A Multilaboratory, Multicountry Study To Determine Bedaquiline MIC Quality Control Ranges for Phenotypic Drug Susceptibility Testing

PubMed Central

Cirillo, Daniela M.; Hoffner, Sven; Ismail, Nazir A.; Kaur, Devinder; Lounis, Nacer; Metchock, Beverly; Pfyffer, Gaby E.; Venter, Amour

2016-01-01

The aim of this study was to establish standardized drug susceptibility testing (DST) methodologies and reference MIC quality control (QC) ranges for bedaquiline, a diarylquinoline antimycobacterial, used in the treatment of adults with multidrug-resistant tuberculosis. Two tier-2 QC reproducibility studies of bedaquiline DST were conducted in eight laboratories using Clinical Laboratory and Standards Institute (CLSI) guidelines. Agar dilution and broth microdilution methods were evaluated. Mycobacterium tuberculosis H37Rv was used as the QC reference strain. Bedaquiline MIC frequency, mode, and geometric mean were calculated. When resulting data occurred outside predefined CLSI criteria, the entire laboratory data set was excluded. For the agar dilution MIC, a 4-dilution QC range (0.015 to 0.12 μg/ml) centered around the geometric mean included 95.8% (7H10 agar dilution; 204/213 observations with one data set excluded) or 95.9% (7H11 agar dilution; 232/242) of bedaquiline MICs. For the 7H9 broth microdilution MIC, a 3-dilution QC range (0.015 to 0.06 μg/ml) centered around the mode included 98.1% (207/211, with one data set excluded) of bedaquiline MICs. Microbiological equivalence was demonstrated for bedaquiline MICs determined using 7H10 agar and 7H11 agar but not for bedaquiline MICs determined using 7H9 broth and 7H10 agar or 7H9 broth and 7H11 agar. Bedaquiline DST methodologies and MIC QC ranges against the H37Rv M. tuberculosis reference strain have been established: 0.015 to 0.12 μg/ml for the 7H10 and 7H11 agar dilution MICs and 0.015 to 0.06 μg/ml for the 7H9 broth microdilution MIC. These methodologies and QC ranges will be submitted to CLSI and EUCAST to inform future research and provide guidance for routine clinical bedaquiline DST in laboratories worldwide. PMID:27654337

In Vitro Antifungal Activities of the New Triazole UR-9825 against Clinically Important Filamentous Fungi

PubMed Central

Capilla, Javier; Ortoneda, Montserrat; Pastor, Francisco Javier; Guarro, Josep

2001-01-01

We used a modified reference microdilution method (the M-38P method) to evaluate the in vitro activities of the new triazole UR-9825 in comparison with those of amphotericin B against 77 strains of opportunistic filamentous fungi. UR-9825 was clearly more active than amphotericin B against all fungi except Fusarium solani and Scytalidium spp. Notably, UR-9825 had low MICs for Aspergillus fumigatus and Paecilomyces lilacinus (MICs at which 90% of isolates are inhibited, 0.125 μg/ml for both species). PMID:11502542

Validation of a commercial dry-form broth microdilution device (Sensititre) for testing tedizolid, a new oxazolidinone.

PubMed

Jones, Ronald N; Holliday, Nicole M; Rhomberg, Paul R

2015-02-01

Tedizolid, a novel oxazolidinone antibacterial with potent activity against a wide range of Gram-positive pathogens, was recently approved by regulatory authorities for the treatment of acute bacterial skin and skin structure infections. A commercial broth microdilution device (Sensititre; Thermo Fisher Scientific) was validated using 285 selected Gram-positive isolates, and the device was documented to have 100.0% essential and categorical agreement with reference MIC results and excellent MIC endpoint reproducibility. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Colistin and Polymyxin B Susceptibility Testing for Carbapenem-Resistant and mcr-Positive Enterobacteriaceae: Comparison of Sensititre, MicroScan, Vitek 2, and Etest with Broth Microdilution

PubMed Central

La, My-Van; Lin, Raymond T. P.

2017-01-01

ABSTRACT Colistin and polymyxin B remain part of the last line of antibiotics for multidrug-resistant Gram-negative bacteria, such as carbapenem-resistant Enterobacteriaceae. Current joint EUCAST-CLSI recommendations are for broth microdilution (BMD) to be performed for MIC testing of colistin. Commercial susceptibility testing methods were evaluated and compared against the reference BMD, using a susceptibility breakpoint of ≤2 mg/liter for both colistin and polymyxin B. Seventy-six Enterobacteriaceae were included, of which 21 were mcr-1 positive (18 Escherichia coli isolates, 2 Klebsiella pneumoniae isolates, and 1 Enterobacter aerogenes isolate). Rates of essential agreement (EA) of colistin test results between BMD and Vitek 2, Sensititre, and Etest were 93.4%, 89.5%, and 75.0%, respectively. Rates of EA of polymyxin B test results between BMD and Vitek 2, Sensititre, and Etest were 96.1%, 96.1%, and 48.7%, respectively. A positive MIC correlation with a categorical agreement of >90% was achieved for Sensititre (colistin Spearman's ρ = 0.863, and polymyxin B Spearman's ρ = 0.877) and Vitek 2 (polymyxin B [only] Spearman's ρ = 0.8917). Although a positive MIC correlation (Spearman's ρ = 0.873) with the reference method was achieved for colistin testing with Vitek 2, categorical agreement was <90%, with very major error rates of 36%. Correlation with the Etest MIC was lower, with very major error rates of 12% (colistin) and 26.1% (polymyxin B). MicroScan (colistin) categorical agreement was 88.2%, with a very major error rate of 4%. Colistin MICs for 15 of the 21 mcr-1-positive isolates were >2 mg/liter, and polymyxin MICs for 17 of them were >2 mg/liter by broth microdilution. The use of a lower breakpoint of ≤1 mg/liter further improves detection of mcr-1 for all testing methods. However, further data on the correlation between MICs and clinical outcome are required to determine the most suitable breakpoint to guide clinical management. PMID:28592552

[In vitro antifungal activity of azoles and amphotericin B against Malassezia furfur by the CLSI M27-A3 microdilution and Etest® methods].

PubMed

Galvis-Marín, Juan Camilo; Rodríguez-Bocanegra, María Ximena; Pulido-Villamarín, Adriana Del Pilar; Castañeda-Salazar, Rubiela; Celis-Ramírez, Adriana Marcela; Linares-Linares, Melva Yomary

Malassezia furfur is a human skin commensal yeast that can cause skin and opportunistic systemic infections. Given its lipid dependant status, the reference methods established by the Clinical and Laboratory Standards Institute (CLSI) to evaluate antifungal susceptibility in yeasts are not applicable. To evaluate the in vitro susceptibility of M. furfur isolates from infections in humans to antifungals of clinical use. The susceptibility profile to amphotericin B, itraconazole, ketoconazole and voriconazole of 20 isolates of M. furfur, using the broth microdilution method (CLSI M27-A3) and Etest ® , was evaluated. Itraconazole and voriconazole had the highest antifungal activity against the isolates tested. The essential agreement between the two methods for azoles antifungal activity was in the region of 60-85% and the categorical agreement was around 70-80%, while the essential and categorical agreement for amphotericin B was 10%. The azoles were the compounds that showed the highest antifungal activity against M. furfur, as determined by the two techniques used; however more studies need to be performed to support that Etest ® is a reliable method before its implementation as a routine clinical laboratory test. Copyright © 2016 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

Validation of Sensititre Dry-Form Broth Microdilution Panels for Susceptibility Testing of Ceftazidime-Avibactam, a Broad-Spectrum-β-Lactamase Inhibitor Combination.

PubMed

Jones, Ronald N; Holliday, Nicole M; Krause, Kevin M

2015-08-01

Ceftazidime-avibactam is a broad-spectrum-β-lactamase inhibitor combination in late-stage clinical development for the treatment of serious infections. In preparation for clinical microbiology laboratory use, a validation experiment was initiated to evaluate a commercial broth microdilution product (Sensititre dried MIC susceptibility system) compared to reference panels using 525 recent clinical isolates. Among 11 pathogen groups, all had Sensititre MIC/reference MIC ratios predominantly at 1 (47.5% to 97.5%), and automated and manual endpoint results did not differ. Enterobacteriaceae MIC comparisons showed a modest skewing of Sensititre MIC results toward an elevated MIC (33.9%), but the essential agreement was 98.9% with 100.0% reproducibility. In conclusion, Sensititre panels produced accurate ceftazidime-avibactam MIC results, allowing quality MIC guidance for therapy following regulatory approvals. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Validation of Sensititre Dry-Form Broth Microdilution Panels for Susceptibility Testing of Ceftazidime-Avibactam, a Broad-Spectrum-β-Lactamase Inhibitor Combination

PubMed Central

Holliday, Nicole M.; Krause, Kevin M.

2015-01-01

Ceftazidime-avibactam is a broad-spectrum-β-lactamase inhibitor combination in late-stage clinical development for the treatment of serious infections. In preparation for clinical microbiology laboratory use, a validation experiment was initiated to evaluate a commercial broth microdilution product (Sensititre dried MIC susceptibility system) compared to reference panels using 525 recent clinical isolates. Among 11 pathogen groups, all had Sensititre MIC/reference MIC ratios predominantly at 1 (47.5% to 97.5%), and automated and manual endpoint results did not differ. Enterobacteriaceae MIC comparisons showed a modest skewing of Sensititre MIC results toward an elevated MIC (33.9%), but the essential agreement was 98.9% with 100.0% reproducibility. In conclusion, Sensititre panels produced accurate ceftazidime-avibactam MIC results, allowing quality MIC guidance for therapy following regulatory approvals. PMID:26014937

Digital antimicrobial susceptibility testing using the MilliDrop technology.

PubMed

Jiang, L; Boitard, L; Broyer, P; Chareire, A-C; Bourne-Branchu, P; Mahé, P; Tournoud, M; Franceschi, C; Zambardi, G; Baudry, J; Bibette, J

2016-03-01

We present the MilliDrop Analyzer (MDA), a droplet-based millifluidic system for digital antimicrobial susceptibility testing (D-AST), which enables us to determine minimum inhibitory concentrations (MICs) precisely and accurately. The MilliDrop technology was validated by using resazurin for fluorescence readout, for comparison with standard methodology, and for conducting reproducibility studies. In this first assessment, the susceptibility of a reference Gram-negative strain Escherichia coli ATCC 25922 to gentamicin, chloramphenicol, and nalidixic acid were tested by the MDA, VITEK®2, and broth microdilution as a reference standard. We measured the susceptibility of clinically relevant Gram-positive strains of Staphylococcus aureus to vancomycin, including vancomycin-intermediate S. aureus (VISA), heterogeneous vancomycin-intermediate S. aureus (hVISA), and vancomycin-susceptible S. aureus (VSSA) strains. The MDA provided results which were much more accurate than those of VITEK®2 and standard broth microdilution. The enhanced accuracy enabled us to reliably discriminate between VSSA and hVISA strains.

Quality control ranges for testing broth microdilution susceptibility of Flavobacterium columnare and F. psychrophilium to nine antimicrobials

USDA-ARS?s Scientific Manuscript database

A multi-laboratory broth microdilution method trial was performed to standardize the specialized test conditions required for fish pathogens Flavobacterium columnare and F. pyschrophilum. Nine laboratories tested the quality control (QC) strains Escherichia coli ATCC 25922 and Aeromonas salmonicid...

Evaluation of traditional Chinese medicinal plants for anti-MRSA activity with reference to the treatment record of infectious diseases.

PubMed

Zuo, Guo-Ying; Zhang, Xin-Juan; Yang, Cui-Xian; Han, Jun; Wang, Gen-Chun; Bian, Zhong-Qi

2012-03-09

The in vitro antimicrobial activities of 30 Chinese medicinal plants were evaluated with reference to the treatment record of infectious diseases in the Traditional Chinese Medicine (TCM) literature. The plant materials were extracted with 80% ethanol and the extracts were primarily screened against conventional clinical pathogens like Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans by the agar diffusion method. Their inhibition zone diameters (IZDs, mm, 50 mg/mL) ranged from 2,048 by the standard broth microdilution method. The seven extracts from M. yunnanensis, S. sinensis, G. morella, E. daneillii, M. squamulata, S. arborescens and B. hancei were determined as the most active extracts, with MICs of 8-64 μg/mL. The results were in good agreement with their traditional applications in skin and other infections.

Interlaboratory Study of Quality Control Isolates for a Broth Microdilution Method (Modified CLSI M38-A) for Testing Susceptibilities of Dermatophytes to Antifungals▿

PubMed Central

Ghannoum, M. A.; Arthington-Skaggs, B.; Chaturvedi, V.; Espinel-Ingroff, A.; Pfaller, M. A.; Rennie, R.; Rinaldi, M. G.; Walsh, T. J.

2006-01-01

The Clinical and Laboratory Standards Institute (CLSI; formerly National Committee for Clinical Laboratory Standards, or NCCLS) M38-A standard for the susceptibility testing of filamentous fungi does not specifically address the testing of dermatophytes. In 2003, a multicenter study investigated the reproducibility of the microdilution method developed at the Center for Medical Mycology, Cleveland, Ohio, for testing the susceptibility of dermatophytes. Data from that study supported the introduction of this method for testing dermatophytes in the future version of the CLSI M38-A standard. In order for the method to be accepted by CLSI, appropriate quality control isolates needed to be identified. To that end, an interlaboratory study, involving the original six laboratories plus two additional sites, was conducted to evaluate potential candidates for quality control isolates. These candidate strains included five Trichophyton rubrum strains known to have elevated MICs to terbinafine and five Trichophyton mentagrophytes strains. Antifungal agents tested included ciclopirox, fluconazole, griseofulvin, itraconazole, posaconazole, terbinafine, and voriconazole. Based on the data generated, two quality control isolates, one T. rubrum isolate and one T. mentagrophytes isolate, were identified and submitted to the American Type Culture Collection (ATCC) for inclusion as reference strains. Ranges encompassing 95.2 to 97.9% of all data points for all seven drugs were established. PMID:17050812

Correlation between microdilution, Etest, and disk diffusion methods for antifungal susceptibility testing of fluconazole against Candida sp. blood isolates.

PubMed

Menezes, Everardo Albuquerque; Vasconcelos Júnior, Antônio Alexandre de; Ângelo, Maria Rozzelê Ferreira; Cunha, Maria da Conceição dos Santos Oliveira; Cunha, Francisco Afrânio

2013-01-01

Antifungal susceptibility testing assists in finding the appropriate treatment for fungal infections, which are increasingly common. However, such testing is not very widespread. There are several existing methods, and the correlation between such methods was evaluated in this study. The susceptibility to fluconazole of 35 strains of Candida sp. isolated from blood cultures was evaluated by the following methods: microdilution, Etest, and disk diffusion. The correlation between the methods was around 90%. The disk diffusion test exhibited a good correlation and can be used in laboratory routines to detect strains of Candida sp. that are resistant to fluconazole.

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

Comparison study of broth macrodilution and microdilution antifungal susceptibility tests for the filamentous fungi.

