytes that cause nail infection than conventional terbinafine preparations. The Transfersome vehicle appears to potentiate the antifungal activity of terbinafine. Clinical investigation of TDT 067 for the topical treatment of onychomycosis is warranted. PMID:21411586

High minimum inhibitory concentration of imipenem as a predictor of fatal outcome in patients with carbapenem non-susceptible Klebsiella pneumoniae.

PubMed

Wu, Ping-Feng; Chuang, Chien; Su, Chin-Fang; Lin, Yi-Tsung; Chan, Yu-Jiun; Wang, Fu-Der; Chuang, Yin-Ching; Siu, L Kristopher; Fung, Chang-Phone

2016-09-02

Carbapenem resistance in Klebsiella pneumoniae is important because of its increasing prevalence and limited therapeutic options. To investigate the clinical and microbiological characteristics of patients infected or colonized with carbapenem non-susceptible K. pneumoniae (CnsKP) in Taiwan, we conducted a retrospective study at Taipei Veterans General Hospital from January 2012 to November 2013. Carbapenem non-susceptibility was defined as a minimum inhibitory concentration (MIC) of ≥2 mg/L for imipenem or meropenem. A total of 105 cases with CnsKP were identified: 49 patients with infection and 56 patients with colonization. Thirty-one isolates had genes that encoded carbapenemases (29.5%), including K. pneumoniae carbapenemase (KPC)-2 (n = 27), KPC-3 (n = 1), VIM-1 (n = 1) and IMP-8 (n = 2). The in-hospital mortality among patients with CnsKP was 43.8%. A MIC for imipenem ≥16 μg/mL, nasogastric intubation and Acute Physiology and Chronic Health Evaluation II score were independent risk factors for in-hospital mortality for all patients with CnsKP. A MIC for imipenem ≥16 μg/mL was also an independent risk factor for 14-day mortality in patients with CnsKP. In conclusion, a positive culture for CnsKP was associated with high in-hospital mortality. A high imipenem MIC of CnsKP can predispose a patient to a poor prognosis.

Are standard doses of piperacillin sufficient for critically ill patients with augmented creatinine clearance?

PubMed

Udy, Andrew A; Lipman, Jeffrey; Jarrett, Paul; Klein, Kerenaftali; Wallis, Steven C; Patel, Kashyap; Kirkpatrick, Carl M J; Kruger, Peter S; Paterson, David L; Roberts, Michael S; Roberts, Jason A

2015-01-30

The aim of this study was to explore the impact of augmented creatinine clearance and differing minimum inhibitory concentrations (MIC) on piperacillin pharmacokinetic/pharmacodynamic (PK/PD) target attainment (time above MIC (fT>MIC)) in critically ill patients with sepsis receiving intermittent dosing. To be eligible for enrolment, critically ill patients with sepsis had to be receiving piperacillin-tazobactam 4.5 g intravenously (IV) by intermittent infusion every 6 hours for presumed or confirmed nosocomial infection without significant renal impairment (defined by a plasma creatinine concentration greater than 171 μmol/L or the need for renal replacement therapy). Over a single dosing interval, blood samples were drawn to determine unbound plasma piperacillin concentrations. Renal function was assessed by measuring creatinine clearance (CLCR). A population PK model was constructed, and the probability of target attainment (PTA) for 50% and 100% fT>MIC was calculated for varying MIC and CLCR values. In total, 48 patients provided data. Increasing CLCR values were associated with lower trough plasma piperacillin concentrations (P < 0.01), such that with an MIC of 16 mg/L, 100% fT>MIC would be achieved in only one-third (n = 16) of patients. Mean piperacillin clearance was approximately 1.5-fold higher than in healthy volunteers and correlated with CLCR (r = 0.58, P < 0.01). A reduced PTA for all MIC values, when targeting either 50% or 100% fT>MIC, was noted with increasing CLCR measures. Standard intermittent piperacillin-tazobactam dosing is unlikely to achieve optimal piperacillin exposures in a significant proportion of critically ill patients with sepsis, owing to elevated drug clearance. These data suggest that CLCR can be employed as a useful tool to determine whether piperacillin PK/PD target attainment is likely with a range of MIC values.

Antimicrobial effects of Citrus sinensis peel extracts against dental caries bacteria: An in vitro study

PubMed Central

Shetty, Sapna B.; Mahin-Syed-Ismail, Prabu; Varghese, Shaji; Thomas-George, Bibin; Kandathil- Thajuraj, Pathinettam; Baby, Deepak; Haleem, Shaista; Sreedhar, Sreeja

2016-01-01

Background Ethnomedicine is gaining admiration since years but still there is abundant medicinal flora which is unrevealed through research. The study was conducted to assess the in vitro antimicrobial potential and also determine the minimum inhibitory concentration (MIC) of Citrus sinensis peel extracts with a view of searching a novel extract as a remedy for dental caries pathogens. Material and Methods Aqueous and ethanol (cold and hot) extracts prepared from peel of Citrus sinensis were screened for in vitro antimicrobial activity against Streptococcus mutans and Lactobacillus acidophilus, using agar well diffusion method. The lowest concentration of every extract considered as the minimal inhibitory concentration (MIC) values were determined for both test organisms. One way ANOVA with Post Hoc Bonferroni test was applied for statistical analysis. Confidence level and level of significance were set at 95% and 5% respectively. Results Dental caries pathogens were inhibited most by hot ethanolic extract of Citrus sinensispeel followed by cold ethanolic extract. Aqueous extracts were effective at very high concentrations. Minimum inhibitory concentration of hot and cold ethanolic extracts of Citrus sinensis peel ranged between 12-15 mg/ml against both the dental caries pathogens. Conclusions Citrus sinensispeels extract was found to be effective against dental caries pathogens and contain compounds with therapeutic potential. Nevertheless, clinical trials on the effect of these plants are essential before advocating large-scale therapy. Key words:Agar well diffusion, antimicrobial activity, dental caries, Streptococcus mutans, Lactobacillus acidophilus. PMID:26855710

Activity of medicinal plants from Ghana against the parasitic gut protist Blastocystis.

PubMed

Bremer Christensen, Charlotte; Soelberg, Jens; Stensvold, Christen R; Jäger, Anna K

2015-11-04

The plants tested in this study were examples of plants historically used to treat or alleviate several types of stomach disorders manifested by e.g. stomachache, diarrhoea or dysentery. These plants have been consumed typically as a decoction, sometimes mixed with other flavourings. The aim of this study was to evaluate the anti-Blastocystis activity of 24 plant parts from 21 medicinal plants from Ghana. The medicinal plants were collected in the Greater Accra region of Ghana. Every plant part was tested in three different extracts; an ethanolic, a warm, and a cold water extract, at a final concentration of 1 mg/mL for the initial screening, and in a range from 0.0156 to 1mg/mL for determination of inhibitory concentrations. The obligate anaerobic parasitic gut protist Blastocystis (subtype 4) was used as a 48 h old subcultivated isolate in the final concentration of 10(6) cells/mL. Plant extracts inoculated with Blastocystis were incubated at 37 °C for 24 h and 48 h. Both MIC minimum inhibitory concentration (MIC90) assays and minimal lethal concentration (MLC) assays were performed after 24 h and 48 h. The half maximal inhibitory concentration (IC50) was derived after 24 h and 48 h. Antimicrobial activity was tested against two Gram-positive and two Gram-negative bacteria for all 24 plant parts at a final concentration of 1mg/mL. Screening of the 24 different plant parts showed significant anti-Blastocystis activity of six of the ethanolic extracts: Mallotus oppositifolius, IC50, 24 h 27.8 µg/mL; Vemonia colorata, IC50, 24 h 117.9 µg/mL; Zanthoxylum zanthoxyloides, cortex IC50, 24 h 255.6 µg/mL; Clausena anisata, IC50, 24 h 314.0 µg/mL; Z. zanthoxyloides, radix IC50, 24 h 335.7 µg/mL and Eythrina senegalensis, IC50, 24 h 527.6 µg/mL. The reference anti-protozoal agent metronidazole (MTZ) had an IC50, 24 h of 7.6 µg/mL. Only C. anisata showed antimicrobial activity at a concentration of 800 µg/mL. Six ethanolic plant extracts showed significant anti-parasitic activity against Blastocystis. M. oppositifolius showed nearly as good activity as the reference anti-protozoal drug MTZ. Historically, the active plants found in this study have been used against dysentery, diarrhoea or other stomach disorders. Nowadays they are not used specifically for dysentery, but they are being used as medicinal plants against various stomach disorders. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Thiocarbamates from Moringa oleifera Seeds Bioactive against Virulent and Multidrug-Resistant Vibrio Species

PubMed Central

de Sousa, Oscarina Viana; Hofer, Ernesto; Mafezoli, Jair; Barbosa, Francisco Geraldo

2017-01-01

Prospect of antibacterial agents may provide an alternative therapy for diseases caused by multidrug-resistant bacteria. This study aimed to evaluate the in vitro bioactivity of Moringa oleifera seed extracts against 100 vibrios isolated from the marine shrimp Litopenaeus vannamei. Ethanol extracts at low (MOS-E) and hot (MOS-ES) temperature are shown to be bioactive against 92% and 90% of the strains, respectively. The most efficient Minimum Inhibitory Concentration (MIC) levels of MOS-E and MOS-ES against a high percentage of strains were 32 µg mL−1. Bioguided screening of bioactive compounds showed that the ethyl acetate fraction from both extracts was the only one that showed antibacterial activity. Vibriocidal substances, niazirine and niazimicine, were isolated from the aforementioned fraction through chromatographic fractionation. PMID:28770224

In vitro antimicrobial activity of pannarin alone and in combination with antibiotics against methicillin-resistant Staphylococcus aureus clinical isolates.

PubMed

Celenza, Giuseppe; Segatore, Bernardetta; Setacci, Domenico; Bellio, Pierangelo; Brisdelli, Fabrizia; Piovano, Marisa; Garbarino, Juan A; Nicoletti, Marcello; Perilli, Mariagrazia; Amicosante, Gianfranco

2012-05-15

The in vitro antimicrobial activities of pannarin, a depsidone isolated from lichens, collected in several Southern regions of Chile (including Antarctica), was evaluated alone and in combination with five therapeutically available antibiotics, using checkerboard microdilution assay against methicillin-resistant clinical isolates strains of Staphylococcus aureus. MIC(90), MIC(50), as well as MBC(90) and MBC(50), were evaluated. A moderate synergistic action was observed in combination with gentamicin, whilst antagonism was observed in combination with levofloxacin. All combinations with erythromycin were indifferent, whilst variability was observed for clindamycin and oxacillin combinations. Data from checkerboard assay were analysed and interpreted using the fractional inhibitory concentration index and the response surface approach using the ΔE model. Discrepancies were found between both methods for some combinations. In order to asses cellular lysis after exposure to pannarin, cell membrane permeability assay was performed. The treatment with pannarin produces bactericidal activity without significant calcein release, consistent with lack of lysis or even significant structural damage to the cytoplasmic membrane. Furthermore, pannarin shows low hemolytic activity and moderate cytotoxic effect on peripheral blood mononuclear cells. These findings suggest that the natural compound pannarin might be a good candidate for the individualization of novel templates for the development of new antimicrobial agents or combinations of drugs for chemotherapy. Copyright © 2012 Elsevier GmbH. All rights reserved.

Antimicrobial and cytotoxic activity of Marrubium alysson and Retama raetam grown in Tunisia.

PubMed

Hayet, Edziri; Samia, Ammar; Patrick, Groh; Ali, Mahjoub Mohamed; Maha, Mastouri; Laurent, Gutmann; Mighri, Zine; Mahjoub, Laouni

2007-05-15

Antibacterial and antifungal activities of extracts obtained from M. alysson, R. raetam were tested using a solid medium technique. We showed that the petroleum ether extract of M. alysson had a Minimum Inhibitory Concentration (MIC) varied from 128 to 2000 microg mL(-1) against different Enterobacteriaceae and antifungal activity against Candida glabrata, Candida albicans, Candida parapsilosis and Candida kreusei with a MIC of 256 microg mL(-1). The ethyl acetate extract of R. raetam showed the best activity against Gram positive organisms with MICs of 128 to 256 microg mL(-1) against methicillin resistant Staphylococcus aureus but low activity against the different Candida species.

[In vitro activity of ertapenem against clinical bacterial isolates in 69 Spanish medical centers (E-test study)].

PubMed

Gobernado, M; Sanz-Rodríguez, C; Villanueva, R; Torroba, L; Redondo, E; González-Esteban, J

2007-12-01

This study was conducted to assess the in vitro activity of ertapenem against clinical bacterial isolates from patients with community-acquired intra-abdominal and lower tract respiratory infections in Spain in 2003. As the study was conducted before the marketing of ertapenem, it was also useful to define a baseline susceptibility pattern for ertapenem in each of the participating hospitals for later surveillance studies. Each partipating site identified a variable number of aerobic and facultative bacteria isolated from patients with community-acquired intra-abdominal infection or pneumonia using standard procedures. E-test strips were used for determining the minimum inhibitory concentration (MIC) of ertapenem, while for other antimicrobials either quantitative dilution techniques or qualitative diffusion procedures were used according to each microbiology laboratory's routine practice. MIC breakpoints for categorization of susceptibility provided by the CLSI were used for interpreting MIC values. A total of 2,901 recent clinical isolates from patients with community-acquired intra-abdominal infection or pneumonia hospitalized in 69 Spanish medical centers were tested. These isolates included 2,039 Gram-negative bacteria (1,646 Enterobacteriaceae, 216 Haemophilus, 123 non-fermenting Gram-negative bacteria [NFGNB] and 54 others) and 862 Gram-positive bacteria (556 pneumococci, 159 staphylococci, 96 streptococci other than S. pneumoniae, 44 enterococci and 7 others). Ertapenem was very active in vitro against Enterobacteriaceae (99.8% susceptible), Haemophilus (96.3% susceptible), pneumococci (99.6% susceptible, of which 31% were penicillin non-susceptible strains), streptococci other than S. pneumoniae (99.0% susceptible) and methicillin-susceptible staphylococci (94.8% susceptible). For other Gram-positive and Gram-negative pathogens for which ertapenem susceptible breakpoints have not been defined, MIC(90) values were 0.38 and 0.064 mg/l, respectively. As expected, ertapenem had minimal activity in vitro against NFGNB, enterococci and methicillin-resistant staphylococci (MIC(90) of >32 mg/l for all three). Ertapenem was highly active in vitro against most bacteria isolated from patients with community-acquired intra-abdominal and lower respiratory tract infections.

Evaluation of Synergistic Interactions Between Cell-Free Supernatant of Lactobacillus Strains and Amikacin and Genetamicin Against Pseudomonas aeruginosa

PubMed Central

Aminnezhad, Sargol; Kermanshahi, Rouha Kasra; Ranjbar, Reza

2015-01-01

Background: The indiscriminate use of antibiotics in the treatment of infectious diseases can increase the development of antibiotic resistance. Therefore, there is a big demand for new sources of antimicrobial agents and alternative treatments for reduction of antibiotic dosage required to decrease the associated side effects. Objectives: In this study, the synergistic action of aminoglycoside antibiotics and cell-free supernatant (CFS) of probiotic (Lactobacillus rahmnosus and L. casei) against Pseudomonas aeruginosa PTCC 1430 was evaluated. Materials and Methods: A growth medium for culturing of probiotic bacteria was separated by centrifugation. The antimicrobial effects of CFS of probiotic bacteria were evaluated using the agar well diffusion assay. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were evaluated using the micro dilution method. Finally, an interaction between CFS and amikacin or gentamicin against P. aeruginosa PTCC 1430 was examined through the checkerboard method and fractional inhibitory concentration (FIC). Furthermore, CFSs from Lactobacillus strains were analyzed by reversed phase HPLC (RP-HPLC) for antimicrobial compounds. Results: The results showed a significant effect of CFS on the growth of P. aeruginosa. The MIC and MBC of CFS from L. casei were 62.5 µL⁄mL while the MIC and MBC of CFS from L. rhamnosus were 62.5 μL⁄mL and 125 μL⁄mL, respectively. Using the FIC indices, synergistic interactions were observed in combination of CFS and antibiotics. Fractional Inhibitory Concentration indices of CFS from L. casei and aminoglycoside antibiotics were 0.124 and 0.312 while FIC indices of CFS from L. rhamnosus and aminoglycoside antibiotics were 0.124 and 0.56, respectively showing a synergism effect. The results of RP-HPLC showed that CFS of Lactobacillus strains contained acetic acid, lactic acid and hydrogen peroxide (H2O2). Conclusions: Our findings indicate that probiotic bacterial strains of Lactobacillus have a significant inhibitory effect on the growth of P. aeruginosa PTCC 1430. The antimicrobial potency of this combination can be useful for designing and developing alternative therapeutic strategies against P. aeruginosa infections. PMID:26034539

Evaluation of Synergistic Interactions Between Cell-Free Supernatant of Lactobacillus Strains and Amikacin and Genetamicin Against Pseudomonas aeruginosa.

PubMed

Aminnezhad, Sargol; Kermanshahi, Rouha Kasra; Ranjbar, Reza

2015-04-01

The indiscriminate use of antibiotics in the treatment of infectious diseases can increase the development of antibiotic resistance. Therefore, there is a big demand for new sources of antimicrobial agents and alternative treatments for reduction of antibiotic dosage required to decrease the associated side effects. In this study, the synergistic action of aminoglycoside antibiotics and cell-free supernatant (CFS) of probiotic (Lactobacillus rahmnosus and L. casei) against Pseudomonas aeruginosa PTCC 1430 was evaluated. A growth medium for culturing of probiotic bacteria was separated by centrifugation. The antimicrobial effects of CFS of probiotic bacteria were evaluated using the agar well diffusion assay. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were evaluated using the micro dilution method. Finally, an interaction between CFS and amikacin or gentamicin against P. aeruginosa PTCC 1430 was examined through the checkerboard method and fractional inhibitory concentration (FIC). Furthermore, CFSs from Lactobacillus strains were analyzed by reversed phase HPLC (RP-HPLC) for antimicrobial compounds. The results showed a significant effect of CFS on the growth of P. aeruginosa. The MIC and MBC of CFS from L. casei were 62.5 µL⁄mL while the MIC and MBC of CFS from L. rhamnosus were 62.5 μL⁄mL and 125 μL⁄mL, respectively. Using the FIC indices, synergistic interactions were observed in combination of CFS and antibiotics. Fractional Inhibitory Concentration indices of CFS from L. casei and aminoglycoside antibiotics were 0.124 and 0.312 while FIC indices of CFS from L. rhamnosus and aminoglycoside antibiotics were 0.124 and 0.56, respectively showing a synergism effect. The results of RP-HPLC showed that CFS of Lactobacillus strains contained acetic acid, lactic acid and hydrogen peroxide (H2O2). Our findings indicate that probiotic bacterial strains of Lactobacillus have a significant inhibitory effect on the growth of P. aeruginosa PTCC 1430. The antimicrobial potency of this combination can be useful for designing and developing alternative therapeutic strategies against P. aeruginosa infections.

Regression analysis and categorical agreement of fluconazole disk zone diameters and minimum inhibitory concentration by broth microdilution of clinical isolates of Candida.

PubMed

Aggarwal, P; Kashyap, B

2017-06-01

Rampant use of fluconazole in Candida infections has led to predominance of less susceptible non-albicans Candida over Candida albicans. The aim of the study was to determine if zone diameters around fluconazole disk can be used to estimate the minimum inhibitory concentration (MIC) for clinical isolates of Candida species and vice versa. Categorical agreement between the Clinical & Laboratory Standards Institute (CLSI) recommended disk diffusion and CLSI broth microdilution method was sought for. Antifungal susceptibility testing by disk diffusion and Broth microdilution was done as per CLSI document M44-S3 and CLSI document M27-S4 for Candida isolates respectively. Regression analysis correlating zone diameters to MIC value was done. Pearson's correlation coefficient was calculated to determine correlation between disk zone diameters and MICs. Candida albicans (33.3%) was clearly outnumbered by other non-albicans species predominantly Candida tropicalis (42.5%) and Candida glabrata (18.4%). Ten percent of the strains were resistant to fluconazole by disk diffusion and 13% by broth microdilution. MIC range for Candida albicans and Candida tropicalis ranged from≤0.25-64μg/ml while that of Candida glabrata ranged from≤0.25-128μg/ml. Categorical agreement between disk diffusion and broth microdilution was 86.8%. Pearson's coefficient of correlation was -0.5975 indicating moderate negative correlation between the two variables. Zone sizes can be used to estimate the MIC values, although with limited accuracy. There should be a constant effort to upgrade the guidelines in view of new clinical data, and laboratories should make an active effort to incorporate them. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Antibacterial assay-guided isolation of active compounds from Artocarpus heterophyllus heartwoods.

PubMed

Septama, Abdi Wira; Panichayupakaranant, Pharkphoom

2015-01-01

Preparations from Artocarpus heterophyllus Lam. (Moraceae) heartwoods are used in the traditional folk medicine for the treatment of inflammation, malarial fever, and to prevent bacterial and fungal infections. The objective of this study was to isolate pure antibacterial compounds from A. heterophyllus heartwoods. The dried and powdered A. heterophyllus heartwoods were successively extracted with the following solvents: hexane, ethyl acetate, and methanol. Each of the extracts was screened for their antibacterial activities using a disc diffusion method (10 mg/disc). Their minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined using a broth microdilution method. The extract that showed the strongest antibacterial activities was fractionated to isolate the active compounds by an antibacterial assay-guided isolation process. The ethyl acetate extract exhibited the strongest antibacterial activities against Streptococcus mutans, S. pyogenes, and Bacillus subtilis with MIC values of 78, 39, and 9.8 µg/mL, respectively. Based on an antibacterial assay-guided isolation, four antibacterial compounds: cycloartocarpin (1), artocarpin (2), artocarpanone (3), and cyanomaclurin (4) were purified. Among these isolated compounds, artocarpin exhibited the strongest antibacterial activity against Gram-positive bacteria, including S. mutans, S. pyogenes, B. subtilis, Staphylococcus aureus, and S. epidermidis with MICs of 4.4, 4.4, 17.8, 8.9, and 8.9 µM, respectively, and MBCs of 8.9, 8.9, 17.8, 8.9, and 8.9 µM, respectively, while artocarpanone showed the strongest activity against Escherichia coli, a Gram-negative bacteria with MIC and MBC values of 12.9 and 25.8 µM, respectively. Only artocarpin showed inhibitory activity against Pseudomonas aeruginosa with an MIC of 286.4 µM.

Combined effects of plant extracts in inhibiting the growth of Bacillus cereus in reconstituted infant rice cereal.

PubMed

Jun, Hyejung; Kim, Jinsol; Bang, Jihyun; Kim, Hoikyung; Beuchat, Larry R; Ryu, Jee-Hoon

2013-01-01

A study was done to determine the potential use of plant extracts to inhibit the growth of Bacillus cereus in reconstituted infant rice cereal. A total of 2116 extracts were screened for inhibitory activity against B. cereus using an agar well diffusion assay. The minimal inhibitory concentrations (MIC) and minimal lethal concentrations (MLC) of 14 promising extracts in tryptic soy broth (TSB) were determined. Dryopteris erythrosora (autumn fern) root extract showed the lowest MIC (0.0156 mg/ml), followed by Siegesbeckia glabrescens (Siegesbeckia herb) leaf (0.0313 mg/ml), Morus alba (white mulberry) cortex (0.0313 mg/ml), Carex pumila (sand sedge) root (0.0625 mg/ml), and Citrus paradisi (grapefruit) seed (0.0625 mg/ml) extracts. The order of MLCs of extracts was D. erythrosora root (0.0156 mg/ml)

Three Phoma spp. synthesised novel silver nanoparticles that possess excellent antimicrobial efficacy.

PubMed

Rai, Mahendra; Ingle, Avinash P; Gade, Aniket K; Duarte, Marta Cristina Teixeira; Duran, Nelson

2015-10-01

The authors report extracellular mycosynthesis of silver nanoparticles (AgNPs) by Phoma capsulatum, Phoma putaminum and Phoma citri. The AgNPs thus synthesised were characterised by UV-visible spectrophotometer, Fourier transform infrared spectroscopy, Nanosight LM20 and transmission electron microscopy, which confirmed the synthesis of mostly spherical and polydisperse nanoparticles capped with proteins. The size of AgNPs was found in the range of 10-80 , 5-80 and 5-90 nm with an average size of 31.85, 25.43 and 23.29 nm by P. capsulatum, P. putaminum and P. citri, respectively. Further, potential antimicrobial activity was reported against Aspergillus niger, Candida albicans, Salmonella choleraesuis, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. The lowest minimal inhibitory concentration (MIC) (0.85 µg/ml) was reported for AgNPs synthesised from P. citri against S. choleraesuis. However, AgNPs synthesised from P. capsulatum showed the highest MIC (10.62 µg/ml) against S. choleraesuis, P. aeruginosa and E. coli (clinical isolate). The same MIC values (10.62 µg/ml) were also reported against P. aeruginosa and both clinical and standard isolates of E. coli for AgNPs synthesised from P. citri. It was also observed that all the silver nanoparticles showed remarkable antifungal and antibacterial activity against these tested pathogens as compared with the commercially available antifungal and antibacterial agents.

Epigenetic Tailoring for the Production of Anti-Infective Cytosporones from the Marine Fungus Leucostoma persoonii

PubMed Central

Beau, Jeremy; Mahid, Nida; Burda, Whittney N.; Harrington, Lacey; Shaw, Lindsey N.; Mutka, Tina; Kyle, Dennis E.; Barisic, Betty; van Olphen, Alberto; Baker, Bill J.

2012-01-01

Recent genomic studies have demonstrated that fungi can possess gene clusters encoding for the production of previously unobserved secondary metabolites. Activation of these attenuated or silenced genes to obtain either improved titers of known compounds or new ones altogether has been a subject of considerable interest. In our efforts to discover new chemotypes that are effective against infectious diseases, including malaria and methicillin-resistant Staphylococcus aureus (MRSA), we have isolated a strain of marine fungus, Leucostoma persoonii, that produces bioactive cytosporones. Epigenetic modifiers employed to activate secondary metabolite genes resulted in enhanced production of known cytosporones B (1, 360%), C (2, 580%) and E (3, 890%), as well as the production of the previously undescribed cytosporone R (4). Cytosporone E was the most bioactive, displaying an IC90 of 13 µM toward Plasmodium falciparum, with A549 cytotoxicity IC90 of 437 µM, representing a 90% inhibition therapeutic index (TI90 = IC90 A459/IC90 P. falciparum) of 33. In addition, cytosporone E was active against MRSA with a minimal inhibitory concentration (MIC) of 72 µM and inhibition of MRSA biofilm at roughly half that value (minimum biofilm eradication counts, MBEC90, was found to be 39 µM). PMID:22690142

Epigenetic tailoring for the production of anti-infective cytosporones from the marine fungus Leucostoma persoonii.

PubMed

Beau, Jeremy; Mahid, Nida; Burda, Whittney N; Harrington, Lacey; Shaw, Lindsey N; Mutka, Tina; Kyle, Dennis E; Barisic, Betty; van Olphen, Alberto; Baker, Bill J

2012-04-01

Recent genomic studies have demonstrated that fungi can possess gene clusters encoding for the production of previously unobserved secondary metabolites. Activation of these attenuated or silenced genes to obtain either improved titers of known compounds or new ones altogether has been a subject of considerable interest. In our efforts to discover new chemotypes that are effective against infectious diseases, including malaria and methicillin-resistant Staphylococcus aureus (MRSA), we have isolated a strain of marine fungus, Leucostoma persoonii, that produces bioactive cytosporones. Epigenetic modifiers employed to activate secondary metabolite genes resulted in enhanced production of known cytosporones B (1, 360%), C (2, 580%) and E (3, 890%), as well as the production of the previously undescribed cytosporone R (4). Cytosporone E was the most bioactive, displaying an IC(90) of 13 µM toward Plasmodium falciparum, with A549 cytotoxicity IC(90) of 437 µM, representing a 90% inhibition therapeutic index (TI(90) = IC(90) A459/IC(90)P. falciparum) of 33. In addition, cytosporone E was active against MRSA with a minimal inhibitory concentration (MIC) of 72 µM and inhibition of MRSA biofilm at roughly half that value (minimum biofilm eradication counts, MBEC90, was found to be 39 µM).

Chemical composition and modulation of bacterial drug resistance of the essential oil from leaves of Croton grewioides.

PubMed

de Medeiros, Vivianne Marcelino; do Nascimento, Yuri Mangueira; Souto, Augusto Lopes; Madeiro, Sara Alves Lucena; Costa, Vicente Carlos de Oliveira; Silva, Suellen Maria P M; Falcão Silva, Vivyanne Dos Santos; Agra, Maria de Fátima; de Siqueira-Júnior, José Pinto; Tavares, Josean Fechine

2017-10-01

The essential oil from leaves of Croton grewioides Baill was obtained by hydrodistillation using Clevenger apparatus, and its chemical composition was analyzed by GC-MS, where 18 compounds were identified, mostly as monoterpenes (55.56%) and sesquiterpenes (44.44%), in which the major constituent was the α-pinene (47.43%). The essential oil of Croton grewioides (EOCg) and its major compound (α-pinene) were evaluated as modulators of antibiotic resistance in strain SA-1199B and IS-58 of Staphylococcus aureus that overexpresses efflux protein. The minimum inhibitory concentrations (MICs) of the antibiotics were determined by the microdilution assay in the absence and in the presence of sub-inhibitory concentration of EOCg and α-pinene. Although the EOCg and α-pinene did not indicate relevant antibacterial activity in vitro, they acted as antibiotic resistance modulators, i.e., EOCg in combination with norfloxacin, reducted its MIC, by 64× whereas in combination with tetracycline it was observed a reduction of 4×. Additionally, it was observed a MIC reduction of tetracycline by 32×, when combined with α-pinene. The results suggest that EOCg and α-pinene modulate or even reverse bacterial resistance as a putative efflux pump inhibitor. Copyright © 2017 Elsevier Ltd. All rights reserved.

Whole Genome Sequence Analysis of Pig Respiratory Bacterial Pathogens with Elevated Minimum Inhibitory Concentrations for Macrolides.

PubMed

Dayao, Denise Ann Estarez; Seddon, Jennifer M; Gibson, Justine S; Blackall, Patrick J; Turni, Conny

2016-10-01

Macrolides are often used to treat and control bacterial pathogens causing respiratory disease in pigs. This study analyzed the whole genome sequences of one clinical isolate of Actinobacillus pleuropneumoniae, Haemophilus parasuis, Pasteurella multocida, and Bordetella bronchiseptica, all isolated from Australian pigs to identify the mechanism underlying the elevated minimum inhibitory concentrations (MICs) for erythromycin, tilmicosin, or tulathromycin. The H. parasuis assembled genome had a nucleotide transition at position 2059 (A to G) in the six copies of the 23S rRNA gene. This mutation has previously been associated with macrolide resistance but this is the first reported mechanism associated with elevated macrolide MICs in H. parasuis. There was no known macrolide resistance mechanism identified in the other three bacterial genomes. However, strA and sul2, aminoglycoside and sulfonamide resistance genes, respectively, were detected in one contiguous sequence (contig 1) of A. pleuropneumoniae assembled genome. This contig was identical to plasmids previously identified in Pasteurellaceae. This study has provided one possible explanation of elevated MICs to macrolides in H. parasuis. Further studies are necessary to clarify the mechanism causing the unexplained macrolide resistance in other Australian pig respiratory pathogens including the role of efflux systems, which were detected in all analyzed genomes.

Composition and antimicrobial properties of essential oils of four Mediterranean Lamiaceae.

PubMed

Panizzi, L; Flamini, G; Cioni, P L; Morelli, I

1993-08-01

Essential oils from Satureja montana L., Rosmarinus officinalis L., Thymus vulgaris L., and Calamintha nepeta (L.) Savi, were chemically analysed and their antimicrobial and fungicide activities evaluated on the basis of their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). All four oils have a biotoxic effect, the most active being those from Calamintha and Thymus.

Cytotoxic and antibacterial substances against multi-drug resistant pathogens from marine sponge symbiont: Citrinin, a secondary metabolite of Penicillium sp.

PubMed

Subramani, Ramesh; Kumar, Rohitesh; Prasad, Pritesh; Aalbersberg, William; Retheesh, S T

2013-04-01

To Isolate, purify, characterize, and evaluate the bioactive compounds from the sponge-derived fungus Penicillium sp. FF001 and to elucidate its structure. The fungal strain FF001 with an interesting bioactivity profile was isolated from a marine Fijian sponge Melophlus sp. Based on conidiophores aggregation, conidia development and mycelia morphological characteristics, the isolate FF001 was classically identified as a Penicillium sp. The bioactive compound was identified using various spectral analysis of UV, high resolution electrospray ionization mass spectra, 1H and 13C NMR spectral data. Further minimum inhibitory concentrations (MICs) assay and brine shrimp cytotoxicity assay were also carried out to evaluate the biological properties of the purified compound. Bioassay guided fractionation of the EtOAc extract of a static culture of this Penicillium sp. by different chromatographic methods led the isolation of an antibacterial, anticryptococcal and cytotoxic active compound, which was identified as citrinin (1). Further, citrinin (1) is reported for its potent antibacterial activity against methicillin-resistant Staphylococcus aureus (S. aureus), rifampicin-resistant S. aureus, wild type S. aureus and vancomycin-resistant Enterococcus faecium showed MICs of 3.90, 0.97, 1.95 and 7.81 µg/mL, respectively. Further citrinin (1) displayed significant activity against the pathogenic yeast Cryptococcus neoformans (MIC 3.90 µg/mL), and exhibited cytotoxicity against brine shrimp larvae LD50 of 96 µg/mL. Citrinin (1) is reported from sponge associated Penicillium sp. from this study and for its strong antibacterial activity against multi-drug resistant human pathogens including cytotoxicity against brine shrimp larvae, which indicated that sponge associated Penicillium spp. are promising sources of natural bioactive metabolites.

Cytotoxic and antibacterial substances against multi-drug resistant pathogens from marine sponge symbiont: Citrinin, a secondary metabolite of Penicillium sp.

PubMed Central

Subramani, Ramesh; Kumar, Rohitesh; Prasad, Pritesh; Aalbersberg, William

2013-01-01

Objective To Isolate, purify, characterize, and evaluate the bioactive compounds from the sponge-derived fungus Penicillium sp. FF001 and to elucidate its structure. Methods The fungal strain FF001 with an interesting bioactivity profile was isolated from a marine Fijian sponge Melophlus sp. Based on conidiophores aggregation, conidia development and mycelia morphological characteristics, the isolate FF001 was classically identified as a Penicillium sp. The bioactive compound was identified using various spectral analysis of UV, high resolution electrospray ionization mass spectra, 1H and 13C NMR spectral data. Further minimum inhibitory concentrations (MICs) assay and brine shrimp cytotoxicity assay were also carried out to evaluate the biological properties of the purified compound. Results Bioassay guided fractionation of the EtOAc extract of a static culture of this Penicillium sp. by different chromatographic methods led the isolation of an antibacterial, anticryptococcal and cytotoxic active compound, which was identified as citrinin (1). Further, citrinin (1) is reported for its potent antibacterial activity against methicillin-resistant Staphylococcus aureus (S. aureus), rifampicin-resistant S. aureus, wild type S. aureus and vancomycin-resistant Enterococcus faecium showed MICs of 3.90, 0.97, 1.95 and 7.81 µg/mL, respectively. Further citrinin (1) displayed significant activity against the pathogenic yeast Cryptococcus neoformans (MIC 3.90 µg/mL), and exhibited cytotoxicity against brine shrimp larvae LD50 of 96 µg/mL. Conclusions Citrinin (1) is reported from sponge associated Penicillium sp. from this study and for its strong antibacterial activity against multi-drug resistant human pathogens including cytotoxicity against brine shrimp larvae, which indicated that sponge associated Penicillium spp. are promising sources of natural bioactive metabolites. PMID:23620853

[Optimization of cluster analysis based on drug resistance profiles of MRSA isolates].

PubMed

Tani, Hiroya; Kishi, Takahiko; Gotoh, Minehiro; Yamagishi, Yuka; Mikamo, Hiroshige

2015-12-01

We examined 402 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from clinical specimens in our hospital between November 19, 2010 and December 27, 2011 to evaluate the similarity between cluster analysis of drug susceptibility tests and pulsed-field gel electrophoresis (PFGE). The results showed that the 402 strains tested were classified into 27 PFGE patterns (151 subtypes of patterns). Cluster analyses of drug susceptibility tests with the cut-off distance yielding a similar classification capability showed favorable results--when the MIC method was used, and minimum inhibitory concentration (MIC) values were used directly in the method, the level of agreement with PFGE was 74.2% when 15 drugs were tested. The Unweighted Pair Group Method with Arithmetic mean (UPGMA) method was effective when the cut-off distance was 16. Using the SIR method in which susceptible (S), intermediate (I), and resistant (R) were coded as 0, 2, and 3, respectively, according to the Clinical and Laboratory Standards Institute (CLSI) criteria, the level of agreement with PFGE was 75.9% when the number of drugs tested was 17, the method used for clustering was the UPGMA, and the cut-off distance was 3.6. In addition, to assess the reproducibility of the results, 10 strains were randomly sampled from the overall test and subjected to cluster analysis. This was repeated 100 times under the same conditions. The results indicated good reproducibility of the results, with the level of agreement with PFGE showing a mean of 82.0%, standard deviation of 12.1%, and mode of 90.0% for the MIC method and a mean of 80.0%, standard deviation of 13.4%, and mode of 90.0% for the SIR method. In summary, cluster analysis for drug susceptibility tests is useful for the epidemiological analysis of MRSA.

In-vitro activity of several antimicrobial agents against methicillin-resistant Staphylococcus aureus (MRSA) isolates expressing aminoglycoside-modifying enzymes: potency of plazomicin alone and in combination with other agents.