PubMed

Pujol, I; Guarro, J; Llop, C; Soler, L; Fernández-Ballart, J

1996-09-01

An evaluation of broth dilution antifungal susceptibility tests was performed by determining both the micro- and macrodilution MICs of amphotericin B, fluconazole, ketoconazole, 5-fluorocytosine, miconazole, and itraconazole against representative species of opportunistic hyphomycetes (Fusarium spp. and Cladosporium [Cladophialophora] spp.) and ascomycetes (Chaetomium spp.). A total of 78 strains were tested, the majority of them twice and some three times on different days. Both methods were performed according to the recommendations of the National Committee for Clinical Laboratory Standards (Document M27-P), with the exception of the temperature of incubation, which was 25 degrees C in our case. A spectrophotometric method for inoculum preparation, RPMI 1640 medium buffered with morpholinepropanesulfonic acid (pH 7.0), and an additive drug dilution procedure were used. The MICs obtained by the two methods were read after 48, 72, and 96 h of incubation for Fusarium spp. and after 72, 96, and 120 h for the remaining isolates. The kappa test was used to calculate the degree of agreement. Considering the three fungal groups together, a good agreement between the results of both tests was observed with almost all the drugs at the different incubation times. There were no cases of poor agreement. The highest level (kappa index = 1) was observed with ketoconazole at the second-day reading. These results support the further evaluation of the broth microdilution test as an alternative to the reference broth macrodilution susceptibility test.

Comparison study of broth macrodilution and microdilution antifungal susceptibility tests for the filamentous fungi.

PubMed Central

Pujol, I; Guarro, J; Llop, C; Soler, L; Fernández-Ballart, J

1996-01-01

An evaluation of broth dilution antifungal susceptibility tests was performed by determining both the micro- and macrodilution MICs of amphotericin B, fluconazole, ketoconazole, 5-fluorocytosine, miconazole, and itraconazole against representative species of opportunistic hyphomycetes (Fusarium spp. and Cladosporium [Cladophialophora] spp.) and ascomycetes (Chaetomium spp.). A total of 78 strains were tested, the majority of them twice and some three times on different days. Both methods were performed according to the recommendations of the National Committee for Clinical Laboratory Standards (Document M27-P), with the exception of the temperature of incubation, which was 25 degrees C in our case. A spectrophotometric method for inoculum preparation, RPMI 1640 medium buffered with morpholinepropanesulfonic acid (pH 7.0), and an additive drug dilution procedure were used. The MICs obtained by the two methods were read after 48, 72, and 96 h of incubation for Fusarium spp. and after 72, 96, and 120 h for the remaining isolates. The kappa test was used to calculate the degree of agreement. Considering the three fungal groups together, a good agreement between the results of both tests was observed with almost all the drugs at the different incubation times. There were no cases of poor agreement. The highest level (kappa index = 1) was observed with ketoconazole at the second-day reading. These results support the further evaluation of the broth microdilution test as an alternative to the reference broth macrodilution susceptibility test. PMID:8878589

Phenotypic detection of broad-spectrum beta-lactamases in microbiological practice

PubMed Central

Sedlakova, Miroslava Htoutou; Hanulik, Vojtech; Chroma, Magdalena; Hricova, Kristyna; Kolar, Milan; Latal, Tomas; Schaumann, Reiner; Rodloff, Arne C.

2011-01-01

Summary Background Enterobacteriaceae producing ESBL and AmpC enzymes can be associated with failure of antibiotic therapy and related morbidity and mortality. Their routine detection in microbiology laboratories is still a problem. The aim of this study was to compare the sensitivity of selected phenotypic methods. Material/Methods A total of 106 strains of the Enterobacteriaceae family were tested, in which molecular biology methods confirmed the presence of genes encoding ESBL or AmpC. In ESBL-positive strains, the sensitivity of the ESBL Etest (AB Biodisk) and a modified double-disk synergy test (DDST) were evaluated. AmpC strains were tested by a modified AmpC disk method using 3-aminophenylboronic acid. For simultaneous detection of ESBL and AmpC, the microdilution method with a modified set of antimicrobial agents was used. Results The sensitivity of the ESBL Etest was 95%; the modified DDST yielded 100% sensitivity for ESBL producers and the AmpC test correctly detected 95% of AmpC-positive strains. The sensitivity of the modified microdilution method was 87% and 95% for ESBL and AmpC beta lactamases, respectively. Conclusions The detection of ESBL and AmpC beta lactamases should be based on specific phenotypic methods such as the modified DDST, ESBL Etest, AmpC disk test and the modified microdilution method. PMID:21525803

Phenotypic detection of broad-spectrum beta-lactamases in microbiological practice.

PubMed

Htoutou Sedlakova, Miroslava; Hanulik, Vojtech; Chroma, Magdalena; Hricova, Kristyna; Kolar, Milan; Latal, Tomas; Schaumann, Reiner; Rodloff, Arne C

2011-05-01

Enterobacteriaceae producing ESBL and AmpC enzymes can be associated with failure of antibiotic therapy and related morbidity and mortality. Their routine detection in microbiology laboratories is still a problem. The aim of this study was to compare the sensitivity of selected phenotypic methods. A total of 106 strains of the Enterobacteriaceae family were tested, in which molecular biology methods confirmed the presence of genes encoding ESBL or AmpC. In ESBL-positive strains, the sensitivity of the ESBL Etest (AB Biodisk) and a modified double-disk synergy test (DDST) were evaluated. AmpC strains were tested by a modified AmpC disk method using 3-aminophenylboronic acid. For simultaneous detection of ESBL and AmpC, the microdilution method with a modified set of antimicrobial agents was used. The sensitivity of the ESBL Etest was 95%; the modified DDST yielded 100% sensitivity for ESBL producers and the AmpC test correctly detected 95% of AmpC-positive strains. The sensitivity of the modified microdilution method was 87% and 95% for ESBL and AmpC beta lactamases, respectively. The detection of ESBL and AmpC beta lactamases should be based on specific phenotypic methods such as the modified DDST, ESBL Etest, AmpC disk test and the modified microdilution method.

Susceptibility Profiles of Amphotericin B and Posaconazole against Clinically Relevant Mucorales Species under Hypoxic Conditions

PubMed Central

Maurer, Elisabeth; Sparber, Manuela; Lackner, Michaela; Caramalho, Rita; Lass-Flörl, Cornelia

2014-01-01

The effect of hypoxic conditions on the in vitro efficacy of amphotericin B and posaconazole against Mucorales was evaluated by defining MICs with Etest and broth microdilution and identifying minimal fungicidal concentrations (MFCs). With Etest, oxygen-dependent changes were detected, while the MIC and the MFC determined with broth microdilution remained unaltered with reduced oxygen levels. The observed differences depended on the method used. PMID:25451049

Determination of Trimethoprim-Sulfamethoxazole Resistance in Streptococcus pneumoniae by Using the E Test with Mueller-Hinton Agar Supplemented with Sheep or Horse Blood May Be Unreliable

PubMed Central

Lovgren, M.; Dell’Acqua, L.; Palacio, R.; Echániz-Aviles, G.; Soto-Noguerón, A.; Castañeda, E.; Agudelo, C. I.; Heitmann, I.; Brandileone, M. C.; Zanella, R. C.; Rossi, A.; Pace, J.; Talbot, J. A.

1999-01-01

An international, multicenter study compared trimethoprim-sulfamethoxazole MICs for 743 Streptococcus pneumoniae isolates (107 to 244 isolates per country) by E test, using Mueller-Hinton agar supplemented with 5% defibrinated horse blood or 5% defibrinated sheep blood, with MICs determined by the National Committee for Clinical Laboratory Standards broth microdilution reference method. Agreement within 1 log2 dilution and minor error rates were 69.3 and 15.5%, respectively, on sheep blood-supplemented agar and 76.9 and 13.6%, respectively, with horse blood as the supplement. Significant interlaboratory variability was observed. E test may not be a reliable method for determining the resistance of pneumococci to trimethoprim-sulfamethoxazole. PMID:9854095

In vitro antifungal susceptibility and molecular identity of 99 clinical isolates of the opportunistic fungal genus Curvularia.

PubMed

da Cunha, Keith C; Sutton, Deanna A; Fothergill, Annette W; Gené, Josepa; Cano, Josep; Madrid, Hugo; Hoog, Sybren de; Crous, Pedro W; Guarro, Josep

2013-06-01

The in vitro antifungal susceptibility of a set of 99 clinical isolates of Curvularia was tested against 9 drugs using a reference microdilution method. The isolates had been identified previously to species level by comparing their ITS rDNA and glyceraldehyde-3-phosphate dehydrogenase gene sequences with those of reference strains. We were able to reliably identify 73.2% of the isolates, the most frequent species being Curvularia aeria, Curvularia geniculata/Curvularia senegalensis, Curvularia lunata, Curvularia inaequalis, Curvularia verruculosa, and Curvularia borreriae. Most of these isolates had been recovered from nasal sinus, which is generally considered one of the most frequent sites of infection by these fungi. In addition, at least 3 phylogenetic species that have not yet been formally described were detected. The most active drugs were the echinocandins, amphotericin B, and posaconazole, whereas voriconazole and itraconazole showed poor activity. Copyright © 2013 Elsevier Inc. All rights reserved.

Susceptibility profiles of amphotericin B and posaconazole against clinically relevant mucorales species under hypoxic conditions.

PubMed

Maurer, Elisabeth; Binder, Ulrike; Sparber, Manuela; Lackner, Michaela; Caramalho, Rita; Lass-Flörl, Cornelia

2015-02-01

The effect of hypoxic conditions on the in vitro efficacy of amphotericin B and posaconazole against Mucorales was evaluated by defining MICs with Etest and broth microdilution and identifying minimal fungicidal concentrations (MFCs). With Etest, oxygen-dependent changes were detected, while the MIC and the MFC determined with broth microdilution remained unaltered with reduced oxygen levels. The observed differences depended on the method used. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Comparison of Disk Diffusion, VITEK 2, and Broth Microdilution Antimicrobial Susceptibility Test Results for Unusual Species of Enterobacteriaceae▿

PubMed Central

Stone, Nimalie D.; O'Hara, Caroline M.; Williams, Portia P.; McGowan, John E.; Tenover, Fred C.

2007-01-01

We compared the antimicrobial susceptibility testing results generated by disk diffusion and the VITEK 2 automated system with the results of the Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) reference method for 61 isolates of unusual species of Enterobacteriaceae. The isolates represented 15 genera and 26 different species, including Buttiauxella, Cedecea, Kluyvera, Leminorella, and Yokenella. Antimicrobial agents included aminoglycosides, carbapenems, cephalosporins, fluoroquinolones, penicillins, and trimethoprim-sulfamethoxazole. CLSI interpretative criteria for Enterobacteriaceae were used. Of the 12 drugs tested by BMD and disk diffusion, 10 showed >95% categorical agreement (CA). CA was lower for ampicillin (80.3%) and cefazolin (77.0%). There were 3 very major errors (all with cefazolin), 1 major error (also with cefazolin), and 26 minor errors. Of the 40 isolates (representing 12 species) that could be identified with the VITEK 2 database, 36 were identified correctly to species level, 1 was identified to genus level only, and 3 were reported as unidentified. VITEK 2 generated MIC results for 42 (68.8%) of 61 isolates, but categorical interpretations (susceptible, intermediate, and resistant) were provided for only 22. For the 17 drugs tested by both BMD and VITEK 2, essential agreement ranged from 80.9 to 100% and CA ranged from 68.2% (ampicillin) to 100%; thirteen drugs exhibited 100% CA. In summary, disk diffusion provides a reliable alternative to BMD for testing of unusual Enterobacteriaceae, some of which cannot be tested, or produce incorrect results, by automated methods. PMID:17135429

Antifungal susceptibility of Malassezia furfur, Malassezia sympodialis, and Malassezia globosa to azole drugs and amphotericin B evaluated using a broth microdilution method.

PubMed

Rojas, Florencia D; Sosa, María de los A; Fernández, Mariana S; Cattana, María E; Córdoba, Susana B; Giusiano, Gustavo E

2014-08-01

We studied the in vitro activity of fluconazole (FCZ), ketoconazole (KTZ), miconazole (MCZ), voriconazole (VCZ), itraconazole (ITZ) and amphotericin B (AMB) against the three major pathogenic Malassezia species, M. globosa, M. sympodialis, and M. furfur. Antifungal susceptibilities were determined using the broth microdilution method in accordance with Clinical and Laboratory Standards Institute reference document M27-A3. To support lipid-dependent yeast development, glucose, peptone, ox bile, malt extract, glycerol, and Tween supplements were added to Roswell Park Memorial Institute RPMI 1640 medium. The supplemented medium allowed good growth of all three species studied. The minimal inhibitory concentrations (MICs) were recorded after 72 h of incubation at 32ºC. The three species showed different susceptibility profiles for the drugs tested. Malassezia sympodialis was the most susceptible and M. furfur the least susceptible species. KTZ, ITZ, and VCZ were the most active drugs, showing low variability among isolates of the same species. FCZ, MCZ, and AMB showed high MICs and wide MIC ranges. Differences observed emphasize the need to accurately identify and evaluate antifungal susceptibility of Malassezia species. Further investigations and collaborative studies are essential for correlating in vitro results with clinical outcomes since the existing limited data do not allow definitive conclusions. © The Author 2014. 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.

Rapid mycobacteria drug susceptibility testing using Gel Microdrop (GMD) Growth Assay and flow cytometry.

PubMed

Akselband, Y; Cabral, C; Shapiro, D S; McGrath, P

2005-08-01

Control of multi-drug-resistant tuberculosis has been hampered by the lack of simple, rapid and sensitive methods for assessing bacterial growth and antimicrobial susceptibility. Due to the increasing incidence and high frequency of mutations, it is unlikely that culture methods will disappear in the foreseeable future. Therefore, the need to modernize methods for rapid detection of viable clinical isolates, at a minimum as a gold standard, will persist. Previously, we confirmed the feasibility of using the Gel Microdrop (GMD) Growth Assay for identifying sub-populations of resistant Mycobacteria by testing different laboratory strains. Briefly, this assay format relies on encapsulating single bacterium in agarose microspheres and identifying clonogenic growth using flow cytometry and fluorescent staining. In this study, we modified the GMD Growth Assay to make it suitable for clinical applications. We demonstrated the effectiveness and safety of this novel approach for detecting drug susceptibility in clinically relevant laboratory strains as well as clinical isolates of Mycobacterium tuberculosis. Correlation between results using the GMD Growth Assay format and results using two well characterized methods (Broth Microdilution MIC and BACTEC 460TB) was 87.5% and 90%, respectively. However, due to the inherent sensitivity of flow cytometry and the ability to detect small (<1%) sub-populations of resistant mycobacteria, the GMD Growth Assay identified more cases of drug resistance. Using 4 clinically relevant mycobacterial strains, we assessed susceptibility to primary anti-tuberculosis drugs using both the Broth Microdilution MIC method and the GMD Growth Assay. We performed 24 tests on isoniazid-resistant BCG, Mycobacterium tuberculosis H37Ra and Mycobacterium avium strains. The Broth Microdilution MIC method identified 7 cases (29.1%) of resistance to INH and EMB compared to the GMD Growth Assay which identified resistance in 10 cases (41.6%); in 3 cases (12.5%), resistance to INH and EMB was detected only with the GMD Growth Assay. In addition, using 20 Mycobacterium tuberculosis clinical isolates, we compared results using BACTEC 460TB method performed by collaborators and the GMD Growth Assay. Eight of 20 (40%) clinical isolates, which were not identified as drug-resistant using the conventional BACTEC 460TB method, were resistant to 1, 2, or 3 different concentrations of drugs using the GMD Growth Assay (13 cases of 140 experiments). In one case (isolate 1879), resistance to 10.0 microg/ml of STR detected using BACTEC 460TB method was not confirmed by the GMD Growth Assay. Thus, the overall agreement between these methods was 90% (14 discrepant results of 140 experiments). These data demonstrate that the GMD Growth Assay is an accurate and sensitive method for rapid susceptibility testing of Mycobacterium tuberculosis for use in clinical reference laboratory settings.

[Antimicrobial susceptibility testing of anaerobic bacteria].

PubMed

García-Sánchez, José E; García-Sánchez, Enrique; García-García, María Inmaculada

2014-02-01

The anaerobic bacteria resistance to antibiotics is increasing, and even has appeared against the most active of those, like metronidazol and carbapenems. This fact forces to make and periodical sensibility tests -at least in the most aggressive and virulent species, in cases that they are isolated from life locations and in the absence of therapeutic response- to check the local sensibility and to establish suitable empiric therapies, all based on multicentric studies carried out in order to this or well to check the activity of new antibiotics. For the laboratory routine, the easiest sensibility method is the E-test/MIC evaluator. Another alternative is microdilution, that's only normalized for Bacteroides. There are preliminary facts that allow the use of disc diffusion method in some species of Bacteroides and Clostridium. For the temporal and multicentric studies, the procedure is dilution in agar plate, the reference method. Copyright © 2014 Elsevier España, S.L. All rights reserved.

Detection of amphotericin B resistance in Candida haemulonii and closely related species by use of the Etest, Vitek-2 yeast susceptibility system, and CLSI and EUCAST broth microdilution methods.

PubMed

Shin, Jong Hee; Kim, Mi-Na; Jang, Sook Jin; Ju, Min Young; Kim, Soo Hyun; Shin, Myung Geun; Suh, Soon Pal; Ryang, Dong Wook

2012-06-01

The emerging fungal pathogens Candida haemulonii and Candida pseudohaemulonii often show high-level resistance to amphotericin B (AMB). We compared the utilities of five antifungal susceptibility testing methods, i.e., the Etest using Mueller-Hinton agar supplemented with glucose and methylene blue (Etest-MH), the Etest using RPMI agar supplemented with glucose (Etest-RPG), the Vitek-2 yeast susceptibility system, and the Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth microdilution methods, for the detection of AMB-resistant isolates of C. haemulonii and closely related species. Thirty-eight clinical isolates (8 C. haemulonii, 10 C. pseudohaemulonii, and 20 Candida auris isolates) were analyzed. Of the 18 C. haemulonii and C. pseudohaemulonii isolates, 18, 15, 18, 10, and 9 exhibited AMB MICs of >1 μg/ml by the Etest-MH, Etest-RPG, Vitek-2, CLSI, and EUCAST methods, respectively. All 20 C. auris isolates showed AMB MICs of ≤1 μg/ml by all five methods. Of the methods, the Etest-MH generated the broadest distribution of AMB MICs for all 38 isolates and showed the best discrimination between the C. haemulonii and C. pseudohaemulonii isolates (4 to 32 μg/ml) and those of C. auris (0.125 to 0.5 μg/ml). Taking the Etest-MH as the reference method, the essential agreements (within two dilutions) for the Etest-RPG, Vitek-2, CLSI, and EUCAST methods were 84, 92, 55, and 55%, respectively; the categorical agreements were 92, 92, 79, and 76%, respectively. This study provides the first data on the efficacy of the Etest-MH and its excellent agreement with Vitek-2 for discriminating AMB-resistant from AMB-susceptible isolates of these Candida species.

Quantifying Antimicrobial Resistance at Veal Calf Farms

PubMed Central

Bosman, Angela B.; Wagenaar, Jaap; Stegeman, Arjan; Vernooij, Hans; Mevius, Dik

2012-01-01

This study was performed to determine a sampling strategy to quantify the prevalence of antimicrobial resistance on veal calf farms, based on the variation in antimicrobial resistance within and between calves on five farms. Faecal samples from 50 healthy calves (10 calves/farm) were collected. From each individual sample and one pooled faecal sample per farm, 90 selected Escherichia coli isolates were tested for their resistance against 25 mg/L amoxicillin, 25 mg/L tetracycline, 0.5 mg/L cefotaxime, 0.125 mg/L ciprofloxacin and 8/152 mg/L trimethoprim/sulfamethoxazole (tmp/s) by replica plating. From each faecal sample another 10 selected E. coli isolates were tested for their resistance by broth microdilution as a reference. Logistic regression analysis was performed to compare the odds of testing an isolate resistant between both test methods (replica plating vs. broth microdilution) and to evaluate the effect of pooling faecal samples. Bootstrap analysis was used to investigate the precision of the estimated prevalence of resistance to each antimicrobial obtained by several simulated sampling strategies. Replica plating showed similar odds of E. coli isolates tested resistant compared to broth microdilution, except for ciprofloxacin (OR 0.29, p≤0.05). Pooled samples showed in general lower odds of an isolate being resistant compared to individual samples, although these differences were not significant. Bootstrap analysis showed that within each antimicrobial the various compositions of a pooled sample provided consistent estimates for the mean proportion of resistant isolates. Sampling strategies should be based on the variation in resistance among isolates within faecal samples and between faecal samples, which may vary by antimicrobial. In our study, the optimal sampling strategy from the perspective of precision of the estimated levels of resistance and practicality consists of a pooled faecal sample from 20 individual animals, of which 90 isolates are tested for their susceptibility by replica plating. PMID:22970313

Comparison of antimicrobial susceptibilities of Corynebacterium species by broth microdilution and disk diffusion methods.

PubMed Central

Weiss, K; Laverdière, M; Rivest, R

1996-01-01

Corynebacterium species are increasingly being implicated in foreign-body infections and in immunocompromised-host infections. However, there are no specific recommendations on the method or the criteria to use in order to determine the in vitro activities of the antibiotics commonly used to treat Corynebacterium infections. The first aim of our study was to compare the susceptibilities of various species of Corynebacterium to vancomycin, erythromycin, and penicillin by using a broth microdilution method and a disk diffusion method. Second, the activity of penicillin against our isolates was assessed by using the interpretative criteria recommended by the National Committee for Clinical Laboratory Standards for the determination of the susceptibility of streptococci and Listeria monocytogenes to penicillin. Overall, 100% of the isolates were susceptible to vancomycin, while considerable variations in the activities of erythromycin and penicillin were noted for the different species tested, including the non-Corynebacterium jeikeium species. A good correlation in the susceptibilities of vancomycin and erythromycin between the disk diffusion and the microdilution methods was observed. However, a 5% rate of major or very major errors was detected with the Listeria criteria, while a high rate of minor errors (18%) was noted when the streptococcus criteria were used. Our findings indicate considerable variations in the activities of erythromycin and penicillin against the various species of Corynebacterium. Because of the absence of definite recommendations, important discrepancies were observed between the methods and the interpretations of the penicillin activity. PMID:8849254

Polymyxin B Etest® compared with gold-standard broth microdilution in carbapenem-resistant Enterobacteriaceae exhibiting a wide range of polymyxin B MICs.

PubMed

Kulengowski, B; Ribes, J A; Burgess, D S

2018-04-16

Polymyxins have been revitalized to combat carbapenem-resistant Enterobacteriaceae (CRE). However, evaluating the activity of these agents by traditional broth dilution methods is not practical for busy clinical laboratories. We compared polymyxin B activity using two quantitative susceptibility testing methods, Etest ® and broth microdilution (BMD), against CRE isolates from patients at an academic medical centre. Polymyxin B activity against 70 CRE clinical isolates was determined by Etest ® according to the manufacturer and by BMD according to CLSI guidelines. Pseudomonas aeruginosa ATCC ® 27853 and Escherichia coli NCTC 13846 served as quality control strains. The EUCAST colistin susceptibility breakpoint of Enterobacteriaceae (≤2 mg/L) was used. Essential agreement was isolates with an MIC within 1 log 2 dilution over total isolates. Categorical agreement was number of isolates in the same susceptibility category (susceptible or resistant) over total isolates. Major and very major error rates were calculated using number of susceptible and number of resistant isolates, respectively, as the denominator. McNemar's test was used for determining a difference in susceptibility between methods. The CRE isolates were primarily Klebsiella spp. (49%) and Enterobacter spp. (36%). Polymyxin B susceptibility was significantly higher by Etest ® compared with BMD (97% versus 77%; p 0.0001). Categorical agreement was 80%, but essential agreement was low (10%). False non-susceptibility was never observed by Etest ® (BMD reference), but the very major errors were high (88%). Etest ® reporting of false susceptibility may result in inappropriate antibiotic use and treatment failure clinically. We do not recommend using Etest ® for polymyxin B susceptibility testing for routine patient care. Copyright © 2018 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Comparison of the Vitek 2 yeast susceptibility system with CLSI microdilution for antifungal susceptibility testing of fluconazole and voriconazole against Candida spp., using new clinical breakpoints and epidemiological cutoff values.

PubMed

Pfaller, Michael A; Diekema, Daniel J; Procop, Gary W; Rinaldi, Michael G

2013-09-01

A commercially available, fully automated yeast susceptibility test system (Vitek 2; bioMérieux, Marcy d'Etoile, France) was compared in 3 different laboratories with the Clinical and Laboratory Standards Institute (CLSI) reference microdilution (BMD) method by testing 2 quality control strains, 10 reproducibility strains, and 425 isolates of Candida spp. against fluconazole and voriconazole. Reference CLSI BMD MIC endpoints and Vitek 2 MIC endpoints were read after 24 hours and 9.1-27.1 hours incubation, respectively. Excellent essential agreement (within 2 dilutions) between the reference and Vitek 2 MICs was observed for fluconazole (97.9%) and voriconazole (96.7%). Categorical agreement (CA) between the 2 methods was assessed using the new species-specific clinical breakpoints (CBPs): susceptible (S) ≤2 μg/mL, susceptible dose-dependent (SDD) 4 μg/mL, and resistant (R) ≥8 μg/mL for fluconazole and Candida albicans, Candida tropicalis, and Candida parapsilosis and ≤32 μg/mL (SDD), ≥64 μg/mL (R) for Candida glabrata; S ≤0.12 μg/mL, SDD 0.25-0.5 μg/mL, R ≥1 μg/mL for voriconazole and C. albicans, C. tropicalis, and C. parapsilosis, and ≤0.5 μg/mL (S), 1 μg/mL (SDD), ≥2 μg/mL (R) for Candida krusei. The epidemiological cutoff value (ECV) of 0.5 μg/mL for voriconazole and C. glabrata was used to differentiate wild-type (WT; MIC ≤ ECV) from non-WT (MIC > ECV) strains of this species. Due to the lack of CBPs for the less common species, the ECVs for fluconazole and voriconazole, respectively, were used for Candida lusitaniae (2 μg/mL and 0.03 μg/mL), Candida dubliniensis (0.5 μg/mL and 0.03 μg/mL), Candida guilliermondii (8 μg/mL and 0.25 μg/mL), and Candida pelliculosa (4 μg/mL and 0.25 μg/mL) to categorize isolates of these species as WT and non-WT. CA between the 2 methods was 96.8% for fluconazole and 96.5% for voriconazole with less than 1% very major errors and 1.3-3.0% major errors. The Vitek 2 yeast susceptibility system remains comparable to the CLSI BMD reference method for testing the susceptibility of Candida spp. when using the new (lower) CBPs and ECVs. © 2013.

Design, synthesis and antibacterial activity of cinnamaldehyde derivatives as inhibitors of the bacterial cell division protein FtsZ.

PubMed

Li, Xin; Sheng, Juzheng; Huang, Guihua; Ma, Ruixin; Yin, Fengxin; Song, Di; Zhao, Can; Ma, Shutao

2015-06-05

In an attempt to discover potential antibacterial agents against the increasing bacterial resistance, novel cinnamaldehyde derivatives as FtsZ inhibitors were designed, synthesized and evaluated for their antibacterial activity against nine significant pathogens using broth microdilution method, and their cell division inhibitory activity against four representative strains. In the in vitro antibacterial activity, the newly synthesized compounds generally displayed better efficacy against Staphylococcus aureus ATCC25923 than the others. In particular, compounds 3, 8 and 10 exerted superior or comparable activity to all the reference drugs. In the cell division inhibitory activity, all the compounds showed the same trend as their in vitro antibacterial activity, exhibiting better activity against S. aureus ATCC25923 than the other strains. Additionally, compounds 3, 6, 7 and 8 displayed potent cell division inhibitory activity with an MIC value of below 1 μg/mL, over 256-fold better than all the reference drugs. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

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.

In Vitro Comparison of Ertapenem, Meropenem, and Imipenem against Isolates of Rapidly Growing Mycobacteria and Nocardia by Use of Broth Microdilution and Etest

PubMed Central

Brown-Elliott, Barbara A.; Killingley, Jessica; Vasireddy, Sruthi; Bridge, Linda

2016-01-01

We compared the activities of the carbapenems ertapenem, meropenem, and imipenem against 180 isolates of rapidly growing mycobacteria (RGM) and 170 isolates of Nocardia using the Clinical and Laboratory Standards Institute (CLSI) guidelines. A subset of isolates was tested using the Etest. The rate of susceptibility to ertapenem and meropenem was limited and less than that to imipenem for the RGM. Analysis of major and minor discrepancies revealed that >90% of the isolates of Nocardia had higher MICs by the broth microdilution method than by Etest, in contrast to the lower broth microdilution MICs seen for >80% of the RGM. Imipenem remains the most active carbapenem against RGM, including Mycobacterium abscessus subsp. abscessus. For Nocardia, imipenem was significantly more active only against Nocardia farcinica. Although there may be utility in testing the activities of the newer carbapenems against Nocardia, their activities against the RGM should not be routinely tested. Testing by Etest is not recommended by the CLSI. PMID:27053677

Multisite reproducibility of the broth microdilution method for susceptibility testing of Nocardia species.

PubMed

Conville, Patricia S; Brown-Elliott, Barbara A; Wallace, Richard J; Witebsky, Frank G; Koziol, Deloris; Hall, Geraldine S; Killian, Scott B; Knapp, Cindy C; Warshauer, David; Van, Tam; Wengenack, Nancy L; Deml, Sharon; Woods, Gail L

2012-04-01

Antimicrobial susceptibility testing (AST) of clinical isolates of Nocardia is recommended to detect resistance to commonly used antimicrobial agents; such testing is complicated by difficulties in inoculum preparation and test interpretation. In this study, six laboratories performed repetitive broth microdilution testing on single strains of Nocardia brasiliensis, Nocardia cyriacigeorgica, Nocardia farcinica, Nocardia nova, and Nocardia wallacei. For each isolate, a total of 30 microdilution panels from three different lots were tested at most sites. The goal of the study was to determine the inter- and intralaboratory reproducibility of susceptibility testing of this group of isolates. Acceptable agreement (>90% agreement at ±1 dilution of the MIC mode) was found for amikacin, ciprofloxacin, clarithromycin, and moxifloxacin. After eliminating MIC values from single laboratories whose results showed the greatest deviation from those of the remaining laboratories, acceptable agreement was also found for amoxicillin-clavulanic acid, linezolid, minocycline, and tobramycin. Results showed unsatisfactory reproducibility of broth microdilution testing of ceftriaxone with N. cyriacigeorgica and N. wallacei, tigecycline with N. brasiliensis and N. cyriacigeorgica, and sulfonamides with N. farcinica and N. wallacei. N. nova ATCC BAA-2227 is proposed as a quality control organism for AST of Nocardia sp., and the use of a disk diffusion test for sulfisoxazole is proposed as a check of the adequacy of the inoculum and to confirm sulfonamide MIC results.

Etest and Sensititre YeastOne Susceptibility Testing of Echinocandins against Candida Species from a Single Center in Austria.