PubMed

López Díaz, María Carmen; Ríos, Esther; Rodríguez-Avial, Iciar; Simaluiza, Rosa Janneth; Picazo, Juan José; Culebras, Esther

2017-08-01

This study investigated the in-vitro activity of clinically relevant aminoglycosides and new antimicrobial agents-plazomicin, ceftobiprole and dalbavancin-against 55 methicillin-resistant Staphylococcus aureus (MRSA) isolates producing aminoglycoside-modifying enzymes (AMEs). The checkerboard method was used to assess synergism between plazomicin and four antibiotics (fosfomycin, ceftobiprole, cefoxitin and meropenem), and time-kill assays were performed for the most active combinations. Among the aminoglycosides tested, plazomicin was the most active agent against MRSA, with >90% of isolates being inhibited at a minimum inhibitory concentration (MIC) of ≤1 mg/L. MIC 50 and MIC 90 values for ceftobiprole and dalbavancin were 2 and 4 mg/L, and 0.125 and 0.125 mg/L, respectively. The most prevalent AME gene was aac(6')Ie-aph(2″)Ia (87.3%), followed by ant(4')Ia (52.7%) and aph(3')IIIa (52.7%). Plazomicin activity was not affected by the type or number of enzymes detected. In checkerboard and time-kill assays, indifference was the most common result achieved for the antibiotic combinations. Notably, no antagonism was observed with any combination tested. Overall, plazomicin in combination with meropenem had the highest synergistic effect, demonstrating synergy against seven isolates in the checkerboard assay and three isolates in time-kill curves. In conclusion, plazomicin showed potent activity against aminoglycoside-resistant MRSA isolates, regardless of the number and type of AMEs present. These findings indicate the potential utility of plazomicin in combination with meropenem for the treatment of MRSA infections. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

In Vitro Activity of Oral Antimicrobial Agents against Pathogens Associated with Community-Acquired Upper Respiratory Tract and Urinary Tract Infections: A Five Country Surveillance Study.

PubMed

Biedenbach, Douglas J; Badal, Robert E; Huang, Ming-Yi; Motyl, Mary; Singhal, Puneet K; Kozlov, Roman S; Roman, Arthur Dessi; Marcella, Stephen

2016-06-01

Bacterial infections that cause community-acquired urinary tract infections (CA-UTI) and upper respiratory tract infections (CA-URTI) are most frequently treated empirically. However, an increase in antimicrobial resistance has become a problem when treating outpatients. This study determined the in vitro activities of oral antibiotics among 1501 pathogens from outpatients with CA-UTI and CA-URTI in medical centers during 2012 and 2013 from Argentina, Mexico, Venezuela, Russia, and the Philippines. Minimal inhibitory concentrations (MICs) were determined using broth microdilution and susceptibility defined by Clinical Laboratory Standards Institute (CLSI) and European Committee for Antimicrobial Susceptibility Testing (EUCAST) criteria. Ceftibuten (MIC50, ≤0.25 mg/L) was more potent in vitro compared to other β-lactams against Enterobacteriaceae from CA-UTI. Susceptibility to fluoroquinolones using CLSI criteria varied: Argentina and Mexico (50%), the Philippines (60%), Venezuela (70%), and Russia (80%). Fosfomycin susceptibility was >90% against Enterobacteriaceae in each country. Susceptibility among Enterobacteriaceae to trimethoprim-sulfamethoxazole was 30.6-75.6% and nitrofurantoin susceptibility also varied among the countries and was higher when EUCAST breakpoints were applied (65->90%) compared to CLSI (52-84%). All Haemophilus influenzae isolates from CA-URTI were susceptible to ceftibuten, cefixime, cefpodoxime, and cefuroxime using CLSI breakpoint criteria. EUCAST criteria produced intermediate and resistant MIC values for these oral cephalosporins. Country-specific susceptibility variation for fluoroquinolones, macrolides, and trimethoprim-sulfamethoxazole was observed among Streptococcus pneumoniae and Streptococcus pyogenes from CA-URTI. This study demonstrated that antimicrobial susceptibility patterns varied in the five countries investigated among pathogens from CA-UTI and CA-URTI. Merck & Co. Inc., Kenilworth, New Jersey, USA.

Inhibitory activities of selected Sudanese medicinal plants on Porphyromonas gingivalis and matrix metalloproteinase-9 and isolation of bioactive compounds from Combretum hartmannianum (Schweinf) bark.

PubMed

Mohieldin, Ebtihal Abdalla M; Muddathir, Ali Mahmoud; Mitsunaga, Tohru

2017-04-20

Periodontal diseases are one of the major health problems and among the most important preventable global infectious diseases. Porphyromonas gingivalis is an anaerobic Gram-negative bacterium which has been strongly implicated in the etiology of periodontitis. Additionally, matrix metalloproteinases-9 (MMP-9) is an important factor contributing to periodontal tissue destruction by a variety of mechanisms. The purpose of this study was to evaluate the selected Sudanese medicinal plants against P. gingivalis bacteria and their inhibitory activities on MMP-9. Sixty two methanolic and 50% ethanolic extracts from 24 plants species were tested for antibacterial activity against P. gingivalis using microplate dilution assay method to determine the minimum inhibitory concentration (MIC). The inhibitory activity of seven methanol extracts selected from the 62 extracts against MMP-9 was determined by Colorimetric Drug Discovery Kit. In search of bioactive lead compounds, Combretum hartmannianum bark which was found to be within the most active plant extracts was subjected to various chromatographic (medium pressure liquid chromatography, column chromatography on a Sephadex LH-20, preparative high performance liquid chromatography) and spectroscopic methods (liquid chromatography-mass spectrometry, Nuclear Magnetic Resonance (NMR)) to isolate and characterize flavogalonic acid dilactone and terchebulin as bioactive compounds. About 80% of the crude extracts provided a MIC value ≤4 mg/ml against bacteria. The extracts which revealed the highest potency were: methanolic extracts of Terminalia laxiflora (wood; MIC = 0.25 mg/ml) followed by Acacia totrtilis (bark), Ambrosia maritima (aerial part), Argemone mexicana (seed), C. hartmannianum (bark), Terminalia brownii (wood) and 50% ethanolic extract of T. brownii (bark) with MIC values of 0.5 mg/ml. T. laxiflora (wood) and C. hartmannianum (bark) which belong to combretaceae family showed an inhibitory activity over 50% at the concentration of 10 μg/ml against MMP-9. Additionally, MMP-9 was significantly inhibited by terchebulin with IC 50 value of 6.7 μM. To the best of our knowledge, flavogalonic acid dilactone and terchebulin were isolated from C. hartmannianium bark for the first time in this study. Because of terchebulin and some crude extracts acting on P. gingivalis bacteria and MMP-9 enzyme that would make them promising natural preference for preventing and treating periodontal diseases.

[Pharmacokinetics and pharmacodynamics of antibiotics in intensive care].

PubMed

Sörgel, F; Höhl, R; Glaser, R; Stelzer, C; Munz, M; Vormittag, M; Kinzig, M; Bulitta, J; Landersdorfer, C; Junger, A; Christ, M; Wilhelm, M; Holzgrabe, U

2017-02-01

Optimized dosage regimens of antibiotics have remained obscure since their introduction. During the last two decades pharmacokinetic(PK)-pharmacodynamic(PD) relationships, originally established in animal experiments, have been increasingly used in patients. The action of betalactams is believed to be governed by the time the plasma concentration is above the minimum inhibitory concentration (MIC). Aminoglycosides act as planned when the peak concentration is a multiple of the MIC and vancomycin seems to work best when the area under the plasma vs. time curve (AUC) to MIC has a certain ratio. Clinicians should be aware that these relationships can only be an indication in which direction dosing should go. Larger studies with sufficiently high numbers of patients and particularly severely sick patients are needed to prove the concepts. In times where all antibiotics can be measured with new technologies, the introduction of therapeutic drug monitoring (TDM) is suggested for ICUs (Intensive Care Unit). The idea of a central lab for TDM of antibiotics such as PEAK (Paul Ehrlich Antibiotika Konzentrationsmessung) is supported.

Determination of antibacterial activity of green coffee bean extract on periodontogenic bacteria like Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans: An in vitro study

PubMed Central

Bharath, Nagaraj; Sowmya, Nagur Karibasappa; Mehta, Dhoom Singh

2015-01-01

Background: The aim of this study was to evaluate the antibacterial activity of pure green coffee bean extract on periodonto pathogenic bacteria Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Fusobacterium nucleatum (Fn) and Aggregatibacter actinomycetemcomitans (Aa). Materials and Methods: Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBC) were used to assess the antibacterial effect of pure green coffee bean extract against periodonto pathogenic bacteria by micro dilution method and culture method, respectively. Results: MIC values of Pg, Pi and Aa were 0.2 μg/ml whereas Fn showed sensitive at concentration of 3.125 μg/ml. MBC values mirrors the values same as that of MIC. Conclusion: Antimicrobial activity of pure green coffee bean extract against Pg, Pi, Fn and Aa suggests that it could be recommended as an adjunct to mechanical therapy in the management of periodontal disease. PMID:26097349

Chemical composition and antifungal activity of the essential oil of Origanum virens on Candida species.

PubMed

Salgueiro, L R; Cavaleiro, C; Pinto, E; Pina-Vaz, C; Rodrigues, A G; Palmeira, A; Tavares, C; Costa-de-Oliveira, S; Gonçalves, M J; Martinez-de-Oliveira, J

2003-09-01

The composition and the antifungal activity of the essential oil of Origanum virens on Candida species were studied. The essential oil was obtained from the aerial parts of the plant by hydrodistillation and analyzed by GC and GC-MS. The oil was characterized by its high content of carvacrol (68.1 %) and its biogenetic precursors, gamma-terpinene (9.9 %) and p-cymene (4.5 %). The minimal inhibitory concentration (MIC) and the minimal lethal concentration (MLC) were used to evaluate the antifungal activity against Candida strains (7 clinical isolates and 3 ATCC type strains). The inhibition of germ tube formation and flow cytometry, using the fluorescent probe propidium iodide (PI), were used to evaluate their mechanisms of action. MIC and MLC values were similar for most tested strains, ranging from 0.16 to 0.32 microL/mL. Concentrations lower than MIC values strongly prevent germ tube formation. The fungicidal effect is primarily due to an extensive lesion of the membrane.

Isolation method (direct plating or enrichment) does not affect antimicrobial susceptibility of Campylobacter from chicken carcasses

USDA-ARS?s Scientific Manuscript database

To determine if Campylobacter isolation method influenced antimicrobial susceptibility results, the minimum inhibitory concentrations (MIC) of nine antimicrobials were compared for 291 pairs of Campylobacter isolates recovered from chicken carcass rinse samples using direct plating and an enrichment...

Alleviating monoterpene toxicity using a two-phase extractive fermentation for the bioproduction of jet fuel mixtures in Saccharomyces cerevisiae.

PubMed

Brennan, Timothy C R; Turner, Christopher D; Krömer, Jens O; Nielsen, Lars K

2012-10-01

Monoterpenes are a diverse class of compounds with applications as flavors and fragrances, pharmaceuticals and more recently, jet fuels. Engineering biosynthetic pathways for monoterpene production in microbial hosts has received increasing attention. However, monoterpenes are highly toxic to many microorganisms including Saccharomyces cerevisiae, a widely used industrial biocatalyst. In this work, the minimum inhibitory concentration (MIC) for S. cerevisiae was determined for five monoterpenes: β-pinene, limonene, myrcene, γ-terpinene, and terpinolene (1.52, 0.44, 2.12, 0.70, 0.53 mM, respectively). Given the low MIC for all compounds tested, a liquid two-phase solvent extraction system to alleviate toxicity during fermentation was evaluated. Ten solvents were tested for biocompatibility, monoterpene distribution, phase separation, and price. The solvents dioctyl phthalate, dibutyl phthalate, isopropyl myristate, and farnesene showed greater than 100-fold increase in the MIC compared to the monoterpenes in a solvent-free system. In particular, the MIC for limonene in dibutyl phthalate showed a 702-fold (308 mM, 42.1 g L(-1) of limonene) improvement while cell viability was maintained above 90%, demonstrating that extractive fermentation is a suitable tool for the reduction of monoterpene toxicity. Finally, we estimated that a limonane to farnesane ratio of 1:9 has physicochemical properties similar to traditional Jet-A aviation fuel. Since farnesene is currently produced in S. cerevisiae, its use as a co-product and extractant for microbial terpene-based jet fuel production in a two-phase system offers an attractive bioprocessing option. Copyright © 2012 Wiley Periodicals, Inc.

Species distribution and antifungal susceptibility patterns of Candida isolates from a public tertiary teaching hospital in the Eastern Cape Province, South Africa.

PubMed

Mnge, P; Okeleye, B I; Vasaikar, S D; Apalata, T

2017-05-15

Candida species are the leading cause of invasive fungal infections, and over the past decade there has been an increased isolation of drug resistant Candida species. This study aimed to identify the species distribution of Candida isolates and to determine their unique antifungal susceptibility and resistance patterns. During a cross-sectional study, 209 Candida isolates (recovered from 206 clinical samples) were collected and their species distribution was determined using ChromAgar Candida. The Vitek-2 system (Biomerieux, South Africa) was used to determine minimum inhibitory concentrations (MICs) to azoles (fluconazole, voriconazole), echinocandins (caspofungin, micafungin), polyenes (amphotericin B) and flucytosine. Four species of Candida were isolated, of which C. albicans was the most frequent, isolated in 45.4% (95/209) of the isolates, followed by C. glabrata: 31.1% (65/209). The MICs of the different antifungal drugs varied amongst the species of Candida. From the 130 isolates tested for MICs, 90.77% (112/130) were susceptible to all antifungal drugs and 6.9% (9/130) of the isolates were multi-drug resistant. C. dubliniensis (n=2) isolates were susceptible to all the above mentioned antifungal drugs. There was no significant difference in species distribution amongst clinical specimens and between patients' genders (P>0.05). An increase in MIC values for fluconazole and flucytosine towards the resistance range was observed. To our knowledge, this is the first report on surveillance of Candida species distribution and antifungal susceptibility at a public tertiary teaching hospital in Eastern Cape, South Africa.

Antibacterial activity of anthraquinone from cassia seed on spiced pig head

NASA Astrophysics Data System (ADS)

Xu, L. Y.; Li, X.; Cui, Y. Q.; Pang, M. X.; Wang, F.; Qi, J. H.

2018-01-01

[Objective] To optimize the extraction of anthraquinone from cassia seed by ultrasonic extraction and its antibacterial activity. [Method] The influences of different extraction time and ethanol concentration, on anthraquinone content were evaluated by a single factor experiment. And anthraquinone content was determined by ultraviolet spectrophotometry. The bacteriostasis of anthraquinone on spiced pig head’s common putrefying bacteria: Staphylococcus, Serratieae, Bacillus, Proteus and the minimal inhibitory concentration (MIC) were studied by oxford plate assay system. [Result] The best extraction time was 30 minutes and the best ethanol concentration was 80%. The antibacterial activity of the cassia seed anthraquinone on Staphylococcus Aureus, Bacillus Proteus is obviously, the minimum inhibitory concentrations were 0.125 g/mL, 0.125 g/mL, 1 g/mL respectively and no inhibitory effect on Serratieae. [Conclusions] The anthraquinones from Cassia seed can inhibit a part of spoilage bacteria in spiced pig heads.

In vitro combined effect of co-amoxiclav concentrations achievable in serum after a 2000/125 mg oral dose, and polymorphonuclear neutrophils against strains of Streptococcus pneumoniae exhibiting decreased susceptibility to amoxicillin.

PubMed

Amores, Raquel; Alou, Luis; Giménez, María José; Sevillano, David; Gómez-Lus, María Luisa; Aguilar, Lorenzo; Prieto, José

2004-07-01

The in vitro effect that the presence of components of non-specific immunity (serum plus polymorphonuclear neutrophils) has on the bactericidal activity of co-amoxiclav was explored against Streptococcus pneumoniae strains exhibiting an amoxicillin MIC > or =4 mg/L. Eight penicillin-resistant clinical isolates non-susceptible to co-amoxiclav with MICs of 4 (two strains), 8 (four strains) and 16 mg/L (two strains) were used. Values of MBC were identical to MIC values in all cases. Time-kill curves were performed with co-amoxiclav concentrations achievable in serum after a single oral dose administration of the new 2000/125 mg sustained-release formulation. Results were expressed as percentage of reduction of initial inocula after 3 h incubation. Control curves showed growth with no reduction of initial inocula. Against strains with MIC of 4 and 8 mg/L, the results obtained with the antibiotic alone or with the presence of factors of non-specific immunity were similar, with a weak combined effect due to the intrinsic activity of co-amoxiclav (reductions of initial inocula ranging from 70 to 99.16%). Against strains with MIC of 16 mg/L, the addition of PMN in the presence of serum increased the reduction of bacterial load provided by the aminopenicillin, even at sub-inhibitory concentrations (25.8% versus 51.1% at 0.5 x MIC concentration--8/0.5 mg/L). This combined activity against strains with an amoxicillin MIC of 16 mg/L which decreased the bacterial load may be important in preventing bacterial proliferation within the host and the transmission of resistant clones to others.

Pharmacokinetics of imipenem in critically ill patients during empirical treatment of nosocomial pneumonia: a comparison of 0.5-h and 3-h infusions.

PubMed

Lipš, Michal; Siller, Michal; Strojil, Jan; Urbánek, Karel; Balík, Martin; Suchánková, Hana

2014-10-01

In critically ill patients, pathophysiological changes alter the pharmacokinetics of antibiotics. Imipenem exhibits primarily time-dependent killing. Its administration by prolonged infusion may increase the time for which its plasma concentration exceeds the minimum inhibitory concentrations (MICs) of suspected pathogens. The objectives of this study were to compare the pharmacokinetic parameters of imipenem administered by standard short infusion (1g imipenem/1g cilastatin over 30min three times daily) and by extended infusion with a reduced total dose (0.5g imipenem/0.5g cilastatin over 3h four times daily) and to compare the target pharmacokinetic/pharmacodynamic indices, namely percentage of the dosing interval for which the free plasma concentration of imipenem exceeds the MIC and 4× MIC (%fT>MIC and %fT>4×MIC) of 0.5, 1, 2 and 4mg/L, for these two regimens in critically ill adult patients with nosocomial pneumonia on Day 2 of empirical antibiotic therapy. The study included 22 patients. Whilst no significant differences were found between both groups for %fT>MIC, %fT>4×MIC was 87.4±12.19%, 68.6±15.08%, 47.31±6.64% and 27.81±9.52% of the 8-h interval in the short infusion group for MICs of 0.5, 1, 2 and 4mg/L, respectively, and 85.15±17.57%, 53.14±27.27%, 13.55±24.47% and 0±0% of the 6-h interval for the extended infusion group. In conclusion, administration of 0.5g of imipenem by a 3-h infusion every 6h does not provide sufficient drug concentrations to treat infections caused by pathogens with a MIC of ≥2mg/L. Copyright © 2014 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

[Sinusal penetration of amoxicillin-clavulanic acid. Formulation 1 g./125 mg., twice daily versus formulation 500 mg./125 mg., three times daily].

PubMed

Jehl, F; Klossek, J M; Peynegre, R; Serrano, E; Castillo, L; Bobin, S; Desprez, D; Renault, C; Neel, V; Rouffiac, E; Borie, C

2002-10-19

In order to meet the evolution of pneumococcus resistance to beta-lactam antibiotics, a new formulation of amoxicillin (AMX) and clavulanic acid (CA), with twice as much AMX (1 g/125 mg vs. 500 mg/125 mg) was developed for the treatment of acute pneumonia in patients at risk. This formulation can also be used in the treatment of acute maxillary sinusitis using a 1 g/125 mg regimen twice-daily. Compare the sinusal penetration of AMX and CA (1 g/125 mg twice-daily vs. 500 mg/125 mg three times a day) when administered at both regimens to demonstrate equivalent pharmacokinetic and pharmacodynamic behaviour of the former when compared to the latter. Concentrations of AMX and CA were measured in the anterior ethmoid, maxillary, posterior ethmoid sinus and in the middle nasa concha in 62 patients undergoing surgery for nasosinusal polyps. Patients randomised in two groups corresponding to 2 oral regimens, received either 1 g/125 mg twice a day or 500 mg/125 mg three times a day for 4 days. The last dose in both groups was administered 1 h 30, 3, 5 or 8 hrs prior to surgery. Serum samples were taken simultaneously to tissue samples. AMX and CA were measured by high performance liquid chromatography. Exogenous and above all endogenous blood contamination were taken into account with the hematocrit as well as blood and tissue haemoglobin concentrations. Comparisons of tissue concentrations were made for each sampling time, according to values obtained for a specific tissue with both doses on one hand, and on the other to values obtained with a specific dose in different tissues. The calculated pharmacodynamic parameters, which are considered to be predictive for bacteriological and clinical efficacy, result directly from tissue concentrations of AMX. tissue inhibitory quotients (IQtissue = Tissue concentration/MIC). time above MICs for serum and tissue concentrations (T > MIC). As regards AMX, whatever the dose, at 1 h 30 and at 3 hrs, tissue concentrations did not differ significantly whatever the tissue studied (from 1.1 to 2.5 micrograms/g). Conversely, at 5 and 8 hrs, they were greater than after the 1 g/125 mg regimen given twice-daily (0.06-0.7 vs. 0.7-1.8 micrograms/g). If we consider a given dose, the comparison between the various tissues showed identical concentrations in the four tissues studied at each sampling time, except in two cases with the dose of 500 mg/125 mg 3 times a day. T > MIC for serum and tissue showed higher values than those required for AMX/pneumococcus association (40-50%) with, nevertheless, greater tissue values for the 1 g/125 mg dose given twice-daily when MIC was of 1 microgram/ml (40-52% vs. 50-66%). The maximum tissue inhibitory quotients were also greater with the twice-daily 1 g/125 mg dose, when calculated with MIC 50 or 90 of S. Pneumoniae, H. influenzae, M. catarrhalis or S. pyogenes. As for CA, concentrations were equivalent for both doses at each sampling time and greater than those required in vitro during respectively 4 and 5 hours for beta-lactamases H. influenzae and M. catarrhalis. A least an equivalence between both dose regimens was observed, with occasionally a superiority of the twice-daily 1 g/125 mg dose, in terms of pharmacokinetics, tissue penetration and pharmacodynamics for both AMX and CA. This new regimen therefore appears more appropriate for the treatment of acute maxillary sinusitis in adults.

Sucralose Increases Antimicrobial Resistance and Stimulates Recovery of Escherichia coli Mutants.

PubMed

Qu, Yilin; Li, Rongyan; Jiang, Mingshan; Wang, Xiuhong

2017-07-01

Because of heavy use of antimicrobials, antimicrobial resistance in bacteria has become of great concern. The effect of some widely used food additives such as sucralose on bacteria in the gut and the environment has also drawn increasing attention. In this study, we investigated the interaction between antimicrobials and sucralose impacting antimicrobial resistance and mutation of Escherichia coli (E. coli). To examine antimicrobial resistance and mutation frequency, different subinhibitory concentrations of sucralose were added to cultures of E.coli BW25113 that were then treated with antimicrobials, oxolinic acid, or moxifloxacin. Then the E.coli were assayed for bacterial survival and recovery of mutants resistant to an unrelated antimicrobial, rifampicin. Pre-treatment of E.coli BW25113 with 1/2 minimal inhibitory concentration (MIC) of sucralose increased the survival rate in oxolinic acid or moxifloxacin. A 1/3 MIC of sucralose increased rifampicin-resistant mutation rate of E.coli BW25113 after 72 h, while rifampicin-resistant mutation rate was increased when co-treated with 1/8 MIC, 1/4 MIC, 1/3 MIC sucralose, and oxolinic acid after 24 h. Sucralose can increase the antimicrobial resistance and mutation frequency of E.coli to some antimicrobials.

Evaluation of antibacterial activities of flomoxef against ESBL producing Enterobacteriaceae analyzed by Monte Carlo simulation.

PubMed

Ito, Akinobu; Tatsumi, Yumiko Matsuo; Wajima, Toshihiro; Nakamura, Rio; Tsuji, Masakatsu

2013-04-01

The growing number of infection caused by extended-spectrum beta-lactamase (ESBL) producing pathogens has prompted a more rational use of available antibiotics because of the paucity of new, effective agents. Flomoxef (FMOX) is one of the beta-lactam antibiotic which is stable against beta-lactamase. In this study, the antibacterial activity of FMOX was investigated, and Monte Carlo Simulation was conducted to determine the appropriate dosing regimens of FMOX based on the probability of target attainment (TA%) at the critical drug exposure metric of time that drug concentrations remain above 40% (showing bacteriostatic effect) or 70% (showing bactericidal effect) of time during which plasma concentration above minimum inhibitory concentration (MIC) of the drug (T(>MIC)) against the ESBL producing Enterobacteriaceae. The effective regimens to achieve 80% of TA% at 70% of T(>MIC) were 1 g every 8 hours with 2-4 hours infusion, and 1 g every 6 hours with 1-4 hours infusion. Moreover, all the tested regimens were effective to achieve 80% of TA% at 40% of T(>MIC). These results of pharmacokinetics/ pharmacodynamics (PK/PD) modeling showed the potential efficacy of FMOX against bacterial infections caused by ESBL producing Enterobacteriaceae.

Tea polyphenols as an antivirulence compound Disrupt Quorum-Sensing Regulated Pathogenicity of Pseudomonas aeruginosa

PubMed Central

Yin, Honging; Deng, Yifeng; Wang, Huafu; Liu, Wugao; Zhuang, Xiyi; Chu, Weihua

2015-01-01

Green tea, a water extract of non-fermented leaves of Camellia sinensis L., is one of the nonalcoholic beverages in China. It is becoming increasingly popular worldwide, because of its refreshing, mild stimulant and medicinal properties. Here we examined the quorum sensing inhibitory potentials of tea polyphenols (TP) as antivirulence compounds both in vitro and in vivo. Biosensor assay data suggested minimum inhibitory concentrations (MICs) of TP against selected pathogens were 6.25 ~ 12.5 mg/mL. At sub-MIC, TP can specifically inhibit the production of violacein in Chromobacterium violaceum 12472 with almost 98% reduction at 3.125 mg/mL without affecting its growth rate. Moreover, TP exhibited inhibitory effects on virulence phenotypes regulated by QS in Pseudomonas aeruginosa. The total proteolytic activity, elastase, swarming motility and biofilm formation were reduced in a concentration-dependent manner. In vivo, TP treatment resulted in the reduction of P. aeruginosa pathogenicity in Caenorhabditis elegans. When its concentration was 3.125 mg/mL, the survival rate reached 63.3%. In the excision wound infection model, the wound contraction percentage in treatment groups was relatively increased and the colony-forming units (CFU) in the wound area were significantly decreased. These results suggested that TP could be developed as a novel non-antibiotic QS inhibitor without killing the bacteria but as an antivirulence compound to control bacterial infection. PMID:26548447

Antimicrobial effect of blueberry (Vaccinium corymbosum L.) extracts against the growth of Listeria monocytogenes and Salmonella Enteritidis

USDA-ARS?s Scientific Manuscript database

We studied the antimicrobial effects of berry extracts obtained from four cultivars (Elliott, Darrow, Bluecrop and Duke) of blueberry (Vaccinium corymbosum L.) on the growth of Listeria monocytogenes and Salmonella Enteritidis. The minimal inhibitory concentration (MIC) and minimal bactericidal conc...

Pharmacodynamic Evaluation and PK/PD-Based Dose Prediction of Tulathromycin: A Potential New Indication for Streptococcus suis Infection.

PubMed

Zhou, Yu-Feng; Peng, Hui-Min; Bu, Ming-Xiao; Liu, Ya-Hong; Sun, Jian; Liao, Xiao-Ping

2017-01-01

Tulathromycin is the first member of the triamilide antimicrobial drugs that has been registered in more than 30 countries. The goal of this study is to provide a potential new indication of tulathromycin for Streptococcus suis infections. We investigated the pharmacokinetic and ex vivo pharmacodynamics of tulathromycin against experimental S. suis infection in piglets. Tulathromycin demonstrated a relatively long elimination half-life (74.1 h) and a mean residence time of 97.6 h after a single intramuscular administration. The minimal inhibitory concentration (MIC) and bactericidal concentration in serum were markedly lower than those in broth culture, with Mueller-Hinton broth/serum ratios of 40.3 and 11.4, respectively. The post-antibiotic effects were at 1.27 h (1× MIC) and 2.03 h (4× MIC) and the post-antibiotic sub-MIC effect values ranged from 2.47 to 3.10 h. The ratio of the area under the concentration-time curve divided by the MIC (AUC/MIC) correlated well with the ex vivo antimicrobial effectiveness of tulathromycin ( R 2 = 0.9711). The calculated AUC 12h /MIC ratios in serum required to produce the net bacterial stasis, 1-log 10 and 2-log 10 killing activities were 9.62, 18.9, and 32.7, respectively. Based on the results of Monte Carlo simulation, a dosage regimen of 3.56 mg/kg tulathromycin was estimated to be effective, achieving for a bacteriostatic activity against S. suis infection over 5 days period. Tulathromycin may become a potential option for the treatment of S. suis infections.

Pharmacokinetic Monitoring Of Vancomycin In Cystic Fibrosis: Is It Time To Move Past Trough Concentrations?

PubMed

Fusco, Nicholas M; Prescott, William A; Meaney, Calvin J

2018-05-04

A correlation between vancomycin trough concentrations (VTC) and area under the curve (AUC) to minimum inhibitory concentration (MIC) ratio (AUC/MIC) has not been established in children/adolescents with cystic fibrosis (CF). The primary objective of this study was to determine the correlation between measured VTCs and AUC/MIC using population-based pharmacokinetics. A retrospective cohort study of children/adolescents diagnosed with CF, age 6 to < 18 years, treated with vancomycin (VAN) for methicillin-resistant Staphylococcus aureus (MRSA) infection was conducted. The relationship between final VTCs and calculated AUC/MIC, using models established by Le et al and Stockmann et al, was assessed using Pearson and Spearman correlations. All tests were two-tailed with alpha set at 0.05. Thirty children/adolescents, age 7 to 17 years (median age 15 [IQR 9-17] years), were included. The mean final VAN dose was 58.03±18.58 mg/kg/day and the median final VTC was 12.6 (11-13.6) mg/L. The mean AUC/MIC was 355.34±138.46 (Le model) versus 426.79±178.92 (Stockmann model) (p=0.089). No correlation existed between VTCs and AUC/MIC using either the model by Le (r=0.140, p=0.461) or Stockmann (r=0.115; p=0.564). Using the Stockmann model: VAN dose (mg/kg/dose) was found to have a strong positive correlation with AUC (r=0.8874, p<0.0001) and AUC/MIC (r=0.7877, p<0.0001). VTCs did not correlate with AUC or AUC/MIC. Further research is needed to determine which estimate of VAN treatment efficacy is most appropriate for children and adolescents with CF infected with MRSA.

Are Vancomycin Trough Concentrations of 15 to 20 mg/L Associated With Increased Attainment of an AUC/MIC ≥ 400 in Patients With Presumed MRSA Infection?

PubMed

Hale, Cory M; Seabury, Robert W; Steele, Jeffrey M; Darko, William; Miller, Christopher D

2017-06-01

To determine whether there is an association between higher vancomycin trough concentrations and attainment of a calculated area under the concentration-time curve (AUC)/minimum inhibitory concentration (MIC) ≥400. A retrospective analysis was conducted among vancomycin-treated adult patients with a positive methicillin-resistant Staphylococcus aureus (MRSA) culture. Attainment of a calculated AUC/MIC ≥400 was compared between patients with troughs in the reference range of 15 to 20 mg/L and those with troughs in the following ranges: <10, 10 to 14.9, and >20 mg/L. Nephrotoxicity was assessed as a secondary outcome based on corrected average vancomycin troughs over 10 days of treatment. Overall, 226 patients were reviewed and 100 included. Relative to troughs ≥10, patients with vancomycin troughs <10 mg/L were 73% less likely to attain an AUC/MIC ≥400 (odds ratio [OR] 0.27, 95% confidence interval [CI]: 0.01-0.75). No difference was found in the attainment of an AUC/MIC ≥400 in patients with troughs of 10 to 14.9 mg/L and >20 mg/L when compared to patients with troughs of 15 to 20 mg/L. The mean corrected average vancomycin trough was higher in patients developing nephrotoxicity compared to those who did not (19.5 vs 14.5 mg/L, P < .001). Achieving vancomycin serum trough concentrations of 15 to 20 mg/L did not result in an increased attainment of the AUC/MIC target relative to troughs of 10 to 14.9 mg/L but may increase nephrotoxicity risk.

Modified Augmented Renal Clearance Score Predicts Rapid Piperacillin and Tazobactam Clearance in Critically Ill Surgery and Trauma Patients

DTIC Science & Technology

2014-04-24

intermittent dosing regimens. CONCLUSION: Given its ability to predict antimicrobial clearance above populationmedians, which could compromise therapy, the...campaign dedicated to improve out- comes.1,2 In the era ofmultiply drug- resistant pathogens and rising antimicrobial minimum inhibitory concentrations (MICs...urinary creatinine clearance significantly exceeds what is predicted by the serum creatinine concentration according to various mathematical

In vitro activity of RP 59500, a semisynthetic injectable pristinamycin, against staphylococci, streptococci, and enterococci.

PubMed Central

Fass, R J

1991-01-01

The in vitro activity of RP 59500, a semisynthetic pristinamycin, was compared with the activities of vancomycin, oxacillin, ampicillin, gentamicin, ciprofloxacin, and rifampin against five Staphylococcus species, five Streptococcus species, and four Enterococcus species. For staphylococci, MICs were 0.13 to 1 microgram/ml and the MICs for 90% of the strains tested (MIC90s) were 0.13 to 0.5 microgram/ml; there were no differences between oxacillin-susceptible and -resistant strains. For streptococci, MICs were 0.03 to 4 micrograms/ml and MIC90s were 0.25 to 2 micrograms/ml; viridans group streptococci were the least susceptible streptococci. For enterococci, MICs were 0.25 to 32 micrograms/ml and MIC90s were 2 to 4 micrograms/ml; Enterococcus faecalis was the least susceptible. Vancomycin was the only comparative drug with consistent activity against all species of gram-positive cocci. With RP 59500, raising the inoculum 100-fold, lowering the pH of cation-adjusted Mueller-Hinton broth to 5.5, or omitting cation supplementation had little effect on MICs, but 50% serum increased MICs 2 to 4 dilution steps. The differences between MBCs and MICs were greater for staphylococci and enterococci than for streptococci. Time-kill studies with 24 strains indicated that RP 59500 concentrations 2-, 4-, and 16-fold greater than the MICs usually killed bacteria of each species at similar rates; reductions in CFU per milliliter were less than those observed with oxacillin or vancomycin against staphylococci and less than those observed with ampicillin against enterococci. RP 59500 antagonized the bactericidal activities of oxacillin and gentamicin against Staphylococcus aureus ATCC 29213 and that of ampicillin against E. faecalis ATCC 29212. Against the latter, combination with gentamicin was indifferent. RP 59500 has a broad spectrum of in vitro activity against gram-positive cocci; combining it with other drugs is not advantageous. PMID:1903912

Potency of marbofloxacin for pig pneumonia pathogens Actinobacillus pleuropneumoniae and Pasteurella multocida: Comparison of growth media.

PubMed

Dorey, L; Hobson, S; Lees, P

2017-04-01

Pharmacodynamic properties of marbofloxacin were established for six isolates each of the pig respiratory tract pathogens, Actinobacillus pleuropneumoniae and Pasteurella multocida. Three in vitro indices of potency were determined; Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and Mutant Prevention Concentration (MPC). For MIC determination Clinical Laboratory Standards Institute guidelines were modified in three respects: (1) comparison was made between two growth media, an artificial broth and pig serum; (2) a high inoculum count was used to simulate heavy clinical bacteriological loads; and (3) five overlapping sets of two-fold dilutions were used to improve accuracy of determinations. Similar methods were used for MBC and MPC estimations. MIC and MPC serum:broth ratios for A. pleuropneumoniae were 0.79:1 and 0.99:1, respectively, and corresponding values for P. multocida were 1.12:1 and 1.32:1. Serum protein binding of marbofloxacin was 49%, so that fraction unbound (fu) serum MIC values were significantly lower than those predicted by correction for protein binding; fu serum:broth MIC ratios were 0.40:1 (A. pleuropneumoniae) and 0.50:1 (P. multocida). For broth, MPC:MIC ratios were 13.7:1 (A. pleuropneumoniae) and 14.2:1 (P. multocida). Corresponding ratios for serum were similar, 17.2:1 and 18.8:1, respectively. It is suggested that, for dose prediction purposes, serum data might be preferable to potency indices measured in broths. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bis-indolic compounds as potential new therapeutic alternatives for tularaemia

PubMed Central

Caspar, Yvan; Sutera, Vivien; Boisset, Sandrine; Denis, Jean-Noël; Maurin, Max

2014-01-01

Francisella tularensis is the etiological agent of tularaemia and a CDC class A biological threat agent. Few antibiotic classes are currently useful in treating tularaemia, including the aminoglycosides gentamicin and streptomycin, fluoroquinolones, and tetracyclines. However, treatment failures and relapses remain frequent and F. tularensis strains resistant to antibiotics have been easily selected in vitro. In this study, we evaluated the activity of new synthetic bis-indole derivatives against this pathogen. Minimum inhibitory concentrations (MICs) of four compounds (dcm01 to dcm04) were determined for the reference strains F. tularensis subsp. holarctica LVS NCTC10857, F. tularensis subsp. novicida CIP56.12 and F. philomiragia ATCC25015, and for 41 clinical strains of F. tularensis subsp. holarctica isolated in France. Minimal bactericidal concentrations (MBCs) were determined for the dcm02 and dcm04 compounds for the LVS and two clinical strains. Killing curves were also determined for the same three strains exposed to dcm04. All tested bis-indole compounds were bacteriostatic against F. tularensis subsp. holarctica strains, with a MIC90 of 8 μg/mL for dcm01, dcm02, and dcm03, and 2 μg/mL for dcm04. Only one strain was resistant to both dcm01 and dcm03, with MICs > 32 μg/mL. In contrast, F. tularensis subsp. novicida was resistant to all derivatives and F. philomiragia was only susceptible to dcm02 and dcm04, with MICs of 16 and 4 μg/mL, respectively. MBC and killing curve experiments revealed significant bactericidal activity (i.e., 3-log reduction of the bacterial inoculum) of the dcm02 and dcm04 compounds only for the LVS strain. In conclusion, we have identified novel synthetic bis-indole compounds that are active against F. tularensis subsp. holarctica. They may be drug candidates for the development of new therapeutic alternatives for tularaemia treatment. Their further characterization is needed, especially identification of their bacterial targets. PMID:24579066

Bis-indolic compounds as potential new therapeutic alternatives for tularaemia.