PubMed

Aigner, Maria; Erbeznik, Thomas; Gschwentner, Martin; Lass-Flörl, Cornelia

2017-08-01

Candida species were tested for susceptibility to caspofungin, anidulafungin, and micafungin in order to evaluate the roles of Etest and Sensititre YeastOne in antifungal susceptibility testing for daily routines and to survey resistance. A total of 104 Candida species isolates detected from blood cultures were investigated. With EUCAST broth microdilution as the reference method, essential agreement (EA), categorical agreement (CA), very major errors (VME), major errors (ME), and minor (MIN) errors were assessed by reading MICs at 18, 24, and 48 h. By use of EUCAST broth microdilution and species-specific clinical breakpoints (CBPs), echinocandin resistance was not detected during the study period. Using EUCAST CBPs, MIC readings at 24 h for the Etest and Sensititre YeastOne resulted in CA levels of 99% and 93% for anidulafungin and 99% and 97% for micafungin. Using revised CLSI CBPs for caspofungin, CA levels were 92% and 99% for Etest and Sensititre YeastOne. The Etest proved an excellent, easy-to-handle alternative method for testing susceptibility to anidulafungin and micafungin. Due to misclassifications, the Etest is less suitable for testing susceptibility to caspofungin (8% of isolates falsely tested resistant). The CA levels of Sensititre YeastOne were 93% and 97% for anidulafungin and micafungin (24 h) by use of EUCAST CBPs and increased to 100% for both antifungals if CLSI CBPs were applied and to 100% and 99% if Sensititre YeastOne epidemiological cutoff values (ECOFFs) were applied. No one echinocandin could be demonstrated to be superior to another in vitro Since resistance was lacking among our Candida isolates, we cannot derive any recommendation from accurate resistance detection by the Etest and Sensititre YeastOne. Copyright © 2017 American Society for Microbiology.

Agreement Assessment of Tigecycline Susceptibilities Determined by the Disk Diffusion and Broth Microdilution Methods among Commonly Encountered Resistant Bacterial Isolates: Results from the Tigecycline In Vitro Surveillance in Taiwan (TIST) Study, 2008 to 2010

PubMed Central

Liu, Jien-Wei; Ko, Wen-Chien; Huang, Cheng-Hua; Liao, Chun-Hsing; Lu, Chin-Te; Chuang, Yin-Ching; Tsao, Shih-Ming; Chen, Yao-Shen; Liu, Yung-Ching; Chen, Wei-Yu; Jang, Tsrang-Neng; Lin, Hsiu-Chen; Chen, Chih-Ming; Shi, Zhi-Yuan; Pan, Sung-Ching; Yang, Jia-Ling; Kung, Hsiang-Chi; Liu, Chun-Eng; Cheng, Yu-Jen; Chen, Yen-Hsu; Lu, Po-Liang; Sun, Wu; Wang, Lih-Shinn; Yu, Kwok-Woon; Chiang, Ping-Cherng; Lee, Ming-Hsun; Lee, Chun-Ming; Hsu, Gwo-Jong

2012-01-01

The Tigecycline In Vitro Surveillance in Taiwan (TIST) study, initiated in 2006, is a nationwide surveillance program designed to longitudinally monitor the in vitro activity of tigecycline against commonly encountered drug-resistant bacteria. This study compared the in vitro activity of tigecycline against 3,014 isolates of clinically important drug-resistant bacteria using the standard broth microdilution and disk diffusion methods. Species studied included methicillin-resistant Staphylococcus aureus (MRSA; n = 759), vancomycin-resistant Enterococcus faecium (VRE; n = 191), extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (n = 602), ESBL-producing Klebsiella pneumoniae (n = 736), and Acinetobacter baumannii (n = 726) that had been collected from patients treated between 2008 and 2010 at 20 hospitals in Taiwan. MICs and inhibition zone diameters were interpreted according to the currently recommended U.S. Food and Drug Administration (FDA) criteria and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. The MIC90 values of tigecycline against MRSA, VRE, ESBL-producing E. coli, ESBL-producing K. pneumoniae, and A. baumannii were 0.5, 0.125, 0.5, 2, and 8 μg/ml, respectively. The total error rates between the two methods using the FDA criteria were high: 38.4% for ESBL-producing K. pneumoniae and 33.8% for A. baumannii. Using the EUCAST criteria, the total error rate was also high (54.6%) for A. baumannii isolates. The total error rates between these two methods were <5% for MRSA, VRE, and ESBL-producing E. coli. For routine susceptibility testing of ESBL-producing K. pneumoniae and A. baumannii against tigecycline, the broth microdilution method should be used because of the poor correlation of results between these two methods. PMID:22155819

In Vitro Comparison of Ertapenem, Meropenem, and Imipenem against Isolates of Rapidly Growing Mycobacteria and Nocardia by Use of Broth Microdilution and Etest.

PubMed

Brown-Elliott, Barbara A; Killingley, Jessica; Vasireddy, Sruthi; Bridge, Linda; Wallace, Richard J

2016-06-01

We compared the activities of the carbapenems ertapenem, meropenem, and imipenem against 180 isolates of rapidly growing mycobacteria (RGM) and 170 isolates of Nocardia using the Clinical and Laboratory Standards Institute (CLSI) guidelines. A subset of isolates was tested using the Etest. The rate of susceptibility to ertapenem and meropenem was limited and less than that to imipenem for the RGM. Analysis of major and minor discrepancies revealed that >90% of the isolates of Nocardia had higher MICs by the broth microdilution method than by Etest, in contrast to the lower broth microdilution MICs seen for >80% of the RGM. Imipenem remains the most active carbapenem against RGM, including Mycobacterium abscessus subsp. abscessus For Nocardia, imipenem was significantly more active only against Nocardia farcinica Although there may be utility in testing the activities of the newer carbapenems against Nocardia, their activities against the RGM should not be routinely tested. Testing by Etest is not recommended by the CLSI. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Consequences of switching from a fixed 2 : 1 ratio of amoxicillin/clavulanate (CLSI) to a fixed concentration of clavulanate (EUCAST) for susceptibility testing of Escherichia coli.

PubMed

Leverstein-van Hall, Maurine A; Waar, Karola; Muilwijk, Jan; Cohen Stuart, James

2013-11-01

The CLSI recommends a fixed 2 : 1 ratio of co-amoxiclav for broth microdilution susceptibility testing of Enterobacteriaceae, while EUCAST recommends a fixed 2 mg/L clavulanate concentration. The aims of this study were: (i) to determine the influence of a switch from CLSI to EUCAST methodology on Escherichia coli susceptibility rates; (ii) to compare susceptibility results obtained using EUCAST-compliant microdilution with those from disc diffusion and the Etest; and (iii) to evaluate the clinical outcome of patients with E. coli sepsis treated with co-amoxiclav in relation to the susceptibility results obtained using either method. Resistance rates were determined in three laboratories that switched from CLSI to EUCAST cards with the Phoenix system (Becton Dickinson) as well as in 17 laboratories that continued to use CLSI cards with the VITEK 2 system (bioMérieux). In one laboratory, isolates were simultaneously tested by both the Phoenix system and either disc diffusion (n = 471) or the Etest (n = 113). Medical and laboratory records were reviewed for E. coli sepsis patients treated with co-amoxiclav monotherapy. Only laboratories that switched methodology showed an increase in resistance rates - from 19% in 2010 to 31% in 2011 (P < 0.0001). All isolates that tested susceptible by microdilution were also susceptible by disc diffusion or the Etest, but of 326 isolates that tested resistant by microdilution, 43% and 59% tested susceptible by disc diffusion and the Etest, respectively. Among the 89 patients included there was a better correlation between clinical response and measured MICs using the Phoenix system than the Etest. EUCAST methodology resulted in higher co-amoxiclav E. coli resistance rates than CLSI methodology, but correlated better with clinical outcome. EUCAST-compliant microdilution and disc diffusion provided discrepant results.

Evaluation of the Rapid Polymyxin NP Test for Polymyxin B Resistance Detection Using Enterobacter cloacae and Enterobacter aerogenes Isolates.

PubMed

Simar, Shelby; Sibley, Diane; Ashcraft, Deborah; Pankey, George

2017-10-01

Polymyxin resistance is an increasing problem worldwide. Currently, determining susceptibility to polymyxins is problematic and lengthy. Polymyxins diffuse poorly into agar, potentially giving inaccurate disk diffusion and Etest results. A rapid screening test (2 h) for the detection of polymyxin resistance in Enterobacteriaceae , developed by P. Nordmann and L. Poirel (rapid polymyxin NP test) in 2016, detects glucose metabolization in the presence of polymyxin E (PE) and PB via pH-induced color change. The sensitivity and specificity were 99.3 and 95.4%, respectively, with results obtained in ≤2 h. Our goal was to evaluate this test using PB against larger numbers of Enterobacter A total of 143 nonduplicate Enterobacter isolates (102 E. cloacae complex, 41 E. aerogenes ) were tested, including 136 collected from Ochsner Health System patients from March to May 2016 and 7 previously determined PB-resistant E. cloacae isolates from JMI Laboratories. MICs were determined via broth microdilution. For the rapid polymyxin NP test, a color change from orange to yellow is positive; a weak/no color change is deemed negative after 4 h. Of 143 Enterobacter isolates, 25 were determined to be PB resistant by broth microdilution (MIC > 2 μg/ml), including all 7 JMI isolates. Of these 25, 7 were positive by the rapid polymyxin NP test (included 3/7 JMI isolates). All 118 isolates determined to be PB susceptible by broth microdilution were NP test negative. The sensitivity and specificity for the rapid polymyxin NP test were 25 and 100%, respectively, compared to broth microdilution. Although the rapid polymyxin NP test is a much faster method (2 to 4 h) for polymyxin resistance determination compared to broth microdilution (16 to 20 h), our study indicates that it may be subject to limitations when testing Enterobacter . Copyright © 2017 American Society for Microbiology.

In vitro susceptibility of bovine mastitis pathogens to a combination of penicillin and framycetin: development of interpretive criteria for testing by broth microdilution and disk diffusion.

PubMed

Pillar, C M; Stoneburner, A; Shinabarger, D L; Abbeloos, E; Goby, L; Bradley, Andrew J

2014-10-01

Dry cow therapy is an important part of mastitis control. This therapy typically consists of an antibiotic or antibiotics administered at a single dose by intramammary infusion at dry off to treat or prevent infection by prevalent mastitis pathogens. A combination dry cow therapy consisting of the active components penicillin and framycetin is currently used in several countries. Despite its use, standardized methods for the susceptibility testing of this combination against mastitis pathogens have not been established. In this study, which used Clinical and Laboratory Standards Institute methodology, preliminary interpretive criteria for the broth microdilution minimum inhibitory concentration (MIC) testing of mastitis pathogens to penicillin combined with framycetin (2:1 wt/wt) were established based on the amount of drug achieved and maintained postadministration in the udder. Based on resulting MIC distributions of recent veterinary field isolates and a subset of isolates preselected for resistance to β-lactams or aminoglycosides and concentrations achieved postadministration, criteria for broth microdilution testing of the combination (susceptible, intermediate, resistant in micrograms per milliliter) were set as follows: Escherichia coli ≤8/4, 16/8, ≥32/16; Staphylococcus spp. ≤2/1, 4/2-8/4, >16/8; Streptococcus uberis and Streptococcus dysgalactiae <0.25/0.12, 0.5/0.25-2/1, >4/2. A disk diffusion test using disks containing 100 μg of framycetin and 10 IU of penicillin was also developed, and preliminary interpretive criteria (susceptible, intermediate, resistant in millimeters) were set based on correlation to broth MIC values and the minimization of interpretive errors between isolates tested concurrently by broth microdilution and disk diffusion as follows: E. coli ≥18, 16-17, ≤15; Staphylococcus spp. ≥21, 18-20, ≤17; Strep. uberis and Strep. dysgalactiae ≥21, 19-20, ≤18. In addition, ranges for the quality control of the testing of this combination by both broth microdilution and disk diffusion are provided. Based on these criteria and recent veterinary mastitis isolates, 96.0/96.8% of E. coli, 93.7/89.1% of Staph. aureus, 94.6/96.4% coagulase-negative staphylococci, 94.5/97.0% of Strep. uberis, and 96.7/100.0% Strep. dysgalactiae were susceptible to the combination by broth microdilution or disk diffusion, respectively. The availability of these methods will allow for the susceptibility testing of clinical isolates in the field and will also provide a way to monitor for resistance development as this combination is used going forward. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Susceptibility of Malassezia pachydermatis to aminoglycosides.

PubMed

Silva, Freddy Alejandro; Conde-Felipe, Magnolia; Rosario, Inmaculada; Ferrer, Otilia; Real, Fernando; Déniz, Soraya; Acosta, Félix; Padilla, Daniel; Acosta-Hernández, Begoña

2017-12-01

Previous studies have evaluated the action of gentamicin against Malassezia pachydermatis. The aim of this study was to evaluate in vitro susceptibility of M. pachydermatis to the aminoglycosides- gentamicin, tobramycin, netilmicin and framycetin. The minimum inhibitory concentration (MIC) of gentamicin was determined following methods M27-A3 microdilution and Etest ® . The Etest ® was used to determine the minimum inhibitory concentration (MIC) of the tobramycin and netilmicin. The Kirby-Bauer test was used to determine the antibiotic susceptibility to the framycetin. The MIC50 and MIC90 were 8.12 μg/mL and 32.5 μg/mL by microdilution method for gentamicin. The MIC50, determined by the Etest ® , was 8 μg/mL for gentamicin and netilmicin and 64 μg/mL for tobramycin. The MIC90 was 16 and 32 μg/mL for gentamicin and netilmicin respectively. The MIC90 was outside of the detectable limits for tobramycin. To framycetin, 28 strains (40%) of the 70 M. pachydermatis isolates tested showed a diameter of 22 mm, 22 strains (31.42%) showed a diameter of 20 mm, 16 strains showed a diameter of ≤ 18 mm, and only 5.71% of the isolates showed a diameter of ≥ 22 mm. This study provides evidence of high in vitro activity of the aminoglycosides-gentamicin, tobramycin, netilmicin and framycetin against M. pachydermatis. For gentamicin Etest ® showed similar values of MIC50 y MIC90 that the obtained by microdilution method. We considered Etest ® method could be a good method for these calculations with aminoglycosides. © 2017 Blackwell Verlag GmbH.

Collaborative investigation of broth microdilution and semisolid agar dilution for in vitro susceptibility testing of Candida albicans.