PubMed

Caspar, Yvan; Sutera, Vivien; Boisset, Sandrine; Denis, Jean-Noël; Maurin, Max

2014-01-01

Francisella tularensis is the etiological agent of tularaemia and a CDC class A biological threat agent. Few antibiotic classes are currently useful in treating tularaemia, including the aminoglycosides gentamicin and streptomycin, fluoroquinolones, and tetracyclines. However, treatment failures and relapses remain frequent and F. tularensis strains resistant to antibiotics have been easily selected in vitro. In this study, we evaluated the activity of new synthetic bis-indole derivatives against this pathogen. Minimum inhibitory concentrations (MICs) of four compounds (dcm01 to dcm04) were determined for the reference strains F. tularensis subsp. holarctica LVS NCTC10857, F. tularensis subsp. novicida CIP56.12 and F. philomiragia ATCC25015, and for 41 clinical strains of F. tularensis subsp. holarctica isolated in France. Minimal bactericidal concentrations (MBCs) were determined for the dcm02 and dcm04 compounds for the LVS and two clinical strains. Killing curves were also determined for the same three strains exposed to dcm04. All tested bis-indole compounds were bacteriostatic against F. tularensis subsp. holarctica strains, with a MIC90 of 8 μg/mL for dcm01, dcm02, and dcm03, and 2 μg/mL for dcm04. Only one strain was resistant to both dcm01 and dcm03, with MICs > 32 μg/mL. In contrast, F. tularensis subsp. novicida was resistant to all derivatives and F. philomiragia was only susceptible to dcm02 and dcm04, with MICs of 16 and 4 μg/mL, respectively. MBC and killing curve experiments revealed significant bactericidal activity (i.e., 3-log reduction of the bacterial inoculum) of the dcm02 and dcm04 compounds only for the LVS strain. In conclusion, we have identified novel synthetic bis-indole compounds that are active against F. tularensis subsp. holarctica. They may be drug candidates for the development of new therapeutic alternatives for tularaemia treatment. Their further characterization is needed, especially identification of their bacterial targets.

In vitro activity of Schinus terebinthifolius (Brazilian pepper tree) on Candida tropicalis growth and cell wall formation.

PubMed

Alves, Lívia A; Freires, Irlan de A; de Souza, Tricia M P A; de Castro, Ricardo D

2012-01-01

The aim of this study was to evaluate the in vitro antifungal activity of Schinus terebinthifolius (Brazilian pepper tree) tincture on planktonic Candida tropicalis (ATCC 40042), which is a microorganism associated to oral cavity infections. Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) were determined through the microdilution technique. Possible action of the tincture on fungal cell wall formation was also studied by adding an osmotic protector (0.8M sorbitol) to the microplates. Nystatin was used as standard control and tests were performed in triplicate. S. terebinthifolius was found to have MIC and MFC values of 625 microg/mL on the strain assayed, whereas nystatin showed MIC and MFC of 6.25 microg/mL. Results suggest that S. terebinthifolius tincture acts on fungal cell walls, since the sorbitol test indicated a MIC of 1.250 microg/mL. It may be concluded that S. terebinthifolius has potential in vitro antifungal activity against C. tropicalis strains, and probably acts by inhibiting fungal cell wall formation.

Effect of 2-Phenylethanol as Antifungal Agent and Common Antifungals (Amphotericin B, Fluconazole, and Itraconazole) on Candida Species Isolated from Chronic and Recurrent Cases of Candidal Vulvovaginitis.

PubMed

Majdabadi, Niloufar; Falahati, Mehraban; Heidarie-Kohan, Fariba; Farahyar, Shirin; Rahimi-Moghaddam, Parvaneh; Ashrafi-Khozani, Mahtab; Razavi, Tandis; Mohammadnejad, Sina

2018-04-01

The antifungal effects of 2-phenylethanol are clearly visible through its intervention in Candida morphogenesis. Chronic and recurrent vulvovaginitis, however, does not respond to this standard experimental therapy; therefore, the study presented in this article investigated the effect of common antifungal drugs (amphotericin B [AMB], fluconazole [FLU], and itraconazole [ITC]), in combination with 2-phenylethanol, on the Candida species isolated from cases of chronic and recurrent vulvovaginitis, thereby allowing the recommendation of a more appropriate treatment option. Forty isolates from patients with chronic and recurrent vaginal candidiasis were investigated in this experimental study. The specimens were examined by direct microscopy, culturing, and PCR to identify the species. The antifungal effects of 2-phenylethanol and conventional drugs, both alone and in combination, were determined in duplicate. Finally, the findings were analyzed. In this study, 40 strains of Candida species were identified, whose agents were Candida albicans (95%) and Candida africana (5%). After 48 h, the minimum inhibitory concentration (MIC) range of the 2-phenylethanol was 800-3,200 μg/mL. Also, in the final study on the MIC levels of common antifungal drugs, AMB (0.42 μg/mL) had the lowest MIC, FLU (40.51 μg/mL) had the highest MIC, and the combination of ITC and 2-phenylethanol had the lowest fractional inhibitory concentration index (FICI) of any of the combinations (FICI range, 0.26-1.03). Combining FLU and ITC with 2-phenylethanol can effectively increase their antifungal effect.

PgTeL, the lectin found in Punica granatum juice, is an antifungal agent against Candida albicans and Candida krusei.

PubMed

da Silva, Pollyanna Michelle; de Moura, Maiara Celine; Gomes, Francis Soares; da Silva Trentin, Danielle; Silva de Oliveira, Ana Patrícia; de Mello, Gabriela Souto Vieira; da Rocha Pitta, Maira Galdino; de Melo Rego, Moacyr Jesus Barreto; Coelho, Luana Cassandra Breitenbach Barroso; Macedo, Alexandre José; de Figueiredo, Regina Celia Bressan Queiroz; Paiva, Patrícia Maria Guedes; Napoleão, Thiago Henrique

2018-03-01

The pomegranate (Punica granatum) sarcotesta contains a chitin-binding lectin (PgTeL) with antibacterial activity against human pathogenic species. In this work, the structural stability of PgTeL was evaluated by fluorimetric analysis and the lectin was evaluated for cytotoxicity to human peripheral blood mononuclear cells (PBMCs) and antifungal activity against Candida albicans and Candida krusei. PgTeL folding was impaired when lectin was incubated at pH≥6.0. On the other hand, the lectin did not undergo unfolding even when heated at 100°C. PgTeL (1, 10, and 100μg/mL) was not cytotoxic to PBMCs. Antifungal activity was detected for C. albicans (MIC: 25μg/mL; MFC: 50μg/mL) and C. krusei (MIC and MFC of 12.5μg/mL). Treatment of yeast cells with PgTeL resulted in decrease of intracellular ATP content even at sub-inhibitory concentrations (½MIC and ¼MIC) and induced lipid peroxidation. In addition, PgTeL damaged the integrity of fungal cell wall of both species, with more pronounced effects in C. krusei. The lectin showed significant antibiofilm activity on C. albicans at sub-inhibitory concentrations (0.195 and 0.39μg/mL). In conclusion, PgTeL is an anti-Candida agent whose action mechanism involves oxidative stress, energetic collapse, damage to the cell wall and rupture of yeast cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Synergistic effect of artocarpin on antibacterial activity of some antibiotics against methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli.

PubMed

Septama, Abdi Wira; Panichayupakaranant, Pharkphoom

2016-01-01

Antibacterial resistance has dramatically increased and resulted in serious health problems worldwide. One appealing strategy to overcome this resistance problem is the use of combinations of antibacterial compounds to increase their potency. The objective of this study is to determine the synergistic effects of artocarpin for ampicillin, norfloxacin, and tetracycline against methicillin-resistant Staphylococcus aureus (MRSA) as well as the Gram-negative bacteria Pseudomonas aeruginosa and Escherichia coli. A broth microdilution method (1.95-250 µg/mL) was used to determine the minimum inhibitory concentration (MIC) of artocarpin and the antibiotics. Any synergistic effects were evaluated at their own MIC using the checkerboard method and a time-kill assay at 37 °C for 24 h. Artocarpin showed antibacterial activity against MRSA and E. coli with an MIC value of 62.5 µg/mL, and against P. aeruginosa with an MIC value of 250 µg/mL. The interaction of artocarpin with all tested antibiotics produced synergistic effects against MRSA with a fractional inhibitory concentration index (FICI) of 0.15-0.37. In addition, a combination of artocarpin and norfloxacin showed a synergistic effect against E. coli with an FICI value of 0.37, while the combinations of artocarpin and tetracycline as well as artocarpin and norfloxacin exhibited synergy interactions against P. aeruginosa with FICI values of 0.24 and 0.37, respectively. Time-kill assays indicated that artocarpin enhanced the antimicrobial activities of tetracycline, ampicillin, and norfloxacin against MRSA as well as Gram-negative bacteria.

In vitro activity of rifampicin alone and in combination with imipenem against multidrug-resistant Acinetobacter baumannii harboring the blaOXA-72 resistance gene.

PubMed

Majewski, Piotr; Wieczorek, Piotr; Ojdana, Dominika; Sacha, Paweł Tomasz; Wieczorek, Anna; Tryniszewska, Elżbieta Anna

2014-04-01

The growing incidence of multidrug resistance (MDR) in bacteria is an emerging challenge in the treatment of infections. Acinetobacter baumannii is an opportunistic pathogen prone to exhibit MDR that contributes significantly to nosocomial infections, particularly in severely ill patients. Thus, we performed research on rifampicin activity against selected MDR OXA-72 carbapenemase-producing A. baumannii strains. Since it is widely accepted that rifampicin should not be used as monotherapy in order to avoid the rapid development of rifampicin resistance, we evaluated the efficacy of combination therapy with imipenem. Minimal inhibitory concentrations (MICs) of both rifampicin and imipenem were determined by use of the broth microdilution method. Evaluations of the interactions between rifampicin and imipenem were performed by analysis of the fractional inhibitory concentration index (∑FIC), determined using the checkerboard titration method. All tested isolates showed full susceptibility to rifampicin. The checkerboard method revealed synergism in 5 isolates (29%) and an additive effect in another 5 isolates (29%); no difference was reported in the remaining 7 isolates (41%). Strains moderately resistant to imipenem (MIC ≤ 64 mg/l) tended to show synergy or additive interaction. We conclude that in vitro synergism or an additive interaction between rifampicin and imipenem most likely occurs in A. baumannii strains showing moderate resistance to imipenem (MIC ≤ 64 mg/l). Moreover, utilizing this combination in the therapy of infections caused by strains exhibiting higher levels of resistance (MIC > 64 mg/l) is not recommended since in this setting imipenem could not prevent the development of rifampicin resistance.

Chemical Characterization and Cytoprotective Effect of the Hydroethanol Extract from Annona coriacea Mart. (Araticum)

PubMed Central

Júnior, José G. A. S.; Coutinho, Henrique D. M.; Boris, Ticiana C. C.; Cristo, Janyketchuly S.; Pereira, Nara L. F.; Figueiredo, Fernando G.; Cunha, Francisco A. B.; Aquino, Pedro E. A.; Nascimento, Polyana A. C.; Mesquita, Francisco J. C.; Moreira, Paulo H. F.; Coutinho, Sáskia T. B.; Souza, Ivon T.; Teixeira, Gabriela C.; Ferreira, Najla M. N.; Farina, Eleonora O.; Torres, Cícero M. G.; Holanda, Vanderlan N.; Pereira, Vandbergue S.; Guedes, Maria I. F.

2016-01-01

Introduction: Annona coriacea Mart. (araticum) is a widely distributed tree in the cerrado. Its value is attributed principally to the consumption of its fruit which possesses a large nutritive potential. The objective was to identify the chemical profile and evaluate the antimicrobial and cytoprotective activity of the hydroethanol extract of A. coriacea Mart. (HEAC) leaves against the toxicity of mercury chloride. Materials and Methods: The characterization of components was carried out using high-performance liquid chromatography (HPLC). The minimum inhibitory concentration (MIC) was determined by microdilution method in broth with strains of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. For evaluation of the modulatory and cytoprotective activity of aminoglycoside antibiotics (gentamicin and amikacin) and mercury chloride (HgCl2), the substances were associated with the HEAC at subinhibitory concentrations (MIC/8). Results and Discussion: The HPLC analysis revealed the presence of flavonoids such as Luteolin (1.84%) and Quercetin (1.19%) in elevated concentrations. The HEAC presented an MIC ≥512 μg/mL and significant antagonistic action in aminoglycosides modulation, and it also showed cytoprotective activity to S. aureus (significance P < 0.0001) and E. coli (significance P < 0.05) bacteria against the mercury chloride heavy metal with significance, this action being attributed to the chelating properties of the flavonoids found in the chemical identification. Conclusions: The results acquired in this study show that the HEAC presents cytoprotective activity over the tested strains in vitro and can also present antagonistic effect when associated with aminoglycosides, reinforcing the necessity of taking caution when combining natural and pharmaceutical products. SUMMARY The hydroalcoholic extract of A. coriacea Mart. presents in vitro cytoprotective activity against the toxic effect of Hg. Abbreviations Used: HPLC-DAD: High-performance liquid chromatography with a diode array detector; MIC: Minimum inhibitory concentration; DMSO: Dimethyl sulfoxide PMID:27695264

Improvement of citral antimicrobial activity by incorporation into nanostructured lipid carriers: a potential application in food stuffs as a natural preservative.

PubMed

Mokarizadeh, Manijeh; Kafil, Hossein Samadi; Ghanbarzadeh, Saeed; Alizadeh, Ainaz; Hamishehkar, Hamed

2017-10-01

At the present time, utilization of essential oils in food preservation to prevent bacterial and fungal growth and improve shelf life and safety of the food products has notably gained increased interest. The aim of the present study was to improve the antimicrobial efficacy of citral as a natural preservative using nanostructured lipid carriers (NLCs). Formulations of NLCs were characterized using particle size analysis and scanning electron microscopy methods. Possible citral-carrier interaction and citral encapsulation efficiency percent (EE%) were assessed by Fourier transform infrared (FTIR) spectroscopy and gas chromatography techniques, respectively. Antimicrobial activity, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of citral-loaded NLCs were evaluated and compared with the conventional citral emulsion against various gram-positive bacteria ( Staphylococcus aureus , Bacillus cereus ), gram-negative bacteria ( Escherichia coli ), and fungi ( Candida albicans ). Citral-loaded NLCs were spherically shaped nanosized (74.8 nm) particles with narrow size distribution, high EE% (99.84%), and appropriate physical stability during 90 days of storage period. FTIR spectra indicated the interaction between citral and formulation ingredients, which justified the obtained high EE% value. The MIC and MBC values of citral-loaded NLCs were lower than those of citral emulsion for all microorganisms. NLCs formulation showed remarkable capability of encapsulating essential oil and increasing antimicrobial properties to offer effective preservation in food industry.

In vitro anti-mycobacterial activity of nine medicinal plants used by ethnic groups in Sonora, Mexico

PubMed Central

2013-01-01

Background Sonoran ethnic groups (Yaquis, Mayos, Seris, Guarijíos, Pimas, Kikapúes and Pápagos) use mainly herbal based preparations as their first line of medicinal treatment. Among the plants used are those with anti-tuberculosis properties; however, no formal research is available. Methods Organic extracts were obtained from nine medicinal plants traditionally used by Sonoran ethnic groups to treat different kinds of diseases; three of them are mainly used to treat tuberculosis. All of the extracts were tested against Mycobacterium tuberculosis H37Rv using the Alamar Blue redox bioassay. Results Methanolic extracts from Ambrosia confertiflora, Ambrosia ambrosioides and Guaiacum coulteri showed minimal inhibitory concentration (MIC) values of 200, 790 and 1000 μg/mL, respectively, whereas no effect was observed with the rest of the methanolic extracts at the concentrations tested. Chloroform, dichloromethane, and ethyl acetate extracts from Ambrosia confertiflora showed a MIC of 90, 120 and 160 μg/mL, respectively. Conclusions A. confertiflora and A. ambrosioides showed the best anti-mycobacterial activity in vitro. The activity of Guaiacum coulteri is consistent with the traditional use by Sonoran ethnic groups as anti-tuberculosis agent. For these reasons, it is important to investigate a broader spectrum of medicinal plants in order to find compounds active against Mycobacterium tuberculosis. PMID:24267469

Cytotoxicity of Ultrasmall Gold Nanoparticles on Planktonic and Biofilm Encapsulated Gram-Positive Staphylococci.

PubMed

Boda, Sunil Kumar; Broda, Janine; Schiefer, Frank; Weber-Heynemann, Josefine; Hoss, Mareike; Simon, Ulrich; Basu, Bikramjit; Jahnen-Dechent, Willi

2015-07-01

The emergence of multidrug resistant bacteria, especially biofilm-associated Staphylococci, urgently requires novel antimicrobial agents. The antibacterial activity of ultrasmall gold nanoparticles (AuNPs) is tested against two gram positive: S. aureus and S. epidermidis and two gram negative: Escherichia coli and Pseudomonas aeruginosa strains. Ultrasmall AuNPs with core diameters of 0.8 and 1.4 nm and a triphenylphosphine-monosulfonate shell (Au0.8MS and Au1.4MS) both have minimum inhibitory concentration (MIC) and minimum bactericidal concentration of 25 × 10(-6) m [Au]. Disc agar diffusion test demonstrates greater bactericidal activity of the Au0.8MS nanoparticles over Au1.4MS. In contrast, thiol-stabilized AuNPs with a diameter of 1.9 nm (AuroVist) cause no significant toxicity in any of the bacterial strains. Ultrasmall AuNPs cause a near 5 log bacterial growth reduction in the first 5 h of exposure, and incomplete recovery after 21 h. Bacteria show marked membrane blebbing and lysis in biofilm-associated bacteria treated with ultrasmall AuNP. Importantly, a twofold MIC dosage of Au0.8MS and Au1.4MS each cause around 80%-90% reduction in the viability of Staphylococci enveloped in biofilms. Altogether, this study demonstrates potential therapeutic activity of ultrasmall AuNPs as an effective treatment option against staphylococcal infections. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Study of marine actinomycetes isolated from the central coast of Peru and their antibacterial activity against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecalis].

PubMed

León, Jorge; Aponte, Juan José; Rojas, Rosario; Cuadra, D'Lourdes; Ayala, Nathaly; Tomás, Gloria; Guerrero, Marco

2011-06-01

To determine the antimicrobial potential of marine actinomycetes against drug-resistant pathogens represented by strains of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VRE). Strains of actinomycetes (29) isolated from marine sediment were evaluated by their characteristics in two culture media and by testing their inhibitory capacity by in vitro antagonism against multi-drug resistant (MDR) pathogenic bacteria for MRSA and VRE. Organic extracts of 3 selected actinomicetes were processed to determine the minimum inhibitory concentration (MIC) of the active compound. Most isolated actinomycetes belong to a homogeneous group of write-gray actinomycetes with a good growth in Marine Agar. The inhibitory rates of the isolates were above 85% for both pathogens with inhibition zones greater than 69 and 78 mm in diameter for MRSA and VRE respectively. Dichloromethane extracts of 3 isolates (I-400A, B1-T61, M10-77) showed strong inhibitory activity of both pathogens, M10-77 being the highest actinomycete strain with antibiotic activity against methicillin-resistant S. aureus ATCC 43300 and vancomycin-resistant E. faecalis ATCC 51299 with a minimum inhibitory concentrations (MIC) of 7.9 and 31.7 μg/ml respectively. Phylogenetic analysis of M10-77 strain showed 99% similarity with the marine species Streptomyces erythrogriseus. Marine sediments of the central coast of Peru, are a source of actinomycetes strains showing high capacity to produce bioactive compounds able to inhibit pathogens classified as multi-drug-resistant such as methicillin-resistant S. aureus and vancomycin-resistant E. faecalis.

In Vitro Pharmacodynamic Activities of ABT-492, a Novel Quinolone, Compared to Those of Levofloxacin against Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis

PubMed Central

Gunderson, Shana M.; Hayes, Robert A.; Quinn, John P.; Danziger, Larry H.

2004-01-01

ABT-492 is a novel quinolone with potent activity against gram-positive, gram-negative, and atypical pathogens, making this compound an ideal candidate for the treatment of community-acquired pneumonia. We therefore compared the in vitro pharmacodynamic activity of ABT-492 to that of levofloxacin, an antibiotic commonly used for the treatment of pneumonia, through MIC determination and time-kill kinetic analysis. ABT-492 demonstrated potent activity against penicillin-sensitive, penicillin-resistant, and levofloxacin-resistant Streptococcus pneumoniae strains (MICs ranging from 0.0078 to 0.125 μg/ml); β-lactamase-positive and β-lactamase-negative Haemophilus influenzae strains (MICs ranging from 0.000313 to 0.00125 μg/ml); and β-lactamase-positive and β-lactamase-negative Moraxella catarrhalis strains (MICs ranging from 0.001 to 0.0025 μg/ml), with MICs being much lower than those of levofloxacin. Both ABT-492 and levofloxacin demonstrated concentration-dependent bactericidal activities in time-kill kinetics studies at four and eight times the MIC with 10 of 12 bacterial isolates exposed to ABT-492 and with 12 of 12 bacterial isolates exposed to levofloxacin. Sigmoidal maximal-effect models support concentration-dependent bactericidal activity. The model predicts that 50% of maximal activity can be achieved with concentrations ranging from one to two times the MIC for both ABT-492 and levofloxacin and that near-maximal activity (90% effective concentration) can be achieved at concentrations ranging from two to five times the MIC for ABT-492 and one to six times the MIC for levofloxacin. PMID:14693540

In vitro pharmacodynamic activities of ABT-492, a novel quinolone, compared to those of levofloxacin against Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.

PubMed

Gunderson, Shana M; Hayes, Robert A; Quinn, John P; Danziger, Larry H

2004-01-01

ABT-492 is a novel quinolone with potent activity against gram-positive, gram-negative, and atypical pathogens, making this compound an ideal candidate for the treatment of community-acquired pneumonia. We therefore compared the in vitro pharmacodynamic activity of ABT-492 to that of levofloxacin, an antibiotic commonly used for the treatment of pneumonia, through MIC determination and time-kill kinetic analysis. ABT-492 demonstrated potent activity against penicillin-sensitive, penicillin-resistant, and levofloxacin-resistant Streptococcus pneumoniae strains (MICs ranging from 0.0078 to 0.125 micro g/ml); beta-lactamase-positive and beta-lactamase-negative Haemophilus influenzae strains (MICs ranging from 0.000313 to 0.00125 micro g/ml); and beta-lactamase-positive and beta-lactamase-negative Moraxella catarrhalis strains (MICs ranging from 0.001 to 0.0025 micro g/ml), with MICs being much lower than those of levofloxacin. Both ABT-492 and levofloxacin demonstrated concentration-dependent bactericidal activities in time-kill kinetics studies at four and eight times the MIC with 10 of 12 bacterial isolates exposed to ABT-492 and with 12 of 12 bacterial isolates exposed to levofloxacin. Sigmoidal maximal-effect models support concentration-dependent bactericidal activity. The model predicts that 50% of maximal activity can be achieved with concentrations ranging from one to two times the MIC for both ABT-492 and levofloxacin and that near-maximal activity (90% effective concentration) can be achieved at concentrations ranging from two to five times the MIC for ABT-492 and one to six times the MIC for levofloxacin.

Activity of semisynthetic penicillins and synergism with mecillinam against Bacteroides species.

PubMed Central

Trestman, I; Kaye, D; Levison, M E

1979-01-01

The minimal inhibitory concentrations (MIC) of six penicillins (ampicillin, carbenicillin, ticarcillin, piperacillin, mezlocillin, and Bay k 4999) against 29 clinical isolates of Bacteriodes spp. (including Bacteroides fragilis, Bacteroides thetaiotaomicron, and Bacteroides vulgatus) were determined by an agar dilution method. Bay k 4999 was most active, followed in descending order by ampicillin, piperacillin, mezlocillin, ticarcillin, and carbenicillin. Mecillinam, a 6 beta-amidino-penicillanic acid, inhibited no strains at 50 micrograms/ml, but when compared with ampicillin, a fourfold or greater increase in MIC for ampicillin (antagonism) was noted in 3 of 29 strains, with no effect on MIC for 26 strains, whereas when combined with carbenicillin, a fourfold or greater decrease in MIC for both antibiotics (synergism) was noted in 12 strains, 4 of which had an MIC of greater than or equal to 250 micrograms/ml for carbenicillin alone. These studies demonstrate the increased activity of some newer semisynthetic penicillins and the potential synergy obtained with mecillinam and carbenicillin against Bacteroides sp. PMID:228593

Antibacterial activity of fresh pomegranate juice against clinical strains of Staphylococcus epidermidis

PubMed Central

Betanzos-Cabrera, Gabriel; Montes-Rubio, Perla Y.; Fabela-Illescas, Héctor E.; Belefant-Miller, Helen; Cancino-Diaz, Juan C.

2015-01-01

Background Polyphenols have received a great deal of attention due to their biological functions. Pomegranate (Punica granatum L.) is a polyphenol-rich fruit. In the past decade, studies testing the antimicrobial activity of pomegranates almost exclusively used solvent extracts instead of fresh pomegranate juice (FPJ). The use of FPJ instead of solvent extracts would reduce toxicity issues while increasing patient acceptance. We established a model to test FPJ as a natural antimicrobial agent. Objective To evaluate the antimicrobial activity of FPJ on clinical isolates of multidrug-resistant Staphylococcus epidermidis strains. Design Sixty strains of S. epidermidis isolated from ocular infections were grown in the presence of FPJ, and minimum inhibitory concentration (MIC) was determined by broth and agar dilution methods. Results FPJ at 20% had a MIC equal to 100% (MIC100%) on all 60 strains tested. This inhibition of FPJ was confirmed by the growth kinetics of a multidrug-resistant strain exposed to different concentrations of FPJ. Additionally, the antimicrobial activity of FPJ was compared against commercial beverages containing pomegranate: Ocean Spray® had a MIC100% at 20%, followed by Del Valle® with a MIC15% at 20% concentration only. The beverages Jumex® and Sonrisa® did not have any antimicrobial activity. FPJ had the highest polyphenol content and antioxidant capacity. Conclusions Overall, FPJ had antimicrobial activity, which might be attributed to its high polyphenol content and antioxidant capacity. PMID:25999265

Fungicidal PMMA-Undecylenic Acid Composites

PubMed Central

Petrović, Milica; Hofmann, Heinrich

2018-01-01

Undecylenic acid (UA), known as antifungal agent, still cannot be used to efficiently modify commercial dental materials in such a way that this affects Candida. Actually, issues with Candida infections and fungal resistance compromise the use of Poly(methyl-methacrylate) (PMMA) as dental material. The challenge remains to turn PMMA into an antifugal material, which can ideally affect both sessile (attached) and planktonic (free-floating) Candida cells. We aimed to tackle this challenge by designing PMMA-UA composites with different UA concentrations (3–12%). We studied their physico-chemical properties, the antifungal effect on Candida and the cytotoxicity toward human cells. We found that UA changes the PMMA surface into a more hydrophilic one. Mainly, as-preparation composites with ≥6% UA reduced sessile Candida for >90%. After six days, the composites were still efficiently reducing the sessile Candida cells (for ~70% for composites with ≥6% UA). Similar results were recorded for planktonic Candida. Moreover, the inhibition zone increased along with the UA concentration. The antifungal effect of UA was also examined at the surface of an UA-loaded agar and the minimal inhibitory concentration (MIC90) was below the lowest-studied 0.0125% UA. Furthermore, the embedded filamentation test after 24 h and 48 h showed complete inhibition of the Candida growth at 0.4% UA. PMID:29316713

In Vitro Activity and Fecal Concentration of Rifaximin after Oral Administration

PubMed Central

Jiang, Zhi-Dong; Ke, Shi; Palazzini, Ernesto; Riopel, Lise; Dupont, Herbert

2000-01-01

Rifaximin showed moderately high MICs (the MIC at which 90% of the isolates tested were inhibited = 50 μg/ml) for 145 bacterial enteropathogens from patients with traveler's diarrhea acquired in Mexico during the summers of 1997 and 1998. Rifaximin concentrations in stool the day after oral administration (800 mg daily for 3 days) were high (average, 7,961 μg/g), proving the value of the drug. PMID:10898704

Antibacterial activity and proposed action mechanism of a new class of synthetic tricyclic flavonoids.

PubMed

Babii, C; Bahrin, L G; Neagu, A-N; Gostin, I; Mihasan, M; Birsa, L M; Stefan, M

2016-03-01

This study reports on the inhibitory and bactericidal properties of a new synthetized flavonoid. Tricyclic flavonoid 1 has been synthesized through a two-step reaction sequence. The antimicrobial effects were tested using the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. Also DNA fragmentation assay, fluorescence microscopy and SEM were used to study the mechanism of action. Our tested flavonoid displayed a strong antimicrobial activity with MIC and MBC values as low as 0·24 μg ml(-1) against Staphylococcus aureus and 3·9 μg ml(-1) against Escherichia coli. Flavonoid 1 displayed antimicrobial properties, causing not only the inhibition of bacterial growth, but also killing bacterial cells. The mechanism of action is related to the impairment of the cell membrane integrity and to cell agglutination. Tricyclic flavonoid 1 was found to have a stronger antibacterial effect at lower concentrations than those described in the earlier reports. Based on the strong antimicrobial activity observed, this new tricyclic flavonoid has a good potential for the design of new antimicrobial agents. © 2016 The Society for Applied Microbiology.

Inhibition of the NorA multi-drug transporter by oxygenated monoterpenes.

PubMed

Coêlho, Mayara Ladeira; Ferreira, Josie Haydée Lima; de Siqueira Júnior, José Pinto; Kaatz, Glenn W; Barreto, Humberto Medeiros; de Carvalho Melo Cavalcante, Ana Amélia

2016-10-01

The aim of this study was to investigate intrinsic antimicrobial activity of three monoterpenes nerol, dimethyl octanol and estragole, against bacteria and yeast strains, as well as, investigate if these compounds are able to inhibit the NorA efflux pump related to fluoroquinolone resistance in Staphylococcus aureus. Minimal inhibitory concentrations (MICs) of the monoterpenes against Staphylococcus aureus, Escherichia coli and Candida albicans strains were determined by micro-dilution assay. MICs of the norfloxacin against a S. aureus strain overexpressing the NorA protein were determined in the absence or in the presence of the monoterpenes at subinhibitory concentrations, aiming to verify the ability of this compounds act as efflux pump inhibitors. The monoterpenes were inactive against S. aureus however the nerol was active against E. coli and C. albicans. The addition of the compounds to growth media at sub-inhibitory concentrations enhanced the activity of norfloxacin against S. aureus SA1199-B. This result shows that bioactives tested, especially the nerol, are able to inhibit NorA efflux pump indicating a potential use as adjuvants of norfloxacin for therapy of infections caused by multi-drug resistant S. aureus strains. Copyright © 2016 Elsevier Ltd. All rights reserved.

Antimicrobial activity of clove and rosemary essential oils alone and in combination.

PubMed

Fu, Yujie; Zu, Yuangang; Chen, Liyan; Shi, Xiaoguang; Wang, Zhe; Sun, Su; Efferth, Thomas

2007-10-01

In the present study, the antimicrobial activity of the essential oils from clove (Syzygium aromaticum (L.) Merr. et Perry) and rosemary (Rosmarinus officinalis L.) was tested alone and in combination. The compositions of the oils were analysed by GC/MS. Minimum inhibitory concentrations (MIC) against three Gram-positive bacteria, three Gram-negative bacteria and two fungi were determined for the essential oils and their mixtures. Furthermore, time-kill dynamic processes of clove and rosemary essential oils against Staphylococcus epidermidis, Escherichia coli and Candida albicans were tested. Both essential oils possessed significant antimicrobial effects against all microorganisms tested. The MICs of clove oil ranged from 0.062% to 0.500% (v/v), while the MICs of rosemary oil ranged from 0.125% to 1.000% (v/v). The antimicrobial activity of combinations of the two essential oils indicated their additive, synergistic or antagonistic effects against individual microorganism tests. The time-kill curves of clove and rosemary essential oils towards three strains showed clearly bactericidal and fungicidal processes of (1)/(2) x MIC, MIC, MBC and 2 x MIC.

Screening of in vitro antimicrobial activity of plants used in traditional Indonesian medicine.

PubMed

Romulo, Andreas; Zuhud, Ervizal A M; Rondevaldova, Johana; Kokoska, Ladislav

2018-12-01

In many regions of Indonesia, there are numerous traditional herbal preparations for treatment of infectious diseases. However, their antimicrobial potential has been poorly studied by modern laboratory methods. This study investigates in vitro antimicrobial activity of 49 ethanol extracts from 37 plant species used in Indonesian traditional medicine for treatment against Candida albicans, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The plants were collected from the Biopharmaca collection garden, Bogor, Indonesia. The plant material was dried, finely grounded, extracted using ethanol, concentrated, and the dried residue was dissolved in 100% DMSO. Antimicrobial activity was determined in terms of a minimum inhibitory concentration (MIC) using a broth microdilution method in 96-well microplates. The extract of Orthosiphon aristatus (Blume) Miq. (Lamiaceae) leaf produced the strongest antimicrobial effect, inhibiting the growth of C. albicans (MIC 128 μg/mL), S. aureus (MIC 256 μg/mL), E. faecalis (MIC 256 μg/mL) and P. aeruginosa (MIC 256 μg/mL). The leaf extract of Woodfordia floribunda Salisb. (Lythraceae) also exhibited significant effect against C. albicans (MIC 128 μg/mL), S. aureus (MIC 256 μg/mL) and E. faecalis (MIC 256 μg/mL). Rotheca serrata (L.) Steane & Mabb. (Lamiaceae) leaf extract inhibited the growth of S. aureus (MIC 256 µg/mL) and C. albicans (MIC 256 µg/mL). The leaf extract of O. aristatus and W. floribunda exhibited a significant anti-candidal effect. Therefore, both of these plants can serve as prospective source materials for the development of new anti-candidal agents.

Acorenone B: AChE and BChE Inhibitor as a Major Compound of the Essential Oil Distilled from the Ecuadorian Species Niphogeton dissecta (Benth.) J.F. Macbr.

PubMed

Calva, James; Bec, Nicole; Gilardoni, Gianluca; Larroque, Christian; Cartuche, Luis; Bicchi, Carlo; Montesinos, José Vinicio

2017-10-31

This study investigated the chemical composition, physical proprieties, biological activity, and enantiomeric analysis of the essential oil from the aerial parts of Niphogeton dissecta (culantrillo del cerro) from Ecuador, obtained by steam distillation. The qualitative and quantitative analysis of the essential oil was realized by gas chromatographic and spectroscopic techniques (GC-MS and GC-FID). Acorenone B was identified by GC-MS and NMR experiments. The enantiomeric distribution of some constituents has been assessed by enantio-GC through the use of a chiral cyclodextrin-based capillary column. We identified 41 components that accounted for 96.46% of the total analyzed, the major components were acorenone B (41.01%) and (E)-β-ocimene (29.64%). The enantiomeric ratio of (+)/(-)-β-pinene was 86.9:13.1, while the one of (+)/(-)-sabinene was 80.9:19.1. The essential oil showed a weak inhibitory activity, expressed as Minimal Inhibitory Concentration (MIC), against Enterococcus faecalis (MIC 10 mg/mL) and Staphylococcus aureus (MIC 5 mg/mL). Furthermore, it inhibited butyrylcholinesterase with an IC 50 value of 11.5 μg/mL. Pure acorenone B showed inhibitory activity against both acetylcholinesterase and butyrylcholinesterase, with IC 50 values of 40.8 μg/mL and 10.9 μg/mL, respectively.

Acorenone B: AChE and BChE Inhibitor as a Major Compound of the Essential Oil Distilled from the Ecuadorian Species Niphogeton dissecta (Benth.) J.F. Macbr

PubMed Central

Calva, James; Bec, Nicole; Gilardoni, Gianluca; Larroque, Christian; Cartuche, Luis; Bicchi, Carlo; Montesinos, José Vinicio

2017-01-01

This study investigated the chemical composition, physical proprieties, biological activity, and enantiomeric analysis of the essential oil from the aerial parts of Niphogeton dissecta (culantrillo del cerro) from Ecuador, obtained by steam distillation. The qualitative and quantitative analysis of the essential oil was realized by gas chromatographic and spectroscopic techniques (GC-MS and GC-FID). Acorenone B was identified by GC-MS and NMR experiments. The enantiomeric distribution of some constituents has been assessed by enantio-GC through the use of a chiral cyclodextrin-based capillary column. We identified 41 components that accounted for 96.46% of the total analyzed, the major components were acorenone B (41.01%) and (E)-β-ocimene (29.64%). The enantiomeric ratio of (+)/(−)-β-pinene was 86.9:13.1, while the one of (+)/(−)-sabinene was 80.9:19.1. The essential oil showed a weak inhibitory activity, expressed as Minimal Inhibitory Concentration (MIC), against Enterococcus faecalis (MIC 10 mg/mL) and Staphylococcus aureus (MIC 5 mg/mL). Furthermore, it inhibited butyrylcholinesterase with an IC50 value of 11.5 μg/mL. Pure acorenone B showed inhibitory activity against both acetylcholinesterase and butyrylcholinesterase, with IC50 values of 40.8 μg/mL and 10.9 μg/mL, respectively. PMID:29088082

Short communication: Interaction of the isomers carvacrol and thymol with the antibiotics doxycycline and tilmicosin: In vitro effects against pathogenic bacteria commonly found in the respiratory tract of calves.

PubMed

Kissels, W; Wu, X; Santos, R R

2017-02-01

Bovine respiratory disease is the major problem faced by cattle, specially calves, leading to reduced animal performance and increased mortality, consequently causing important economic losses. Hence, calves must be submitted to antibiotic therapy to counteract this infection usually initiated by the combination of environmental stress factors and viral infection, altering the animal's defense mechanism, and thus allowing lung colonization by the opportunistic bacteria Mannheimia haemolytica and Pasteurella multocida. Essential oils appear to be candidates to replace antibiotics or to act as antibiotic adjuvants due to their antimicrobial properties. In the present study, we aimed to evaluate the 4 essential oil components carvacrol, thymol, trans-anethole, and 1,8 cineole as antibacterial agents or as adjuvants for the antibiotics doxycycline and tilmicosin against M. haemolytica and P. multocida. Bacteria were cultured according to standard protocols, followed by the determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration. A checkerboard assay was applied to detect possible interactions between components, between antibiotics, and between components and antibiotics. Doxycycline at 0.25 and 0.125 μg/mL inhibited the growth of P. multocida and M. haemolytica, respectively, whereas tilmicosin MIC values were 1.0 and 4.0 μg/mL for P. multocida and M. haemolytica, respectively. Carvacrol MIC values were 2.5 and 1.25 mM for P. multocida and M. haemolytica, respectively, whereas thymol MIC values were 1.25 and 0.625 mM for P. multocida and M. haemolytica, respectively. Trans-anethole and 1,8 cineole did not present any antibacterial effect even at 40 mM against the investigated pathogens. All minimum bactericidal concentration values were the same as MIC, except when thymol was tested against M. haemolytica, being twice the MIC data (i.e., 1.25 mM thymol). Based on fractional inhibitory concentration checkerboard assay, no interaction was observed between doxycycline and tilmicosin. Carvacrol and thymol presented an additive effect when one of them was combined with tilmicosin. Additive effect was also observed when doxycycline was combined with thymol. Synergism was observed when carvacrol was combined with doxycycline or with thymol. Although the antibacterial effects of the tested essential oil components were observed at high concentrations for in vitro conditions, the additive and synergic effects of carvacrol and thymol with antibiotics suggest the option to apply them as antibiotic adjuvants. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Antimicrobial activity of plant extracts against the honeybee pathogens, Paenibacillus larvae and Ascosphaera apis and their topical toxicity to Apis mellifera adults.

PubMed

Chaimanee, V; Thongtue, U; Sornmai, N; Songsri, S; Pettis, J S

2017-11-01

To explore alternative nonchemical control measures against two honeybee pathogens, Paenibacillus larvae and Ascosphaera apis, 37 plant species were screened for antimicrobial activity. The activity of selected plant extracts was screened using an in vitro disc diffusion assay and the minimal inhibitory concentration (MIC) was determined by the broth microdilution method. The results showed that 36 plant extracts had some antibacterial activity on P. larvae by disc diffusion assay. Chromolaena odorata showed the greatest antibacterial activity against P. larvae (MIC 16-64 μg ml -1 ). Of the 37 tested plants, only seven species, Amomum krervanh, Allium sativum, Cinnamomum sp., Piper betle, Piper ribesioides, Piper sarmentosum and Syzygium aromaticum had inhibitory effects on A. apis (MICs of 32-64 μg ml -1 ). The results demonstrated that promising plant extracts were not toxic to adult bees at the concentrations used in this study. The results demonstrate the potential antimicrobial activity of natural products against honeybee diseases caused by P. larvae and A. apis. Chromolaena odorata in particular showed high bioactivity against P. larvae. Further study is recommended to develop these nonchemical treatments against American foulbrood and chalkbrood in honeybees. This work proposes new natural products for the control of American foulbrood and chalkbrood in honeybees. © 2017 The Society for Applied Microbiology.

Curcumin, an antibiotic resistance breaker against a multiresistant clinical isolate of Mycobacterium abscessus.

PubMed

Marini, Emanuela; Di Giulio, Mara; Magi, Gloria; Di Lodovico, Silvia; Cimarelli, Maria Enrica; Brenciani, Andrea; Nostro, Antonia; Cellini, Luigina; Facinelli, Bruna

2018-03-01

Curcumin, a phenolic compound extracted from Curcuma longa, exerts multiple pharmacological effects, including an antimicrobial action. Mycobacterium abscessus, an environmental, nontuberculous, rapidly growing mycobacterium, is an emerging human pathogen causing serious lung infections and one of the most difficult to treat, due to its multidrug resistance and biofilm-forming ability. We wanted to evaluate the antimicrobial and antivirulence activity of curcumin and its ability to synergize with antibiotics against a clinical M. abscessus strain (29904), isolated from the bronchoaspirate of a 66-year-old woman admitted to hospital for suspected tuberculosis. Curcumin [minimum inhibitory concentrations (MIC) = 128 mg/L] was synergic (fractional inhibitory concentration index ≤0.5) with amikacin, clarithromycin, ciprofloxacin, and linezolid, to which strain 29904 showed resistance/intermediate susceptibility. Curcumin at 1/8 × MIC significantly reduced motility, whereas at 4 × MIC, it completely inhibited 4- and 8-day mature biofilms. Synergistic combinations of curcumin and amikacin induced a general reduction in microbial aggregates and substantial loss in cell viability. Disruption of 4- and 8-day biofilms was the main effect detected when curcumin was the predominant compound. The present findings support previous evidence that curcumin is a potential antibiotic resistance breaker. Curcumin, either alone or combined with antibiotics, could provide a novel strategy to combat antibiotic resistance and virulence of M. abscessus. Copyright © 2017 John Wiley & Sons, Ltd.

In Vitro Antimicrobial Activity of Razupenem (SMP-601, PTZ601) against Anaerobic Bacteria▿

PubMed Central

Tran, Chau Minh; Tanaka, Kaori; Yamagishi, Yuka; Goto, Takatsugu; Mikamo, Hiroshige; Watanabe, Kunitomo

2011-01-01

We evaluated the in vitro antianaerobic activity of razupenem (SMP-601, PTZ601), a new parenterally administered carbapenem, against 70 reference strains and 323 clinical isolates. Razupenem exhibited broad-spectrum activity against anaerobes, inhibiting most of the reference strains when used at a concentration of ≤1 μg/ml. Furthermore, it exhibited strong activity, comparable to those of other carbapenems (meropenem and doripenem), against clinically isolated non-fragilis Bacteroides spp. (MIC90s of 2 μg/ml), with MIC90 values of 0.06, 0.03, and 0.5 μg/ml against Prevotella spp., Porphyromonas spp., and Fusobacterium spp., respectively. Clinical isolates of anaerobic Gram-positive cocci, Eggerthella spp., and Clostridium spp. were highly susceptible to razupenem (MIC90s, 0.03 to 1 μg/ml). PMID:21343447

Effectiveness of Persea major Kopp (Lauraceae) extract against Enterococcus faecalis: a preliminary in vitro study.

PubMed

Volpato, Lusiane; Gabardo, Marilisa Carneiro Leão; Leonardi, Denise Piotto; Tomazinho, Paulo Henrique; Maranho, Leila Teresinha; Baratto-Filho, Flares

2017-03-06

Persea major Kopp (Lauraceae) is a plant with wound healing, antibacterial, and analgesic properties. The aim of this study was to assess the in vitro antibacterial activity of the concentrated crude extract (CCE) and ethyl acetate fraction (EAF) of this plant against Enterococcus faecalis and compare it with calcium hydroxide [Ca(OH) 2 ] paste and 2% chlorhexidine digluconate (CHX). The plant material was collected, and an extract was prepared according to the requirements of the study (CCE and EAF). The minimum inhibitory concentrations (MICs) of CCE, EAF, Ca(OH) 2 , Ca(OH) 2  + CCE, and CHX against E. faecalis were determined using the broth microdilution method RESULTS: The EAF inhibited E. faecalis at concentrations of 166.50, 83.25, and 41.62 mg mL -1 , and 1.00, 0.50, and 0.25% of CHX solutions showed antimicrobial activity. The MICs of Ca(OH) 2 paste were 166.50 and 83.25 mg mL -1 , whereas Ca(OH) 2  + CCE showed antimicrobial activity only at a concentration of 166.50 mg mL -1 . CCE showed no inhibitory effect at any of the concentrations tested CONCLUSIONS: The CCE did not show any antimicrobial activity against E. faecalis; however, the EAF was the most effective among the three highest concentrations tested.

Radiosensitization of Aspergillus niger and Penicillium chrysogenum using basil essential oil and ionizing radiation for food decontamination.

USDA-ARS?s Scientific Manuscript database

The Minimum Inhibitory Concentration (MIC) of basil oil, was determined for two pathogenic fungi of rice, Aspergillus niger and Penicillium chrysogenum. The antifungal activity of the basil oil in combination with ionising radiation was then investigated to determine if basil oil caused radiosensit...

Rice hull smoke extract inactivates Salmonella Typhimurium in laboratory media and protects infected mice against mortality

USDA-ARS?s Scientific Manuscript database

A recently discovered and characterized rice hull liquid smoke extract was tested for bactericidal activity against Salmonella Typhimurium using the disc-agar method. The Minimum Inhibitory Concentration (MIC) value of rice hull smoke extract was found to be 0.822% (v/v). The in vivo antibacterial a...

Antimicrobial isothiocyanates from the seeds of Moringa oleifera Lam.

PubMed

Padla, Eleanor P; Solis, Ludivina T; Levida, Ruel M; Shen, Chien-Chang; Ragasa, Consolacion Y

2012-01-01

4-(alpha-L-Rhamnosyloxy)benzyl isothiocyanate (1) and 4-(4'-O-acetyl-alpha-L-rhamnosyloxy)-benzyl isothiocyanate (2) isolated from Moringa oleifera seeds were screened for their antibacterial activities against Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, and Pseudomonas aeruginosa, and for their antifungal activities against Candida albicans, Trichophyton rubrum, and Epidermophyton floccosum using the disk diffusion method. Isothiocyanates 1 and 2 were found active at the lowest inhibitory concentration of 1 mg/ml against all Gram-positive bacteria tested (S. aureus, S. epidermidis, B. subtilis) and against the dermatophytic fungi E. floccosum and T. rubrum. Statistically significant differences were found between the mean inhibition zones (IZ) of 1 and 2 and the standard drugs, ofloxacin and clotrimazole. The minimum inhibitory concentration (MIC) values confirmed the good antimicrobial activity of 1 and 2 against S. aureus, good to moderate activity against S. epidermidis, moderate activity against B. subtilis, and weak activity against E. floccosum and T. rubrum. The in vitro bactericidal effect of 1 and 2 against the Gram-positive bacterial strains tested is suggested by MBC:MIC ratios of 2:1.

Effect of aqueous and ethanolic extracts of Lippia citriodora on candida albicans

PubMed Central

Ghasempour, Maryam; Omran, Saeid Mahdavi; Moghadamnia, Ali Akbar; Shafiee, Faranak

2016-01-01

Introduction Because of resistance and side effects to common antifungal drugs activity, the research on herbal substances with antifungal activity is frequent. Lemon verbena (Lippia citriodora) is a member of Verbenaceae family. The aim of this study was to determine the anti-candida activities of the ethanolic and aqueous extracts of the lemon verbena leaves and compare them with nystatin and fluconazole. Methods In this 2015 study, 15 clinical isolates and standard strain of candida albicans PTCC 5027 were used, and the inhibitory effects of the ethanolic and aqueous extracts, Nystatin and Fluconazole, were evaluated using disk and well diffusion methods. Also, the minimal inhibitory concentration (MIC) was determined. Five concentrations of aqueous and ethanolic extracts (156–2500 μg/ml), Nystatin (8–128 μg/ml) and Fluconazole (4–64 μg/ml) were used in disk and well diffusion methods, and nine concentrations of aqueous and ethanolic extracts (19–5000 μg/ml), Nystatin (0.5–128 μg/ml), and Fluconazole (0.25–64 μg/ml) were applied for MIC. Data were analyzed using Tukey’s post-hoc and one-way ANOVA tests. The significant level was considered p < 0.05 in the current study. Results In the well and disk diffusion techniques, limited growth inhibition halos were produced around some clinical isolates at different concentrations of ethanolic extract; however, no growth inhibitory halo was observed with any concentrations of the aqueous extract. The MIC values of ethanolic extract, aqueous extract, Nystatin and Fluconazole for clinical isolated and standard strain were 833 ± 78.5and 625μg/ml; 4156 ± 67.4 and 2500 μg/ml; 10.13 ± 1.91 and 4 μg/ml; and 1.97 ± 0.25 and 1 μg/ml, respectively. Conclusion The results showed that the ethanolic extract was stronger than the aqueous extract of this plant, which can be used as an alternative for drugs. It is recommended that the ethanolic extract of this plant be investigated in vivo for better evaluation of its efficacy and properties. PMID:27757185

Inhibitory Activity of Avocado Seed Fatty Acid Derivatives (Acetogenins) Against Listeria Monocytogenes.

PubMed

Salinas-Salazar, Carmen; Hernández-Brenes, Carmen; Rodríguez-Sánchez, Dariana Graciela; Castillo, Elena Cristina; Navarro-Silva, Jesús Manuel; Pacheco, Adriana

2017-01-01

High standards regarding Listeria monocytogenes control and consumer demands for food products without synthetic additives represent a challenge to food industry. We determined the antilisterial properties of an enriched acetogenin extract (EAE) from avocado seed, compared it to two commercial antimicrobials (one enriched in avocado acetogenins), and tested purified molecules. Acetogenin composition in pulp and seed of Hass avocado was quantified. EAE were obtained by two sequential centrifuge partition chromatography separations and molecules purified by preparative chromatography and quantified by HPLC-MS-TOF and HPLC-PDA. Avocado seed extracts which are the following two: 1) EAE and 2) the commercially available antimicrobial Avosafe®, presented similar inhibition zones and chemical profiles. Minimum inhibitory concentration (MIC) values of extracts and two isolated acetogenins varied between 7.8 and 15.6 mg/L, were effective at 37 and 4 °C, and showed a bactericidal effect probably caused by increased membrane permeability and lytic effects, evidenced by flow cytometry at 10 and 100× MIC. Activity was comparable to Mirenat®. Most potent acetogenins were Persenone C (5) and A (6), and AcO-avocadenyne (1), the latter exclusively present in seed. Common features of bioactive molecules were the acetyl moiety and multiple unsaturations (2 to 3) in the aliphatic chain, some persenones also featured a trans-enone group. Seeds contained 1.6 times higher levels of acetogenins than pulp (5048.1 ± 575.5 and 3107.0 ± 207.2 mg/kg fresh weight, respectively), and total content in pulp was 199 to 398 times higher than MIC values. Therefore, acetogenin levels potentially consumed by humans are higher than inhibitory concentrations. Results document properties of avocado seed acetogenins as natural antilisterial food additives. © 2016 Institute of Food Technologists®.

Antitubercular cassane furanoditerpenoids from the roots of Caesalpinia pulcherrima.

PubMed

Promsawan, Netnapa; Kittakoop, Prasat; Boonphong, Surat; Nongkunsarn, Pakawan

2003-08-01

Activity-guided fractionation of a root extract of Caesalpinia pulcherrima led to the isolation of two cassane-furanoditerpenoids, 6 beta-benzoyl-7 beta-hydroxyvouacapen-5 alpha-ol (1) and 6 beta-cinnamoyl-7beta-hydroxyvouacapen-5 alpha-ol (2). Compound 2 showed strong antitubercular activity with a minimum inhibitory concentration (MIC) of 6.25 microg/mL, whereas the benzoyl analogue (1) was less active (MIC 25 microg/mL). Both compounds expressed moderate cytotoxic activity towards KB (human oral carcinonoid cancer), BC (human breast cancer) and NCl-H187 (small cell lung cancer) cell lines.

In vitro assessment of the antimicrobial susceptibility of caprine isolates of Mycoplasma mycoides subsp. capri.

PubMed

Paterna, A; Tatay-Dualde, J; Amores, J; Prats-van der Ham, M; Sánchez, A; de la Fe, C; Contreras, A; Corrales, J C; Gómez-Martín, Á

2016-08-01

The minimum inhibitory concentration (MIC) and minimum mycoplasmacidal concentration (MMC) of 17 antimicrobials against 41 Spanish caprine isolates of Mycoplasma mycoides subsp. capri (Mmc) obtained from different specimens (milk, external auricular canal and semen) were determined using a liquid microdilution method. For half of the isolates, the MIC was also estimated for seven of the antimicrobials using an epsilometric test (ET), in order to compare both methods and assess the validity of ET. Mutations in genes gyrA, gyrB, parC and parE conferring fluoroquinolone resistance, which have been recently described in Mmc, were investigated using PCR. The anatomical origin of the isolate had no effect on its antimicrobial susceptibility. Moxifloxacin and doxycycline had the lowest MIC values. The rest of the fluoroquinolones studied (except norfloxacin), together with tylosin and clindamycin, also had low MIC values, although the MMC obtained for clindamycin was higher than for the other antimicrobials. For all the aminoglycosides, spiramycin and erythromycin, a notable level of resistance was observed. The ET was in close agreement with broth microdilution at low MICs, but not at intermediate or high MICs. The analysis of the genomic sequences revealed the presence of an amino acid substitution in codon 83 of the gene gyrA, which has not been described previously in Mmc. Copyright © 2016 Elsevier Ltd. All rights reserved.

DALI: defining antibiotic levels in intensive care unit patients: are current β-lactam antibiotic doses sufficient for critically ill patients?

PubMed

Roberts, Jason A; Paul, Sanjoy K; Akova, Murat; Bassetti, Matteo; De Waele, Jan J; Dimopoulos, George; Kaukonen, Kirsi-Maija; Koulenti, Despoina; Martin, Claude; Montravers, Philippe; Rello, Jordi; Rhodes, Andrew; Starr, Therese; Wallis, Steven C; Lipman, Jeffrey

2014-04-01

Morbidity and mortality for critically ill patients with infections remains a global healthcare problem. We aimed to determine whether β-lactam antibiotic dosing in critically ill patients achieves concentrations associated with maximal activity and whether antibiotic concentrations affect patient outcome. This was a prospective, multinational pharmacokinetic point-prevalence study including 8 β-lactam antibiotics. Two blood samples were taken from each patient during a single dosing interval. The primary pharmacokinetic/pharmacodynamic targets were free antibiotic concentrations above the minimum inhibitory concentration (MIC) of the pathogen at both 50% (50% f T>MIC) and 100% (100% f T>MIC) of the dosing interval. We used skewed logistic regression to describe the effect of antibiotic exposure on patient outcome. We included 384 patients (361 evaluable patients) across 68 hospitals. The median age was 61 (interquartile range [IQR], 48-73) years, the median Acute Physiology and Chronic Health Evaluation II score was 18 (IQR, 14-24), and 65% of patients were male. Of the 248 patients treated for infection, 16% did not achieve 50% f T>MIC and these patients were 32% less likely to have a positive clinical outcome (odds ratio [OR], 0.68; P = .009). Positive clinical outcome was associated with increasing 50% f T>MIC and 100% f T>MIC ratios (OR, 1.02 and 1.56, respectively; P < .03), with significant interaction with sickness severity status. Infected critically ill patients may have adverse outcomes as a result of inadeqaute antibiotic exposure; a paradigm change to more personalized antibiotic dosing may be necessary to improve outcomes for these most seriously ill patients.

Mutations in the quinolone resistance determining region in Staphylococcus epidermidis recovered from conjunctiva and their association with susceptibility to various fluoroquinolones.

PubMed

Yamada, M; Yoshida, J; Hatou, S; Yoshida, T; Minagawa, Y

2008-06-01

Staphylococcus epidermidis is one of the prominent pathogens in ocular infection. The prevalence of mutations in the quinolone resistance determining region (QRDR) area in S epidermidis isolated from the ocular surface and its association with fluoroquinolone resistance has not been fully elucidated. Mutations in the QRDR of gyrA, gyrB, parC, and parE genes of 138 isolates of S epidermidis recovered from the human conjunctival flora were analysed. The minimal inhibitory concentrations (MICs) of four fluoroquinolones (levofloxacin, gatifloxacin, moxifloxacin and tosufloxacin) against these isolates were also determined using agar dilution methods. The MIC(90) values of levofloxacin, gatifloxacin, moxifloxacin and tosufloxacin were 3.13, 1.56, 0.78 and 3.13 microg/ml, respectively. The MIC values of all fluoroquinolones showed a bimodal distribution (susceptible strain and less susceptible strain). Mutations with amino acid substitution in the QRDR were present in 70 (50.7%) isolates. 19 different combinations of mutations were detected: 3 isolates (2.2%) had four mutations, 8 (5.8%) had three mutations, 43 (31.2%) had double mutations and 16 (11.6%) had single mutations. Isolates with mutations in the QRDR of both gyrA and parC (n = 53) were less susceptible to fluoroquinolones. The present findings show that approximately half the S epidermidis isolates from the normal human conjunctiva have mutation(s) in the QRDR. The presence of mutations in both gyrA and parC is strongly associated with reduced susceptibility to fluoroquinolones.

Effect of multipurpose solutions against Acinetobacter carrying QAC genes.

PubMed

Boost, Maureen V; Chan, Jessica; Shi, Guang-sen; Cho, Pauline

2014-03-01

Acinetobacter has low virulence but causes infections in subjects with reduced immunity. It has been reported in ocular infections including those of patients using contact lenses. Treatment is difficult because Acinetobacter is frequently multidrug resistant. Antibiotic-resistant strains frequently also harbor genes for antiseptic resistance (quaternary ammonium compound [QAC]) genes. Because Acinetobacter is part of the normal flora, it may contaminate contact lens and accessories. This study aims to investigate carriage rates of QAC genes in household and clinical isolates of Acinetobacter and to determine the effectiveness of two multipurpose solutions (MPSs) for soft lenses against organisms carrying QAC genes. DNA was extracted from 11 bathroom isolates and 15 clinical isolates and amplified by polymerase chain reaction to determine the presence of qacEΔ1. Gene-positive and gene-negative control strains were used to challenge the two MPSs, and minimum inhibitory concentrations (MICs) of these organisms to benzalkonium chloride and chlorhexidine gluconate were determined. More than 90% of isolates carried qacEΔ1. The MICs of clinical isolates were higher than those of isolates of bathrooms. Both MPSs were able to produce a 3-log reduction in the numbers of all isolates. Although most isolates carried qacEΔ1 and elevated MICs to benzalkonium chloride and chlorhexidine gluconate were observed, all were susceptible to both MPSs tested. However, if there were to be poor compliance with care procedures, it is probable that such organisms could survive in the presence of diluted or expired solutions.

Comparison of antimicrobial activities of naphthoquinones from Impatiens balsamina.

PubMed

Sakunphueak, Athip; Panichayupakaranant, Pharkphoom

2012-01-01

Lawsone (1), lawsone methyl ether (2), and methylene-3,3'-bilawsone (3) are the main naphthoquinones in the leaf extracts of Impatiens balsamina L. (Balsaminaceae). Antimicrobial activities of these three naphthoquinones against dermatophyte fungi, yeast, aerobic bacteria and facultative anaerobic and anaerobic bacteria were evaluated by determination of minimal inhibitory concentrations (MICs) and minimal bactericidal or fungicidal concentrations (MBCs or MFCs) using a modified agar dilution method. Compound 2 showed the highest antimicrobial activity. It showed antifungal activity against dermatophyte fungi and Candida albicans with the MICs and MFCs in the ranges of 3.9-23.4 and 7.8-23.4 µg mL(-1), respectively, and also had some antibacterial activity against aerobic, facultative anaerobic and anaerobic bacteria with MICs in the range of 23.4-93.8, 31.2-62.5 and 125 µg mL(-1), respectively. Compound 1 showed only moderate antimicrobial activity against dermatophytes (MICs and MFCs in the ranges of 62.5-250 and 125-250 µg mL(-1), respectively), but had low potency against aerobic bacteria, and was not active against C. albicans and facultative anaerobic bacteria. In contrast, 3 showed significant antimicrobial activity only against Staphylococus epidermidis and Bacillus subtilis (MIC and MBC of 46.9 and 93.8 µg mL(-1), respectively).

In vitro effect of branch extracts of Juniperus species from Turkey on Staphylococcus aureus biofilm.

PubMed

Marino, Andreana; Bellinghieri, Valentina; Nostro, Antonia; Miceli, Natalizia; Taviano, Maria Fernanda; Güvenç, Ayşegül; Bisignano, Giuseppe

2010-08-01

Methanol and aqueous branch extracts of five Juniperus species were examined for their effects on Staphylococcus aureus ATCC 6538P and S. aureus 810 biofilm. The Turkish plant material was Juniperus communis L. var. communis, J. communis L. var. saxatilis Pall., Juniperus drupacea Labill., Juniperus oxycedrus L. ssp. oxycedrus, J. oxycedrus L. ssp. macrocarpa (Sibth. & Sm.) Ball. The Juniperus extracts were subjected to preliminary phytochemical analysis by thin-layer chromatography. The antimicrobial activity was evaluated using the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The effects of the extracts on biofilm formation and preformed biofilm were quantified by both biomass OD and the CFU counting method. The phytochemical screening revealed the presence of polyphenols, coumarins, lignans, steroids, alkaloids and terpenes. For both strains, the MICs of all extracts were in the range of 4.88-78.12 microg mL(-1). On S. aureus ATCC 6538P, the effects of subinhibitory concentration (0.5 MIC) of the extracts were minimal on planktonic growth and on adhering cells, whereas they were greater on biofilm formation. Differently, on S. aureus 810, they showed only a rather low efficacy on biofilm formation. The extracts at 2 MIC demonstrated a good activity on a preformed biofilm of S. aureus ATCC 6538P.

Antibacterial screening of some Peruvian medicinal plants used in Callería District.

PubMed

Kloucek, P; Polesny, Z; Svobodova, B; Vlkova, E; Kokoska, L

2005-06-03

Nine ethanol extracts of Brunfelsia grandiflora (Solanaceae), Caesalpinia spinosa (Caesalpiniaceae), Dracontium loretense (Araceae), Equisetum giganteum (Equisetaceae), Maytenus macrocarpa (Celastraceae), Phyllanthus amarus (Euphorbiaceae), Piper aduncum (Piperaceae), Terminalia catappa (Combretaceae), and Uncaria tomentosa (Rubiaceae), medicinal plants traditionally used in Calleria District for treating conditions likely to be associated with microorganisms, were screened for antimicrobial activity against nine bacterial strains using the broth microdilution method. Among the plants tested, Phyllanthus amarus and Terminalia catappa showed the most promising antibacterial properties, inhibiting all of the strains tested with minimum inhibitory concentrations (MICs) ranging from 0.25 to 16 mg/ml. The extract from aerial part of Piper aduncum was significantly more active against Gram-positive (MICs ranging from 1 to 2 mg/ml) than against Gram-negative bacteria (MICs > 16 mg/ml).

In vitro antimycoplasmal activities of rufloxacin and its metabolite MF 922.

PubMed Central

Furneri, P M; Bisignano, G; Cerniglia, G; Nicoletti, G; Cesana, M; Tempera, G

1994-01-01

The in vitro activities of rufloxacin and its metabolite, MF 922, were compared with those of ofloxacin, ciprofloxacin, erythromycin, and minocycline against Mycoplasma pneumoniae, Mycoplasma hominis, Mycoplasma fermentans, and Ureaplasma urealyticum. Rufloxacin, MF 922, and ciprofloxacin shared similar activities against all mycoplasmas tested. (MICs for 90% of isolates tested [MIC90s], 0.5 to 4 micrograms/ml. Ofloxacin had the lowest MIC90s for U. urealyticum, M. fermentans, and M. hominis (MIC90s, 0.25 to 1 micrograms/ml) and erythromycin had the lowest MIC90 for M. pneumoniae (MIC90, 0.004 micrograms/ml). PMID:7872762

Susceptibility patterns for amoxicillin/clavulanate tests mimicking the licensed formulations and pharmacokinetic relationships: do the MIC obtained with 2:1 ratio testing accurately reflect activity against beta-lactamase-producing strains of Haemophilus influenzae and Moraxella catarrhalis?

PubMed

Pottumarthy, Sudha; Sader, Helio S; Fritsche, Thomas R; Jones, Ronald N

2005-11-01

Amoxicillin/clavulanate has recently undergone formulation changes (XR and ES-600) that represent 14:1 and 16:1 ratios of amoxicillin/clavulanate. These ratios greatly differ from the 2:1 ratio used in initial formulations and in vitro susceptibility testing. The objective of this study was to determine if the reference method using a 2:1 ratio accurately reflects the susceptibility to the various clinically used amoxicillin/clavulanate formulations and their respective serum concentration ratios. A collection of 330 Haemophilus influenzae strains (300 beta-lactamase-positive and 30 beta-lactamase-negative) and 40 Moraxella catarrhalis strains (30 beta-lactamase-positive and 10 beta-lactamase-negative) were tested by the broth microdilution method against eight amoxicillin/clavulanate combinations (4:1, 5:1, 7:1, 9:1, 14:1, and 16:1 ratios; 0.5 and 2 microg/mL fixed clavulanate concentrations) and the minimum inhibitory concentration (MIC) results were compared with those obtained with the reference 2:1 ratio testing. For the beta-lactamase-negative strains of both genera, there was no demonstrable change in the MIC values obtained for all ratios analyzed (2:1 to 16:1). For the beta-lactamase-positive strains of H. influenzae and M. catarrhalis, at ratios >or=4:1 there was a shift in the central tendency of the MIC scatterplot compared with the results of testing 2:1 ratio. As a result, there was a 2-fold dilution increase in the MIC(50) and MIC(90) values, most evident for H. influenzae and BRO-1-producing M. catarrhalis strains. For beta-lactamase-positive strains of H. influenzae, the shift resulted in a change in the interpretive result for 3 isolates (1.0%) from susceptible using the reference method (2:1 ratio) to resistant (8/4 microg/mL; very major error) at the 16:1 ratio. In addition, the number of isolates with MIC values at or 1 dilution lower than the breakpoint (4/2 microg/mL) increased from 5% at 2:1 ratio to 32-33% for ratios 14:1 and 16:1. Our results indicate that, for the beta-lactamase-positive strains of H. influenzae and M. catarrhalis, the results of the amoxicillin/clavulanate reference 2:1 ratio testing do not accurately represent all the currently licensed formulations. Pharmacokinetic/pharmacodynamic (PK/PD) target attainment might be compromised when higher amoxicillin/clavulanate ratios are used clinically. With a better understanding of PK/PD parameters, reevaluation of the amoxicillin/clavulanate in vitro susceptibility testing should be considered by the standardizing authorities to reflect the licensed formulations and accurately predict clinical outcomes.

Maximum-biomass prediction of homofermentative Lactobacillus.

PubMed

Cui, Shumao; Zhao, Jianxin; Liu, Xiaoming; Chen, Yong Q; Zhang, Hao; Chen, Wei

2016-07-01

Fed-batch and pH-controlled cultures have been widely used for industrial production of probiotics. The aim of this study was to systematically investigate the relationship between the maximum biomass of different homofermentative Lactobacillus and lactate accumulation, and to develop a prediction equation for the maximum biomass concentration in such cultures. The accumulation of the end products and the depletion of nutrients by various strains were evaluated. In addition, the minimum inhibitory concentrations (MICs) of acid anions for various strains at pH 7.0 were examined. The lactate concentration at the point of complete inhibition was not significantly different from the MIC of lactate for all of the strains, although the inhibition mechanism of lactate and acetate on Lactobacillus rhamnosus was different from the other strains which were inhibited by the osmotic pressure caused by acid anions at pH 7.0. When the lactate concentration accumulated to the MIC, the strains stopped growing. The maximum biomass was closely related to the biomass yield per unit of lactate produced (YX/P) and the MIC (C) of lactate for different homofermentative Lactobacillus. Based on the experimental data obtained using different homofermentative Lactobacillus, a prediction equation was established as follows: Xmax - X0 = (0.59 ± 0.02)·YX/P·C. Copyright © 2016. Published by Elsevier B.V.

Pharmacokinetics of meropenem after intravenous, intramuscular and subcutaneous administration to cats.

PubMed

Albarellos, Gabriela A; Montoya, Laura; Passini, Sabrina M; Lupi, Martín P; Lorenzini, Paula M; Landoni, María F

2016-12-01

The aim of the study was to describe the pharmacokinetics and predicted efficacy of meropenem after intravenous (IV), intramuscular (IM) and subcutaneous (SC) administration to cats at a single dose of 10 mg/kg. Five adult healthy cats were used. Blood samples were withdrawn at predetermined times over a 12 h period. Meropenem concentrations were determined by microbiological assay. Pharmacokinetic analyses were performed with computer software. Initial estimates were determined using the residual method and refitted by non-linear regression. The time that plasma concentrations were greater than the minimum inhibitory concentration (T >MIC) was estimated by applying bibliographic MIC values and meropenem MIC breakpoint. Maximum plasma concentrations of meropenem were 101.02 µg/ml (C p(0) , IV), 27.21 µg/ml (C max , IM) and 15.57 µg/ml (C max , SC). Bioavailability was 99.69% (IM) and 96.52 % (SC). Elimination half-lives for the IV, IM and SC administration were 1.35, 2.10 and 2.26 h, respectively. Meropenem, when administered to cats at a dose of 10 mg/kg q12h,, is effective against bacteria with MIC values of 6 μg/ml, 7 μg/ml and 10 μg/ml for IV, IM and SC administration, respectively. However, clinical trials are necessary to confirm clinical efficacy of the proposed dosage regimen. © The Author(s) 2015.

Comparison of Active Drug Concentrations in the Pulmonary Epithelial Lining Fluid and Interstitial Fluid of Calves Injected with Enrofloxacin, Florfenicol, Ceftiofur, or Tulathromycin

PubMed Central

Foster, Derek M.; Martin, Luke G.; Papich, Mark G.

2016-01-01

Bacterial pneumonia is the most common reason for parenteral antimicrobial administration to beef cattle in the United States. Yet there is little information describing the antimicrobial concentrations at the site of action. The objective of this study was to compare the active drug concentrations in the pulmonary epithelial lining fluid and interstitial fluid of four antimicrobials commonly used in cattle. After injection, plasma, interstitial fluid, and pulmonary epithelial lining fluid concentrations and protein binding were measured to determine the plasma pharmacokinetics of each drug. A cross-over design with six calves per drug was used. Following sample collection and drug analysis, pharmacokinetic calculations were performed. For enrofloxacin and metabolite ciprofloxacin, the interstitial fluid concentration was 52% and 78% of the plasma concentration, while pulmonary fluid concentrations was 24% and 40% of the plasma concentration, respectively. The pulmonary concentrations (enrofloxacin + ciprofloxacin combined) exceeded the MIC90 of 0.06 μg/mL at 48 hours after administration. For florfenicol, the interstitial fluid concentration was almost 98% of the plasma concentration, and the pulmonary concentrations were over 200% of the plasma concentrations, exceeding the breakpoint (≤ 2 μg/mL), and the MIC90 for Mannheimia haemolytica (1.0 μg/mL) for the duration of the study. For ceftiofur, penetration to the interstitial fluid was only 5% of the plasma concentration. Pulmonary epithelial lining fluid concentration represented 40% of the plasma concentration. Airway concentrations exceeded the MIC breakpoint for susceptible respiratory pathogens (≤ 2 μg/mL) for a short time at 48 hours after administration. The plasma and interstitial fluid concentrations of tulathromcyin were lower than the concentrations in pulmonary fluid throughout the study. The bronchial concentrations were higher than the plasma or interstitial concentrations, with over 900% penetration to the airways. Despite high diffusion into the bronchi, the tulathromycin concentrations achieved were lower than the MIC of susceptible bacteria at most time points. PMID:26872361

Antimicrobial effect of Dinoponera quadriceps (Hymenoptera: Formicidae) venom against Staphylococcus aureus strains.

PubMed

Lima, D B; Torres, A F C; Mello, C P; de Menezes, R R P P B; Sampaio, T L; Canuto, J A; da Silva, J J A; Freire, V N; Quinet, Y P; Havt, A; Monteiro, H S A; Nogueira, N A P; Martins, A M C

2014-08-01

Dinoponera quadriceps venom (DqV) was examined to evaluate the antibacterial activity and its bactericidal action mechanism against Staphylococcus aureus. DqV was tested against a standard strain of methicillin-sensitive Staphylococcus aureus (MSSA), Staph. aureus ATCC 6538P and two standard strains of methicillin-resistant Staphylococcus aureus (MRSA), Staph. aureus ATCC 33591 and Staph. aureus CCBH 5330. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), the rate of kill and pH sensitivity of the DqV were determined by microdilution tests. Bactericidal and inhibitory concentrations of DqV were tested to check its action on Staph. aureus membrane permeability and cell morphology. The MIC and MBC of DqV were 6·25 and 12·5 μg ml(-1) for Staph. aureus ATCC 6538P, 12·5 and 50 μg ml(-1) for Staph. aureus CCBH 5330 and 100 and 100 μg ml(-1) for Staph. aureus ATCC 33591, respectively. Complete bacterial growth inhibition was observed after 4 h of incubation with the MBC of DqV. A lowest MIC was observed in alkaline pH. Alteration in membrane permeability was observed through the increase in crystal violet uptake, genetic material release and morphology in atomic force microscopy. The results suggest antibacterial activity of DqV against Staph. aureus and that the venom acts in the cell membrane. Alteration in membrane permeability may be associated with the antimicrobial activity of hymenopteran venoms. © 2014 The Society for Applied Microbiology.

Mode of action and synergistic effect of valinomycin and cereulide with amphotericin B against Candida albicans and Cryptococcus albidus.

PubMed

Makarasen, A; Reukngam, N; Khlaychan, P; Chuysinuan, P; Isobe, M; Techasakul, S

2018-03-01

Both valinomycin and cereulide are cyclic depsipeptides and are known K + ion-selective ionophores. Valinomycin and cereulide feature low minimum inhibitory concentration (MIC) values against Candida albicans and Cryptococcus albidus. This study aims at investigating the mode of action and verifying the efficacy of valinomycin or cereulide alone and in combination with amphotericin B (AmB) in vitro against both microorganisms. Based on the results from membrane permeability and fluidity assays for detection of plasma membrane permeabilization and membrane dynamics, the present study demonstrated that valinomycin and cereulide exhibit antifungal activity against C. albicans and C. albidus by interrupting membrane-associated function. The mode of action of both valinomycin and cereulide are similar with that of AmB. Time-kill kinetics assay showed that valinomycin and cereulide exhibit fungistatic activity, whereas AmB features fungicidal activity. Additionally, the combination of compounds between each cyclic peptide and AmB reached maximal fungicidal activity more rapidly than AmB alone. This result corresponded with findings of scanning electron microscopy, fractional inhibitory concentration index and minimum fungicidal concentration (MFC)/MIC ratio, indicating that combinations of the drugs show synergistic effects for inhibiting the growth of these fungal strains. Sorbitol and ergosterol assays showed that both cyclic peptides affected cell wall and membrane components due to increases in MIC value, as observed in medium with sorbitol and ergosterol. Valinomycin and cereulide may promote permeability of fungal cell wall and cell membrane when used in combination with AmB. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

ASK2 Bioactive Compound Inhibits MDR Klebsiella pneumoniae by Antibiofilm Activity, Modulating Macrophage Cytokines and Opsonophagocytosis

PubMed Central

Lalitha, Cheepurupalli; Raman, Thiagarajan; Rathore, Sudarshan S.; Ramar, Manikandan; Munusamy, Arumugam; Ramakrishnan, Jayapradha

2017-01-01

The emergence and spread of pathogens harboring extended spectrum beta-lactamase (ESBL) like carbapenem resistant Gram negative bacteria are the major emerging threat to public health. Of particular concern Klebsiella pneumoniae carbapenamase- producing strains have been recorded worldwide. Catheter associated urinary tract infections (CAUTI) caused by K. pneumoniae are significantly associated with morbidity and mortality. Hence the present work was aimed to develop a strategy for addressing these issues through an innovative approach of antibiofilm and immunomodulation. These two independent activities were analyzed in a Streptomyces derived ASK2 bioactive compound. While analysing the effect of sub-minimum inhibitory concentrations (sub-MICs), 0.5x of Minimum Inhibitory Concentration (MIC) was found to be more effective in preventing biofilm formation on coverslip and silicone catheter. The minimum biofilm eradication concentration (MBEC) was found to be 15-fold higher MIC with eradication of 75% of 3 day old biofilm. Apart from its antibiofilm potential, ASK2 also acts as an opsonin and enhances phagocytic response of macrophages against multidrug resistant K. pneumoniae. In addition, ASK2 resulted in elevated levels of nitric oxide generation by the macrophages and has a stimulating effect on IL-12, IFN-γ, and TNF-α proinflammatory cytokines. The opsonic role of ASK2 and its potential in modulating proinflammatory cytokines secreted by macrophages implies the importance of ASK2 in modulating cellular immune response of macrophages against MDR K. pneumoniae. The present study proposes ASK2 as a promising candidate for treating MDR K. pneumoniae infections with its dual properties of antibiofilm and immunomodulatory activities. PMID:28824881

In Vitro Activity of Sodium New Houttuyfonate Alone and in Combination with Oxacillin or Netilmicin against Methicillin-Resistant Staphylococcus aureus

PubMed Central

Li, Xue; Lu, Yun; Ren, Zhitao; Zhao, Longyin; Hu, Xinxin; Jiang, Jiandong; You, Xuefu

2013-01-01

Background Staphylococcus aureus can cause severe infections, including bacteremia and sepsis. The spread of methicillin-resistant Staphylococcus aureus (MRSA) highlights the need for novel treatment options. Sodium new houttuyfonate (SNH) is an analogue of houttuynin, the main antibacterial ingredient of Houttuynia cordata Thunb. The aim of this study was to evaluate in vitro activity of SNH and its potential for synergy with antibiotics against hospital-associated MRSA. Methodology A total of 103 MRSA clinical isolates recovered in two hospitals in Beijing were evaluated for susceptibility to SNH, oxacillin, cephalothin, meropenem, vancomycin, levofloxacin, minocycline, netilmicin, and trimethoprim/sulfamethoxazole by broth microdilution. Ten isolates were evaluated for potential for synergy between SNH and the antibiotics above by checkerboard assay. Time-kill analysis was performed in three isolates to characterize the kill kinetics of SNH alone and in combination with the antibiotics that engendered synergy in checkerboard assays. Besides, two reference strains were included in all assays. Principal Findings SNH inhibited all test strains with minimum inhibitory concentrations (MICs) ranging from 16 to 64 µg/mL in susceptibility tests, and displayed inhibition to bacterial growth in concentration-dependent manner in time-kill analysis. In synergy studies, the combinations of SNH-oxacillin, SNH-cephalothin, SNH-meropenem and SNH-netilmicin showed synergistic effects against 12 MRSA strains with median fractional inhibitory concentration (FIC) indices of 0.38, 0.38, 0.25 and 0.38 in checkerboard assays. In time-kill analysis, SNH at 1/2 MIC in combination with oxacillin at 1/128 to 1/64 MIC or netilmicin at 1/8 to 1/2 MIC decreased the viable colonies by ≥2log10 CFU/mL. Conclusions/Significance SNH demonstrated in vitro antibacterial activity against 103 hospital-associated MRSA isolates. Combinations of sub-MIC levels of SNH and oxacillin or netilmicin significantly improved the in vitro antibacterial activity against MRSA compared with either drug alone. The SNH-based combinations showed promise in combating MRSA. PMID:23844154

Isolation and identification of antimicrobial compound from Mentha longifolia L. leaves grown wild in Iraq.