PubMed Central

Shawar, R; Paetznick, V; Witte, Z; Ensign, L G; Anaissie, E; LaRocco, M

1992-01-01

A study was performed in two laboratories to evaluate the effect of growth medium and test methodology on inter- and intralaboratory variations in the MICs of amphotericin B (AMB), flucytosine (5FC), fluconazole (FLU), itraconazole (ITRA), and the triazole Sch 39304 (SCH) against 14 isolates of Candida albicans. Testing was performed by broth microdilution and semisolid agar dilution with the following media, buffered to pH 7.0 with morpholinepropanesulfonic acid (MOPS): buffered yeast nitrogen base (BYNB), Eagle's minimal essential medium (EMEM), RPMI 1640 medium (RPMI), and synthetic amino acid medium for fungi (SAAMF). Inocula were standardized spectrophotometrically, and endpoints were defined by the complete absence of growth for AMB and by no more than 25% of the growth in the drug-free control for all other agents. Comparative analyses of median MICs, as determined by each test method, were made for all drug-medium combinations. Both methods yielded similar (+/- 1 twofold dilution) median MICs for AMB in EMEM and RPMI, 5FC in all media, and FLU in EMEM, RPMI, and SAAMF. In contrast, substantial between-method variations in median MICs were seen for AMB in BYNB and SAAMF, FLU In BYNB, and ITRA and SCH in all media. Interlaboratory concordance of median MICs was good for AMB, 5FC, and FLU but poor for ITRA and SCH in all media. Endpoint determinations were analyzed by use of kappa statistical analyses for evaluating the strength of observer agreement. Moderate to almost perfect interlaboratory agreement occurred with AMB and 5FC in all media and with FLU in EMEM, RPMI, and SAAMF, irrespective of the test method. Slight to almost perfect interlaboratory agreement occurred with ITRA and SCH in EMEM, RPMI, and SAAMF when tested by semisolid agar dilution but not broth microdilution. Kappa values assessing intralaboratory agreement between methods were high for 5FC in all media, for AMB in BYNB, ENEM, and RPMI, and for FLU in EMEM, RPMI, and SAAMF. One laboratory, but not the other, reported substantial to almost perfect agreement between methods for ITRA, and SCH in EMEM, RPMI, and SAAMF. Both laboratories reported poor agreement between methods for the azoles in BYNB. Discrepancies noted in azole-BYNB combinations were largely due to the greater inhibitory effect of these agents in BYNB than in other media. These results indicate that the semisolid agar dilution and broth microdilution methods with EMEM or RPMI yield equivalent and reproducible MICs for AMB, 5FC, and FLU but not ITRA and SCH. PMID:1500502

Collaborative investigation of broth microdilution and semisolid agar dilution for in vitro susceptibility testing of Candida albicans.

PubMed

Shawar, R; Paetznick, V; Witte, Z; Ensign, L G; Anaissie, E; LaRocco, M

1992-08-01

A study was performed in two laboratories to evaluate the effect of growth medium and test methodology on inter- and intralaboratory variations in the MICs of amphotericin B (AMB), flucytosine (5FC), fluconazole (FLU), itraconazole (ITRA), and the triazole Sch 39304 (SCH) against 14 isolates of Candida albicans. Testing was performed by broth microdilution and semisolid agar dilution with the following media, buffered to pH 7.0 with morpholinepropanesulfonic acid (MOPS): buffered yeast nitrogen base (BYNB), Eagle's minimal essential medium (EMEM), RPMI 1640 medium (RPMI), and synthetic amino acid medium for fungi (SAAMF). Inocula were standardized spectrophotometrically, and endpoints were defined by the complete absence of growth for AMB and by no more than 25% of the growth in the drug-free control for all other agents. Comparative analyses of median MICs, as determined by each test method, were made for all drug-medium combinations. Both methods yielded similar (+/- 1 twofold dilution) median MICs for AMB in EMEM and RPMI, 5FC in all media, and FLU in EMEM, RPMI, and SAAMF. In contrast, substantial between-method variations in median MICs were seen for AMB in BYNB and SAAMF, FLU In BYNB, and ITRA and SCH in all media. Interlaboratory concordance of median MICs was good for AMB, 5FC, and FLU but poor for ITRA and SCH in all media. Endpoint determinations were analyzed by use of kappa statistical analyses for evaluating the strength of observer agreement. Moderate to almost perfect interlaboratory agreement occurred with AMB and 5FC in all media and with FLU in EMEM, RPMI, and SAAMF, irrespective of the test method. Slight to almost perfect interlaboratory agreement occurred with ITRA and SCH in EMEM, RPMI, and SAAMF when tested by semisolid agar dilution but not broth microdilution. Kappa values assessing intralaboratory agreement between methods were high for 5FC in all media, for AMB in BYNB, ENEM, and RPMI, and for FLU in EMEM, RPMI, and SAAMF. One laboratory, but not the other, reported substantial to almost perfect agreement between methods for ITRA, and SCH in EMEM, RPMI, and SAAMF. Both laboratories reported poor agreement between methods for the azoles in BYNB. Discrepancies noted in azole-BYNB combinations were largely due to the greater inhibitory effect of these agents in BYNB than in other media. These results indicate that the semisolid agar dilution and broth microdilution methods with EMEM or RPMI yield equivalent and reproducible MICs for AMB, 5FC, and FLU but not ITRA and SCH.

Comparison of Minocycline Susceptibility Testing Methods for Carbapenem-Resistant Acinetobacter baumannii.

PubMed

Wang, Peng; Bowler, Sarah L; Kantz, Serena F; Mettus, Roberta T; Guo, Yan; McElheny, Christi L; Doi, Yohei

2016-12-01

Treatment options for infections due to carbapenem-resistant Acinetobacter baumannii are extremely limited. Minocycline is a semisynthetic tetracycline derivative with activity against this pathogen. This study compared susceptibility testing methods that are used in clinical microbiology laboratories (Etest, disk diffusion, and Sensititre broth microdilution methods) for testing of minocycline, tigecycline, and doxycycline against 107 carbapenem-resistant A. baumannii clinical isolates. Susceptibility rates determined with the standard broth microdilution method using cation-adjusted Mueller-Hinton (MH) broth were 77.6% for minocycline and 29% for doxycycline, and 92.5% of isolates had tigecycline MICs of ≤2 μg/ml. Using MH agar from BD and Oxoid, susceptibility rates determined with the Etest method were 67.3% and 52.3% for minocycline, 21.5% and 18.7% for doxycycline, and 71% and 29.9% for tigecycline, respectively. With the disk diffusion method using MH agar from BD and Oxoid, susceptibility rates were 82.2% and 72.9% for minocycline and 34.6% and 34.6% for doxycycline, respectively, and rates of MICs of ≤2 μg/ml were 46.7% and 23.4% for tigecycline. In comparison with the standard broth microdilution results, very major rates were low (∼2.8%) for all three drugs across the methods, but major error rates were higher (∼5.6%), especially with the Etest method. For minocycline, minor error rates ranged from 14% to 37.4%. For tigecycline, minor error rates ranged from 6.5% to 69.2%. The majority of minor errors were due to susceptible results being reported as intermediate. For minocycline susceptibility testing of carbapenem-resistant A. baumannii strains, very major errors are rare, but major and minor errors overcalling strains as intermediate or resistant occur frequently with susceptibility testing methods that are feasible in clinical laboratories. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Optimizing the HRP-2 In Vitro Malaria Drug Susceptibility Assay Using a Reference Clone to Improve Comparisons of Plasmodium falciparum Field Isolates

DTIC Science & Technology

2012-09-13

6. Desjardins RE, Canfield CJ, Haynes JD, Chulay JD: Quantitative assessment of antimalarial activity in vitro by a semiautomated microdilution...vitro antimalarial drug efficacy testing and application to clinical isolates. Antimicrob Agents Chemother 2007, 51:1172–1178. 12. Akala HM, Eyase FL...Cheruiyot AC, Omondi AA, Ogutu BR, Waters NC, Johnson JD, Polhemus ME, Schnabel DC, Walsh DS: Antimalarial drug sensitivity profile of western Kenya

Comparison of results of fluconazole disk diffusion testing for Candida species with results from a central reference laboratory in the ARTEMIS global antifungal surveillance program.

PubMed

Pfaller, M A; Hazen, K C; Messer, S A; Boyken, L; Tendolkar, S; Hollis, R J; Diekema, D J

2004-08-01

The accuracy of antifungal susceptibility tests is important for accurate resistance surveillance and for the clinical management of patients with serious infections. Our main objective was to compare the results of fluconazole disk diffusion testing of Candida spp. performed by ARTEMIS participating centers with disk diffusion and MIC results obtained by the central reference laboratory. A total of 2,949 isolates of Candida spp. were tested by NCCLS disk diffusion and reference broth microdilution methods in the central reference laboratory. These results were compared to the results of disk diffusion testing performed in the 54 participating centers. All tests were performed and interpreted following NCCLS recommendations. Overall categorical agreement between participant disk diffusion test results and reference laboratory MIC results was 87.4%, with 0.2% very major errors (VME) and 3.3% major errors (ME). The categorical agreement between the disk diffusion test results obtained in the reference laboratory with the MIC test results was similar: 92.8%. Likewise, good agreement was observed between participant disk diffusion test results and reference laboratory disk diffusion test results: 90.4%, 0.4% VME, and 3.4% ME. The disk diffusion test was especially reliable in detecting those isolates of Candida spp. that were characterized as resistant by reference MIC testing. External quality assurance data obtained by surveillance programs such as the ARTEMIS Global Antifungal Surveillance Program ensure the generation of useful surveillance data and result in the continued improvement of antifungal susceptibility testing practices.

[Evaluation of methods for studying susceptibility to oxacillin and penicillin in 60 Staphylococcus lugdunensis isolates].

PubMed

Batista, Nínive; Fernández, M Paula; Lara, Magdalena; Laich, Federico; Méndez, Sebastián

2009-03-01

Staphylococcus lugdunensis is a coagulase-negative staphylococcus associated with a variety of clinical infections. In this paper we present the results of a comparative study using 4 methods to determine antimicrobial susceptibility to oxacillin and penicillin in 60 S. lugdunensis isolates. We studied 60 S. lugdunensis isolates obtained from clinical specimens sent to our laboratory over an 8-year period. All isolates were free coagulase-negative and DNase-negative, and biochemically identified by API ID 32 STAPH (bioMérieux). Presence of mecA and ss-lactamase production were studied in all cases. Antimicrobial susceptibility was determined by the Vitek 2 System (bioMérieux) and broth microdilution (Wider) (Soria Melguizo) for penicillin and oxacillin, and the E-test (AB Biodisk) and cefoxitin disk diffusion test (BD BBLTM) for oxacillin. All isolates lacked the mecA gene and were susceptible to oxacillin by broth microdilution, E-test, and cefoxitin disk diffusion test. Only two isolates were oxacillin-resistant by the Vitek 2 System. Twenty-four isolates (40%) were ss-lactamase-positive, 4 after induction. Susceptibility testing to penicillin determined that 48 isolates showed concordance between the results obtained by broth microdilution and Vitek 2, but 12 isolates (20%), showed divergent results. We detected no resistance to oxacillin in S. lugdunensis. All the methods evaluated were adequate for determining oxacillin resistance. The Vitek 2 System is useful for detecting penicillin resistance, but the ss-lactamase test should be applied to isolates with a MIC=0.25microg/ml to avoid the interpretation of false resistance to this antibiotic.

Activities of E1210 and comparator agents tested by CLSI and EUCAST broth microdilution methods against Fusarium and Scedosporium species identified using molecular methods.

PubMed

Castanheira, Mariana; Duncanson, Frederick P; Diekema, Daniel J; Guarro, Josep; Jones, Ronald N; Pfaller, Michael A

2012-01-01

Fusarium (n = 67) and Scedosporium (n = 63) clinical isolates were tested by two reference broth microdilution (BMD) methods against a novel broad-spectrum (active against both yeasts and molds) antifungal, E1210, and comparator agents. E1210 inhibits the inositol acylation step in glycophosphatidylinositol (GPI) biosynthesis, resulting in defects in fungal cell wall biosynthesis. Five species complex organisms/species of Fusarium (4 isolates unspeciated) and 28 Scedosporium apiospermum, 7 Scedosporium aurantiacum, and 28 Scedosporium prolificans species were identified by molecular techniques. Comparator antifungal agents included anidulafungin, caspofungin, itraconazole, posaconazole, voriconazole, and amphotericin B. E1210 was highly active against all of the tested isolates, with minimum effective concentration (MEC)/MIC(90) values (μg/ml) for E1210, anidulafungin, caspofungin, itraconazole, posaconazole, voriconazole, and amphotericin B, respectively, for Fusarium of 0.12, >16, >16, >8, >8, 8, and 4 μg/ml. E1210 was very potent against the Scedosporium spp. tested. The E1210 MEC(90) was 0.12 μg/ml for S. apiospermum, but 1 to >8 μg/ml for other tested agents. Against S. aurantiacum, the MEC(50) for E1210 was 0.06 μg/ml versus 0.5 to >8 μg/ml for the comparators. Against S. prolificans, the MEC(90) for E1210 was only 0.12 μg/ml, compared to >4 μg/ml for amphotericin B and >8 μg/ml for itraconazole, posaconazole, and voriconazole. Both CLSI and EUCAST methods were highly concordant for E1210 and all comparator agents. The essential agreement (EA; ±2 doubling dilutions) was >93% for all comparisons, with the exception of posaconazole and F. oxysporum species complex (SC) (60%), posaconazole and S. aurantiacum (85.7%), and voriconazole and S. aurantiacum (85.7%). In conclusion, E1210 exhibited very potent and broad-spectrum antifungal activity against azole- and amphotericin B-resistant strains of Fusarium spp. and Scedosporium spp. Furthermore, in vitro susceptibility testing of E1210 against isolates of Fusarium and Scedosporium may be accomplished using either of the CLSI or EUCAST BMD methods, each producing very similar results.

Activities of E1210 and Comparator Agents Tested by CLSI and EUCAST Broth Microdilution Methods against Fusarium and Scedosporium Species Identified Using Molecular Methods

PubMed Central

Duncanson, Frederick P.; Diekema, Daniel J.; Guarro, Josep; Jones, Ronald N.; Pfaller, Michael A.

2012-01-01

Fusarium (n = 67) and Scedosporium (n = 63) clinical isolates were tested by two reference broth microdilution (BMD) methods against a novel broad-spectrum (active against both yeasts and molds) antifungal, E1210, and comparator agents. E1210 inhibits the inositol acylation step in glycophosphatidylinositol (GPI) biosynthesis, resulting in defects in fungal cell wall biosynthesis. Five species complex organisms/species of Fusarium (4 isolates unspeciated) and 28 Scedosporium apiospermum, 7 Scedosporium aurantiacum, and 28 Scedosporium prolificans species were identified by molecular techniques. Comparator antifungal agents included anidulafungin, caspofungin, itraconazole, posaconazole, voriconazole, and amphotericin B. E1210 was highly active against all of the tested isolates, with minimum effective concentration (MEC)/MIC90 values (μg/ml) for E1210, anidulafungin, caspofungin, itraconazole, posaconazole, voriconazole, and amphotericin B, respectively, for Fusarium of 0.12, >16, >16, >8, >8, 8, and 4 μg/ml. E1210 was very potent against the Scedosporium spp. tested. The E1210 MEC90 was 0.12 μg/ml for S. apiospermum, but 1 to >8 μg/ml for other tested agents. Against S. aurantiacum, the MEC50 for E1210 was 0.06 μg/ml versus 0.5 to >8 μg/ml for the comparators. Against S. prolificans, the MEC90 for E1210 was only 0.12 μg/ml, compared to >4 μg/ml for amphotericin B and >8 μg/ml for itraconazole, posaconazole, and voriconazole. Both CLSI and EUCAST methods were highly concordant for E1210 and all comparator agents. The essential agreement (EA; ±2 doubling dilutions) was >93% for all comparisons, with the exception of posaconazole and F. oxysporum species complex (SC) (60%), posaconazole and S. aurantiacum (85.7%), and voriconazole and S. aurantiacum (85.7%). In conclusion, E1210 exhibited very potent and broad-spectrum antifungal activity against azole- and amphotericin B-resistant strains of Fusarium spp. and Scedosporium spp. Furthermore, in vitro susceptibility testing of E1210 against isolates of Fusarium and Scedosporium may be accomplished using either of the CLSI or EUCAST BMD methods, each producing very similar results. PMID:22083469

In Vitro Activity of Posaconazole against Talaromyces marneffei by Broth Microdilution and Etest Methods and Comparison to Itraconazole, Voriconazole, and Anidulafungin

PubMed Central

Lam, Clare S. K.; Ngan, Antonio H. Y.; Wu, Alan K. L.; Tsang, Dominic N. C.; Tse, Cindy W. S.; Que, Tak-Lun; Tang, Bone S. F.