PubMed

Al-Bayati, Firas A

2009-06-12

Mentha longifolia L. (Lamiaceae) leaves have been traditionally implemented in the treatment of minor sore throat and minor mouth or throat irritation by the indigenous people of Iraq, although the compounds responsible for the medicinal properties have not been identified. In the present study, an antimicrobial compound was isolated and characterized, and its biological activity was assessed. The compound was isolated and characterized from the extracted essential oil using different spectral techniques: TLC, FTIR spectra and HPLC. Antimicrobial activity of the compound was assessed using both disc diffusion and microdilution method in 96 multi-well microtiter plates. A known compound was isolated from the essential oil of the plant and was identified as (-) menthol. The isolated compound was investigated for its antimicrobial activity against seven selected pathogenic and non-pathogenic microorganisms: Staphylococcus aureus, Streptococcus mutans, Streptococcus faecalis, Streptococcus pyogenis, Lactobacillus acidophilus, Pseudomonas aeruginosa and the yeast Candida albicans. Menthol at different concentrations (1:1, 1:5, 1:10, 1:20) was active against all tested bacteria except for P. aeruginosa, and the highest inhibitory effect was observed against S. mutans (zone of inhibition: 25.3 mm) using the disc diffusion method. Minimal inhibitory concentration MIC values ranged from 15.6-125.0 microg/ml, and the most promising results were observed against S. aureus and S. mutans (MIC 15.6 microg/ml) while, S. faecalis, S. pyogenis and L. acidophilus ranked next (MIC 31.2 microg/ml). Furthermore, menthol achieved considerable antifungal activity against the yeast C. albicans (zone of inhibition range: 7.1-18.5 mm; MIC: 125.0). The isolation of an antimicrobial compound from M. longifolia leaves validates the use of this plant in the treatment of minor sore throat and minor mouth or throat irritation.

Pharmacokinetics and Pharmacodynamics of Tildipirosin Against Pasteurella multocida in a Murine Lung Infection Model

PubMed Central

Zeng, Dongping; Sun, Meizhen; Lin, Zhoumeng; Li, Miao; Gehring, Ronette; Zeng, Zhenling

2018-01-01

Tildipirosin, a 16-membered-ring macrolide antimicrobial, has recently been approved for the treatment of swine respiratory disease and bovine respiratory disease. This macrolide is extensively distributed to the site of respiratory infection followed by slow elimination. Clinical efficacy has been demonstrated in cattle and swine clinical field trials. However, the pharmacokinetic/pharmacodynamic (PK/PD) index that best correlates with the efficacy of tildipirosin remains undefined. The objective of this study was to develop a PK/PD model following subcutaneous injection of tildipirosin against Pasteurella multocida in a murine lung infection model. The PK studies of unbound (f) tildipirosin in plasma were determined following subcutaneous injection of single doses of 1, 2, 4, 6, and 8 mg/kg of body weight in neutropenic lung-infected mice. The PD studies were conducted over 24 h based on twenty intermittent dosing regimens, of which total daily dose ranged from 1 to 32 mg/kg and dosage intervals included 6, 8, 12, and 24 h. The minimum inhibitory concentration (MIC) of tildipirosin against P. multocida was determined in serum. The inhibitory effect Imax model was employed for PK/PD modeling. The area under the unbound concentration-time profile over 24 h to MIC (fAUC0-24 h/MIC) was the PK/PD index that best described the antibacterial activity in the murine infection model. The fAUC0-24 h/MIC targets required to achieve the bacteriostatic action, a 1-log10 kill and 2-log10 kill of bacterial counts were 19.93, 31.89, and 53.27 h, respectively. These results can facilitate efforts to define more rational designs of dosage regimens of tildipirosin using classical PK/PD concepts for the treatment of respiratory diseases in pigs and cattle. PMID:29867911

Impact of psm-mec in the mobile genetic element on the clinical characteristics and outcome of SCCmec-II methicillin-resistant Staphylococcus aureus bacteraemia in Japan.

PubMed

Aoyagi, T; Kaito, C; Sekimizu, K; Omae, Y; Saito, Y; Mao, H; Inomata, S; Hatta, M; Endo, S; Kanamori, H; Gu, Y; Tokuda, K; Yano, H; Kitagawa, M; Kaku, M

2014-09-01

Over-expression of alpha-phenol-soluble modulins (PSMs) results in high virulence of community-associated methicillin-resistant Staphylococcus aureus (MRSA). The psm-mec gene, located in the mobile genetic element SCCmec-II, suppresses PSMαs production. Fifty-two patients with MRSA bacteraemia were enrolled. MRSA isolates were evaluated with regard to the psm-mec gene sequence, bacterial virulence, and the minimum inhibitory concentration (MIC) of vancomycin and teicoplanin. Fifty-one MRSA isolates were classified as SCCmec-II, and 10 had one point mutation in the psm-mec promoter. We compared clinical characteristics and outcomes between mutant MRSA and wild-type MRSA. Production of PSMα3 in mutant MRSA was significantly increased, but biofilm formation was suppressed. Wild-type MRSA caused more catheter-related bloodstream infections (30/41 vs. 3/10, p 0.0028), whereas mutant MRSA formed more deep abscesses (4/10 vs. 3/41, p 0.035). Bacteraemia caused by mutant MRSA was associated with reduced 30-day mortality (1/10 vs. 13/41, p 0.25), although this difference was not significant. The MIC90 of teicoplanin was higher for wild-type MRSA (1.5 mg/L vs. 1 mg/L), but the MIC of vancomycin was not different between the two groups. The 30-day mortality of MRSA with a high MIC of teicoplanin (≥1.5 mg/L) was higher than that of strains with a lower MIC (≤0.75 mg/L) (6/10 vs. 6/33, p 0.017). Mutation of the psm-mec promoter contributes to virulence of SCCmec-II MRSA, and the product of psm-mec may determine the clinical characteristics of bacteraemia caused by SCCmec-II MRSA, but it does not affect mortality. © 2014 The Authors Clinical Microbiology and Infection © 2014 European Society of Clinical Microbiology and Infectious Diseases.

Occurrence of porphyromonas gingivalis and its antibacterial susceptibility to metronidazole and tetracycline in patients with chronic periodontitis.

PubMed

Gamboa, Fredy; Acosta, Adriana; García, Dabeiba-Adriana; Velosa, Juliana; Araya, Natalia; Ledergerber, Roberto

2014-01-01

Chronic periodontitis is a multifactorial infectious disease associated with Gram-negative strict anaerobes which are immersed in the subgingival biofilm. Porphyromonas gingivalis, an important periodontal pathogen, is frequently detected in patients with chronic periodontitis. Although isolates of P. gingivalis tend to be susceptible to most antimicrobial agents, relatively little information is available on its in vitro antimicrobial susceptibility. The aim of this study was to determine the frequency of P. gingivalis in patients with chronic periodontitis and to assess antimicrobial susceptibility in terms of minimum inhibitory concentration (MIC) of clinical isolates to metronidazole and tetracycline. A descriptive, observational study was performed including 87 patients with chronic periodontitis. Samples were taken from the periodontal pocket using paper points, which were placed in thioglycollate broth. Samples were incubated for 4 hours at 37°C in anaerobic conditions and finally replated on Wilkins-Chalgren anaerobic agar (Oxoid). Bacteria were identified using the RapIDTMANAII system (Remel) and antimicrobial susceptibility was determined with the M.I.C. Evaluator test (MICE, Oxoid). P. gingivalis was identified in 30 of the 87 patients with chronic periodontitis, which represents a frequency of 34.5%. All 30 isolates (100%) were sensitive to metronidazole, with MIC values ranging from 0015-4ug/ml. Regarding tetracycline, 27 isolates (90%) were sensitive, with MIC values ranging from <0.015 to 4 ug /ml, the remaining three isolates (10%) were resistant to tetracycline with MIC values of 8ug/ ml. There was no statistically significant difference in age, gender, pocket depth, clinical attachment level and severity of periodontitis between the group of patients with chronic periodontitis and P. gingivalis and the group of patients with chronic periodontitis without P. gingivalis. In conclusion, P. gingivalis was found at a frequency of 34.5% in patients with chronic periodontitis and clinical isolates were highly sensitive to metronidazole and tetracycline.

Bacteriocins and other bioactive substances of probiotic lactobacilli as biological weapons against Neisseria gonorrhoeae.

PubMed

Ruíz, Francisco O; Pascual, Liliana; Giordano, Walter; Barberis, Lucila

2015-04-01

In the search of new antimicrobial agents against Neisseria gonorrhoeae, the bacteriocins-producing probiotic lactobacilli deserve special attention. The inhibitory effects of biosubstances such as organic acids, hydrogen peroxide and each bacteriocin-like inhibitory substance (BLIS) L23 and L60 on the growth of different gonococcal strains were investigated. Different non-treated and treated cell-free supernatants of two probiotic lactobacilli containing these metabolites were used. The aims of this work were (i) to evaluate the antimicrobial activity of the biosubstances produced by two probiotic lactobacilli, estimating the proportion in which each of them is responsible for the inhibitory effect, (ii) to define their minimum inhibitory concentrations (MICs) and, (iii) to determine the potential interactions between these biosubstances against N. gonorrhoeae. The main antimicrobial metabolites were the BLIS-es L23 and L60 in comparison with other biosubstances. Proportionally, their contributions to the inhibition on the gonococcal growth were 87.28% and 80.66%, respectively. The MIC values of bacteriocins were promising since these substances, when diluted, showed considerable inhibitory activity for all gonococci. In the interaction between bacteriocins, 100% of synergism was found on the gonococcal growth. In summary, this study indicates that both L23 and L60 could potentially serve to design new bioproducts against N. gonorrhoeae. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Antibiotic Susceptibility of Staphylococci Isolates from Patients with Chronic Conjunctivitis: Including Associated Factors and Clinical Evaluation

PubMed Central

Núñez, María Ximena

2013-01-01

Abstract Purpose To determine species of staphylococci in chronic conjunctivitis, their antibiotic susceptibility pattern, patient treatments, clinical course, and clinical conditions. Methods In this prospective study, 243 conjunctival cultures were taken from 191 patients with chronic conjunctivitis, we obtained staphylococci susceptibility patterns with E-test, and they were analyzed in coagulase-positive and negative. The minimum inhibitory concentration for 90% of isolates (MIC90) was determined for Staphylococcus aureus and Staphylococcus epidermidis. Additionally, clinical follow-up and associated factors of all patients were analyzed depending on methicillin resistance (MR) or susceptibility (MS) bacterial state. Results One hundred and eight (44%) cultures were positive; 81 positive cultures were Gram-positive of which, 77 were staphylococci, 29 coagulase-positive with S. aureus as the most prevalent, 89% MS, and 11% MR. And 48 were coagulase-negative with S. epidermidis as the most isolated with 36% of MS and 64% of MR. Poor susceptibility was found in the staphylococcus coagulase-negative/MR group. Moxifloxacin and vancomycin show the best in vitro activity for all isolates. The MIC90 of moxifloxacin and vancomycin were 0.064/1.5, 0.64/3.0, and 1/3.0 for S. aureus-MS, S. epidermidis-MS, and S. epidermidis-MR, respectively. The most frequently associated factors found in patients with positive culture for staphylococcus were exposure to the health care system 23 (29.87%) of 77 patients and dry eye 23 (29.87%) of 77 patients. Both with a proportion of 3 in 10. Conclusion Coagulase-negative staphylococci were the most frequently isolated from the conjunctiva with 58.33% of MR; even though multiresistance was detected, their susceptibility to a fourth-generation fluoroquinolone, commonly used, such as moxifloxacin, was preserved. PMID:23944906

Role of gyrB Mutations in Pre-extensively and Extensively Drug-Resistant Tuberculosis in Thai Clinical Isolates

PubMed Central

Disratthakit, Areeya; Prammananan, Therdsak; Tribuddharat, Chanwit; Thaipisuttikul, Iyarit; Doi, Norio; Leechawengwongs, Manoon

2016-01-01

DNA gyrase mutations are a major cause of quinolone resistance in Mycobacterium tuberculosis. We therefore conducted the first comprehensive study to determine the diversity of gyrase mutations in pre-extensively drug-resistant (pre-XDR) (n = 71) and extensively drug-resistant (XDR) (n = 30) Thai clinical tuberculosis (TB) isolates. All pre-XDR-TB and XDR-TB isolates carried at least one mutation within the quinolone resistance-determining region of GyrA (G88A [1.1%], A90V [17.4%], S91P [1.1%], or D94A/G/H/N/V/Y [72.7%]) or GyrB (D533A [1.1%], N538D [1.1%], or E540D [2.2%]). MIC and DNA gyrase supercoiling inhibition assays were performed to determine the role of gyrase mutations in quinolone resistance. Compared to the MICs against M. tuberculosis H37Rv, the levels of resistance to all quinolones tested in the isolates that carried GyrA-D94G or GyrB-N538D (8- to 32-fold increase) were significantly higher than those in isolates bearing GyrA-D94A or GyrA-A90V (2- to 8-fold increase) (P < 0.01). Intriguingly, GyrB-E540D led to a dramatic resistance to later-generation quinolones, including moxifloxacin, gatifloxacin, and sparfloxacin (8- to 16-fold increases in MICs and 8.3- to 11.2-fold increases in 50% inhibitory concentrations [IC50s]). However, GyrB-E540D caused low-level resistance to early-generation quinolones, including ofloxacin, levofloxacin, and ciprofloxacin (2- to 4-fold increases in MICs and 1.5- to 2.0-fold increases in IC50s). In the present study, DC-159a was the most active antituberculosis agent and was little affected by the gyrase mutations described above. Our findings suggest that although they are rare, gyrB mutations have a notable role in quinolone resistance, which may provide clues to the molecular basis of estimating quinolone resistance levels for drug and dose selection. PMID:27297489

Antibiotic loaded nanocapsules functionalized with aptamer gates for targeted destruction of pathogens.

PubMed

Kavruk, M; Celikbicak, O; Ozalp, V C; Borsa, B A; Hernandez, F J; Bayramoglu, G; Salih, B; Arica, M Y

2015-05-18

In this study, we designed aptamer-gated nanocapsules for the specific targeting of cargo to bacteria with controlled release of antibiotics based on aptamer-receptor interactions. Aptamer-gates caused a specific decrease in minimum inhibitory concentration (MIC) values of vancomycin for Staphylococcus aureus when mesoporous silica nanoparticles (MSNs) were used for bacteria-targeted delivery.

Bactericidal effects of various concentrations of enrofloxacin, florfenicol, tilmicosin phosphate, and tulathromycin on clinical isolates of Mannheimia haemolytica.

PubMed

Blondeau, Joseph M; Shebelski, Shantelle D; Hesje, Christine K

2015-10-01

To determine bactericidal effects of enrofloxacin, florfenicol, tilmicosin, and tulathromycin on clinical isolates of Mannheimia haemolytica at various bacterial densities and drug concentrations. 4 unique isolates of M haemolytica recovered from clinically infected cattle. Minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) were determined for each drug and isolate. Mannheimia haemolytica suspensions (10(6) to 10(9) CFUs/mL) were exposed to the determined MIC and MPC and preestablished maximum serum and tissue concentrations of each drug. Log10 reduction in viable cells (percentage of cells killed) was measured at various points. Bacterial killing at the MIC was slow and incomplete. After 2 hours of isolate exposure to the MPC and maximum serum and tissue concentrations of the tested drugs, 91% to almost 100% cell killing was achieved with enrofloxacin, compared with 8% growth to 93% cell killing with florfenicol, 199% growth to 63% cell killing with tilmicosin, and 128% growth to 43% cell killing with tulathromycin over the range of inoculum tested. For all drugs, killing of viable organisms was evident at all bacterial densities tested; however, killing was more substantial at the MPC and maximum serum and tissue drug concentrations than at the MIC and increased with duration of drug exposure. Rank order of drugs by killing potency was enrofloxacin, florfenicol, tilmicosin, and tulathromycin. Findings suggested that antimicrobial doses that equaled or exceeded the MPC provided rapid killing of M haemolytica by the tested drugs, decreasing opportunities for antimicrobial-resistant subpopulations of bacteria to develop during drug exposure.

Escherichia coli Cell Surface Perturbation and Disruption Induced by Antimicrobial Peptides BP100 and pepR*

PubMed Central

Alves, Carla S.; Melo, Manuel N.; Franquelim, Henri G.; Ferre, Rafael; Planas, Marta; Feliu, Lidia; Bardají, Eduard; Kowalczyk, Wioleta; Andreu, David; Santos, Nuno C.; Fernandes, Miguel X.; Castanho, Miguel A. R. B.

2010-01-01

The potential of antimicrobial peptides (AMPs) as an alternative to conventional therapies is well recognized. Insights into the biological and biophysical properties of AMPs are thus key to understanding their mode of action. In this study, the mechanisms adopted by two AMPs in disrupting the Gram-negative Escherichia coli bacterial envelope were explored. BP100 is a short cecropin A-melittin hybrid peptide known to inhibit the growth of phytopathogenic Gram-negative bacteria. pepR, on the other hand, is a novel AMP derived from the dengue virus capsid protein. Both BP100 and pepR were found to inhibit the growth of E. coli at micromolar concentrations. Zeta potential measurements of E. coli incubated with increasing peptide concentrations allowed for the establishment of a correlation between the minimal inhibitory concentration (MIC) of each AMP and membrane surface charge neutralization. While a neutralization-mediated killing mechanism adopted by either AMP is not necessarily implied, the hypothesis that surface neutralization occurs close to MIC values was confirmed. Atomic force microscopy (AFM) was then employed to visualize the structural effect of the interaction of each AMP with the E. coli cell envelope. At their MICs, BP100 and pepR progressively destroyed the bacterial envelope, with extensive damage already occurring 2 h after peptide addition to the bacteria. A similar effect was observed for each AMP in the concentration-dependent studies. At peptide concentrations below MIC values, only minor disruptions of the bacterial surface occurred. PMID:20566635

Inhibitory and bactericidal potential of crude acetone extracts of Combretum molle (Combretaceae) on drug-resistant strains of Helicobacter pylori.

PubMed

Njume, Collise; Afolayan, Anthony J; Samie, Amidou; Ndip, Roland N

2011-10-01

Infection with Helicobacter pylori is strongly associated with a number of gastroduodenal pathologies. Antimicrobial resistance to commonly-used drugs has generated a considerable interest in the search for novel therapeutic compounds from medicinal plants. As an ongoing effort of this search, the susceptibility of 32 clinical strains of H. pylori and a reference strain-NCTC 11,638-was evaluated against five solvent extracts of Combretum molle, a plant widely used for the treatment of gastric ulcers and other stomach-related morbidities in South Africa. The extracts were screened for activity by the agar-well diffusion method, and the most active one of them was tested against the same strains by micro-broth dilution and time kill assays. Metronidazole and amoxicillin were included in these experiments as positive control antibiotics. The solvent extracts all demonstrated anti-H. pylori activity with zone diameters of inhibition between 0 and 38 mm. The most potent anti-H. pylori activity was demonstrated by the acetone extract, to which 87.5% of the clinical strains were susceptible. The minimum inhibitory concentration (MIC90) values for this extract ranged from 1.25 to 5.0 mg/mL while those for amoxicillin and metronidazole ranged from 0.001 to 0.94 mg/mL and from 0.004 to 5.0 mg/mL respectively. The acetone extract was highly bactericidal at a concentration of 2.5 and 5.0 mg/mL, with complete elimination of the test organisms in 24 hours. Its inhibitory activity was better than that of metronidazole (p<0.05) as opposed to amoxicillin (p<0.05). The results demonstrate that C. molle may contain therapeutically-useful compounds against H. pylori, which are mostly concentrated in the acetone extract.

In Vitro Activity and MIC of Sitafloxacin against Multidrug-Resistant and Extensively Drug-Resistant Mycobacterium tuberculosis Isolated in Thailand

PubMed Central

Leechawengwongs, Manoon; Prammananan, Therdsak; Jaitrong, Sarinya; Billamas, Pamaree; Makhao, Nampueng; Thamnongdee, Nongnard; Thanormchat, Arirat; Phurattanakornkul, Arisa; Rattanarangsee, Somcharn; Ratanajaraya, Chate; Disratthakit, Areeya

2017-01-01

ABSTRACT New fluoroquinolones (FQs) have been shown to be more active against drug-resistant Mycobacterium tuberculosis strains than early FQs, such as ofloxacin. Sitafloxacin (STFX) is a new fluoroquinolone with in vitro activity against a broad range of bacteria, including M. tuberculosis. This study aimed to determine the in vitro activity of STFX against all groups of drug-resistant strains, including multidrug-resistant M. tuberculosis (MDR M. tuberculosis), MDR M. tuberculosis with quinolone resistance (pre-XDR), and extensively drug-resistant (XDR) strains. A total of 374 drug-resistant M. tuberculosis strains were tested for drug susceptibility by the conventional proportion method, and 95 strains were randomly submitted for MIC determination using the microplate alamarBlue assay (MABA). The results revealed that all the drug-resistant strains were susceptible to STFX at a critical concentration of 2 μg/ml. Determination of the MIC90s of the strains showed different MIC levels; MDR M. tuberculosis strains had a MIC90 of 0.0625 μg/ml, whereas pre-XDR and XDR M. tuberculosis strains had identical MIC90s of 0.5 μg/ml. Common mutations within the quinolone resistance-determining region (QRDR) of gyrA and/or gyrB did not confer resistance to STFX, except that double mutations of GyrA at Ala90Val and Asp94Ala were found in strains with a MIC of 1.0 μg/ml. The results indicated that STFX had potent in vitro activity against all the groups of drug-resistant M. tuberculosis strains and should be considered a new repurposed drug for treatment of multidrug-resistant and extensively drug-resistant TB. PMID:29061759

Pharmacokinetics/pharmacodynamics of levofloxacin 750 mg once daily in young women with acute uncomplicated pyelonephritis.

PubMed

Nicolle, Lindsay; Duckworth, Heather; Sitar, Dan; Bryski, Lisa; Harding, Godfrey; Zhanel, George

2008-03-01

This pilot study was undertaken to characterise the pharmacokinetics, pharmacodynamics and potential clinical efficacy of levofloxacin 750 mg once daily for 5 days for treatment of women with acute uncomplicated pyelonephritis. Four women diagnosed with acute pyelonephritis were enrolled. Following pre-therapy specimen collection, an initial oral dose of 750 mg levofloxacin was administered. The mean pharmacokinetic parameters for the first dose were: maximum serum concentration (C(max)) 12.5+/-4.7 mg/L (range 5.6-16.0mg/L) (fC(max) 8.8+/-3.3, where f indicates the levofloxacin free or non-protein-bound fraction), area under the serum concentration-time curve (AUC) 85.4+/-14.1 mgh/L (range 66.2-96.8 mgh/L) (fAUC 59.8+/-9.9) and serum half-life (t(1/2)) 6.7+/-0.5h. Mean urine concentrations were 88.0+/-100mg/L at the 0-3 h collection, 307+/-143 mg/L at 3-6 h, 170+/-107 mg/L at 6-12 h and 85+/-8 mg/L at 12-24 h. Mean levofloxacin serum pharmacodynamics for infecting Escherichia coli were: C(max)/minimum inhibitory concentration (MIC) 323+/-185(fC(max)/MIC 226+/-129); and AUC/MIC 2339+/-830(fAUC/MIC 1647+/-579). Mean urine levofloxacin concentration/MIC ratios were: 900+/-1389 for 0-3 h, 12100+/-4950 for 3-6 h, 5922+/-3912 for 6-12 h and 2233+/-1037 for 12-24 h. Levofloxacin eradicated E. coli from the urine by 3-6 h after the first dose. Levofloxacin 750 mg once daily for 5 days has pharmacodynamics that support further evaluation of this regimen for treatment of women with acute uncomplicated pyelonephritis.

Olive leaf extract activity against Candida albicans and C. dubliniensis - the in vitro viability study.

PubMed

Zorić, Nataša; Kopjar, Nevenka; Kraljić, Klara; Oršolić, Nada; Tomić, Siniša; Kosalec, Ivan

2016-09-01

Olive leaf extract is characterized by a high content of polyphenols (oleuropein, hydroxytyrosol and their derivatives), which is associated with its therapeutic properties. The objective of the present research was to evaluate the antifungal activity of olive leaf extract against Candida albicans ATCC 10231 and C. dubliniensis CBS 7987 strains. Minimum inhibitory concentrations (MIC) of the extract were determined by several in vitro assays. The extract showed a concentration depended effect on the viability of C. albicans with MIC value of 46.875 mg mL-1 and C. dubliniensis with MIC value 62.5 mg mL-1. Most sensitive methods for testing the antifungal effect of the extracts were the trypan blue exclusion method and fluorescent dye exclusion method while MIC could not be determined by the method according to the EUCAST recommendation suggesting that herbal preparations contain compounds that may interfere with this susceptibility testing. The fluorescent dye exclusion method was also used for the assessment of morphological changes in the nuclei of treated cells. According to the obtained results, olive leaf extract is less effective against the tested strains than hydroxytyrosol, an olive plant constituent tested in our previous study.

Evaluation of the antimicrobial efficacy of Minthostachys verticillata essential oil and limonene against Streptococcus uberis strains isolated from bovine mastitis.

PubMed

Montironi, Ivana D; Cariddi, Laura N; Reinoso, Elina B

Bovine mastitis is a disease that causes great economic losses per year, being Streptococcus uberis the main environmental pathogen involved. The aim of the present study was to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of Minthostachys verticillata essential oil and limonene for S. uberis strains isolated from bovine mastitis. In addition, the effect of MIC on biofilm formation was analyzed. MIC values for the essential oil ranged from 14.3 to 114.5mg/ml (1.56-12.5%v/v) and MBC between 114.5 and 229mg/ml (12.5-25%v/v). MICs for limonene ranged from 3.3 to 52.5mg/ml (0.39-6.25%v/v) and MBC was 210mg/ml (25%v/v). Both compounds showed antibacterial activity and affected the biofilm formation of most of the strains tested. In conclusion, these compounds could be used as an alternative and/or complementary therapy for bovine mastitis caused by S. uberis. Copyright © 2016 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Chemical composition, antibacterial and antifungal activities of essential oil from Cordia verbenacea DC leaves.

PubMed

Rodrigues, Fabiola F G; Oliveira, Liana G S; Rodrigues, Fábio F G; Saraiva, Manuele E; Almeida, Sheyla C X; Cabral, Mario E S; Campos, Adriana R; Costa, Jose Galberto M

2012-07-01

Cordia verbenacea is a Brazilian coastal shrub popularly known as "erva baleeira". The essential oil from fresh leaves was obtained by hydrodistillation and analyzed by CG/MS. The main components were identified as β-caryophyllene (25.4%), bicyclogermacrene (11.3%), δ-cadinene (9.%) and α-pinene (9.5%). In this study, the antimicrobial activity of Cordia verbenacea was evaluated. The minimal inhibitory concentration (MIC) of the essential oil was obtained using the broth microdilution assay (from 512 to 8 μg/ml). The results showed that the essential oil presented fungistatic activity against Candida albicans and Candida krusei and antibacterial activity against Gram-positive strains (Staphylococcus aureus and Bacillus cereus) and against multiresistant Gram-negative (Escherichia coli 27), in all tests the MIC was 64 μg/ml. When the essential oil was associated to aminoglycosides (subinhibitory concentrations, MIC/8), a synergic and antagonic activity was verified. The synergic effect was observed to the amikacin association (MIC reduction from 256 mlto 64 μg/ml) in all strains tested. The essential oil of Cordia verbenacea influences the activity of antibiotics and may be used as an adjuvant in antibiotic therapy against respiratory tract bacterial pathogens.

Evaluation of antioxidant and antimicrobial activities of essential oils from Carum copticum seed and Ferula assafoetida latex.

PubMed

Kavoosi, Gholamreza; Tafsiry, Asad; Ebdam, Ali Asghar; Rowshan, Vahid

2013-02-01

Carum copticum and Ferula assafoetida have several medicinal properties including antispasmodic, carminative, sedative, analgesic, and antiseptic. Reactive oxygen species (ROS), reactive nitrogen species (RNS), hydrogen peroxide (H(2) O(2) ), and thiobarbituric acid reactive substances (TBARS) scavenging activities of Carum and Ferula oils along with their antibacterial and antifungal activities were examined. Thymol (40.25%), γ-terpinene (38.7%) and p-cymene (15.8%) were detected as the main components of Carum oil while, β-pinene (47.1%), α-pinene (21.36%), and 1, 2-dithiolane (18.6%) were the main components of Ferula oil. Inhibitory concentrations (IC50) for total radical scavenging were between 40 and 60 and 130 and 160 μg/mL of Carum and Ferula oil, respectively. Minimal inhibitory concentration (MIC) for Salmonella typhi, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Aspergillus niger, and Candida albicans were 78 ± 8, 65 ± 7, 14 ± 3, 5 ± 2, 5.6 ± 1.3, and 8.8 ± 2.2 μg/mL of Carum oil, respectively. MIC for S. typhi, E. coli, S. aureus, B. subtilis, A. niger, and C. albicans were >200, >200, 125 ± 17, 80 ± 12, 85 ± 5, and 90 ± 11 μg/mL of Ferula oil, respectively. Accordingly, Carum and Ferula oils could be used as safe and effective natural antioxidants to improve the oxidative stability of fatty foods during storage and to preserve foods against food burn pathogens. This study clearly demonstrates the potential of Carum and Ferula oil especially Carum oil as natural antioxidant and antimicrobial agent. The chemical composition of essential oils was identified. Thus, identification of such compounds also helps to discover of new antioxidant, antibacterial and antifungal agents for potential applications in food safety and food preservation. © 2013 Institute of Food Technologists®

Modulation of the norfloxacin resistance in Staphylococcus aureus by Cordia verbenaceae DC.

PubMed

Matias, Edinardo F F; Santos, Karla K A; Falcão-Silva, Vivyanne S; Siqueira-Junior, Jose P; Costa, Jose G M; Coutinho, Henrique D M

2013-01-01

Several chemical compounds isolated from natural sources have antibacterial activity and some enhance the antibacterial activity of antibiotics reversing the natural resistance of bacteria to certain antibiotics. In this study, the hexane and methanol extract of Cordia verbenaceae were assessed for antibacterial activity alone and combinated with norfloxacin against the Staphylococcus aureus strain SA1199B. The minimum inhibitory concentration (MIC) of extracts was assayed using microdilution assay and the modulatory activity was evaluated using plate diffusion assay. The MIC observed varied between 256 to >1024 μg/ml. However, the antibiotic activity of norfloxacin was enhanced in the presence of subinhibitory concentrations of hexane extract of C. verbenaceae (HECV). INTERPRETATIONS & CONCLUSIONS: Our results indicate that Cordia verbenaceae DC. can be a source of plant derived products with antibiotic modifying activity.

Reduced susceptibility to chlorhexidine disinfectant among New Delhi metallo-beta-lactamase-1 positive Enterobacteriaceae and other multidrug-resistant organisms: Report from a tertiary care hospital in Karachi, Pakistan.

PubMed

Mal, P B; Farooqi, J; Irfan, S; Hughes, M A; Khan, E

2016-01-01

We analysed susceptibility of multidrug-resistant organisms (MDROs) including New Delhi metallo-beta-lactamase-1 positive Enterobacteriaceae to chlorhexidine and compared results to their susceptible counterparts. Susceptibilities of chlorhexidine digluconate in a standard (CHX-S) preparation and two commercial disinfectants containing different CHX concentrations (2% w/v and 4% w/w) were performed. MDROs had narrower range of higher CHX-S minimum inhibitory concentrations (MICs) as compared to pan-sensitive organisms. The MIC values for commercial disinfectants products for MDROs were many folds higher (20-600 times), than CHX-S for in vitro use. Increasing antibiotic resistance among bacterial isolates can be an indirect marker of reduced susceptibility to chlorhexidine in hospital setting.

Antibacterial activity of selected Malaysian honey

PubMed Central

2013-01-01

Background Antibacterial activity of honey is mainly dependent on a combination of its peroxide activity and non-peroxide components. This study aims to investigate antibacterial activity of five varieties of Malaysian honey (three monofloral; acacia, gelam and pineapple, and two polyfloral; kelulut and tualang) against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa. Methods Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were performed for semi-quantitative evaluation. Agar well diffusion assay was used to investigate peroxide and non-peroxide activities of honey. Results The results showed that gelam honey possessed lowest MIC value against S. aureus with 5% (w/v) MIC and MBC of 6.25% (w/v). Highest MIC values were shown by pineapple honey against E. coli and P. aeruginosa as well as acacia honey against E. coli with 25% (w/v) MIC and 50% (w/v) MBC values. Agar inhibition assay showed kelulut honey to possess highest total antibacterial activity against S. aureus with 26.49 equivalent phenol concentrations (EPC) and non-peroxide activity of 25.74 EPC. Lowest antibacterial activity was observed in acacia honey against E. coli with total activity of 7.85 EPC and non-peroxide activity of 7.59 EPC. There were no significant differences (p > 0.05) between the total antibacterial activities and non-peroxide activities of Malaysian honey. The intraspecific correlation between MIC and EPC of E. coli (r = -0.8559) was high while that between MIC and EPC of P. aeruginosa was observed to be moderate (r = -0.6469). S. aureus recorded a smaller correlation towards the opposite direction (r = 0.5045). In contrast, B.cereus showed a very low intraspecific correlation between MIC and EPC (r = -0.1482). Conclusions Malaysian honey, namely gelam, kelulut and tualang, have high antibacterial potency derived from total and non-peroxide activities, which implies that both peroxide and other constituents are mutually important as contributing factors to the antibacterial property of honey. PMID:23758747

Antibacterial activity of selected Malaysian honey.

PubMed

Zainol, Mohd Izwan; Mohd Yusoff, Kamaruddin; Mohd Yusof, Mohd Yasim

2013-06-10

Antibacterial activity of honey is mainly dependent on a combination of its peroxide activity and non-peroxide components. This study aims to investigate antibacterial activity of five varieties of Malaysian honey (three monofloral; acacia, gelam and pineapple, and two polyfloral; kelulut and tualang) against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were performed for semi-quantitative evaluation. Agar well diffusion assay was used to investigate peroxide and non-peroxide activities of honey. The results showed that gelam honey possessed lowest MIC value against S. aureus with 5% (w/v) MIC and MBC of 6.25% (w/v). Highest MIC values were shown by pineapple honey against E. coli and P. aeruginosa as well as acacia honey against E. coli with 25% (w/v) MIC and 50% (w/v) MBC values. Agar inhibition assay showed kelulut honey to possess highest total antibacterial activity against S. aureus with 26.49 equivalent phenol concentrations (EPC) and non-peroxide activity of 25.74 EPC. Lowest antibacterial activity was observed in acacia honey against E. coli with total activity of 7.85 EPC and non-peroxide activity of 7.59 EPC. There were no significant differences (p > 0.05) between the total antibacterial activities and non-peroxide activities of Malaysian honey. The intraspecific correlation between MIC and EPC of E. coli (r = -0.8559) was high while that between MIC and EPC of P. aeruginosa was observed to be moderate (r = -0.6469). S. aureus recorded a smaller correlation towards the opposite direction (r = 0.5045). In contrast, B.cereus showed a very low intraspecific correlation between MIC and EPC (r = -0.1482). Malaysian honey, namely gelam, kelulut and tualang, have high antibacterial potency derived from total and non-peroxide activities, which implies that both peroxide and other constituents are mutually important as contributing factors to the antibacterial property of honey.

Bactericidal activity and post-antibiotic effect of ozenoxacin against Propionibacterium acnes.

PubMed

Kanayama, Shoji; Okamoto, Kazuaki; Ikeda, Fumiaki; Ishii, Ritsuko; Matsumoto, Tatsumi; Hayashi, Naoki; Gotoh, Naomasa

2017-06-01

Ozenoxacin, a novel non-fluorinated topical quinolone, is used for the treatment of acne vulgaris in Japan. We investigated bactericidal activity and post-antibiotic effect (PAE) of ozenoxacin against Propionibacterium acnes, a major causative bacterium of acne vulgaris. The minimum inhibitory concentrations (MICs) of ozenoxacin against 3 levofloxacin-susceptible strains (MIC of levofloxacin; ≤4 μg/mL) and 3 levofloxacin-resistant strains (MIC of levofloxacin; ≥8 μg/mL) ranged from 0.03 to 0.06 μg/mL and from 0.25 to 0.5 μg/mL, respectively. These MICs of ozenoxacin were almost the same or lower than nadifloxacin and clindamycin. The minimum bactericidal concentrations (MBCs) of ozenoxacin against the levofloxacin-susceptible and -resistant strains were from 0.06 to 8 μg/mL and from 0.5 to 4 μg/mL, respectively. These MBCs were lower than those of nadifloxacin and clindamycin. In time-kill assay, ozenoxacin at 1/4, 1 and 4 times the respective MIC against both levofloxacin-susceptible and -resistant strains showed a concentration-dependent bactericidal activity. Ozenoxacin at 4 times the MICs against the levofloxacin-susceptible strains showed more potent and more rapid onset of bactericidal activity compared to nadifloxacin and clindamycin at 4 times the respective MICs. The PAEs of ozenoxacin at 4 times the MICs against the levofloxacin-susceptible strains were from 3.3 to 17.1 h, which were almost the same or longer than nadifloxacin and clindamycin. In contrast, the PAEs were hardly induced by any antimicrobial agents against the levofloxacin-resistant strains. The present findings suggest that ozenoxacin has a potent bactericidal activity against both levofloxacin-susceptible and -resistant P. acnes, and a long-lasting PAE against levofloxacin-susceptible P. acnes. Copyright © 2017 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Re-Examining the Role of Hydrogen Peroxide in Bacteriostatic and Bactericidal Activities of Honey

PubMed Central

Brudzynski, Katrina; Abubaker, Kamal; St-Martin, Laurent; Castle, Alan

2011-01-01

The aim of this study was to critically analyze the effects of hydrogen peroxide on growth and survival of bacterial cells in order to prove or disprove its purported role as a main component responsible for the antibacterial activity of honey. Using the sensitive peroxide/peroxidase assay, broth microdilution assay and DNA degradation assays, the quantitative relationships between the content of H2O2 and honey’s antibacterial activity was established. The results showed that: (A) the average H2O2 content in honey was over 900-fold lower than that observed in disinfectants that kills bacteria on contact. (B) A supplementation of bacterial cultures with H2O2 inhibited E. coli and B. subtilis growth in a concentration-dependent manner, with minimal inhibitory concentrations (MIC90) values of 1.25 mM/107 cfu/ml and 2.5 mM/107 cfu/ml for E. coli and B. subtilis, respectively. In contrast, the MIC90 of honey against E. coli correlated with honey H2O2 content of 2.5 mM, and growth inhibition of B. subtilis by honey did not correlate with honey H2O2 levels at all. (C) A supplementation of bacterial cultures with H2O2 caused a concentration-dependent degradation of bacterial DNA, with the minimum DNA degrading concentration occurring at 2.5 mM H2O2. DNA degradation by honey occurred at lower than ≤2.5 mM concentration of honey H2O2 suggested an enhancing effect of other honey components. (D) Honeys with low H2O2 content were unable to cleave DNA but the addition of H2O2 restored this activity. The DNase-like activity was heat-resistant but catalase-sensitive indicating that H2O2 participated in the oxidative DNA damage. We concluded that the honey H2O2 was involved in oxidative damage causing bacterial growth inhibition and DNA degradation, but these effects were modulated by other honey components. PMID:22046173

Re-examining the role of hydrogen peroxide in bacteriostatic and bactericidal activities of honey.

PubMed

Brudzynski, Katrina; Abubaker, Kamal; St-Martin, Laurent; Castle, Alan

2011-01-01

The aim of this study was to critically analyze the effects of hydrogen peroxide on growth and survival of bacterial cells in order to prove or disprove its purported role as a main component responsible for the antibacterial activity of honey. Using the sensitive peroxide/peroxidase assay, broth microdilution assay and DNA degradation assays, the quantitative relationships between the content of H(2)O(2) and honey's antibacterial activity was established(.) The results showed that: (A) the average H(2)O(2) content in honey was over 900-fold lower than that observed in disinfectants that kills bacteria on contact. (B) A supplementation of bacterial cultures with H(2)O(2) inhibited E. coli and B. subtilis growth in a concentration-dependent manner, with minimal inhibitory concentrations (MIC(90)) values of 1.25 mM/10(7) cfu/ml and 2.5 mM/10(7) cfu/ml for E. coli and B. subtilis, respectively. In contrast, the MIC(90) of honey against E. coli correlated with honey H(2)O(2) content of 2.5 mM, and growth inhibition of B. subtilis by honey did not correlate with honey H(2)O(2) levels at all. (C) A supplementation of bacterial cultures with H(2)O(2) caused a concentration-dependent degradation of bacterial DNA, with the minimum DNA degrading concentration occurring at 2.5 mM H(2)O(2). DNA degradation by honey occurred at lower than ≤2.5 mM concentration of honey H(2)O(2) suggested an enhancing effect of other honey components. (D) Honeys with low H(2)O(2) content were unable to cleave DNA but the addition of H(2)O(2) restored this activity. The DNase-like activity was heat-resistant but catalase-sensitive indicating that H(2)O(2) participated in the oxidative DNA damage. We concluded that the honey H(2)O(2) was involved in oxidative damage causing bacterial growth inhibition and DNA degradation, but these effects were modulated by other honey components.

The PK/PD Interactions of Doxycycline against Mycoplasma gallisepticum

PubMed Central

Zhang, Nan; Gu, Xiaoyan; Ye, Xiaomei; Wu, Xun; Zhang, Bingxu; Zhang, Longfei; Shen, Xiangguang; Jiang, Hongxia; Ding, Huanzhong

2016-01-01

Mycoplasma gallisepticum is one of the most important pathogens that cause chronic respiratory disease in chicken. This study investigated the antibacterial activity of doxycycline against M. gallisepticum strain S6. In static time–killing studies with constant antibiotic concentrations [0–64 minimum inhibitory concentration (MIC)], M. gallisepticum colonies were quantified and kill rates were calculated to estimate the drug effect. The half-life of doxycycline in chicken was 6.51 ± 0.63 h. An in vitro dynamic model (the drug concentrations are fluctuant) was also established and two half-lives of 6.51 and 12 h were simulated. The samples were collected for drug concentration determination and viable counting of M. gallisepticum. In static time–killing studies, doxycycline produced a maximum antimycoplasmal effect of 5.62log10 (CFU/mL) reduction and the maximum kill rate was 0.11 h−1. In the in vitro dynamic model, doxycycline had a mycoplasmacidal activity in the two regimens, and the maximum antimycoplasmal effects were 4.1 and 4.75log10 (CFU/mL) reduction, respectively. Furthermore, the cumulative percentage of time over a 48-h period that the drug concentration exceeds the MIC (%T > MIC) was the pharmacokinetic–pharmacodynamic index that best correlated with antimicrobial efficacy (R2 = 0.986, compared with 0.897 for the peak level divided by the MIC and 0.953 for the area under the concentration–time curve over 48 h divided by the MIC). The estimated %T > MIC values for 0log10 (CFU/mL) reduction, 2log10 (CFU/mL) reduction and 3log10 (CFU/mL) reduction were 32.48, 45.68, and 54.36%, respectively, during 48 h treatment period of doxycycline. In conclusion, doxycycline shows excellent effectiveness and time-dependent characteristics against M. gallisepticum strain S6 in vitro. Additionally, these results will guide optimal dosing strategies of doxycycline in M. gallisepticum infection. PMID:27199972

In vivo antibacterial effects of tretinoin-clindamycin and clindamycin alone on Propionibacterium acnes with varying clindamycin minimum inhibitory.

PubMed

Leyden, James J

2012-12-01

To quantify the antimicrobial effect of clindamycin phosphate 1.2% and tretinoin 0.025% gel and 1% clindamycin phosphate gel in patients with Propionibacterium acnes of varying sensitivity to clindamycin. Study 1 was an initial range-finding study that was neither blinded nor randomized. Study 2 was an open-label, randomized, splitface, single-center study. Both studies were conducted in Pennsylvania. Study 1 (n=20) and study 2 (n=22) involved healthy patients aged 18 years or older with initial P acnes levels #104/cm2 and minimum inhibitory concentrations (MICs) #8 μg/mL for clindamycin. Study 1, clindamycin gel applied twice daily for 6 weeks. Study 2; once-daily application with the combination gel to one cheek and clindamycin gel to the other side for 6 weeks. The comparative effectiveness of each product vs P acnes of varying sensitivity to clindamycin at 3 and 6 weeks posttreatment. For study 1, at 3 and 6 weeks, clindamycin-treated patients with MICs of %256 μg/mL showed greater reductions than those with MICs #512 μg/mL (P=.0001). Study 2 showed a significant reduction in P acnes for both products, with no differences found. Clindamycin alone was more effective in vivo in patients with MIC levels of %256 μg/mL than patients with higher MIC levels. The combination product produced a greater reduction than clindamycin alone after 6 weeks in patients with high MICs #512 μg/mL (P=.0047). These studies suggest that 1% clindamycin alone produces a varying in vivo antimicrobial effect, with a breakpoint at %256 μg/mL. Use of clindamycin phosphate 1.2% and tretinoin 0.025% gel resulted in a significantly greater in vivo antimicrobial effect than clindamycin alone in patients carrying P acnes with MICs of #512 μg/mL (P=.0047).

In vitro activity of the novel antifungal compound F901318 against difficult-to-treat Aspergillus isolates.

PubMed

Buil, J B; Rijs, A J M M; Meis, J F; Birch, M; Law, D; Melchers, W J G; Verweij, P E

2017-09-01

F901318 is a new antifungal agent with a novel mechanism of action with activity against Aspergillus species. We investigated the in vitro activity of F901318 against a collection of Aspergillus isolates. A total of 213 Aspergillus isolates were used in this study. A total of 143 Aspergillus fumigatus sensu stricto isolates were used, of which 133 were azole resistant [25 TR34/L98H; 25 TR46/Y121F/T289A; 33 A. fumigatus with cyp51A-associated point mutations (25 G54, 1 G432 and 7 M220); and 50 azole-resistant A. fumigatus without known resistance mechanisms]. Ten azole-susceptible A. fumigatus isolates were used as WT controls. The in vitro activity was also determined against Aspergillus calidoustus (25 isolates), Aspergillus flavus (10), Aspergillus nidulans (10) and Aspergillus tubingensis (25). F901318 activity was compared with that of itraconazole, voriconazole, posaconazole, isavuconazole, amphotericin B and anidulafungin. Minimum effective concentrations and MICs were determined using the EUCAST broth microdilution method. F901318 was active against all tested isolates: A. fumigatus WT, MIC90 0.125 mg/L (range 0.031-0.125); TR34/L98H,TR46/Y121F/T289A and azole resistant without known resistance mechanisms, MIC90 0.125 mg/L (range 0.031-0.25); A. fumigatus with cyp51A-associated point mutations, MIC90 0.062 mg/L (range 0.015-0.125); and other species, A. calidoustus MIC90 0.5 mg/L (range 0.125-0.5), A. flavus MIC90 0.062 mg/L (range 0.015-0.62), A. nidulans MIC90 0.125 mg/L (range 0.062-0.25) and A. tubingensis MIC90 0.062 mg/L (range 0.015-0.25). F901318 showed potent and consistent in vitro activity against difficult-to-treat Aspergillus spp. with intrinsic and acquired antifungal resistance due to known and unknown resistance mechanisms, suggesting no significant implications of azole resistance mechanisms for the mode of action of F901318. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Anti-Candida albicans effectiveness of citral and investigation of mode of action.

PubMed

Lima, Igara Oliveira; de Medeiros Nóbrega, Fernanda; de Oliveira, Wylly Araújo; de Oliveira Lima, Edeltrudes; Albuquerque Menezes, Everardo; Cunha, Francisco Afrânio; Formiga Melo Diniz, Margareth de Fátima

2012-12-01

Candidiasis is a mycosis caused by Candida species, which is of clinical importance due to the increase in resistant yeasts. Candida infection has been a serious health problem due to the inappropriate use of antibiotics. Therefore, it is necessary to study molecules with an antifungal action. Citral is a monoterpene with known pharmacological properties, including antimicrobial action. The aim of this work was to determine the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of citral and the probable mode of action. The MIC of citral was determined by the broth microdilution method using Sabouraud dextrose medium. Additionally, the interference of citral in cell wall (sorbitol assay) and the binding of citral to ergosterol and cholesterol were studied, carried out by broth microdilution method. The MIC and MFC of citral were 512 and 1024 µg/mL, respectively. The MIC of amphotericin B was 1 µg/mL. The mechanism of action did not involve either the cell wall or ergosterol. However, the presence of cholesterol increased the MIC of citral to 1024 µg/mL, indicating there is some interaction between citral and cholesterol. Amphotericin B was used as the positive control, and it showed a high MIC in the presence of ergosterol (32 µg/mL), while in the presence of cholesterol MIC increased to 4 µg/mL. Citral inhibits the growth of C. albicans. The probable mechanism of action did not involve the cell wall or ergosterol. Citral is able to interact with cholesterol. More studies are necessary to describe their effects completely.

Pharmacodynamic Evaluation and PK/PD-Based Dose Prediction of Tulathromycin: A Potential New Indication for Streptococcus suis Infection

PubMed Central

Zhou, Yu-Feng; Peng, Hui-Min; Bu, Ming-Xiao; Liu, Ya-Hong; Sun, Jian; Liao, Xiao-Ping

2017-01-01

Tulathromycin is the first member of the triamilide antimicrobial drugs that has been registered in more than 30 countries. The goal of this study is to provide a potential new indication of tulathromycin for Streptococcus suis infections. We investigated the pharmacokinetic and ex vivo pharmacodynamics of tulathromycin against experimental S. suis infection in piglets. Tulathromycin demonstrated a relatively long elimination half-life (74.1 h) and a mean residence time of 97.6 h after a single intramuscular administration. The minimal inhibitory concentration (MIC) and bactericidal concentration in serum were markedly lower than those in broth culture, with Mueller–Hinton broth/serum ratios of 40.3 and 11.4, respectively. The post-antibiotic effects were at 1.27 h (1× MIC) and 2.03 h (4× MIC) and the post-antibiotic sub-MIC effect values ranged from 2.47 to 3.10 h. The ratio of the area under the concentration–time curve divided by the MIC (AUC/MIC) correlated well with the ex vivo antimicrobial effectiveness of tulathromycin (R2 = 0.9711). The calculated AUC12h/MIC ratios in serum required to produce the net bacterial stasis, 1-log10 and 2-log10 killing activities were 9.62, 18.9, and 32.7, respectively. Based on the results of Monte Carlo simulation, a dosage regimen of 3.56 mg/kg tulathromycin was estimated to be effective, achieving for a bacteriostatic activity against S. suis infection over 5 days period. Tulathromycin may become a potential option for the treatment of S. suis infections. PMID:29033841

Combination of fluconazole with silver nanoparticles produced by Fusarium oxysporum improves antifungal effect against planktonic cells and biofilm of drug-resistant Candida albicans.

PubMed

Longhi, Carline; Santos, Jussevania Pereira; Morey, Alexandre Tadachi; Marcato, Priscyla Daniely; Durán, Nelson; Pinge-Filho, Phileno; Nakazato, Gerson; Yamada-Ogatta, Sueli Fumie; Yamauchi, Lucy Megumi

2016-05-01

Silver nanoparticles (AgNPs) have been extensively studied because of their anti-microbial potential. Here, we evaluated the effect of biologically synthesized silver nanoparticles (AgNPbio) alone and in combination with fluconazole (FLC) against planktonic cells and biofilms of FLC-resistant Candida albicans AgNPbio exhibited a fungicidal effect, with a minimal inhibitory concentration (MIC) and fungicidal concentration ranging from 2.17 to 4.35 μg/ml. The combination of AgNPbio and FLC reduced the MIC of FLC around 16 to 64 times against planktonic cells of allC. albicans There was no significant inhibitory effect of AgNPbio on biofilm cells. However, FLC combined with AgNPbio caused a significant dose-dependent decrease in the viability of both initial and mature biofilm. All concentrations of AgNPbio, alone or in combination with FLC, were not cytotoxic to mammalian cells.The results highlight the effectiveness of the combination of AgNPbio with FLC against FLC-resistant C. albicans. © The Author 2015. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The Anti-Staphylococcus aureus Effect of Combined Echinophora platyloba Essential Oil and Liquid Smoke in Beef

PubMed Central

Pilevar, Zahra; Hajimehdipoor, Homa; Shahraz, Farzaneh; Alizadeh, Leyla; Mahmoudzadeh, Maryam

2017-01-01

Summary In the current study, the antibacterial effect of Echinophora platyloba essential oil and common liquid smoke (individually and in combination) against Staphylococcus aureus in beef meat samples is investigated. Using an automated microbiological growth analyser and the turbidimetric technique, the minimum inhibitory concentrations (MIC) and the minimum bactericidal concentrations (MBC) of the essential oil and liquid smoke were determined. Anti-S. aureus activity of essential oil and liquid smoke (individually and in combination) was defined by disk diffusion assay, generation time and cell constituent release. Apart from that, the interactions between these two compounds were measured by the checkerboard assay and by calculating the fractional inhibitory concentration (FIC) indices. Related MIC values of essential oil and smoke were found to be 7200 and 5500 mg/L, and MBC values were 8500 and 8000 mg/L, respectively. The conducted organoleptic assay showed that the addition of 0.05 g of essential oil and 0.6 g of liquid smoke to 100 g of meat samples did not have adverse effect on the overall acceptance. Weaker antibacterial effect against Staphylococcus aureus was observed when only Echinophora platyloba essential oil was used than when it was used in combination with liquid smoke. PMID:28559740

Antibacterial Activity of Ethanolic Extract of Cinnamon Bark, Honey, and Their Combination Effects against Acne-Causing Bacteria

PubMed Central

Julianti, Elin; Rajah, Kasturi K.; Fidrianny, Irda

2017-01-01

Propionibacterium acnes and Staphylococcus epidermidis are the major skin bacteria that cause the formation of acne. The present study was conducted to investigate antibacterial activity of ethanolic extract of cinnamon bark, honey, and their combination against acne bacteria. The antibacterial activity of extract of cinnamon bark and honey were investigated against P. acnes and S. epidermidis using disc diffusion. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were attained using Clinical and Laboratory Standard Institute (CLSI) methods. The interaction between cinnamon bark extract and honey was determined using a checkerboards method. The results showed that the MICs of cinnamon bark extract and honey against P. acne were 256 µg/mL and 50% v/v, respectively, while those against S. epidermidis were 1024 µg/mL and 50% v/v, respectively. The MBC of cinnamon bark extract against P. acnes and S. epidermidis were more than 2048 µg/mL, whereas the MBC for honey against P. acnes and S. epidermidis were 100%. The combination of cinnamon bark extract and honey against P. acnes and S. epidermidis showed additive activity with a fractional inhibitory concentration index (FICI) value of 0.625. Therefore, the combination of cinnamon bark extract and honey has potential activity against acne-causing bacteria. PMID:28398231

Facile synthesis of silver nanoparticles mediated by polyacrylamide-reduction approach to antibacterial application.

PubMed

Salaheldin, Hosam I; Almalki, Meshal H K; Hezma, Abd Elhameed M; Osman, Gamal E H

2017-06-01

The current time increase in the prevalence of antibiotic resistant 'super-bugs' and the risks associated with food safety have become global issues. Therefore, further research is warranted to identify new and effective antimicrobial substances. Silver nanoparticles (Ag-NPs) were synthesized by autoclaving technique using, different concentrations of Ag salt (AgNO 3 ) solution (1, 5, 10, and 25 mM). Their presence was confirmed by a surface plasmon resonance band at ∼435 nm using UV-Vis absorption spectra. The morphology of the synthesized Ag-NPs stabilized by polyacrylamide (PAM) was examined by TEM, SAED, and EDS. TEM images revealed that the synthesized Ag-NPs had an average diameter of 2.98±0.08 nm and SAED and EDS results confirmed the formation of Ag-NPs. In addition, FT-IR spectroscopy revealed that a PAM polymer matrix stabilized the Ag-NPs. The well diffusion method, was used to test, Gram positive and Gram negative bacteria were examined. Also the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were studied against Ag-NPs. The Ag-NPs exhibited strong inhibitory activity, MIC and MBC against the tested clinical bacterial isolates. These results suggest that Ag-NPs stabilized in PAM are highly effective against clinical bacterial isolates can be applied in medical fields.

In Vitro Evaluation of the Type of Interaction Obtained by the Combination of Terbinafine and Itraconazole, Voriconazole, or Amphotericin B against Dematiaceous Molds▿

PubMed Central

Biancalana, Fernanda Simas Corrêa; Lyra, Luzia; Schreiber, Angélica Zaninelli

2011-01-01

In vitro associations using the checkerboard microdilution method indicated lower MIC ranges and MIC median values for each drug (terbinafine, itraconazole, voriconazole, and amphotericin B) in association than those obtained for each single drug. Fractional inhibitory concentration index (FIC) results showed 100% synergism in the association of terbinafine with voriconazole, 96.5% in the association of terbinafine with amphotericin B, and 75.9% in the association of terbinafine with itraconazole. Drug combinations may be useful for treatment of dematiaceous mold infections as an alternative treatment to enhance the effectiveness of each drug. PMID:21690288

Semisynthetic Phenol Derivatives Obtained from Natural Phenols: Antimicrobial Activity and Molecular Properties.

PubMed

Pinheiro, Patrícia Fontes; Menini, Luciana Alves Parreira; Bernardes, Patrícia Campos; Saraiva, Sérgio Henriques; Carneiro, José Walkimar Mesquita; Costa, Adilson Vidal; Arruda, Társila Rodrigues; Lage, Mateus Ribeiro; Gonçalves, Patrícia Martins; Bernardes, Carolina de Oliveira; Alvarenga, Elson Santiago; Menini, Luciano

2018-01-10

Semisynthetic phenol derivatives were obtained from the natural phenols: thymol, carvacrol, eugenol, and guaiacol through catalytic oxychlorination, Williamson synthesis, and aromatic Claisen rearrangement. The compounds characterization was carried out by 1 H NMR, 13 C NMR, and mass spectrometry. The natural phenols and their semisynthetic derivatives were tested for their antimicrobial activity against the bacteria: Staphylococcus aureus, Escherichia coli, Listeria innocua, Pseudomonas aeruginosa, Salmonella enterica Typhimurium, Salmonella enterica ssp. enterica, and Bacillus cereus. Minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values were determined using concentrations from 220 to 3.44 μg mL -1 . Most of the tested compounds presented MIC values ≤220 μg mL -1 for all the bacteria used in the assays. The molecular properties of the compounds were computed with the PM6 method. Through principle components analysis, the natural phenols and their semisynthetic derivatives with higher antimicrobial potential were grouped.

Antifungal activity of extracts of Rosmarinus officinalis and Thymus vulgaris against Aspergillus flavus and A. ochraceus.

PubMed

Centeno, S; Calvo, M A; Adelantado, C; Figueroa, S

2010-05-01

The antifungal activity of ethanolic extracts of Rosmarinus officinalis and Thymus vulgaris were tested against strains of Aspergillus flavus and A. ochraceus, since these two species are common contaminants of cereals and grains and are able to produce and accumulate mycotoxins. The methodology used is based on measuring the inhibition halos produced by discs impregnated with the extracts and establishing their Minimum Inhibitory Concentration (MIC) as well as the Minimum Fungicide Concentration (MFC). The results obtained suggest that the assayed extracts affect the proper development of A. flavus and A. ochraceus; leading to a lower MIC (1200 ppm) and MFC (2400 ppm) for T. vulgaris extract against A. ochraceus than against A. flavus. The results show, that the extracts of Rosmarinus officinalis and Thymus vulgaris used at low concentrations could have significant potential for the biological control of fungi in foodstuffs.

Introducing Urtica dioica, A Native Plant of Khuzestan, As an Antibacterial Medicinal Plant.

PubMed

Motamedi, Hossein; Seyyednejad, Seyyed Mansour; Bakhtiari, Ameneh; Vafaei, Mozhan

2014-11-01

Urtica dioica is a flowering plant with long history of use in folk medicine and as a food source. This study examined in vitro antibacterial potential of alcoholic extracts of U. dioica. Hydroalcoholic extracts from aerial parts were prepared using aqueous solution of ethanol and methanol and their inhibitory effects against clinical isolates was examined by disc diffusion method at different doses. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentration (MBC) indexes were also investigated. The scanning electron microscopy (SEM) analysis was also performed to find structural changes of affected bacteria consequent to exposing with extracts. Both extracts were active against Bacillus cereus, Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli with respectively 16, 10, 18, and 14 mm (methanolic) and 11, 9, 17, and 16 mm (ethanolic) inhibition zone. The MIC of ethanolic extract against S. epidermidis and E. coli was respectively 10 and 40 mg/mL. The MIC of methanolic extract against S. aureus and S. epidermidis was 40 and 10 mg/mL, respectively. The MBC was found only for S. epidermidis (20 mg/mL). In SEM analysis the round shape of S. epidermidis was changed and irregular shapes were appeared, which suggest that the main target of these extracts was cell wall. Extracts of U. dioica showed significant antibacterial effect against some clinically important pathogenic bacteria. Based on the obtained results it can be concluded that U. dioica is useful as antibacterial and bactericidal agent in treating infectious diseases.

Enhanced in vitro activity of tigecycline in the presence of chelating agents.

PubMed

Deitchman, Amelia N; Singh, Ravi Shankar Prasad; Rand, Kenneth H; Derendorf, Hartmut

2018-05-01

The lack of availability of novel antibiotic agents and the rise of resistance to existing therapies has led clinicians to utilise combination therapy to adequately treat bacterial infections. Here we examined how chelators may impact the in vitro activity of tigecycline (TIG) against Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae. Minimum inhibitory concentrations (MICs) were determined by broth dilution with and without various combinations of chelators (EDTA and other tetracyclines) and metal ions (i.e. calcium, magnesium). Trimethoprim (TMP) was used as a non-chelating control. Addition of metal ions led to increases in MICs, whilst addition of EDTA led to decreases in MICs. The chelating effects of EDTA were reversed by addition of magnesium and most profoundly calcium. Similar effects of EDTA and calcium were observed for tetracycline (TET) and TMP. When other tetracyclines (TET, oxytetracycline (OXY) and chlortetracycline (CHL)) were used as chelators at concentrations below their MICs, TIG MICs decreased for P. aeruginosa but not for E. coli. Some decreases in TIG MICs were observed for K. pneumoniae when TET and CHL were added. A dose-dependent decrease in TIG MIC was observed for TET and was reversed by the addition of calcium. The presence of effects of EDTA and calcium on TMP MICs indicates that mechanisms outside of TIG chelation likely play a role in enhanced activity. Full characterisation of an unexpected interaction such as TIG-TET with different microorganisms could provide valuable insights into the underlying mechanisms and design of physiologically viable chelators as candidates for future combinations regimens. Copyright © 2018 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Pilot Study of Antimicrobial Resistance in Northern Bobwhites (Colinus virginianus).

PubMed

Zhang, Michael; Shen, Zhenyu; Rollins, Dale; Fales, William; Zhang, Shuping

2017-09-01

Antimicrobial resistance (AMR) is an important issue for both wildlife conservation and public health. The purpose of this study was to screen for AMR in fecal bacteria isolated from northern bobwhite (Colinus virginianus), a species that is an ecologically and economically important natural resource in the southern United States. The antimicrobial susceptibility profiles of 45 Escherichia coli isolates, 20 Enterococcus faecalis isolates, and 10 Enterococcus faecium isolates were determined using the Sensititer TM microbroth dilution minimum inhibitory concentration (MIC) plate, AVIAN1F. Overall, E. coli isolates had high MIC values for the following classes of antimicrobials: aminocoumarins, beta-lactams, lincosamides, macrolides, florfenicol, and sulfonamides. Enterococcus faecalis and E. faecium isolates had high MICs for aminocyclitols, aminoglycosides, beta-lactams, lincosamides, and sulfonamides. Enterococcus faecalis isolates also showed high MICs for aminocoumarins, while E. faecium isolates had high MICs for trimethoprim/sulfamethoxazole and tetracycline. Based on available veterinary interpretive criteria, 15% and 33% of E. coli isolates were resistant to sulphathiazole and sulphadimethoxine, respectively. Intermediate susceptibility to florfenicol was seen with 17.8% of E. coli isolates. Twenty percent of E. faecalis and 80% of E. faecium isolates were resistant to high-concentration streptomycin. One third of E. faecalis and 70% of E. faecium isolates were intermediately susceptible to erythromycin. Ten percent of E. faecium isolates were resistant to tetracycline and oxytetracycline. A comparison of available MIC suggests that AMR in wild bobwhite is less severe than in domestic poultry. Further investigation is needed to determine the source of AMR in wild bobwhite.

A microbiological method for determining serum levels of broad spectrum β-lactam antibiotics in critically ill patients.

PubMed

Fridlund, Jimmy; Woksepp, Hanna; Schön, Thomas

2016-10-01

Recent studies show that suboptimal blood levels of β-lactam antibiotics are present in intensive care unit (ICU) patients. A common reference method for assessing drug concentrations is liquid chromatography coupled with mass-spectrometry (LC-MS) which is highly accurate but rarely available outside reference centres. Thus, our aim was to develop a microbiological method for monitoring β-lactam antibiotic serum levels which could be used at any hospital with a microbiological laboratory. The method was developed as a 96-well broth microdilution format to assess the concentrations of cefotaxime (CTX), meropenem (MER), and piperacillin (PIP). Patient serum containing antibiotics were diluted in suspensions of bacteria with known minimal inhibitory concentrations (MICs). Serum antibiotic concentrations were calculated by dividing the MIC with the dilution factor at which the serum inhibited growth of the bacterial suspension. Serum (n=88) from ICU patients at four hospitals in south-east Sweden were analysed and compared to LC-MS analysis. The overall accuracy and precision for spiked samples and patient samples was within the pre-set target of ±20.0% for all drugs. There was a significant correlation between the microbiological assay and LC-MS for the patient samples (CTX: r=0.86, n=31; MER: r=0.96, n=11; PIP: r=0.88, n=39) and the agreement around the clinical cut-off for CTX (4.0mg/l), MER (2.0mg/l) and PIP (16.0mg/l) was 90%, 100% and 87%, respectively. The microbiological method has a performance for determination of serum levels of meropenem, piperacillin and cefotaxime suitable for clinical use. It is an inexpensive method applicable in any microbiology laboratory. Copyright © 2016 Elsevier B.V. All rights reserved.

Antibacterial and synergy of berberines with antibacterial agents against clinical multi-drug resistant isolates of methicillin-resistant Staphylococcus aureus (MRSA).

PubMed

Zuo, Guo-Ying; Li, Yang; Han, Jun; Wang, Gen-Chun; Zhang, Yun-Ling; Bian, Zhong-Qi

2012-08-29

Antibacterial activity of berberine (Ber) and 8-acetonyl-dihydroberberine (A-Ber) alone and combined uses with antibacterial agents ampicillin (AMP), azithromycin (AZM), cefazolin (CFZ) and levofloxacin (LEV) was studied on 10 clinical isolates of SCCmec III type methicillin-resistant Staphylococcus aureus (MRSA). Susceptibility to each agent alone was tested using a broth microdilution method and the chequerboard and time-kill tests for the combined evaluations, respectively. The alone MICs/MBCs (μg/mL) ranges were 32-128/64-256 (Ber) and 32-128/128-512 (A-Ber). Significant synergies were observed for the Ber (A-Ber)/AZM and Ber (A-Ber)/LEV combinations against 90% of the tested MRSA strains, with fractional inhibitory concentration indices (FICIs) values ranged from 0.188 to 0.500. An additivity result was also observed for the Ber/AZM combination by time-kill curves. These results demonstrated for the first time that Ber and A-Ber enhanced the in vitro inhibitory efficacy of AZM and LEV to a same extent, which had potential for further investigation in combinatory therapeutic applications of patients infected with MRSA.

Determination of minimum inhibitory concentrations of itraconazole, terbinafine and ketoconazole against dermatophyte species by broth microdilution method.

PubMed

Bhatia, V K; Sharma, P C

2015-01-01

Various antifungal agents both topical and systemic have been introduced into clinical practice for effectively treating dermatophytic conditions. Dermatophytosis is the infection of keratinised tissues caused by fungal species of genera Trichophyton, Epidermophyton and Microsporum, commonly known as dermatophytes affecting 20-25% of the world's population. The present study aims at determining the susceptibility patterns of dermatophyte species recovered from superficial mycoses of human patients in Himachal Pradesh to antifungal agents; itraconazole, terbinafine and ketoconazole. The study also aims at determining the minimum inhibitory concentrations (MICs) of these agents following the recommended protocol of Clinical and Laboratory Standards Institute (CLSI) (M38-A2). A total of 53 isolates of dermatophytes (T. mentagrophyte-34 in no., T. rubrum-18 and M. gypseum-1) recovered from the superficial mycoses were examined. Broth microdilution method M38-A2 approved protocol of CLSI (2008) for filamentous fungi was followed for determining the susceptibility of dermatophyte species. T. mentagrophyte isolates were found more susceptible to both itraconazole and ketoconazole as compared to terbinafine (MIC50: 0.125 µg/ml for itraconazole, 0.0625 µg/ml for ketoconazole and 0.5 µg/ml for terbinafine). Three isolates of T. mentagrophytes (VBS-5, VBSo-3 and VBSo-73) and one isolate of T. rubrum (VBPo-9) had higher MIC values of itraconazole (1 µg/ml). Similarly, the higher MIC values of ketoconazole were observed in case of only three isolates of T. mentagrophyte (VBSo-30 = 2 µg/ml; VBSo-44, VBM-2 = 1 µg/ml). The comparative analysis of the three antifungal drugs based on t-test revealed that 'itraconazole and terbinafine' and 'terbinafine and ketoconazole' were found independent based on the P < 0.005 in case of T. mentagrophyte isolates. In case of T. rubrum, the similarity existed between MIC values of 'itraconazole and ketoconazole' and 'terbinafine and ketoconazole'. The MIC values observed in the present study based on standard protocol M38-A2 of CLSI 2008 might serve as reference for further studies covering large number of isolates from different geographic regions of the state. Such studies might reflect on the acquisition of drug resistance among isolates of dermatophyte species based on MIC values.

Streptococcus suis infection: a series of 41 cases from Chiang Mai University Hospital.

PubMed

Wangkaew, Suparaporn; Chaiwarith, Romanee; Tharavichitkul, Prasit; Supparatpinyo, Khuanchai

2006-06-01

The objectives of this study were (1) to assess the clinical manifestations, treatment, and outcome of Streptococcus suis infection in adult patients in northern Thailand, (2) to evaluate the anti-microbial sensitivity pattern and (3) to determine the predicting factors of high mortality rate. A retrospective study was conducted at Chiang Mai University Hospital from May 2000 to December 2002. Anti-microbial susceptibility test was performed by agar disk diffusion and the minimal inhibitory concentration (MIC) by E-test. Forty-one patients (32 men and nine women, mean age 51 years) with S. suis infection were identified. Three patients had a history of exposure to pig or pork and one patient had a history of raw beef consumption. Clinical manifestations included infective endocarditis, meningitis, sepsis, spondylodiscitis, and endophthalmitis in 16, 13, 10, 1, and 1 patients, respectively. The overall mortality rate was 19.5%. On univariate analysis, low serum albumin, high serum total bilirubin, low platelet, and rapid onset of illness were significantly correlated with high mortality rate. All isolates were sensitive to penicillin (mean MIC90=0.027 microg/ml). S. suis infection is not uncommon in northern Thailand. High suspicion and early detection are important and could lead to the successful treatment.

Silver colloidal nanoparticles: antifungal effect against adhered cells and biofilms of Candida albicans and Candida glabrata.

PubMed

Monteiro, D R; Gorup, L F; Silva, S; Negri, M; de Camargo, E R; Oliveira, R; Barbosa, D B; Henriques, M

2011-08-01

The aim of this study was to evaluate the effect of silver nanoparticles (SN) against Candida albicans and Candida glabrata adhered cells and biofilms. SN (average diameter 5 nm) were synthesized by silver nitrate reduction with sodium citrate and stabilized with ammonia. Minimal inhibitory concentration (MIC) tests were performed for C. albicans (n = 2) and C. glabrata (n = 2) grown in suspension following the Clinical Laboratory Standards Institute microbroth dilution method. SN were applied to adhered cells (2 h) or biofilms (48 h) and after 24 h of contact their effect was assessed by enumeration of colony forming units (CFUs) and quantification of total biomass (by crystal violet staining). The MIC results showed that SN were fungicidal against all strains tested at very low concentrations (0.4-3.3 μg ml(-1)). Furthermore, SN were more effective in reducing biofilm biomass when applied to adhered cells (2 h) than to pre-formed biofilms (48 h), with the exception of C. glabrata ATCC, which in both cases showed a reduction ∼90%. Regarding cell viability, SN were highly effective on adhered C. glabrata and respective biofilms. On C. albicans the effect was not so evident but there was also a reduction in the number of viable biofilm cells. In summary, SN may have the potential to be an effective alternative to conventional antifungal agents for future therapies in Candida-associated denture stomatitis.

In-vitro activity of solithromycin against anaerobic bacteria from the normal intestinal microbiota.

PubMed

Weintraub, Andrej; Rashid, Mamun-Ur; Nord, Carl Erik

2016-12-01

Solithromycin is a novel fluoroketolide with high activity against bacteria associated with community-acquired respiratory tract infections as well as gonorrhea. However, data on the activity of solithromycin against anaerobic bacteria from the normal intestinal microbiota are scarce. In this study, 1024 Gram-positive and Gram-negative anaerobic isolates from the normal intestinal microbiota were analyzed for in-vitro susceptibility against solithromycin and compared to azithromycin, amoxicillin/clavulanic acid, ceftriaxone, metronidazole and levofloxacin by determining the minimum inhibitory concentration (MIC). Solithromycin was active against Bifidobacteria (MIC 50 , 0.008 mg/L) and Lactobacilli (MIC 50 , 0.008 mg/L). The MIC 50 for Clostridia, Bacteroides, Prevotella and Veillonella were 0.5, 0.5, 0.125 and 0.016 mg/L, respectively. Gram-positive anaerobes were more susceptible to solithromycin as compared to the other antimicrobials tested. The activity of solithromycin against Gram-negative anaerobes was equal or higher as compared to other tested agents. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Influence of Mueller-Hinton broth on the in vitro activities of cefuzoname, flomoxef, imipenem, and minocycline against Staphylococcus aureus].