2016-01-01

ABSTRACT We determined the susceptibilities of 57 Talaromyces marneffei strains to anidulafungin, itraconazole, voriconazole, and posaconazole with MICs of 2 to 8, 0.002 to 0.004, 0.016 to 0.063, and 0.001 to 0.002 μg/ml by broth microdilution and >32, ≤0.002 to 0.008, ≤0.002 to 0.008, and ≤0.002 μg/ml by Etest, respectively, at yeast phase; MICs at mycelial phase for anidulafungin and posaconazole were 1 to 2 and 0.004 to 0.063 μg/ml, respectively. The results suggest promising activities of posaconazole. Etest can be used for testing of azoles against T. marneffei. PMID:28031205

Antianaerobic Antimicrobials: Spectrum and Susceptibility Testing

PubMed Central

Wexler, Hannah M.; Goldstein, Ellie J. C.

2013-01-01

SUMMARY Susceptibility testing of anaerobic bacteria recovered from selected cases can influence the choice of antimicrobial therapy. The Clinical and Laboratory Standards Institute (CLSI) has standardized many laboratory procedures, including anaerobic susceptibility testing (AST), and has published documents for AST. The standardization of testing methods by the CLSI allows comparisons of resistance trends among various laboratories. Susceptibility testing should be performed on organisms recovered from sterile body sites, those that are isolated in pure culture, or those that are clinically important and have variable or unique susceptibility patterns. Organisms that should be considered for individual isolate testing include highly virulent pathogens for which susceptibility cannot be predicted, such as Bacteroides, Prevotella, Fusobacterium, and Clostridium spp.; Bilophila wadsworthia; and Sutterella wadsworthensis. This review describes the current methods for AST in research and reference laboratories. These methods include the use of agar dilution, broth microdilution, Etest, and the spiral gradient endpoint system. The antimicrobials potentially effective against anaerobic bacteria include beta-lactams, combinations of beta-lactams and beta-lactamase inhibitors, metronidazole, chloramphenicol, clindamycin, macrolides, tetracyclines, and fluoroquinolones. The spectrum of efficacy, antimicrobial resistance mechanisms, and resistance patterns against these agents are described. PMID:23824372

Potential of the essential oil from Pimenta pseudocaryophyllus as an antimicrobial agent.

PubMed

Suzuki, Érika Yoko; Baptista, Edilene Bolutari; Resende Do Carmo, Antônio Márcio; Miranda Chaves, Maria Das Graças Afonso; Chicourel, Elizabeth Lemos; Barbosa Raposo, Nádia Rezende

2014-09-01

This study evaluated the effectiveness of the essential oil of Pimenta pseudocaryophyllus in inhibiting the growth of the main bacteria responsible for bad perspiration odor (Staphylococcus epidermidis, Proteus hauseri, Micrococcus yunnanensis and Corynebacterium xerosis). The chemical profile of the essential oil was evaluated by high-resolution gas chromatography (HR-GC) and four constituents were identified, eugenol being the major component (88.6%). The antimicrobial activity was evaluated by means of the turbidimetric method, using the microdilution assay. The minimum inhibitory concentration (MIC) values of the essential oil ranged from 500 to 1,000 μg mL⁻¹. Scanning electron microscope (SEM) observations confirmed the physical damage and morphological alteration of the test bacteria treated with the essential oil, reference drugs and eugenol. The findings of the study demonstrated that this essential oil can be used in the formulation of personal care products.

Antibiotic susceptibility of bifidobacterial strains distributed in the Japanese market.

PubMed

Xiao, Jin-Zhong; Takahashi, Sachiko; Odamaki, Toshitaka; Yaeshima, Tomoko; Iwatsuki, Keiji

2010-01-01

The aim of the present study was to analyze the antibiotic susceptibility of bifidobacterial strains distributed in the Japanese market. A total of 23 strains, including probiotic isolates from foods, supplements, pharmaceuticals and reference strains of each species (or subspecies), were tested for susceptibility to 15 antibiotics by the broth microdilution method and examined for the presence of possible resistant determinants. The strains were susceptible overall to chloramphenicol, ampicillin, vancomycin and linezolid, and were intrinsically resistant to aminoglycoside group agents. Susceptibility to erythromycin, clindamycin, rifampicin, tetracycline and trimethoprim varied among the strains. All strains of Bifidobacterium animalis subsp. lactis were resistant to tetracycline and appeared to harbor tet(W) genes. No risk factor for safety was found for bifidobacterial strains distributed in the Japanese market in respect of their antimicrobial resistance, although the presence of the tet(W) gene in some strains stresses the need for future evaluation.

Broth Microdilution In Vitro Screening: An Easy and Fast Method to Detect New Antifungal Compounds.

PubMed

de-Souza-Silva, Calliandra Maria; Guilhelmelli, Fernanda; Zamith-Miranda, Daniel; de Oliveira, Marco Antônio; Nosanchuk, Joshua Daniel; Silva-Pereira, Ildinete; Albuquerque, Patrícia

2018-02-14

Fungal infections have become an important medical condition in the last decades, but the number of available antifungal drugs is limited. In this scenario, the search for new antifungal drugs is necessary. The protocol reported here details a method to screen peptides for their antifungal properties. It is based on the broth microdilution susceptibility test from the Clinical and Laboratory Standards Institute (CLSI) M27-A3 guidelines with modifications to suit the research of antimicrobial peptides as potential new antifungals. This protocol describes a functional assay to evaluate the activity of antifungal compounds and may be easily modified to suit any particular class of molecules under investigation. Since the assays are performed in 96-well plates using small volumes, a large-scale screening can be completed in a short amount of time, especially if carried out in an automation setting. This procedure illustrates how a standardized and adjustable clinical protocol can help the bench-work pursuit of new molecules to improve the therapy of fungal diseases.

Rhanterium epapposum Oliv. essential oil: Chemical composition and antimicrobial, insect-repellent and anticholinesterase activities.

PubMed

Demirci, Betul; Yusufoglu, Hasan Soliman; Tabanca, Nurhayat; Temel, Halide Edip; Bernier, Ulrich R; Agramonte, Natasha M; Alqasoumi, Saleh Ibrahim; Al-Rehaily, Adnan Jathlan; Başer, Kemal Husnu Can; Demirci, Fatih

2017-07-01

The essential oil (EO) of the aerial parts of Rhanterium epapposum Oliv. (Asteraceae), was obtained by hydrodistillation. The oil was subsequently analyzed by both GC-FID and GC-MS, simultaneously. Forty-five components representing 99.2% of the oil composition were identified. The most abundant compounds were camphene (38.5%), myrcene (17.5%), limonene (10.1%) and α-pinene (8.7%). Referring to the ethnobotanical utilization, an insecticidal assay was performed, where the oil repelled the yellow fever mosquito Aedes aegypti L. at a minimum effective dose (MED of 0.035 ± 0.010 mg/cm 2 ) compared to the positive control DEET (MED of 0.015 ± 0.004 mg/cm 2 ). Additionally, the in vitro antimicrobial activity against a panel of pathogens was determined using a microdilution method. The acetyl- and butyrylcholine esterase inhibitory activities were measured using the colorimetric Ellman method. The bioassay results showed that the oil was rather moderate in antimicrobial and cholinesterase inhibitions when compared to the standard compounds.

Antifungal Susceptibility Testing of Aspergillus spp. by Using a Composite Correlation Index (CCI)-Based Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Method Appears To Not Offer Benefit over Traditional Broth Microdilution Testing

PubMed Central

Gitman, Melissa R.; McTaggart, Lisa; Spinato, Joanna; Poopalarajah, Rahgavi; Lister, Erin; Husain, Shahid

2017-01-01

ABSTRACT Aspergillus spp. cause serious invasive lung infections, and Aspergillus fumigatus is the most commonly encountered clinically significant species. Voriconazole is considered to be the drug of choice for treating A. fumigatus infections; however, rising resistance rates have been reported. We evaluated a matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS)-based method for the differentiation between wild-type and non-wild-type isolates of 20 Aspergillus spp. (including 2 isolates of Aspergillus ustus and 1 of Aspergillus calidoustus that were used as controls due their intrinsic low azole susceptibility with respect to the in vitro response to voriconazole). At 30 and 48 h of incubation, there was complete agreement between Cyp51A sequence analysis, broth microdilution, and MALDI-TOF MS classification of isolates as wild type or non-wild type. In this proof-of-concept study, we demonstrated that MALDI-TOF MS can be used to accurately detect A. fumigatus strains with reduced voriconazole susceptibility. However, rather than proving to be a rapid and simple method for antifungal susceptibility testing, this particular MS-based method showed no benefit over conventional testing methods. PMID:28404678

Antifungal Susceptibility Testing of Aspergillus spp. by Using a Composite Correlation Index (CCI)-Based Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Method Appears To Not Offer Benefit over Traditional Broth Microdilution Testing.

PubMed

Gitman, Melissa R; McTaggart, Lisa; Spinato, Joanna; Poopalarajah, Rahgavi; Lister, Erin; Husain, Shahid; Kus, Julianne V

2017-07-01

Aspergillus spp. cause serious invasive lung infections, and Aspergillus fumigatus is the most commonly encountered clinically significant species. Voriconazole is considered to be the drug of choice for treating A. fumigatus infections; however, rising resistance rates have been reported. We evaluated a matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based method for the differentiation between wild-type and non-wild-type isolates of 20 Aspergillus spp. (including 2 isolates of Aspergillus ustus and 1 of Aspergillus calidoustus that were used as controls due their intrinsic low azole susceptibility with respect to the in vitro response to voriconazole). At 30 and 48 h of incubation, there was complete agreement between Cyp51A sequence analysis, broth microdilution, and MALDI-TOF MS classification of isolates as wild type or non-wild type. In this proof-of-concept study, we demonstrated that MALDI-TOF MS can be used to accurately detect A. fumigatus strains with reduced voriconazole susceptibility. However, rather than proving to be a rapid and simple method for antifungal susceptibility testing, this particular MS-based method showed no benefit over conventional testing methods. © Crown copyright 2017.

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.

Regional Resistance Surveillance Program Results for 12 Asia-Pacific Nations (2011)

PubMed Central

Mendes, Rodrigo E.; Mendoza, Myrna; Banga Singh, Kirnpal K.; Castanheira, Mariana; Bell, Jan M.; Turnidge, John D.; Lin, Stephen S. F.

2013-01-01

The Regional Resistance Surveillance program monitored susceptibility rates and developing resistance by geographic region, including 12 Asia-Pacific (APAC) countries. Reference broth microdilution methods for susceptibility/interpretations were applied, processing 5,053 strains. Among Staphylococcus aureus isolates (37% methicillin-resistant S. aureus [MRSA], highest in South Korea [73%]), linezolid (LZD), tigecycline (TIG), and vancomycin were 100% active, but 33 and 34% of strains were levofloxacin (LEV) or macrolide resistant, respectively. Streptococcus pneumoniae was most resistant to β-lactams and macrolides (45%) but was LZD, LEV, and TIG susceptible (>98%). Extended-spectrum β-lactamase (ESBL) phenotype rates in Escherichia coli and Klebsiella spp. were 48 and 47%, respectively, and were highest in Taiwan, at 75 to 91%. The best anti-ESBL-phenotype agents were amikacin (81 to 96% susceptible), colistin (COL; >98%), TIG (>98%), and carbapenems (81 to 97%). Pseudomonas aeruginosa showed ≥20% resistance to all drugs except COL (99% susceptible). In conclusion, endemic evolving antimicrobial resistances in APAC nations show compromised roles for many commonly used antimicrobials. PMID:23959306

Accuracy of the Thermo Fisher Scientific (Sensititre™) dry-form broth microdilution MIC product when testing ceftaroline.

PubMed

Jones, Ronald N; Holliday, Nicole M; Critchley, Ian A

2015-04-01

Ceftaroline, the active metabolite of the ceftaroline fosamil pro-drug, was the first advanced-spectrum cephalosporin with potent activity against methicillin-resistant Staphylococcus aureus to be approved by the US Food and Drug Administration for acute bacterial skin and skin structure infections. After 4 years of clinical use, few ceftaroline commercial susceptibility testing devices other than agar diffusion methods (disks and stable gradient) are available. Here, we validate a broth microdilution product (Sensititre™; Thermo Fisher Scientific, Cleveland, OH, USA) that achieved 99.2% essential agreement (manual and automated reading) and 95.3-100.0% categorical agreement, with high reproducibility (98.0-100.0%). Sensititre™ MIC values for ceftaroline, however, were slightly skewed toward an elevated value (0.5 × log2 dilution step), greatest when testing for streptococci and Enterobacteriaceae. Copyright © 2015 Elsevier Inc. All rights reserved.

Antimicrobial activity of Bryum argenteum.

PubMed

Sabovljevic, Aneta; Sokovic, Marina; Sabovljevic, Marko; Grubisic, Dragoljub

2006-02-01

The antimicrobial activity of Bryum argenteum ethanol extracts was evaluated by microdilution method against four bacterial (Escherichia coli, Bacillus subtilis, Micrococcus luteus and Staphilococcus aureus) and four fungal species (Aspergillus niger, Penicillium ochrochloron, Candida albicans and Trichophyton mentagrophyes). All the investigated ethanol extracts have been proved to be active against all bacteria and fungi tested.

Oligomerization of esculin improves its antibacterial activity and modulates antibiotic resistance.

PubMed

Mokdad-Bzeouich, Imen; Mustapha, Nadia; Chaabane, Fadwa; Ghedira, Zied; Ghedira, Kamel; Ghoul, Mohamed; Chebil, Latifa; Chekir-Ghedira, Leila

2015-03-01

In this particular study, the antibacterial activity of esculin and oligomer fractions was assessed. MIC values of esculin and its oligomer fractions as well as of some antibiotics against Gram-positive and Gram-negative strains and against Escherichia coli multiresistant variants were determined by the standard broth microdilution method. Both esculin and oligoesculin fractions exhibited antibacterial effect against reference strains; Staphylococcus aureus, Enterococcus faecalis, Salmonella enteritidis and Salmonella typhimurium. It appears that E3 oligomer fraction had the greatest antibacterial activity against these reference strains. Besides, as E2 and E3 revealed the best antibacterial effect against multiresistant variants of E. coli, we decided to test the effect of each, combined to the antibiotic against which the variants were resistant. In the interaction study, E2 and E3 oligoesculin fractions were found to be effective in reducing the resistance of E. coli 6574 to ofloxacin and the resistance of E. coli 6228 to amoxicillin. Only E3 oligoesculin fraction showed a synergetic interaction with amoxicillin and tetracyclin against E. coli 6708, but no interaction was found either with E2 or E3 fractions against E. coli 6234. Our study allowed us to conclude that oligomerization of esculin increases its antibacterial potential, according to the degree of polymerization.

Comparison of the Vitek 2 Antifungal Susceptibility System with the Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) Broth Microdilution Reference Methods and with the Sensititre YeastOne and Etest Techniques for In Vitro Detection of Antifungal Resistance in Yeast Isolates ▿ ‖

PubMed Central

Cuenca-Estrella, Manuel; Gomez-Lopez, Alicia; Alastruey-Izquierdo, Ana; Bernal-Martinez, Leticia; Cuesta, Isabel; Buitrago, Maria J.; Rodriguez-Tudela, Juan L.

2010-01-01

The commercial technique Vitek 2 system for antifungal susceptibility testing of yeast species was evaluated. A collection of 154 clinical yeast isolates, including amphotericin B- and azole-resistant organisms, was tested. Results were compared with those obtained by the reference procedures of both the CLSI and the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Two other commercial techniques approved for clinical use, the Etest and the Sensititre YeastOne, were included in the comparative exercise as well. The average essential agreement (EA) between the Vitek 2 system and the reference procedures was >95%, comparable with the average EAs observed between the reference procedures and the Sensititre YeastOne and Etest. The EA values were >97% for Candida spp. and stood at 92% for Cryptococcus neoformans. Intraclass correlation coefficients (ICC) between the commercial techniques and the reference procedures were statistically significant (P < 0.01). Percentages of very major errors were 2.6% between Vitek 2 and the EUCAST technique and 1.6% between Vitek 2 and the CLSI technique. The Vitek 2 MIC results were available after 14 to 18 h of incubation for all Candida spp. (average time to reading, 15.5 h). The Vitek 2 system was shown to be a reliable technique to determine antifungal susceptibility testing of yeast species and a more rapid and easier alternative for clinical laboratories than the procedures developed by either the CLSI or EUCAST. PMID:20220169

Direct Comparison of the Histidine-rich Protein-2 Enzyme-linked Immunosorbent Assay (HRP-2 ELISA) and Malaria SYBR Green I Fluorescence (MSF) Drug Sensitivity Tests in Plasmodium falciparum Reference Clones and Fresh ex vivo Field Isolates from Cambodia

DTIC Science & Technology

2013-07-12

assessment of antimalarial activity in vitro by a semiautomated microdilution technique. Antimicrob Agents Chemother 1979, 16:710–718. 3. Noedl H, Attlmayr B...40:685–691. 32. Hawley SR, Bray PG, Mungthin M, Atkinson JD, O’Neill PM, Ward SA: Relationship between antimalarial drug activity , accumulation, and...success rate when testing DHA, AS, MQ, QN, CQ, and PPQ activities . A “successful” IC50 assay result for each P. falciparum clinical isolate was defined as

Comparison of BD Phoenix to Vitek 2, MicroScan MICroSTREP, and Etest for Antimicrobial Susceptibility Testing of Streptococcus pneumoniae▿

PubMed Central

Mittman, Scott A.; Huard, Richard C.; Della-Latta, Phyllis; Whittier, Susan

2009-01-01

The performance of the BD Phoenix Automated Microbiology System (BD Diagnostic Systems) was compared to those of the Vitek 2 (bioMérieux), the MicroScan MICroSTREP plus (Siemens), and Etest (bioMérieux) for antibiotic susceptibility tests (AST) of 311 clinical isolates of Streptococcus pneumoniae. The overall essential agreement (EA) between each test system and the reference microdilution broth reference method for S. pneumoniae AST results was >95%. For Phoenix, the EAs of individual antimicrobial agents ranged from 90.4% (clindamycin) to 100% (vancomycin and gatifloxacin). The categorical agreements (CA) of Phoenix, Vitek 2, MicroScan, and Etest for penicillin were 95.5%, 94.2%, 98.7%, and 97.7%, respectively. The overall CA for Phoenix was 99.3% (1 very major error [VME] and 29 minor errors [mEs]), that for Vitek 2 was 98.8% (7 VMEs and 28 mEs), and those for MicroScan and Etest were 99.5% each (19 and 13 mEs, respectively). The average times to results for Phoenix, Vitek 2, and the manual methods were 12.1 h, 9.8 h, and 24 h, respectively. From these data, the Phoenix AST results demonstrated a high degree of agreement with all systems evaluated, although fewer VMEs were observed with the Phoenix than with the Vitek 2. Overall, both automated systems provided reliable AST results for the S. pneumoniae-antibiotic combinations in half the time required for the manual methods, rendering them more suitable for the demands of expedited reporting in the clinical setting. PMID:19741088

Use of the VITEK 2 system to identify and test the antifungal susceptibility of clinically relevant yeast species

PubMed Central

Melhem, MSC; Bertoletti, A; Lucca, HRL; Silva, RBO; Meneghin, FA; Szeszs, MW

2013-01-01

Eleven quality control isolates (Candida albicans ATCC 64548, C. tropicalis ATCC 200956, C. glabrata ATCC 90030, C. lusitaniae ATCC 200951, C. parapsilosis ATCC 22019, C. krusei ATCC 6258, C. dubliniensis ATCC 6330, Saccharomyces cerevisiae ATCC 9763, Cryptococcus neoformans ATCC 90012, C. gattii FIOCRUZ-CPF 60, and Trichosporon mucoides ATCC 204094) and 32 bloodstream isolates, including C. albicans, C. tropicalis, C. parapsilosis, C. glabrata, C. krusei, C. guilliermondii, C. pelliculosa (Pichia anomala), C. haemulonii, C. lusitaniae, and C. kefyr were identified at the species level by the VITEK 2 system. A set of clinical isolates (32 total) were used as challenge strains to evaluate the ability of the VITEK 2 system to determine the antifungal susceptibility of yeasts compared with the CLSI and EUCAST BMD reference standards. The VITEK 2 system correctly identified 100% of the challenge strains. The identification of yeast species and the evaluation of their susceptibility profiles were performed in an automated manner by the VITEK 2 system after approximately 15 h of growth for most species of Candida. The VITEK 2 system ensures that each test is performed in a standardized manner and provides quantitative MIC results that are reproducible and accurate when compared with the BMD reference methods. This system was able to determine the MICs of amphotericin B, flucytosine, voriconazole, and fluconazole in 15 h or less for the most common clinically relevant Candida species. In addition, the VITEK 2 system could reliably identify resistance to flucytosine, voriconazole, and fluconazole and exhibits excellent quantitative and qualitative agreement with the CLSI or EUCAST broth microdilution reference methods. PMID:24688520

Combination Studies of Oreganum Vulgare Extract Fractions and Volatile Oil along with Ciprofloxacin and Fluconazole against Common Fish Pathogens

PubMed Central

Bharti, Veni; Vasudeva, Neeru; Dhuhan, Joginder Singh

2013-01-01

Purpose: The study is aimed at finding new antibiotic therapy for aquaculture due to potential of bacteria to develop resistance to the existing therapies. Use of large quantities of synthetic antibiotics in aquaculture thus has the potential to be detrimental to fish health, to the environment and wildlife and to human health. Methods: Antimicrobial potential of volatile oil and fractions of chloroform extract of Oreganum vulgare was evaluated alone and in the presence of standard antimicrobials against common fish pathogens by disc-diffusion, agar well assay and two fold microdilution method by nanodrop spectrophotometric method. Results: The best results were represented by volatile oil followed by phenolic fraction by disc-diffusion, agar well and microdilution assays (Minimum inhibitory concentration). By the interaction studies, it was observed that the volatile oil and phenolic fraction were able to inhibit the pathogens at very low concentration compared to standard drugs. The fractional inhibitory concentration index (FICI) was calculated and volatile oil and phenolic fractions were found to be synergistic against Pseudomonas fluorescens and Candida albicans. Conclusion: The experimental data suggests the use of volatile oil and phenolic fraction in combination with standard antimicrobials to maintain healthy aquaculture with lesser adverse effects as compared to synthetic antibiotic therapy. PMID:24312842

Comparison of the EUCAST and CLSI Broth Microdilution Methods for Testing Isavuconazole, Posaconazole, and Amphotericin B against Molecularly Identified Mucorales Species

PubMed Central

Singh, Pradeep Kumar; Kathuria, Shallu

2015-01-01

We compared EUCAST and CLSI antifungal susceptibility testing (AFST) methods for triazoles and amphotericin B against 124 clinical Mucorales isolates. The EUCAST method yielded MIC values 1- to 3-fold dilutions higher than those of the CLSI method for amphotericin B. The essential agreements between the two methods for triazoles were high, i.e., 99.1% (voriconazole), 98.3% (isavuconazole), and 87% (posaconazole), whereas it was significantly lower for amphotericin B (66.1%). Strategies for harmonization of the two methods for Mucorales AFST are warranted. PMID:26438489

Anti-Inflammatory and Antimicrobial Properties of Flavonoids from Heliotropium subulatum Exudate.

PubMed

Singh, Bharat; Sharma, Ram A

2015-01-01

Heliotropium subulatum is an erect or procumbent perennial herb; leaves contain foliar trichomes and its resinous exudate is used in traditional medicine. The anti-inflammatory activity of dichloromethane fraction and isolated flavonoids was evaluated by using carrageenan and CFA-induced paw oedema models. Similarly, the disc diffusion and microdilution methods were used for the assessment of antimicrobial activity. Five isolated flavonoids were investigated for their antiinflammatory and antimicrobial activities. Eriodictyol demonstrated maximum anti-inflammatory activity (53.09%) at 30.0 mg/kg dose on 6(th) h and similarly, it inhibited the CFA-induced arthritis swelling (41.84%) with 30.0 mg/kg dose on 8(th) day respectively. As per disc diffusion and microdilution methods used for antimicrobial activity determination, the pinocembrin was found to be most active against Staphylococcus aureus (IZ=27±0.7 mm, 08 μg/ml dose) and Candida albicans (IZ=17±0.9 mm; 12 μg/ml dose). These investigated results revealed that the eriodictyol and pinocembrin showed significant anti-inflammatory and antimicrobial activities. Further studies which aimed to investigate the mechanism of action of these isolated flavonoids in the treatment of inflammations and various types of infections have been initiated.

Antifungal activity of Cymbopogon winterianus jowitt ex bor against Candida albicans

PubMed Central

de Oliveira, Wylly Araújo; de Oliveira Pereira, Fillipe; de Luna, Giliara Carol Diniz Gomes; Lima, Igara Oliveira; Wanderley, Paulo Alves; de Lima, Rita Baltazar; de Oliveira Lima, Edeltrudes

2011-01-01

Candida albicans is an opportunistic yeast and a member of the normal human flora that commonly causes infections in patients with any type of deficiency of the immune system. The essential oils have been tested for antimycotic activity and pose much potential as antifungal agents. This work investigated the activity of the essential oil of Cymbopogon winterianus against C. albicans by MIC, MFC and time-kill methods. The essential oil (EO) was obtained by hydrodistillation using a Clevenger-type apparatus. It was tested fifteen strains of C. albicans. The MIC was determined by the microdilution method and the MFC was determined when an aliquot of the broth microdilution was cultivated in SDA medium. The phytochemical analysis of EO showed presence of citronellal (23,59%), geraniol (18,81%) and citronellol (11,74%). The EO showed antifungal activity, and the concentrations 625 µg/mL and 1250 µg/mL inhibited the growth of all strains tested and it was fungicidal, respectively. The antimicrobial activity of various concentrations of EO was analyzed over time, it was found concentration-dependent antifungal activity, whose behavior was similar to amphotericin B and nystatin. PMID:24031651

Current status of antifungal susceptibility testing methods.

PubMed

Arikan, Sevtap

2007-11-01

Antifungal susceptibility testing is a very dynamic field of medical mycology. Standardization of in vitro susceptibility tests by the Clinical and Laboratory Standards Institute (CLSI) and the European Committee for Antimicrobial Susceptibility Testing (EUCAST), and current availability of reference methods constituted the major remarkable steps in the field. Based on the established minimum inhibitory concentration (MIC) breakpoints, it is now possible to determine the susceptibilities of Candida strains to fluconazole, itraconazole, voriconazole, and flucytosine. Moreover, utility of fluconazole antifungal susceptibility tests as an adjunct in optimizing treatment of candidiasis has now been validated. While the MIC breakpoints and clinical significance of susceptibility testing for the remaining fungi and antifungal drugs remain yet unclear, modifications of the available methods as well as other methodologies are being intensively studied to overcome the present drawbacks and limitations. Among the other methods under investigation are Etest, colorimetric microdilution, agar dilution, determination of fungicidal activity, flow cytometry, and ergosterol quantitation. Etest offers the advantage of practical application and favorable agreement rates with the reference methods that are frequently above acceptable limits. However, MIC breakpoints for Etest remain to be evaluated and established. Development of commercially available, standardized colorimetric panels that are based on CLSI method parameters has added more to the antifungal susceptibility testing armamentarium. Flow cytometry, on the other hand, appears to offer rapid susceptibility testing but requires specified equipment and further evaluation for reproducibility and standardization. Ergosterol quantitation is another novel approach, which appears potentially beneficial particularly in discrimination of azole-resistant isolates from heavy trailers. The method is yet investigational and requires to be further studied. Developments in methodology and applications of antifungal susceptibility testing will hopefully provide enhanced utility in clinical guidance of antifungal therapy. However, and particularly in immunosuppressed host, in vitro susceptibility is and will remain only one of several factors that influence clinical outcome.

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 (

Antimicrobial Properties of Copper Nanoparticles and Amino Acid Chelated Copper Nanoparticles Produced by Using a Soya Extract.

PubMed

DeAlba-Montero, I; Guajardo-Pacheco, Jesús; Morales-Sánchez, Elpidio; Araujo-Martínez, Rene; Loredo-Becerra, G M; Martínez-Castañón, Gabriel-Alejandro; Ruiz, Facundo; Compeán Jasso, M E

2017-01-01

This paper reports a comparison of the antibacterial properties of copper-amino acids chelates and copper nanoparticles against Escherichia coli , Staphylococcus aureus , and Enterococcus faecalis . These copper-amino acids chelates were synthesized by using a soybean aqueous extract and copper nanoparticles were produced using as a starting material the copper-amino acids chelates species. The antibacterial activity of the samples was evaluated by using the standard microdilution method (CLSI M100-S25 January 2015). In the antibacterial activity assays copper ions and copper-EDTA chelates were included as references, so that copper-amino acids chelates can be particularly suitable for acting as an antibacterial agent, so they are excellent candidates for specific applications. Additionally, to confirm the antimicrobial mechanism on bacterial cells, MTT assay (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) was carried out. A significant enhanced antimicrobial activity and a specific strain were found for copper chelates over E. faecalis . Its results would eventually lead to better utilization of copper-amino acids chelate for specific application where copper nanoparticles can be not used.

Antimicrobial Properties of Copper Nanoparticles and Amino Acid Chelated Copper Nanoparticles Produced by Using a Soya Extract

PubMed Central

DeAlba-Montero, I.; Morales-Sánchez, Elpidio; Araujo-Martínez, Rene

2017-01-01

This paper reports a comparison of the antibacterial properties of copper-amino acids chelates and copper nanoparticles against Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis. These copper-amino acids chelates were synthesized by using a soybean aqueous extract and copper nanoparticles were produced using as a starting material the copper-amino acids chelates species. The antibacterial activity of the samples was evaluated by using the standard microdilution method (CLSI M100-S25 January 2015). In the antibacterial activity assays copper ions and copper-EDTA chelates were included as references, so that copper-amino acids chelates can be particularly suitable for acting as an antibacterial agent, so they are excellent candidates for specific applications. Additionally, to confirm the antimicrobial mechanism on bacterial cells, MTT assay (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) was carried out. A significant enhanced antimicrobial activity and a specific strain were found for copper chelates over E. faecalis. Its results would eventually lead to better utilization of copper-amino acids chelate for specific application where copper nanoparticles can be not used. PMID:28286459

In vitro activity of salicylamide derivatives against vancomycin-resistant enterococci.