PubMed

Fujita, S; Tonohata, A

1990-05-01

The influence of Mueller-Hinton (MH) broth (from BBL Microbiology Systems, and Difco Laboratories) of minimum inhibitory concentrations (MIC) of cefuzoname (CZON), flomoxef (FMOX), imipenem (IPM), and minocycline (MINO) for 100 strains of Staphylococcus aureus was investigated. Antibacterial activity of MINO was stronger than any other antibiotics. MICs of CZON for 16 strains (14 of 50 methicillin-resistant S. aureus (MRSA), 2 of 50 methicillin-sensitive S. aureus) were greater than or equal to 4-fold greater when tested in BBL MH broth than when tested in Difco MH broth, thus, different media altered categories of some strains (8 of 50 MRSA) from susceptible to resistant. MICs of FMOX in the BBL MH broth for 12 of 50 MRSA strains rose greater than or equal to 4-fold compared to the Difco MH broth. On the other hand, MICs of IPM and MINO were affected very little by the different brand of MH broth used.

Essential oils from Origanum vulgare and Salvia officinalis exhibit antibacterial and anti-biofilm activities against Streptococcus pyogenes.

PubMed

Wijesundara, Niluni M; Rupasinghe, H P Vasantha

2018-04-01

In the present study, essential oils (EOs) extracted from oregano, sage, cloves, and ginger were evaluated for the phytochemical profile, antibacterial, and anti-biofilm activities against Streptococcus pyogenes. The broth microdilution method was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of EOs. The minimum biofilm inhibitory concentrations (MBICs) were determined using MTT assay and fixed biofilms were observed through scan electron microscopy. The oregano and sage EOs showed the lowest MIC as well as MBC of 0.25-0.5 mg/mL. Time kill assay results showed that oregano and sage EOs exhibited bactericidal effects within 5 min and 4 h, respectively. Both oregano and sage extracts acts as a potent anti-biofilm agent with dual actions, preventing and eradicating the biofilm. The microscopic visualization of biofilms treated with EOs have shown morphological and density changes compared to the untreated control. Oregano EO was constituted predominantly carvacrol (91.6%) and in sage EO, higher levels of α-thujone (28.5%) and camphor (16.6%) were revealed. EOs of oregano and sage inhibit the growth and biofilm formation of S. pyogenes. Effective concentrations of oregano and sage EOs and their phytochemicals can be used in developing potential plant-derived antimicrobial agents in the management of streptococcal pharyngitis. Copyright © 2018 Elsevier Ltd. All rights reserved.

Changing trends of culture-positive typhoid fever and antimicrobial susceptibility in a tertiary care North Indian Hospital over the last decade.

PubMed

Sharma, Priyanka; Dahiya, Sushila; Manral, Neelam; Kumari, Bhavana; Kumar, Sambuddha; Pandey, Sangeeta; Sood, Seema; Das, Bimal Kumar; Kapil, Arti

2018-01-01

The present study was undertaken to analyse the trend in prevalence of culture-positive typhoid fever during the last decade and to determine antimicrobial susceptibility profile of Salmonella Typhi and Salmonella Paratyphi A isolated from patients of enteric fever presenting to our hospital. All the culture-positive enteric fever cases during 2005-2016 presenting to our Hospital were included in the study. Antimicrobial susceptibility was done against chloramphenicol, amoxicillin, co-trimoxazole, ciprofloxacin, ofloxacin, levofloxacin, pefloxacin, ceftriaxone and azithromycin as per corresponding CLSI guidelines for each year. We also analysed the proportion of culture positivity during 1993-2016 in light of the antibiotic consumption data from published literature. A total of 1066 strains-S. Typhi (772) and S. Paratyphi A (294) were isolated from the blood cultures during the study. A maximum number of cases were found in July-September. Antimicrobial susceptibility for chloramphenicol, amoxicillin and co-trimoxazole was found to be 87.9%, 75.5%, 87.3% for S. Typhi and 94.2%, 90.1% and 94.2% for S. Paratyphi A, respectively. Ciprofloxacin, ofloxacin and levofloxacin susceptibility were 71.3%, 70.8% and 70.9% for S. Typhi and 58.1%, 57.4% and 57.1% for S. Paratyphi A, respectively. Azithromycin susceptibility was 98.9% in S. Typhi. Although susceptibility to ceftriaxone and cefixime was 100% in our isolates, there is a continuous increase in ceftriaxone minimum inhibitory concentration (MIC) 50 and MIC 90 values over the time. The proportion of blood culture-positive cases during 1993-2016 ranged from a minimum of 0.0006 in 2014 to a maximum of 0.0087 in 1999. We found that the most common etiological agent of enteric fever is S. Typhi causing the majority of cases from July to October in our region. MIC to ceftriaxone in typhoidal salmonellae is creeping towards resistance and more data are needed to understand the azithromycin susceptibility.

Isolation of Abscisic Acid from Korean Acacia Honey with Anti-Helicobacter pylori Activity

PubMed Central

Kim, SeGun; Hong, InPyo; Woo, SoonOk; Jang, HyeRi; Pak, SokCheon; Han, SangMi

2017-01-01

Background: Helicobacter pylori (H. pylori) is linked to the development of the majority of peptic ulcers and some types of gastric cancers, and its antibiotic resistance is currently found worldwide. Objective: This study is aimed at evaluating the anti-H. pylori activity of Korean acacia honey and isolating the related active components using organic solvents. Material and Methods: The crude acacia honey was extracted with n-hexane, dichloromethane, ethyl acetate (EtOAc), and n-butanol. The EtOAc extract was subjected to octadecyl-silica chromatography. The extracts and fractions were then examined for anti-H. pylori activity using the agar well diffusion method. The antimicrobial activity of abscisic acid against H. pylori was investigated by determining the minimum inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs), and by performing a time-kill assay. Results: Abscisic acid related to the botanical origins of acacia honey from Korea has been analyzed using ultra-performance liquid chromatography. The MICs and MBCs of abscisic acid were 2.7 ± 1.3 and 6.9 ± 1.9 μg/mL, respectively. The bactericidal activity of abscisic acid (at 10.8 μg/mL corresponding to 4 × MIC) killed the organism within 36–72 h. These results suggest that abscisic acid isolated from Korean acacia honey has antibacterial activity against H. pylori. Conclusion: Abscisic acid isolated from Korean acacia honey can be therapeutic and may be further exploited as a potential lead candidate for the development of treatments for H. pylori-induced infections. SUMMARY The crude acacia honey was extracted with n-hexane, dichloromethane, EtOAc, and n-butanolThe EtOAc extract yielded eight fractions and four subfractions were subsequently obtained chromatographicallyAbscisic acid was isolated from one subfractionAll the solvent extracts and fractions showed antibacterial activity against H. pyloriAbscisic acid exhibited antibacterial activity against H. pylori. Abbreviations used: MeOH: Methanol; EtOAc: Ethyl acetate; TSB: Trypticase soy broth; MIC: Minimum inhibitory concentration; MBC: Minimum bactericidal concentration; CFU: Colony-forming units; UPLC: Ultra-performance liquid chromatography; DAD: Diode array detector; UV: Ultraviolet; ODS: Octadecyl-silica; MS: Mass spectrometry; SE: Standard error. PMID:28808376

Isolation of Abscisic Acid from Korean Acacia Honey with Anti-Helicobacter pylori Activity.

PubMed

Kim, SeGun; Hong, InPyo; Woo, SoonOk; Jang, HyeRi; Pak, SokCheon; Han, SangMi

2017-07-01

Helicobacter pylori ( H. pylori ) is linked to the development of the majority of peptic ulcers and some types of gastric cancers, and its antibiotic resistance is currently found worldwide. This study is aimed at evaluating the anti- H. pylori activity of Korean acacia honey and isolating the related active components using organic solvents. The crude acacia honey was extracted with n -hexane, dichloromethane, ethyl acetate (EtOAc), and n -butanol. The EtOAc extract was subjected to octadecyl-silica chromatography. The extracts and fractions were then examined for anti- H. pylori activity using the agar well diffusion method. The antimicrobial activity of abscisic acid against H. pylori was investigated by determining the minimum inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs), and by performing a time-kill assay. Abscisic acid related to the botanical origins of acacia honey from Korea has been analyzed using ultra-performance liquid chromatography. The MICs and MBCs of abscisic acid were 2.7 ± 1.3 and 6.9 ± 1.9 μg/mL, respectively. The bactericidal activity of abscisic acid (at 10.8 μg/mL corresponding to 4 × MIC) killed the organism within 36-72 h. These results suggest that abscisic acid isolated from Korean acacia honey has antibacterial activity against H. pylori . Abscisic acid isolated from Korean acacia honey can be therapeutic and may be further exploited as a potential lead candidate for the development of treatments for H. pylori -induced infections. The crude acacia honey was extracted with n -hexane, dichloromethane, EtOAc, and n -butanolThe EtOAc extract yielded eight fractions and four subfractions were subsequently obtained chromatographicallyAbscisic acid was isolated from one subfractionAll the solvent extracts and fractions showed antibacterial activity against H. pylori Abscisic acid exhibited antibacterial activity against H. pylori . Abbreviations used: MeOH: Methanol; EtOAc: Ethyl acetate; TSB: Trypticase soy broth; MIC: Minimum inhibitory concentration; MBC: Minimum bactericidal concentration; CFU: Colony-forming units; UPLC: Ultra-performance liquid chromatography; DAD: Diode array detector; UV: Ultraviolet; ODS: Octadecyl-silica; MS: Mass spectrometry; SE: Standard error.

In vitro anti-mycobacterial activities of three species of Cola plant extracts (Sterculiaceae).

PubMed

Adeniyi, B A; Groves, M J; Gangadharam, P R J

2004-05-01

Extracts obtained from three Nigerian Sterculiaceae plants: Cola accuminata, C. nitida and C. milleni were screened for anti-mycobacterium properties using a slow growing Mycobacterium bovis ATCC 35738 (designated BCG Mexican and known to have some virulence in mouse and guinea pig) at 1000 microg/ml using the radiometric (BACTEC) method. The extracts were also tested against six fast growing ATCC strains of M. vaccae using the broth microdilution method. The methanol extracts from both leaves, stem bark and root bark of Cola accuminata and from the leaves and stem bark of C. nitida and C. milleni were not active at the highest concentration of 1000 microg/ml. Only the methanol extract of root bark for both C. nitida and C. milleni were found to be potent against both M. bovis and strains of M. vaccae. The minimum inhibitory concentration (MIC) of C. nitida against M. bovis is 125 microg/ml while the MIC of C. milleni against M. bovis is 62.5 microg/ml after at least 6 days of inhibition with growth index (GI) units lesser than or equal to the change in GI units inoculated with a 1/100 of the BACTEC inoculum for a control vial. The minimum inhibitory concentration of C. milleni against the six ATCC strain of M. vaccae ranged from 62.5 microg/ml to 250 microg/ml while for C. nitida ranged from 500 microg/ml to above 1000microg/ml. Evidently, C. milleni has the highest inhibitory activity against both M. bovis and strains of M. vaccae used. Rifampicin, the positive control used has strong activity against M. bovis at the tested concentration of 5 microg and 10 microg/ml and 4 to 8 microg/ml against the six strains of M. vaccae. Copyright 2004 John Wiley & Sons, Ltd.

Effect of aqueous and alcoholic Stevia (Stevia rebaudiana) extracts against Streptococcus mutans and Lactobacillus acidophilus in comparison to chlorhexidine: An in vitro study

PubMed Central

Ajagannanavar, Sunil Lingaraj; Shamarao, Supreetha; Battur, Hemant; Tikare, Shreyas; Al-Kheraif, Abdulaziz Abdullah; Al Sayed, Mohammed Sayed Al Esawy

2014-01-01

Introduction: Stevia (S. rebaudiana) a herb which has medicinal value and was used in ancient times as a remedy for a great diversity of ailments and sweetener. Leaves of Stevia contain a high concentration of Stevioside and Rebaudioside which are supposed to be sweetening agents. Aim: To compare the efficacy of aqueous and alcoholic S. rebaudiana extract against Streptococcus mutans and Lactobacillus acidophilus in comparison to chlorhexidine. Materials and Methods: In the first part of the study, various concentrations of aqueous and ethanolic Stevia extract were prepared in the laboratory of Pharmacy College. It was then subjected to microbiological assay to determine its zone of inhibition using Agar disk diffusion test and minimum inhibitory concentration (MIC) using serial broth dilution method against Streptococcus mutans and Lactobacillus acidophilus. Chlorhexidine was used as a positive control. One way Analysis of Variance (ANOVA) test was used for multiple group comparisons followed by Tukey post hoc for group wise comparisons. Results: Minimum inhibitory concentration (MIC) of aqueous and ethnolic Stevia extract against Streptococcus mutans and Lactobacillus acidophilus were 25% and 12.5% respectively. Mean zone of inhibition of the aqueous and alcoholic Stevia extracts against Streptococcus mutans at 48 hours were 22.8 mm and 26.7 mm respectively. Mean zone of inhibition of the aqueous and alcoholic Stevia extracts against Lactobacillus acidophilus at 48 hours were 14.4 mm and 15.1 mm respectively. Mean zone of inhibition of the chlorhexidine against Streptococcus mutans and Lactobacillus acidophilus at 48 hours was 20.5 and 13.2 respectively. Conclusion: The inhibitory effect shown by alcoholic Stevia extract against Streptococcus mutans and Lactobacillus acidophilus was superior when compared with that of aqueous form and was inferior when compared with Chlorhexidine. PMID:25558451

Susceptibility and PK/PD relationships of Staphylococcus aureus strains from ovine and caprine with clinical mastitis against five veterinary fluoroquinolones.

PubMed

Serrano-Rodríguez, J M; Cárceles-García, C; Cárceles-Rodríguez, C M; Gabarda, M L; Serrano-Caballero, J M; Fernández-Varón, E

2017-04-15

Minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) of veterinary fluoroquinolones as enrofloxacin, its metabolite ciprofloxacin, danofloxacin, difloxacin and marbofloxacin against Staphylococcus aureus strains (n=24) isolated from milk of sheep and goats affected by clinical mastitis were evaluated. The authors have used the MIC and MPC, as well as the pharmacokinetic-pharmacodynamic relationships in plasma and milk. MIC values were significantly different between drugs, unlike MPC values. Lower MIC values were obtained for danofloxacin and difloxacin, middle and higher values for enrofloxacin, ciprofloxacin and marbofloxacin. However, differences in MPC values were not found between drugs. At conventional doses, the AUC 24 /MIC and AUC 24 /MPC ratios were close to 30-80 hours and 5-30 hours, with exception of danofloxacin, in plasma and milk. The time inside the mutant selection window (T MSW ) was close to 3-6 hours for enrofloxacin, ciprofloxacin and marbofloxacin, near to 8 hours for danofloxacin and 12-22 hours for difloxacin. From these data, the mutant selection window could be higher for danofloxacin and difloxacin compared with the other fluoroquinolones tested. The authors concluded that enrofloxacin and marbofloxacin, at conventional doses, could prevent the selection of bacterial subpopulations of S aureus , unlike danofloxacin and difloxacin, where higher doses could be used. British Veterinary Association.

The extraction of antimicrobials component of andaliman (Zanthoxylum acanthopodium DC.) and its application on catfish (Pangasius sutchi) fillet

NASA Astrophysics Data System (ADS)

Muzafri, A.; Julianti, E.; Rusmarilin, H.

2018-02-01

Andaliman (Zanthoxylum acanthopodium DC.) is a well known wild species in North Sumatera and used for seasoning in Batak’s traditional cuisine. This study was aimed to examine the phytochemical constituents of andaliman fruit extracts after simple macerated in water, methanol, ethyl acetate and hexana using qualitative phytochemical analysis, and to determine its potential antimicrobial activity against Staphylococus aureus, Escherichia coli and Salmonella sp by using agar well difussion method and minimum inhibitory concentration (MIC). Phytochemicals such as alkaloids, flavonoid, glycosides, saponins, tannins, triterpene/steroid and glycoside anthroquinones were detected in the methanol extracts, but steroids and glycisode antraquinones were absent in the ethyl acetate extract. The ethyl acetate extracts showed maximum zone of inhibition and minimum inhibitory concentration against all the experimental microorganisms. The minimum zone of inhibition was determined in hexane extracts showing less antimicrobial activity against all the experimental microorganisms. The MIC of the ethyl acetate extracts was 0,5% w/v for all tested bacteria. Apllication of ethyl acetate extracts of andaliman fruits showed effective for catfish (Pangasius Sutchi) fillet stored in refrigerator (5 °C) for 3 days.

Evaluation of natural antimicrobials on typical meat spoilage bacteria in vitro and in vacuum-packed pork meat.

PubMed

Schirmer, Bjørn Christian; Langsrud, Solveig

2010-03-01

The aim of this study was to investigate the inhibitory effect of natural antimicrobials on the growth of typical spoilage bacteria from marinated pork. Minimum inhibitory concentrations (MIC) of thymol, cinnamaldehyde, allyl isothiocyanate, citric acid, ascorbic acid, a rosemary extract, and a grapefruit seed extract against Lactobacillus algidus, Leuconostoc mesenteroides, Leuconostoc carnosum, Carnobacterium maltaromaticum, Carnobacterium divergens, Brochothrix thermosphacta, and Serratia proteamaculans were determined in a microplate assay. Combinations of antimicrobials were tested and several combinations showed synergistic effects in inhibiting bacterial growth. Single and combined antimicrobials were added to vacuum-packed pork meat to evaluate preserving effects. Antimicrobial concentrations of up to 10 times the MIC values showed no effect on total bacterial growth in vacuum packed pork meaning that although most antimicrobials inhibited the growth of spoilage bacteria in vitro, results from the microplate assay could not be transferred to the meat system. Most natural antimicrobials possess strong odor and flavor that limit their use as a food preservative. In conclusion, this study showed that the use of natural antimicrobials in meat products is limited and that bacterial quality and shelf life was not enhanced under the chosen conditions.

Antimicrobial activity of ethanol extracts of Laminaria japonica against oral microorganisms.

PubMed

Kim, Yeon-Hee; Kim, Jeong Hwan; Jin, Hyung-Joo; Lee, Si Young

2013-06-01

Laminaria japonica is a brown alga, which is consumed widely in Korea, Japan, and China. This study investigated the antimicrobial activity of ethanol extracts of L. japonica against oral microbial species to assess the possible application of L. japonica extracts in dental care products. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined in culture medium using a microdilution method. The MICs of ethanol extracts of L. japonica with oral streptococci were 62.5-500 μg/ml and the MBCs were 125-1000 μg/ml. The MICs of Actinomyces naeslundii and Actinomyces odontolyticus were 250 and 62.5 μg/ml, respectively. The MBCs of A. naeslundii and A. odontolyticus were 500 and 250 μg/ml, respectively. The MICs were 250 and 62.5 μg/ml for Fusobacterium nucleatum and Porphyromonas gingivalis, respectively. The killing of Streptococcus mutans and P. gingivalis was dependent on the incubation time. The killing of S. mutans, A. odontolyticus, and P. gingivalis was significantly dependent on the extract concentration. Bacterial treatment with L. japonica extracts changed the cell surface texture of S. mutans, A. odontolyticus, and P. gingivalis. The results of this study suggest that L. japonica extracts may be useful for the development of antimicrobial agents to combat oral pathogens. Copyright © 2013 Elsevier Ltd. All rights reserved.

Melanins Protect Sporothrix brasiliensis and Sporothrix schenckii from the Antifungal Effects of Terbinafine

PubMed Central

Almeida-Paes, Rodrigo; Figueiredo-Carvalho, Maria Helena Galdino; Brito-Santos, Fábio; Almeida-Silva, Fernando; Oliveira, Manoel Marques Evangelista; Zancopé-Oliveira, Rosely Maria

2016-01-01

Terbinafine is a recommended therapeutic alternative for patients with sporotrichosis who cannot use itraconazole due to drug interactions or side effects. Melanins are involved in resistance to antifungal drugs and Sporothrix species produce three different types of melanin. Therefore, in this study we evaluated whether Sporothrix melanins impact the efficacy of antifungal drugs. Minimal inhibitory concentrations (MIC) and minimal fungicidal concentrations (MFC) of two Sporothrix brasiliensis and four Sporothrix schenckii strains grown in the presence of the melanin precursors L-DOPA and L-tyrosine were similar to the MIC determined by the CLSI standard protocol for S. schenckii susceptibility to amphotericin B, ketoconazole, itraconazole or terbinafine. When MICs were determined in the presence of inhibitors to three pathways of melanin synthesis, we observed, in four strains, an increase in terbinafine susceptibility in the presence of tricyclazole, a DHN-melanin inhibitor. In addition, one S. schenckii strain grown in the presence of L-DOPA had a higher MFC value when compared to the control. Growth curves in presence of 2×MIC concentrations of terbinafine showed that pyomelanin and, to a lesser extent, eumelanin were able to protect the fungi against the fungicidal effect of this antifungal drug. Our results suggest that melanin protects the major pathogenic species of the Sporothrix complex from the effects of terbinafine and that the development of new antifungal drugs targeting melanin synthesis may improve sporotrichosis therapies. PMID:27031728

Melanins Protect Sporothrix brasiliensis and Sporothrix schenckii from the Antifungal Effects of Terbinafine.

PubMed

Almeida-Paes, Rodrigo; Figueiredo-Carvalho, Maria Helena Galdino; Brito-Santos, Fábio; Almeida-Silva, Fernando; Oliveira, Manoel Marques Evangelista; Zancopé-Oliveira, Rosely Maria

2016-01-01

Terbinafine is a recommended therapeutic alternative for patients with sporotrichosis who cannot use itraconazole due to drug interactions or side effects. Melanins are involved in resistance to antifungal drugs and Sporothrix species produce three different types of melanin. Therefore, in this study we evaluated whether Sporothrix melanins impact the efficacy of antifungal drugs. Minimal inhibitory concentrations (MIC) and minimal fungicidal concentrations (MFC) of two Sporothrix brasiliensis and four Sporothrix schenckii strains grown in the presence of the melanin precursors L-DOPA and L-tyrosine were similar to the MIC determined by the CLSI standard protocol for S. schenckii susceptibility to amphotericin B, ketoconazole, itraconazole or terbinafine. When MICs were determined in the presence of inhibitors to three pathways of melanin synthesis, we observed, in four strains, an increase in terbinafine susceptibility in the presence of tricyclazole, a DHN-melanin inhibitor. In addition, one S. schenckii strain grown in the presence of L-DOPA had a higher MFC value when compared to the control. Growth curves in presence of 2×MIC concentrations of terbinafine showed that pyomelanin and, to a lesser extent, eumelanin were able to protect the fungi against the fungicidal effect of this antifungal drug. Our results suggest that melanin protects the major pathogenic species of the Sporothrix complex from the effects of terbinafine and that the development of new antifungal drugs targeting melanin synthesis may improve sporotrichosis therapies.

Synergistic antimicrobial profiling of violacein with commercial antibiotics against pathogenic micro-organisms.

PubMed

Subramaniam, Shankar; Ravi, Venkatraman; Sivasubramanian, Aravind

2014-01-01

Chromobacterium violaceum Bergonzini (Neisseriaceae), a Gram-negative bacterium, secretes a spectacular pigment called violacein. Violacein is a quorum-sensing metabolite and is also an active antimicrobial, anticancer agent. However, its efficiency as a potential drug, alone or in synergy with other active principles, has not being completely exploited. With the advent of different multi-drug resistant strains, it becomes essential to find a new natural product(s) that could be effectively used as a therapeutic agent. This work focused on the extraction of violacein from an isolated strain of C. violaceum and determined the combinatory effect of violacein with commercial antibiotics against various pathogens. Violacein production was optimized and was later extracted using ethanol and characterized by liquid chromatography-mass spectrometry and infrared spectroscopy. Then, individual minimum inhibitory concentration (MIC) values for each of the antibiotics were determined followed by violacein-commercial antibiotics (1:1) combinations, tested at different concentrations starting from 500 to 1 µg/ml against major pathogens. The individual MIC data for violacein was found to be 5.7 µg/ml (Staphylococcus aureus), 15.6 µg/ml (Klebsiella pneumoniae), 18.5 µg/ml (Pseudomonas aeruginosa), 20.0 µg/ml (Vibrio cholerae) and 5.7 µg/ml (Salmonella typhi). Violacein-gentamicin and violacein-cefadroxil combinations had MIC of 1.0 µg/ml against S. aureus. Most violacein-macrolide and violacein--aminoglycoside class combinations revealed fractional inhibitory concentration indices (FICI) of <0.5, thus exhibiting synergism. Furthermore, violacein-azithromycin and violacein-kanamycin combination, exhibited significant synergy (FICI-0.3) against S. typhi. Violacein works synergistically with most commercial antibiotics and could be used as drug in combination with other antimicrobial agents.

Antimicrobial Activity and Phytochemical Analysis of Organic Extracts from Cleome spinosa Jaqc.

PubMed Central

da Silva, Ana P. Sant'Anna; Nascimento da Silva, Luís C.; Martins da Fonseca, Caíque S.; de Araújo, Janete M.; Correia, Maria T. dos Santos; Cavalcanti, Marilene da Silva; Lima, Vera L. de Menezes

2016-01-01

Due to the use of Cleome spinosa Jacq. (Cleomaceae) in traditional medicine against inflammatory and infectious processes, this study evaluated the in vitro antimicrobial potential and phytochemical composition of extracts from its roots and leaves. From leaves (L) and roots (R) of C. spinosa different extracts were obtained (cyclohexane: ChL and ChR; chloroform: CL and CR; ethyl acetate: EAL and EAR, methanol: ML and MR). The antimicrobial activity was evaluated by the broth microdilution method to obtain the minimum inhibitory (MIC) and microbicidal (MMC) concentrations against 17 species, including bacteria and yeasts. Additionally, antimicrobial and combinatory effects with oxacillin were assessed against eight clinical isolates of Staphylococcus aureus. All C. spinosa extracts showed a broad spectrum of antimicrobial activity, as they have inhibited all tested bacteria and yeasts. This activity seems to be related to the phytochemicals (flavonoid, terpenoids and saponins) detected into the extracts of C. spinosa. ChL and CL extracts were the most actives, with MIC less than 1 mg/mL against S. aureus, Bacillus subtilis, and Micrococcus luteus. It is important to note that these concentrations are much lower than their 50% hemolysis concentration (HC50) values. Strong correlations were found between the average MIC against S. aureus and their phenolic (r = −0.89) and flavonoid content (r = −0.87), reinforcing the possible role of these metabolite classes on the antimicrobial activity of C. spinosa derived extracts. Moreover, CL and CR showed the best inhibitory activity against S. aureus clinical isolates, they also showed synergistic action with oxacillin against all these strains (at least at one combined proportion). These results encourage the identification of active substances which could be used as lead(s) molecules in the development of new antimicrobial drugs. PMID:27446005

Antimicrobial Activity and Biocompatibility of the Psidium cattleianum Extracts for Endodontic Purposes.

PubMed

Massunari, Loiane; Novais, Renata Zoccal; Oliveira, Márcio Teixeira; Valentim, Diego; Dezan Junior, Eloi; Duque, Cristiane

2017-01-01

Psidium cattleianum (PC) has been displaying inhibitory effect against a variety of microorganisms, but this effect has not yet been tested against endodontic pathogens. The aim of this study was to evaluate the antimicrobial activity and biocompatibility of the aqueous (PCAE) and hydroethanolic (PCHE) extracts from Psidium cattleianum (PC) leaves. Minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) were determined using the microdilution broth method in order to analyze the antimicrobial effect against Enterococcus faecalis, Pseudomonas aeruginosa, Actinomyces israelii and Candida albicans in planktonic conditions. Biofilm assays were conducted only with the extracts that were able to determine the MLC for microorganisms in planktonic conditions. Immediate and late tissue reactions against PC extracts were evaluated using edemogenic test and histological analysis of subcutaneous implants in Wistar rats. The results showed that the MIC and MLC values ranged between 0.25 and 4 mg/mL. The MLC obtained for PCHE inhibited 100% growth of all the tested strains, except for C. albicans. PCAE had the same effect for E. faecalis and P. aeruginosa. Both PC extracts were able to eliminate E. faecalis biofilms and only the PCHE eliminated P. aeruginosa biofilms. The positive controls inhibited the growth of all tested strains in MIC and MLC essays, but no CHX tested concentrations were able to eliminate A. israelii biofilm. PCAE caused a discrete increase in the edema over time, while PCHE caused a higher initial edema, which decreased progressively. Both PCAE and PCHE extracts were biocompatible, but PCHE showed better results with slight levels of inflammation at 28 days. In conclusion, PCHE was biocompatible and presented better antimicrobial effect against important pathogens associated with persistent endodontic infections.

Growth Inhibitory Effects of Adhatoda vasica and Its Potential at Reducing Listeria monocytogenes in Chicken Meat

PubMed Central

Shukla, Shruti; Ahirwal, Laxmi; Bajpai, Vivek K.; Huh, Yun Suk; Han, Young-Kyu

2017-01-01

The inhibitory effects of Adhatoda vasica ethanolic leaf extract (AVELE) against Listeria monocytogenes were examined to assess its potential to preserve minimally processed meat products safely. The total phenolic, flavonoid, and alkaloid levels in AVELE were 10.09 ± 4.52 mg of gallic acid equivalents (GAE)/g, 22.43 ± 1.62 mg of quercetin equivalents/g, and 19.43 ± 3.90 mg/g, respectively. AVELE (1, 5, 10, or 20%) had considerable antibacterial effects against L. monocytogenes NCIM 24563 in terms of the inhibitory zones (7.4–13.6 mm), MIC (100 mg/mL or 10% formulated solution), reduced cell viability, potassium ion efflux, and the release of 260-nm absorbing materials and extracellular ATP. AVELE was used as a rinse solution (5, 10, and 20%) for raw chicken breast meat. A 20% rinsing solution applied for 60 min inhibited the L. monocytogenes NCIM 24563 counts significantly on raw chicken breast meat. Moreover, L. monocytogenes NCIM 24563 did not grow in the meat sample when the rinse time was increased to 90 min at the same concentration. L. monocytogenes showed a greater reduction to ~3 CFU/g after rinsing with a 10 and 20% AVELE solution for 30 min than with a 5% AVELE solution. The rinsing processes with AVELE produced the final cooked chicken products with higher sensory attribute scores, such as taste, juiciness, and tenderness, compared to the control group along with a decrease in microbial contamination. Chicken meat rinsed with AVELE (rinsing time of 90 min) showed better sensory attribute scores of juiciness and tenderness, as well as the overall sensory quality compared to the untreated group. This research highlights the effectiveness of AVELE against L. monocytogenes NCIM 24563, suggesting that AVELE can be used as an effective antimicrobial marinade and/or a rinse for meat preservation. PMID:28769879

Nitrotriazole- and imidazole-based amides and sulfonamides as antitubercular agents.

PubMed

Papadopoulou, Maria V; Bloomer, William D; Rosenzweig, Howard S; Arena, Alexander; Arrieta, Francisco; Rebolledo, Joseph C J; Smith, Diane K

2014-11-01

Twenty-three 3-nitrotriazole-based and 2-nitroimidazole-based amides and sulfonamides were screened for antitubercular (anti-TB) activity in aerobic Mycobacterium tuberculosis H37Rv by using the BacTiter-Glo (BTG) microbial cell viability assay. In general, 3-nitrotriazole-based sulfonamides demonstrated anti-TB activity, whereas 3-nitrotriazole-based amides and 2-nitroimidazole-based amides and sulfonamides were inactive. Three 3-nitrotriazole-based sulfonamides (compounds 4, 2, and 7) demonstrated 50% inhibitory concentration (IC50), IC90, and MIC values of 0.38, 0.43, and 1.56 μM (compound 4), 0.57, 0.98, and 3.13 μM (compound 2), and 0.79, 0.87, and 3.13 μM (compound 7), respectively. For 3-nitrotriazole-based sulfonamides, anti-TB activity increased with lipophilicity, whereas the one-electron reduction potential (E1/2) did not play a role. 2-Nitroimidazole-based analogs, which were inactive in the BTG assay, were significantly more active in the low-oxygen assay and more active than the 3-nitrotriazoles. All active nitrotriazoles in the BTG assay were similarly active or more potent (lower MIC values) against resistant strains, with the exception of compounds 2, 3, 4, and 8, which demonstrated greater MIC values against isoniazid-resistant strains. Five 3-nitrotriazole-based sulfonamides demonstrated activity in infected murine J774 macrophages, causing log reductions similar to those seen with rifampin. However, some compounds caused toxicity in uninfected macrophages. In conclusion, the classes of 3-nitrotriazole-based amides and sulfonamides merit further investigation as potential antitubercular agents. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Nitrotriazole- and Imidazole-Based Amides and Sulfonamides as Antitubercular Agents

PubMed Central

Bloomer, William D.; Rosenzweig, Howard S.; Arena, Alexander; Arrieta, Francisco; Rebolledo, Joseph C. J.; Smith, Diane K.

2014-01-01

Twenty-three 3-nitrotriazole-based and 2-nitroimidazole-based amides and sulfonamides were screened for antitubercular (anti-TB) activity in aerobic Mycobacterium tuberculosis H37Rv by using the BacTiter-Glo (BTG) microbial cell viability assay. In general, 3-nitrotriazole-based sulfonamides demonstrated anti-TB activity, whereas 3-nitrotriazole-based amides and 2-nitroimidazole-based amides and sulfonamides were inactive. Three 3-nitrotriazole-based sulfonamides (compounds 4, 2, and 7) demonstrated 50% inhibitory concentration (IC50), IC90, and MIC values of 0.38, 0.43, and 1.56 μM (compound 4), 0.57, 0.98, and 3.13 μM (compound 2), and 0.79, 0.87, and 3.13 μM (compound 7), respectively. For 3-nitrotriazole-based sulfonamides, anti-TB activity increased with lipophilicity, whereas the one-electron reduction potential (E1/2) did not play a role. 2-Nitroimidazole-based analogs, which were inactive in the BTG assay, were significantly more active in the low-oxygen assay and more active than the 3-nitrotriazoles. All active nitrotriazoles in the BTG assay were similarly active or more potent (lower MIC values) against resistant strains, with the exception of compounds 2, 3, 4, and 8, which demonstrated greater MIC values against isoniazid-resistant strains. Five 3-nitrotriazole-based sulfonamides demonstrated activity in infected murine J774 macrophages, causing log reductions similar to those seen with rifampin. However, some compounds caused toxicity in uninfected macrophages. In conclusion, the classes of 3-nitrotriazole-based amides and sulfonamides merit further investigation as potential antitubercular agents. PMID:25182645

Mutations in the quinolone resistance determining region in Staphylococcus epidermidis recovered from conjunctiva and their association with susceptibility to various fluoroquinolones

PubMed Central

Yamada, M; Yoshida, J; Hatou, S; Yoshida, T; Minagawa, Y

2008-01-01

Background: Staphylococcus epidermidis is one of the prominent pathogens in ocular infection. The prevalence of mutations in the quinolone resistance determining region (QRDR) area in S epidermidis isolated from the ocular surface and its association with fluoroquinolone resistance has not been fully elucidated. Methods: Mutations in the QRDR of gyrA, gyrB, parC, and parE genes of 138 isolates of S epidermidis recovered from the human conjunctival flora were analysed. The minimal inhibitory concentrations (MICs) of four fluoroquinolones (levofloxacin, gatifloxacin, moxifloxacin and tosufloxacin) against these isolates were also determined using agar dilution methods. Results: The MIC90 values of levofloxacin, gatifloxacin, moxifloxacin and tosufloxacin were 3.13, 1.56, 0.78 and 3.13 μg/ml, respectively. The MIC values of all fluoroquinolones showed a bimodal distribution (susceptible strain and less susceptible strain). Mutations with amino acid substitution in the QRDR were present in 70 (50.7%) isolates. 19 different combinations of mutations were detected: 3 isolates (2.2%) had four mutations, 8 (5.8%) had three mutations, 43 (31.2%) had double mutations and 16 (11.6%) had single mutations. Isolates with mutations in the QRDR of both gyrA and parC (n = 53) were less susceptible to fluoroquinolones. Conclusions: The present findings show that approximately half the S epidermidis isolates from the normal human conjunctiva have mutation(s) in the QRDR. The presence of mutations in both gyrA and parC is strongly associated with reduced susceptibility to fluoroquinolones. PMID:18460536

Inhibition of Staphylococcus aureus biofilm by Lactobacillus isolated from fine cocoa.

PubMed

Melo, Tauá Alves; Dos Santos, Thalis Ferreira; de Almeida, Milena Evangelista; Junior, Luiz Alberto Gusmão Fontes; Andrade, Ewerton Ferraz; Rezende, Rachel Passos; Marques, Lucas Miranda; Romano, Carla Cristina

2016-10-28

Biofilm production represents an important virulence and pathogenesis factor for Staphylococcus aureus. The formation of biofilms on medical devices is a major concern in hospital environments, as they can become a constant source of infection. Probiotic bacteria, such as Lactobacillus fermentum and L. plantarum, have been found to inhibit biofilm formation; however little is known about the underlying mechanism. In this study, we tested the activity of supernatants produced by L. fermentum TCUESC01 and L. plantarum TCUESC02, isolated during the fermentation of fine cocoa, against S. aureus CCMB262 biofilm production. We measured inhibition of biofilm formation in vitro and analyzed biofilm structure by confocal and electronic microscopy. Additionally, we quantified the expression of S. aureus genes icaA and icaR involved in the synthesis of the biofilm matrix by real-time PCR. Both Lactobacillus supernatants inhibited S. aureus growth. However, only L. fermentum TCUESC01 significantly reduced the thickness of the biofilm, from 14 μm to 2.83 μm (at 18 mg∙mL -1 , 90 % of the minimum inhibitory concentration, MIC), 3.12 μm (at 14 mg∙mL -1 , 70 % of the MIC), and 5.21 μm (at 10 mg∙mL -1 , 50 % of the MIC). Additionally, L. fermentum TCUESC01 supernatant modulated the expression of icaA and icaR. L. fermentum TCUESC01 reduces the formation of S. aureus biofilm under subinhibitory conditions. Inhibition of biofilm production probably depends on modulation of the ica operon.

Tolerance to chitosan by Trichoderma species is associated with low membrane fluidity.

PubMed

Zavala-González, Ernesto A; Lopez-Moya, Federico; Aranda-Martinez, Almudena; Cruz-Valerio, Mayra; Lopez-Llorca, Luis Vicente; Ramírez-Lepe, Mario

2016-07-01

The effect of chitosan on growth of Trichoderma spp., a cosmopolitan genus widely exploited for their biocontrol properties was evaluated. Based on genotypic (ITS of 18S rDNA) characters, four isolates of Trichoderma were identified as T. pseudokoningii FLM16, T. citrinoviride FLM17, T. harzianum EZG47, and T. koningiopsis VSL185. Chitosan reduces radial growth of Trichoderma isolates in concentration-wise manner. T. koningiopsis VSL185 was the most chitosan tolerant isolate in all culture media amended with chitosan (0.5-2.0 mg ml(-1) ). Minimal Inhibitory Concentration (MIC) and Minimal Fungicidal Concentration (MFC) were determined showing that T. koningiopsis VSL185 displays higher chitosan tolerance with MIC value >2000 μg ml(-1) while for other Trichoderma isolates MIC values were around 10 μg ml(-1) . Finally, free fatty acid composition reveals that T. koningiopsis VSL185, chitosan tolerant isolate, displays lower linolenic acid (C18:3) content than chitosan sensitive Trichoderma isolates. Our findings suggest that low membrane fluidity is associated with chitosan tolerance in Trichoderma spp. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antibacterial activity of Rosmarinus officinalis L. and Thymus vulgaris L. essential oils and their combination against food-borne pathogens and spoilage bacteria in ready-to-eat vegetables.

PubMed

Iseppi, Ramona; Sabia, Carla; de Niederhäusern, Simona; Pellati, Federica; Benvenuti, Stefania; Tardugno, Roberta; Bondi, Moreno; Messi, Patrizia

2018-06-06

The antibacterial activity of Rosmarinus officinalis L. and Thymus vulgaris L. essential oils (EOs), and their combination against food-borne and spoilage bacteria (Listeria monocytogenes, Salmonella enteritidis, Yersinia enterocolitica, Escherichia coli and Pseudomonas spp.) was determined. The EOs inhibitory effect was evaluated both in vitro by using the disk diffusion assay and the minimum inhibitory concentration (MIC) determination, and on food by using an artificially contaminated ready-to-eat (RTE) vegetables. The results showed that the lowest MIC values were obtained with R. officinalis and T. vulgaris EOs against E. coli (4 and 8 μL/mL, respectively). The incorporation of the EOs alone or their combination in RTE vegetables reduced the viable counts of all the tested strains. Lastly, in the on food study we simulated the worst hygienic conditions, obtaining results that can be considered a warranty of safety.

Role of renal function in risk assessment of target non-attainment after standard dosing of meropenem in critically ill patients: a prospective observational study.

PubMed

Ehmann, Lisa; Zoller, Michael; Minichmayr, Iris K; Scharf, Christina; Maier, Barbara; Schmitt, Maximilian V; Hartung, Niklas; Huisinga, Wilhelm; Vogeser, Michael; Frey, Lorenz; Zander, Johannes; Kloft, Charlotte

2017-10-21

Severe bacterial infections remain a major challenge in intensive care units because of their high prevalence and mortality. Adequate antibiotic exposure has been associated with clinical success in critically ill patients. The objective of this study was to investigate the target attainment of standard meropenem dosing in a heterogeneous critically ill population, to quantify the impact of the full renal function spectrum on meropenem exposure and target attainment, and ultimately to translate the findings into a tool for practical application. A prospective observational single-centre study was performed with critically ill patients with severe infections receiving standard dosing of meropenem. Serial blood samples were drawn over 4 study days to determine meropenem serum concentrations. Renal function was assessed by creatinine clearance according to the Cockcroft and Gault equation (CLCR CG ). Variability in meropenem serum concentrations was quantified at the middle and end of each monitored dosing interval. The attainment of two pharmacokinetic/pharmacodynamic targets (100%T >MIC , 50%T >4×MIC ) was evaluated for minimum inhibitory concentration (MIC) values of 2 mg/L and 8 mg/L and standard meropenem dosing (1000 mg, 30-minute infusion, every 8 h). Furthermore, we assessed the impact of CLCR CG on meropenem concentrations and target attainment and developed a tool for risk assessment of target non-attainment. Large inter- and intra-patient variability in meropenem concentrations was observed in the critically ill population (n = 48). Attainment of the target 100%T >MIC was merely 48.4% and 20.6%, given MIC values of 2 mg/L and 8 mg/L, respectively, and similar for the target 50%T >4×MIC . A hyperbolic relationship between CLCR CG (25-255 ml/minute) and meropenem serum concentrations at the end of the dosing interval (C 8h ) was derived. For infections with pathogens of MIC 2 mg/L, mild renal impairment up to augmented renal function was identified as a risk factor for target non-attainment (for MIC 8 mg/L, additionally, moderate renal impairment). The investigated standard meropenem dosing regimen appeared to result in insufficient meropenem exposure in a considerable fraction of critically ill patients. An easy- and free-to-use tool (the MeroRisk Calculator) for assessing the risk of target non-attainment for a given renal function and MIC value was developed. Clinicaltrials.gov, NCT01793012 . Registered on 24 January 2013.

Asymmetric total synthesis of 6-Tuliposide B and its biological activities against tulip pathogenic fungi.

PubMed

Shigetomi, Kengo; Omoto, Shoko; Kato, Yasuo; Ubukata, Makoto

2011-01-01

The structure-activity relationship was investigated to evaluate the antifungal activities of tuliposides and tulipalins against tulip pathogenic fungi. 6-Tuliposide B was effectively synthesized via the asymmetric Baylis-Hillman reaction. Tuliposides and tulipalins showed antifungal activities against most of the strains tested at high concentrations (2.5 mM), while Botrytis tulipae was resistant to tuliposides. Tulipalin formation was involved in the antifungal activity, tulipalin A showed higher inhibitory activity than 6-tuliposide B and tulipalin B. Both the tuliposides and tulipalins showed pigment-inducing activity against Gibberella zeae and inhibitory activity against Fusarium oxysporum f. sp tulipae. These activities were induced at a much lower concentration (0.05 mM) than the antifungal MIC values.

In Vitro Activity of Aztreonam-Avibactam against Enterobacteriaceae and Pseudomonas aeruginosa Isolated by Clinical Laboratories in 40 Countries from 2012 to 2015.

PubMed

Karlowsky, James A; Kazmierczak, Krystyna M; de Jonge, Boudewijn L M; Hackel, Meredith A; Sahm, Daniel F; Bradford, Patricia A

2017-09-01

The combination of the monobactam aztreonam and the non-β-lactam β-lactamase inhibitor avibactam is currently in clinical development for the treatment of serious infections caused by metallo-β-lactamase (MBL)-producing Enterobacteriaceae , a difficult-to-treat subtype of carbapenem-resistant Enterobacteriaceae for which therapeutic options are currently very limited. The present study tested clinically significant isolates of Enterobacteriaceae ( n = 51,352) and Pseudomonas aeruginosa ( n = 11,842) collected from hospitalized patients in 208 medical center laboratories from 40 countries from 2012 to 2015 for in vitro susceptibility to aztreonam-avibactam, aztreonam, and comparator antimicrobial agents using a standard broth microdilution methodology. Avibactam was tested at a fixed concentration of 4 μg/ml in combination with 2-fold dilutions of aztreonam. The MIC 90 s of aztreonam-avibactam and aztreonam were 0.12 and 64 μg/ml, respectively, for all Enterobacteriaceae isolates; >99.9% of all isolates and 99.8% of meropenem-nonsusceptible isolates ( n = 1,498) were inhibited by aztreonam-avibactam at a concentration of ≤8 μg/ml. PCR and DNA sequencing identified 267 Enterobacteriaceae isolates positive for MBL genes (NDM, VIM, IMP); all Enterobacteriaceae carrying MBLs demonstrated aztreonam-avibactam MICs of ≤8 μg/ml and a MIC 90 of 1 μg/ml. Against all P. aeruginosa isolates tested, the MIC 90 of both aztreonam-avibactam and aztreonam was 32 μg/ml; against MBL-positive P. aeruginosa isolates ( n = 452), MIC 90 values for aztreonam-avibactam and aztreonam were 32 and 64 μg/ml, respectively. The current study demonstrated that aztreonam-avibactam possesses potent in vitro activity against a recent, sizeable global collection of Enterobacteriaceae clinical isolates, including isolates that were meropenem nonsusceptible, and against MBL-positive isolates of Enterobacteriaceae , for which there are few treatment options. Copyright © 2017 American Society for Microbiology.

In Vitro Activity of Aztreonam-Avibactam against Enterobacteriaceae and Pseudomonas aeruginosa Isolated by Clinical Laboratories in 40 Countries from 2012 to 2015

PubMed Central

Karlowsky, James A.; de Jonge, Boudewijn L. M.; Hackel, Meredith A.; Sahm, Daniel F.

2017-01-01

ABSTRACT The combination of the monobactam aztreonam and the non-β-lactam β-lactamase inhibitor avibactam is currently in clinical development for the treatment of serious infections caused by metallo-β-lactamase (MBL)-producing Enterobacteriaceae, a difficult-to-treat subtype of carbapenem-resistant Enterobacteriaceae for which therapeutic options are currently very limited. The present study tested clinically significant isolates of Enterobacteriaceae (n = 51,352) and Pseudomonas aeruginosa (n = 11,842) collected from hospitalized patients in 208 medical center laboratories from 40 countries from 2012 to 2015 for in vitro susceptibility to aztreonam-avibactam, aztreonam, and comparator antimicrobial agents using a standard broth microdilution methodology. Avibactam was tested at a fixed concentration of 4 μg/ml in combination with 2-fold dilutions of aztreonam. The MIC90s of aztreonam-avibactam and aztreonam were 0.12 and 64 μg/ml, respectively, for all Enterobacteriaceae isolates; >99.9% of all isolates and 99.8% of meropenem-nonsusceptible isolates (n = 1,498) were inhibited by aztreonam-avibactam at a concentration of ≤8 μg/ml. PCR and DNA sequencing identified 267 Enterobacteriaceae isolates positive for MBL genes (NDM, VIM, IMP); all Enterobacteriaceae carrying MBLs demonstrated aztreonam-avibactam MICs of ≤8 μg/ml and a MIC90 of 1 μg/ml. Against all P. aeruginosa isolates tested, the MIC90 of both aztreonam-avibactam and aztreonam was 32 μg/ml; against MBL-positive P. aeruginosa isolates (n = 452), MIC90 values for aztreonam-avibactam and aztreonam were 32 and 64 μg/ml, respectively. The current study demonstrated that aztreonam-avibactam possesses potent in vitro activity against a recent, sizeable global collection of Enterobacteriaceae clinical isolates, including isolates that were meropenem nonsusceptible, and against MBL-positive isolates of Enterobacteriaceae, for which there are few treatment options. PMID:28630192

The Sensitivity of Endodontic Enterococcus spp. Strains to Geranium Essential Oil.

PubMed

Łysakowska, Monika E; Sienkiewicz, Monika; Banaszek, Katarzyna; Sokołowski, Jerzy

2015-12-21

Enterococci are able to survive endodontic procedures and contribute to the failure of endodontic therapy. Thus, it is essential to identify novel ways of eradicating them from infected root canals. One such approach may be the use of antimicrobials such as plant essential oils. Enterococcal strains were isolated from endodontically treated teeth by standard microbiological methods. Susceptibility to antibiotics was evaluated by the disc-diffusion method. The minimal inhibitory concentration (MIC) of geranium essential oil was investigated by microdilution in 96-well microplates in Mueller Hinton Broth II. Biofilm eradication concentrations were checked in dentin tests. Geranium essential oil inhibited enterococcal strains at concentrations ranging from 1.8-4.5 mg/mL. No correlation was shown between resistance to antibiotics and the MICs of the test antimicrobials. The MICs of the test oil were lower than those found to show cytotoxic effects on the HMEC-1 cell line. Geranium essential oil eradicated enterococcal biofilm at concentrations of 150 mg/mL. Geranium essential oil inhibits the growth of endodontic enterococcal species at lower concentrations than those required to reach IC50 against the HMEC-1 cell line, and is effective against bacteria protected in biofilm at higher concentrations. In addition, bacteria do not develop resistance to essential oils. Hence, geranium essential oil represents a possible alternative to other antimicrobials during endodontic procedures.

[Activity of doripenem against anaerobic bacteria].

PubMed

Dubreuil, L; Neut, C; Mahieux, S; Muller-Serieys, C; Jean-Pierre, H; Marchandin, H; Soussy, C J; Miara, A

2011-04-01

This study examines the activity of doripenem, a new carbapenem compound compared with amoxicillin-clavulanic acid, piperacillin+tazobactam, imipenem, clindamycin and metronidazole against 316 anaerobes. Inoculum preparation and agar dilution method were performed according to the CLSI method for anaerobes (M11A7). At a concentration of 4μg/ml doripenem and imipenem (IMP) inhibited 122 (96 %) and 126 (99 %) strains of the Bacteroides fragilis group, respectively. In contrast, doripenem appeared more potent than IMP against Gram-positive anaerobes inhibiting at the same concentration of 4μg/ml 145/145 strains (100 %) versus 115/145 for IMP (79.3 %). Against 316 anaerobic strains, the carbapenem doripenem had an MIC(50) of 0.25μg/ml and an MIC(90) of 2μg/ml. Results were similar to those for imipenem (MIC(50) of 0.125μg/ml and MIC(90) of 4μg/ml). If we consider the resistant breakpoints of the two carbapenems as defined by EUCAST, the resistance rate for doripenem (MIC>4μg/ml) 1.6 % is similar to that of imipenem (MIC>8μg/ml) 1.3 %. Thus independently of the PK/PD parameters the two carbapenems demonstrated very close activity; doripenem was more potent on Gram-positive anaerobes and slightly less potent against Gram-negative anaerobes mainly the B. fragilis group. Further clinical studies are needed to assess its usefulness in patients. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

Extraction, separation and isolation of volatiles from Vitex agnus-castus L. (Verbenaceae) wild species of Sardinia, Italy, by supercritical CO2.

PubMed

Marongiu, Bruno; Piras, Alessandra; Porcedda, Silvia; Falconieri, Danilo; Goncalves, Maria J; Salgueiro, Ligia; Maxia, Andrea; Lai, Roberta

2010-04-01

Isolation of volatile concentrates from leaves, flowers and fruits of Vitex agnus-castus L. have been obtained by supercritical extraction with carbon dioxide. The composition of the volatile concentrates has been analysed by GC/MS. In all plant organs, the extracts are composed chiefly of alpha-pinene, sabinene, 1,8-cineole, alpha-terpinyl acetate, (E)-caryophyllene, (E)-beta-farnesene, bicyclogermacrene, spathulenol and manool. The main difference observed was in the content of sclarene, which was not present in the samples from flowers or fruits. To complete the investigation, a comparison with the hydrodistilled oil has been carried out. The minimal inhibitory concentration (MIC) and the minimal lethal concentration were used to evaluate the antifungal activity of the oils against dermatophyte strains (Trichophyton mentagrophytes, Microsporum canis, T. rubrum, M. gypseum and Epidermophyton floccosum). Antifungal activity of the leaf essential oil was the highest, with MIC values of 0.64 microL mL(-1) for most of the strains.

Mycobacterium massiliense BRA100 strain recovered from postsurgical infections: resistance to high concentrations of glutaraldehyde and alternative solutions for high level disinfection.

PubMed

Lorena, Nádia Suely de Oliveira; Pitombo, Marcos Bettini; Côrtes, Patrícia Barbur; Maya, Maria Cristina Araújo; Silva, Marlei Gomes da; Carvalho, Ana Carolina da Silva; Coelho, Fábrice Santana; Miyazaki, Neide Hiromi Tokumaru; Marques, Elizabeth Andrade; Chebabo, Alberto; Freitas, Andréa D'Avila; Lupi, Otília; Duarte, Rafael Silva

2010-10-01

To evaluate the minimum inhibitory concentration (MIC) of GTA against these microorganisms and alternative disinfectants for high-level disinfection (HLD). Reference mycobacteria and clinical M. massiliense strains were included in this study. Active cultures were submitted to susceptibility qualitative tests with GTA dilutions (ranging from 1.5% to 8%), and commercial orthophthaldehyde (OPA) and peracetic acid (PA)-based solutions, during the period of exposure as recommended by National Agency of Sanitary Surveillance for HLD. All reference and M. massiliense non-BRA100 strains, recovered from sputum, were susceptible to any GTA concentration, OPA and PA solutions. M. massiliense BRA100 strains presented MIC of 8% GTA and were susceptible to OPA and PA. M. massiliense BRA100 strain is resistant to high GTA concentrations (up to 7%), which proves that this product is non-effective against specific rapidly growing mycobacteria and should be substituted by OPA or PA-based solutions for HLD.

Nontoxic concentration of ceftazidime and flomoxef sodium for intravitreal use--evaluated by in-vitro ERG.

PubMed

Tanabe, J; Kitano, K; Suzuki, T; Okayama, Y; Mochizuki, K; Kawasaki, K

1990-01-01

The effects of ceftazidime (CAZ) and flomoxef sodium (FMOX) on the in-vitro electroretinogram (ERG) of albino rabbits were studied. The a-wave, the b-wave and the oscillatory potential (OP) were unchanged by 0.3mM (0.19mg/ml) CAZ-containing solution. The OP was suppressed by 0.5mM (0.32mg/ml) CAZ. The a-wave, the b-wave and the OP were unchanged by 0.5mM (0.26mg/ml) FMOX. The OP was suppressed and its peak latency was delayed by 2mM (0.52mg/ml) FMOX. The concentration of 0.3mM (0.19mg/ml) CAZ was higher than its minimum inhibitory concentration (MIC) against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Serratia marcescens and Propionibacterium acnes. The concentration of 0.5mM (0.26mg/ml) FMOX was higher than its MIC against Staphylococcus aureus, Staphylococcus epidermidis, Serratia marcescens and Propionibacterium acnes.

Effect of citral and carvacrol on the susceptibility of Listeria monocytogenes and Listeria innocua to antibiotics.

PubMed

Zanini, S F; Silva-Angulo, A B; Rosenthal, A; Rodrigo, D; Martínez, A

2014-05-01

The aim of this study was to evaluate the antibiotic susceptibility of Listeria innocua (L. innocua) and Listeria monocytogenes (L. monocytogenes) cells in the presence of citral and carvacrol at sublethal concentrations in an agar medium. The presence of terpenes in the L. monocytogenes and L. innocua culture medium provided a reduction in the minimal inhibitory concentration (MIC) of all the antibiotics tested. These effects were dependent on the concentration of terpenes present in the culture medium. The combination of citral and carvacrol potentiated antibiotic activity by reducing the MIC values of bacitracin and colistin from 32.0 and 128.0 μg ml⁻¹ to 1.0 and 2.0 μg ml⁻¹, respectively. Thus, both Listeria species became more susceptible to these drugs. In this way, the colistin and bacitracin resistance of L. monocytogenes and L. innocua was reversed in the presence of terpenes. Results obtained in this study show that the phytochemicals citral and carvacrol potentiate antibiotic activity, reducing the MIC values of cultured L. monocytogenes and L. innocua. Phytochemicals citral and carvacrol potentiate antibiotic activity of erythromycin, bacitracin and colistin by reducing the MIC values of cultured Listeria monocytogenes and Listeria innocua. This effect in reducing the MIC values of the antibiotics tested in both micro-organisms was increased when natural antimicrobials were combined. This finding indicated that the combination among terpenes and antibiotic may contribute in reducing the required dosage of antibiotics due to the possible effect of terpenes on permeation barrier of the micro-organism cell membrane. © 2014 The Society for Applied Microbiology.

In vitro effects of Melaleuca alternifolia essential oil on growth and production of volatile sulphur compounds by oral bacteria.

PubMed

Graziano, Talita Signoreti; Calil, Caroline Morini; Sartoratto, Adilson; Franco, Gilson César Nobre; Groppo, Francisco Carlos; Cogo-Müller, Karina

2016-01-01

Halitosis can be caused by microorganisms that produce volatile sulphur compounds (VSCs), which colonize the surface of the tongue and subgingival sites. Studies have reported that the use of natural products can reduce the bacterial load and, consequently, the development of halitosis. The aim of this study was to evaluate the antimicrobial activity of the essential oil of Melaleuca alternifolia on the growth and volatile sulphur compound (VSC) production of oral bacteria compared with chlorhexidine. The effects of these substances were evaluated by the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) in planktonic cultures of Porphyromonas gingivalis and Porphyromonas endodontalis. In addition, gas chromatography analyses were performed to measure the concentration of VSCs from bacterial cultures and to characterize M. alternifolia oil components. The MIC and MBC values were as follows: M. alternifolia - P. gingivalis (MIC and MBC=0.007%), P. endodontalis (MIC and MBC=0.007%=0.5%); chlorhexidine - P. gingivalis and P. endodontalis (MIC and MBC=1.5 mg/mL). M. alternifolia significantly reduced the growth and production of hydrogen sulfide (H2S) by P. gingivalis (p<0.05, ANOVA-Dunnet) and the H2S and methyl mercaptan (CH3SH) levels of P. endodontalis (p<0.05, ANOVA-Dunnet). Chlorhexidine reduced the growth of both microorganisms without altering the production of VSC in P. endodontalis. For P. gingivalis, the production of H2S and CH3SH decreased (p<0.05, ANOVA-Dunnet). M. alternifolia can reduce bacterial growth and VSCs production and could be used as an alternative to chlorhexidine.

Modulation of the norfloxacin resistance in Staphylococcus aureus by Cordia verbenaceae DC

PubMed Central

Matias, Edinardo F.F.; Santos, Karla K. A.; Falcão-Silva, Vivyanne S.; Siqueira-Júnior, José P.; Costa, José G. M.; Coutinho, Henrique D.M.

2013-01-01

Background & objectives: Several chemical compounds isolated from natural sources have antibacterial activity and some enhance the antibacterial activity of antibiotics reversing the natural resistance of bacteria to certain antibiotics. In this study, the hexane and methanol extract of Cordia verbenaceae were assessed for antibacterial activity alone and combinated with norfloxacin against the Staphylococcus aureus strain SA1199B. Methods: The minimum inhibitory concentration (MIC) of extracts was assayed using microdilution assay and the modulatory activity was evaluated using plate diffusion assay. Results: The MIC observed varied between 256 to >1024 μg/ml. However, the antibiotic activity of norfloxacin was enhanced in the presence of subinhibitory concentrations of hexane extract of C. verbenaceae (HECV). Interpretations & conclusions: Our results indicate that Cordia verbenaceae DC. can be a source of plant derived products with antibiotic modifying activity. PMID:23481069

Imaging the antimicrobial mechanism(s) of cathelicidin-2

PubMed Central

Schneider, Viktoria A. F.; Coorens, Maarten; Ordonez, Soledad R.; Tjeerdsma-van Bokhoven, Johanna L. M.; Posthuma, George; van Dijk, Albert; Haagsman, Henk P.; Veldhuizen, Edwin J. A.

2016-01-01

Host defence peptides (HDPs) have the potential to become alternatives to conventional antibiotics in human and veterinary medicine. The HDP chicken cathelicidin-2 (CATH-2) has immunomodulatory and direct killing activities at micromolar concentrations. In this study the mechanism of action of CATH-2 against Escherichia coli (E. coli) was investigated in great detail using a unique combination of imaging and biophysical techniques. Live-imaging with confocal fluorescence microscopy demonstrated that FITC-labelled CATH-2 mainly localized at the membrane of E. coli. Upon binding, the bacterial membrane was readily permeabilized as was shown by propidium iodide influx into the cell. Concentration- and time-dependent effects of the peptide on E. coli cells were examined by transmission electron microscopy (TEM). CATH-2 treatment was found to induce dose-dependent morphological changes in E. coli. At sub-minimal inhibitory concentrations (sub-MIC), intracellular granulation, enhanced vesicle release and wrinkled membranes were observed, while membrane breakage and cell lysis occurred at MIC values. These effects were visible within 1–5 minute of peptide exposure. Immuno-gold TEM showed CATH-2 binding to bacterial membranes. At sub-MIC values the peptide rapidly localized intracellularly without visible membrane permeabilization. It is concluded that CATH-2 has detrimental effects on E. coli at concentrations that do not immediately kill the bacteria. PMID:27624595

Postantibiotic effect of various antibiotics on Legionella pneumophila strains isolated from water systems.

PubMed

Birteksöz-Tan, Ayşe Seher; Zeybek, Zuhal

2012-11-01

The postantibiotic effects (PAE) of azithromycin, clarithromycin, ciprofloxacin, and levofloxacin were investigated against Legionella pneumophila (L. pneumophila) strains isolated from several hot water systems of different buildings in Istanbul. Each strain in logarithmic phase of growth was exposed to concentrations of antibiotics equal to minimum inhibitory concentration (MIC) and 4× MIC for 1 h. Recovery periods of test cultures were evaluated after centrifugation using the viable counting method. The mean values of PAEs for the strains of L. pneumophila, azithromycin at a concentration equal to and 4 times of MIC values were found 1.75 ± 0.28 h and 4.06 ± 0.44 h, for clarithromycin 2.98 ± 0.70 h and 4.18 ± 0.95 h, for ciprofloxacin 2.97 ± 0.63 h and 4.70 ± 0.63 h, for levofloxacin 2.05 ± 0.33 h and 3.78 ± 0.46 h, respectively. All of the antibiotics showed increased PAE values in a concentration-dependent manner. The findings of our study may play useful role in selecting the appropriate timing of doses during therapy with antimicrobials to treat patients infected with L. pneumophila.

[Emerging pathogen: Candida kefyr (Kluvyeromyces marxianus)].

PubMed

Çuhadar, Tuğba; Kalkancı, Ayşe

2017-10-01

In the central microbiology laboratory of Gazi University Hospital Candida kefyr was isolated from different clinical samples as 5.3% in 2016 and in 2017 this rate increased to 9.3% which was nearly two-fold and this has drawn our attention. The aim of this study was to evaluate the special characteristics, antifungal susceptibility and virulence properties of C.keyfr species. Germ tube, corn meal-tween 80 agar morphology and carbohydrate assimilation profiles on ID32C yeast identification system were used for the diagnosis of Candida species. In this study, DNA sequencing was performed using ITS1 and ITS4 primers amplifying fungal gene between 5.8S and 18S regions of rRNA. Antifungal susceptibility was performed using M27A microdilution method recommended by Clinical and Laboratory Standards Institute (CLSI). Minimum inhibitory concentration (MIC) values for amphotericin B, fluconazole, voriconazole and itraconazole were determined. MIC distribution, MIC50 and MIC90 values and geometric mean (GM) were detected. The existence of virulence factors caseinase, secreted aspartyl proteinase, esterase and phospholipase were investigated in vitro. A total of 865 Candida species were isolated from different clinical samples in the central microbiology laboratory of Gazi University Hospital in 2016. Among them, 46 (5.3%) were C.kefyr. In the first four months of 2017, 30 (9.3%) C.kefyr were identified among 320 Candida isolates. Ten isolates which have shown atypical morphology on corn meal agar were selected. Among these 10 isolates, nine of them were identified as C.kefyr by using ID32C system and DNA sequencing method. Amphotericin B MIC value was 2 µg/ml for one isolate, and fluconazole MIC value was 8 µg/ml for another isolate among 46 isolates. Among the 30 isolates of the year 2017, one of them presented MIC value for fluconazole as 8 µg/ml. No marked antifungal resistance was detected in our isolate group. Caseinase was positive in one C.kefyr isolate, and phospholipase were positive in eight of nine isolates. As a result, the reason of increase in the incidence of this Candida species, which does not show significant resistance and presents mostly phospholipase activity as a virulence factor, should be investigated in more detail.

In vitro activity of Ceftaroline against bacterial pathogens isolated from patients with skin and soft tissue and respiratory tract infections in African and Middle Eastern countries: AWARE global surveillance program 2012-2014.

PubMed

Karlowsky, James A; Biedenbach, Douglas J; Bouchillon, Samuel K; Hackel, Meredith; Iaconis, Joseph P; Sahm, Daniel F

2016-10-01

The objective of this report was to document antimicrobial susceptibility testing surveillance data for ceftaroline and comparative agents from the AWARE (Assessing Worldwide Antimicrobial Resistance Evaluation) global surveillance program for bacterial pathogens causing skin and soft tissue and respiratory tract infections in African and Middle Eastern countries from 2012 through 2014. Pathogen identities were confirmed by MALDI-TOF and antimicrobial susceptibility testing performed by CLSI broth microdilution methodology in a central laboratory. All methicillin-susceptible Staphylococcus aureus (MSSA) (n= 923; MIC90, 0.25 μg/mL) and 91.8% of methicillin-resistant S. aureus (MRSA) (n= 1161; MIC90, 1 μg/mL) tested were susceptible to ceftaroline. The maximum ceftaroline MIC observed for isolates of MRSA was 2 μg/mL. All Streptococcus pyogenes (n= 174; MIC90, 0.008 μg/mL), Streptococcus agalactiae (n= 44; MIC90, 0.015 μg/mL), Streptococcus pneumoniae (n= 351; MIC90, 0.25 μg/mL), and Haemophilus influenzae (n= 84; MIC90, ≤0.015 μg/mL) were susceptible to ceftaroline. Rates of susceptibility to ceftaroline among ESBL-negative Escherichia coli (n= 338), Klebsiella pneumoniae (n= 241), and Klebsiella oxytoca (n= 97) were 89.1% (MIC90, 1 μg/mL), 94.2% (MIC90, 0.5 μg/mL), and 99.0% (MIC90, 0.5 μg/mL), respectively. Copyright © 2016. Published by Elsevier Inc.

Comparison of standardised versus non-standardised methods for testing the in vitro potency of oxytetracycline against Mannheimia haemolytica and Pasteurella multocida.

PubMed

Lees, P; Illambas, J; Pelligand, L; Toutain, P-L

2016-12-01

The in vitro pharmacodynamics of oxytetracycline was established for six isolates of each of the calf pneumonia pathogens Mannheimia haemolytica and Pasteurella multocida. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and bacterial time-kill curves were determined in two matrices, Mueller Hinton broth (MHB) and calf serum. Geometric mean MIC ratios, serum:MHB, were 25.2:1 (M. haemolytica) and 27.4:1 (P. multocida). The degree of binding of oxytetracycline to serum protein was 52.4%. Differences between serum and broth MICs could not be accounted for by oxytetracycline binding to serum protein. In vitro time-kill data suggested a co-dependent killing action of oxytetracycline. The in vitro data indicate inhibition of the killing action of oxytetracycline by serum factor(s). The nature of the inhibition requires further study. The outcome of treatment with oxytetracycline of respiratory tract infections in calves caused by M. haemolytica and P. multocida may not be related solely to a direct killing action. Copyright © 2016 Elsevier Ltd. All rights reserved.

Antimicrobial activity of five essential oils from lamiaceae against multidrug-resistant Staphylococcus aureus.

PubMed

Kot, Barbara; Wierzchowska, Kamila; Piechota, Małgorzata; Czerniewicz, Paweł; Chrzanowski, Grzegorz

2018-06-11

Analysis of Lamiaceae essential oils (EOs) by GC-FID-MS revealed the presence as the major constituents of linalool (16.8%), linalyl acetate (15.7%) in Lavandula angustifolia, menthol (29.0%), menthone (22.7%), menthyl acetate (19.2%) in Mentha x piperita, terpinen-4-ol (27.1%), (E)-sabinene hydrate (12.1%), γ-terpinene (10.0%) in Origanum majorana, α-thujone (19.5%), camphor (19.0%), viridiflorol (13.5%) in Salvia officinalis, thymol (61.9%), p-cymene (10.0%), γ-terpinene (10.0%) in Thymus vulgaris. Based on the MIC and MBC values (0.09-0.78 mg/mL) and ratio MBC/MIC showed that EO from T. vulgaris (TO) had the strong inhibitory and bactericidal effect against multidrug-resistant Staphylococcus aureus. The bacterial cells were total killed by TO at 2MIC concentration after 6 h. The higher concentrations of other EOs were needed to achieve bactericidal effects. The strong bactericidal effect of TO against these bacteria indicates the possibility of topical use of TO but it requires research under clinical conditions.

β-galactosidase-catalyzed synthesis of galactosyl chlorphenesin and its characterization.

PubMed

Lee, Sang-Eun; Jo, Tae-Min; Lee, Hyang-Yeol; Lee, Jongsung; Jung, Kyung-Hwan

2013-11-01

We synthesized galactosyl chlorphenesin (CPN-G) using β-gal-containing Escherichia coli (E. coli) cells in which the conversion yield of chlorphenesin (CPN) to CPN-G reached about 64 % during 12 h. CPN-G was identified and characterized using high-performance liquid chromatography, liquid chromatography-mass spectrometry, Fourier transform-infrared spectrometry, and nuclear magnetic resonance analysis ((1)H and (13)C). We verified that a galactose was covalently bound to a CPN alcohol group during CPN-G synthesis throughout these analyses. In particular, by the hydrolysis of CPN-G using β-gal, it was confirmed that a galactose was bound to CPN. The minimal inhibitory concentration (MIC) results showed that the CPN-G MICs were fairly similar to those of CPN. HACAT cell viability was significantly higher in CPN-G-treated cells than in CPN-treated cells at concentrations of 0.0-20.0 mM. Finally, we accomplished the synthesis of less toxic CPN-G, compared with CPN, using β-gal-containing E. coli cells as whole cells without changes in the MICs against microorganisms.

1-[(3-Aryloxy-3-aryl)propyl]-1H-imidazoles, new imidazoles with potent activity against Candida albicans and dermatophytes. Synthesis, structure-activity relationship, and molecular modeling studies.

PubMed

La Regina, Giuseppe; D'Auria, Felicia Diodata; Tafi, Andrea; Piscitelli, Francesco; Olla, Stefania; Caporuscio, Fabiana; Nencioni, Lucia; Cirilli, Roberto; La Torre, Francesco; De Melo, Nadja Rodrigues; Kelly, Steven L; Lamb, David C; Artico, Marino; Botta, Maurizio; Palamara, Anna Teresa; Silvestri, Romano

2008-07-10

New 1-[(3-aryloxy-3-aryl)propyl]-1 H-imidazoles were synthesized and evaluated against Candida albicans and dermatophytes in order to develop structure-activity relationships (SARs). Against C. albicans the new imidazoles showed minimal inhibitory concentrations (MICs) comparable to those of ketoconazole, miconazole, and econazole, and were more potent than fluconazole. Several derivatives ( 10, 12, 14, 18- 20, 24, 28, 29, 30, and 34) turned out to be potent inhibitors of C. albicans strains resistant to fluconazole, with MIC values less than 10 microg/mL. Against dermatophytes strains, compounds 20, 25, and 33 (MIC

In Vitro Susceptibility of Malassezia pachydermatis Isolates from Canine Skin with Atopic Dermatitis to Ketoconazole and Itraconazole in East Asia

PubMed Central

WATANABE, Shion; KOIKE, Anna; KANO, Rui; NAGATA, Masahiko; CHEN, Charles; HWANG, Cheol-Yong; HASEGAWA, Atsuhiko; KAMATA, Hiroshi

2013-01-01

ABSTRACT Topical or oral azole antifungals are commonly used in canine atopic dermatitis (AD), as the lipophilic yeast Malassezia pachydermatis exacerbates canine AD. To examine whether canine AD lesions harbor azole-resistant M. pachydermatis isolates in East Asia, we investigated the in vitro susceptibility of M. pachydermatis isolates to ketoconazole (KTZ) and itraconazole (ITZ) obtained from AD lesions of canines in Japan, Korea and Taiwan. The minimum inhibitory concentrations (MICs) of KTZ and ITZ were measured by the E-test using Sabouraud dextrose agar with 0.5% Tween 40. The MICs of KTZ and ITZ for isolates from canines with AD were significantly higher than the MICs for isolates from healthy canines. Our findings suggested that the clinical isolates from canine AD skin lesions were less susceptible to azoles than those from normal canine skin in East Asia. PMID:24334863

In vitro susceptibility of Malassezia pachydermatis isolates from canine skin with atopic dermatitis to ketoconazole and itraconazole in East Asia.

PubMed

Watanabe, Shion; Koike, Anna; Kano, Rui; Nagata, Masahiko; Chen, Charles; Hwang, Cheol-Yong; Hasegawa, Atsuhiko; Kamata, Hiroshi

2014-04-01

Topical or oral azole antifungals are commonly used in canine atopic dermatitis (AD), as the lipophilic yeast Malassezia pachydermatis exacerbates canine AD. To examine whether canine AD lesions harbor azole-resistant M. pachydermatis isolates in East Asia, we investigated the in vitro susceptibility of M. pachydermatis isolates to ketoconazole (KTZ) and itraconazole (ITZ) obtained from AD lesions of canines in Japan, Korea and Taiwan. The minimum inhibitory concentrations (MICs) of KTZ and ITZ were measured by the E-test using Sabouraud dextrose agar with 0.5% Tween 40. The MICs of KTZ and ITZ for isolates from canines with AD were significantly higher than the MICs for isolates from healthy canines. Our findings suggested that the clinical isolates from canine AD skin lesions were less susceptible to azoles than those from normal canine skin in East Asia.

In Vitro Antimicrobial and Modulatory Activity of the Natural Products Silymarin and Silibinin

PubMed Central

Rakelly de Oliveira, Dayanne; Relison Tintino, Saulo; Morais Braga, Maria Flaviana Bezerra; Boligon, Aline Augusti; Linde Athayde, Margareth; Douglas Melo Coutinho, Henrique; de Menezes, Irwin Rose Alencar; Fachinetto, Roselei

2015-01-01

Silymarin is a standardized extract from the dried seeds of the milk thistle (Silybum marianum L. Gaertn.) clinically used as an antihepatotoxic agent. The aim of this study was to investigate the antibacterial and antifungal activity of silymarin and its major constituent (silibinin) against different microbial strains and their modulatory effect on drugs utilized in clinical practice. Silymarin demonstrated antimicrobial activity of little significance against the bacterial strains tested, with MIC (minimum inhibitory concentration) values of 512 µg/mL. Meanwhile, silibinin showed significant activity against Escherichia coli with a MIC of 64 µg/mL. The results for the antifungal activity of silymarin and silibinin demonstrated a MIC of 1024 µg/mL for all strains. Silymarin and silibinin appear to have promising potential, showing synergistic properties when combined with antibacterial drugs, which should prompt further studies along this line. PMID:25866771

Antimicrobial activity of honokiol and magnolol isolated from Magnolia officinalis.

PubMed

Ho, K Y; Tsai, C C; Chen, C P; Huang, J S; Lin, C C

2001-03-01

The antimicrobial activity of honokiol and magnolol, the main constituents of Magnolia officinalis was investigated. The antimicrobial activity was assayed by the agar dilution method using brain heart infusion medium and the minimum inhibitory concentration (MIC) were determined for each compound using a twofold serial dilution assay. The results showed that honokiol and magnolol have a marked antimicrobial effect (MIC = 25 microg/mL) against Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Micrococcus luteus and Bacillus subtilis, but did not show antimicrobial activity (MIC > or = 100 microg/mL) for Shigella flexneii, Staphylococcus epidermidis, Enterobacter aerogenes, Proteus vulgaris, Escherichia coli and Pseudomonas aeruginosa. Our results indicate that honokiol and magnolol, although less potent than tetracycline, show a significant antimicrobial activity for periodontal pathogens. Hence we suggest that honokiol and magnolol might have the potential to be an adjunct in the treatment of periodontitis. Copyright 2001 John Wiley & Sons, Ltd.