PubMed

Pospisilova, Sarka; Michnova, Hana; Kauerova, Tereza; Pauk, Karel; Kollar, Peter; Vinsova, Jarmila; Imramovsky, Ales; Cizek, Alois; Jampilek, Josef

2018-07-01

A series of 13 salicylamide derivatives was assessed for antibacterial activity against three isolates of vancomycin-resistant Enterococcus faecalis (VRE) and Enterococcus faecalis ATCC 29212 as a quality standard. The minimum inhibitory concentration was determined by the broth microdilution method with subsequent subcultivation of aliquots to assess minimum bactericidal concentration. The growth kinetics was established by the time-kill assay. Ampicillin, ciprofloxacin, tetracycline and vancomycin were used as the reference antibacterial drugs. Three of the investigated compounds showed strong bacteriostatic activity against VRE (0.199-25 µM) comparable to or more potent than ampicillin and ciprofloxacin. In addition, these compounds were tested for synergistic effect with vancomycin, ciprofloxacin and tetracycline, while 5-chloro-2-hydroxy-N-[4-(trifluoromethyl)phenyl]benzamide showed the highest potency as well as synergistic activity with vancomycin against VRE 368. Screening of the cytotoxicity of the most effective compounds was performed using human monocytic leukemia THP-1 cells, and based on LD 50 values, it can be stated that the compounds have insignificant toxicity against human cells. Copyright © 2018 Elsevier Ltd. All rights reserved.

Carbapenem Susceptibility Testing Errors Using Three Automated Systems, Disk Diffusion, Etest, and Broth Microdilution and Carbapenem Resistance Genes in Isolates of Acinetobacter baumannii-calcoaceticus Complex

DTIC Science & Technology

2011-10-01

Phoenix, and Vitek 2 systems). Discordant results were categorized as very major errors (VME), major errors (ME), and minor errors (mE). DNA sequences...01 OCT 2011 2 . REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Carbapenem Susceptibility Testing Errors Using Three Automated...FDA standards required for device approval (11). The Vitek 2 method was the only automated susceptibility method in our study that satisfied FDA

Blad-containing oligomer: a novel fungicide used in crop protection as an alternative treatment for tinea pedis and tinea versicolor.

PubMed

Carreira, Alexandra; Ferreira, João Boavida; Pereira, Iliana; Ferreira, João; Filipe, Paulo; Ferreira, Ricardo Boavida; Monteiro, Sara

2018-02-01

The lack of novel antifungal drugs and the increasing incidence and severity of fungal infections are major concerns worldwide. Herein, we tested the activity of the Blad-containing oligomer (BCO), a new antifungal molecule already in use for agriculture, on Malassezia spp. and dermatophytes, the causal agents of human tinea versicolor and tinea pedis. Given the lack of a standard method for Malassezia susceptibility testing and the plethora of published methods, we also developed an improved method for this genus. The efficacy of BCO was assessed in vitro and compared to that of the drugs currently utilized in the treatment of tinea versicolor (fluconazole and itraconazole) and tinea pedis (itraconazole and terbinafine). For dermatophytes, the standard microdilution broth-based method was used, with small adjustments, and several broth formulations and inocula sizes were tested to develop an improved susceptibility method for Malassezia spp. We successfully developed a microdilution broth-based method with considerable advantages over other available methods, and used it for all in vitro susceptibility tests of Malassezia spp. isolates. We report that, on a molar basis, BCO was more effective than fluconazole or itraconazole on most strains of Malassezia spp. isolated from clinical samples (n=29). By contrast, BCO was less effective than itraconazole or terbinafine on the common dermatophytes Trichophyton rubrum and Trichophyton interdigitale. These data place BCO as a promising drug for the treatment of Malassezia-associated skin diseases. Further in vivo studies are now required to ascertain its applicability in the clinical setting.

Detecting imipenem resistance in Acinetobacter baumannii by automated systems (BD Phoenix, Microscan WalkAway, Vitek 2); high error rates with Microscan WalkAway

PubMed Central

2009-01-01

Background Increasing reports of carbapenem resistant Acinetobacter baumannii infections are of serious concern. Reliable susceptibility testing results remains a critical issue for the clinical outcome. Automated systems are increasingly used for species identification and susceptibility testing. This study was organized to evaluate the accuracies of three widely used automated susceptibility testing methods for testing the imipenem susceptibilities of A. baumannii isolates, by comparing to the validated test methods. Methods Selected 112 clinical isolates of A. baumanii collected between January 2003 and May 2006 were tested to confirm imipenem susceptibility results. Strains were tested against imipenem by the reference broth microdilution (BMD), disk diffusion (DD), Etest, BD Phoenix, MicroScan WalkAway and Vitek 2 automated systems. Data were analysed by comparing the results from each test method to those produced by the reference BMD test. Results MicroScan performed true identification of all A. baumannii strains while Vitek 2 unidentified one strain, Phoenix unidentified two strains and misidentified two strains. Eighty seven of the strains (78%) were resistant to imipenem by BMD. Etest, Vitek 2 and BD Phoenix produced acceptable error rates when tested against imipenem. Etest showed the best performance with only two minor errors (1.8%). Vitek 2 produced eight minor errors(7.2%). BD Phoenix produced three major errors (2.8%). DD produced two very major errors (1.8%) (slightly higher (0.3%) than the acceptable limit) and three major errors (2.7%). MicroScan showed the worst performance in susceptibility testing with unacceptable error rates; 28 very major (25%) and 50 minor errors (44.6%). Conclusion Reporting errors for A. baumannii against imipenem do exist in susceptibility testing systems. We suggest clinical laboratories using MicroScan system for routine use should consider using a second, independent antimicrobial susceptibility testing method to validate imipenem susceptibility. Etest, whereever available, may be used as an easy method to confirm imipenem susceptibility. PMID:19291298

Comparison of the EUCAST and CLSI Broth Microdilution Methods for Testing Isavuconazole, Posaconazole, and Amphotericin B against Molecularly Identified Mucorales Species.

PubMed

Chowdhary, Anuradha; Singh, Pradeep Kumar; Kathuria, Shallu; Hagen, Ferry; Meis, Jacques F

2015-12-01

We compared EUCAST and CLSI antifungal susceptibility testing (AFST) methods for triazoles and amphotericin B against 124 clinical Mucorales isolates. The EUCAST method yielded MIC values 1- to 3-fold dilutions higher than those of the CLSI method for amphotericin B. The essential agreements between the two methods for triazoles were high, i.e., 99.1% (voriconazole), 98.3% (isavuconazole), and 87% (posaconazole), whereas it was significantly lower for amphotericin B (66.1%). Strategies for harmonization of the two methods for Mucorales AFST are warranted. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Rifaximin disc diffusion test for in vitro susceptibility testing of Clostridium difficile

PubMed Central

Huhulescu, Steliana; Sagel, Ulrich; Fiedler, Anita; Pecavar, Verena; Blaschitz, Marion; Wewalka, Guenther; Allerberger, Franz

2011-01-01

Rifaximin is a rifampicin derivative, poorly absorbed by the gastro-intestinal tract. We studied the in vitro susceptibility to rifamixin of 1082 Clostridium difficile isolates; among these,184 isolates from a strain collection were tested by an in-house rifaximin disc (40 µg) diffusion test, by an in-house rifaximin broth microdilution test, by rifampicin Etest and by rpoB gene sequencing. In the absence of respective CLSI or EUCAST MIC breakpoints for rifaximin and rifampicin against C. difficile we chose MIC ≥32 µg ml−1 as criterion for reduced in vitro susceptibility. To further validate the disc diffusion test 898 consecutive clinical isolates were analysed using the disc diffusion test, the Etest and rpoB gene sequence analysis for all resistant strains. Rifaximin broth microdilution tests of the 184 reference strains yielded rifaximin MICs ranging from 0.001 (n = 1) to ≥1024 µg ml−1 (n = 61); 62 isolates showed a reduced susceptibility (MIC ≥32 µg ml−1). All of these 62 strains showed rpoB gene mutations producing amino acid substitutions; the rifampicin- and rifaximin-susceptible strains showed either a wild-type sequence or silent amino acid substitutions (19 strains). For 11 arbitrarily chosen isolates with rifaximin MICs of >1024 µg ml−1, rifaximin end-point MICs were determined by broth dilution: 4096 µg ml−1 (n = 2), 8192 µg ml−1 (n = 6), 16 384 µg ml−1 (n = 2) and 32 678 µg ml−1 (n = 1). Rifampicin Etests on the 184 C. difficile reference strains yielded MICs ranging from ≤0.002 (n = 117) to ≥32 µg ml−1 (n = 59). Using a 38 mm inhibition zone as breakpoint for reduced susceptibility the use of rifaximin disc diffusion yielded 59 results correlating with those obtained by use of rifaximin broth microdilution in 98.4 % of the 184 strains tested. Rifampicin Etests performed on the 898 clinical isolates revealed that 67 isolates had MICs of ≥32 µg ml−1. There were no discordant results observed among these isolates with reduced susceptibility using an MIC of ≥32 µg ml−1 as breakpoint for reduced rifampicin susceptibility and a <38 mm inhibition zone as breakpoint for reduced rifaximin susceptibility. The prevalence of reduced susceptibility was 7.5 % for all isolates tested. However, for PCR ribotype 027 the prevalence of reduced susceptibility was 26 %. Susceptibility testing in the microbiology laboratory therefore could have an impact on the care and outcome of patients with infection. Our results show that rifaximin – despite its water-insolubility – may be a suitable candidate for disc diffusion testing. PMID:21292853

Examination of bacteria drug resistance utilizing surface plasmon resonance

NASA Astrophysics Data System (ADS)

Chiang, Ya-Ling; Chen, How-Foo; Lin, Chi-Hung; Chen, Shean-Jen

2007-05-01

An antimicrobial testing method using surface plasmon resonance to improve the present techniques is reported in this paper. Different from conventional methods, namely Kirby-Bauer disk diffusion and variations of broth microdilution, the examination time is reduced from 18-24 hours or more to less than one hour after the treatment of antibiotics. E-coli resistant and susceptible to ampicillin are used in the test to demonstrate this innovative method. It is generally known that discovering a method to exam the bacterium resistance rapidly and correctly is very important for patients and for preventing infective disease from spreading. The method reported can benefit this requirement.

Identification of Candida parapsilosis Sensu Lato in Pediatric Patients and Antifungal Susceptibility Testing

PubMed Central

Dudiuk, Catiana; Fernández, Mariana; Rojas, Florencia; Alegre, Liliana; Córdoba, Susana; Garcia-Effron, Guillermo; Giusiano, Gustavo

2017-01-01

ABSTRACT A total of 59 Candida parapsilosis sensu stricto and 1 Candida orthopsilosis recovered from catheters and blood cultures of pediatric patients from the northeastern region of Argentina were studied. Susceptibility to azoles, amphotericin B, and echinocandins was tested by the broth microdilution method. According to CLSI clinical breakpoints, >91% of the strains were azole susceptible, whereas 15% showed high amphotericin B MICs. PMID:28483957

Antifungal activities of diphenyl diselenide and ebselen alone and in combination with antifungal agents against Fusarium spp.

PubMed

Venturini, Tarcieli Pozzebon; Chassot, Francieli; Loreto, Érico Silva; Keller, Jéssica Tairine; Azevedo, Maria Izabel; Zeni, Gilson; Santurio, Janio Morais; Alves, Sydney Hartz

2016-07-01

Herein, we describe the in vitro activity of a combination of the organoselenium compounds diphenyl diselenide and ebselen alone and in combination with amphotericin B, caspofungin, itraconazole, and voriconazole against 25 clinical isolates of Fusarium spp. For this analysis, we used the broth microdilution method based on the M38-A2 technique and checkerboard microdilution method. Diphenyl diselenide (MIC range = 4-32 μg/ml) and ebselen (MIC range = 2-8 μg/ml) showed in vitro activity against the isolates tested. The most effective combinations were (synergism rates): ebselen + amphotericin B (88%), ebselen + voriconazole (80%), diphenyl diselenide + amphotericin B (72%), and diphenyl diselenide + voriconazole (64%). Combination with caspofungin resulted in low rates of synergism: ebselen + caspofungin, 36%, and diphenyl diselenide + caspofungin, 28%; combination with itraconazole demonstrated indifferent interactions. Antagonistic effects were not observed for any of the combinations tested. Our findings suggest that the antifungal potential of diphenyl diselenide and ebselen deserves further investigation in in vivo experimental models, especially in combination with amphotericin B and voriconazole. © 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.

Emergence of Stenotrophomonas maltophilia nosocomial isolates in a Saudi children's hospital. Risk factors and clinical characteristics.

PubMed

Alqahtani, Jobran M

2017-05-01

  To describe the clinical characteristics of pediatric patients colonized or infected by Stenotrophomonas maltophilia (S. maltophilia) at a Saudi children's hospital, to identify risk factors associated with infection, and to investigate the antimicrobial resistance patterns of this emerging pathogen.  Methods: In this cross-sectional observational study, 64 non-duplicating S. maltophilia strains were isolated  in Najran Maternity and Children's Hospital, Najran,  Saudi Arabia between January 2015 to February 2016. Antimicrobial susceptibility testing was performed using the reference broth microdilution method.  Results: In this study, 48 (75%) isolates were identified in true infections and 16 (25%) isolates were considered colonization. The main types of S. maltophilia infection were pneumonia in 22 (45.8%) patients and bloodstream infection in 14 (29.2%) patients. The significant risk factors included exposure to invasive procedure (p=0.02), and presence of acute leukemia as an underlying disease (p=0.02). The most active antimicrobials were trimethoprim/sulfamethoxazole (100% sensitivity) and tigecycline (93.7% sensitivity). Conclusions: Stenotrophomonas maltophilia is an emerging nosocomial pathogen among pediatric patients. Accurate identification and susceptibility testing of this emerging pathogen are crucial for the management of infected patients and prevention of spread of this nosocomial pathogen.

Microdilution Susceptibility Testing of Amphotericin B, Itraconazole, and Voriconazole against Clinical Isolates of Aspergillus and Fusarium Species

PubMed Central

Arikan, Sevtap; Lozano-Chiu, Mario; Paetznick, Victor; Nangia, Sunaina; Rex, John H.

1999-01-01

We compared the activities of amphotericin B, itraconazole, and voriconazole against clinical Aspergillus (n = 82) and Fusarium (n = 22) isolates by a microdilution method adopted from the National Committee for Clinical Laboratory Standards (NCCLS-M27A). RPMI 1640 (RPMI), RPMI 1640 supplemented to 2% glucose (RPMI-2), and antibiotic medium 3 supplemented to 2% glucose (AM3) were used as test media. MICs were determined after 24, 48, and 72 h. A narrow range of amphotericin B MICs was observed for Aspergillus isolates, with minor variations among species. MICs for Fusarium isolates were higher than those for Aspergillus isolates. MICs of itraconazole were prominently high for two previously defined itraconazole-resistant Aspergillus fumigatus isolates and Fusarium solani. Voriconazole showed good in vitro activity against itraconazole-resistant isolates, but the MICs of voriconazole for F. solani were high. RPMI was the most efficient medium for detection of itraconazole-resistant isolates, followed by RPMI-2. While the significance remains unclear, AM3 lowered the MICs, particularly those of amphotericin B. PMID:10565912

Assessment of Minimum Inhibitory Concentrations of Telavancin by Revised Broth Microdilution Method in Phase 3 Hospital-Acquired Pneumonia/Ventilator-Associated Pneumonia Clinical Isolates.

PubMed

Smart, Jennifer I; Corey, Gordon Ralph; Stryjewski, Martin E; Wang, Whedy; Barriere, Steven L

2016-12-01

The broth microdilution method (BMD) for testing telavancin minimum inhibitory concentrations (MICs) was revised (rBMD) in 2014 to improve the accuracy, precision, and reproducibility of the testing method. The aim of this study was to determine the effect of the revised method on telavancin MIC values for Staphylococcus aureus (S. aureus) clinical isolates obtained from hospital-acquired pneumonia (HAP) patients. Isolates from patients who participated in the phase 3 Assessment of Telavancin for Treatment of HAP Studies were retested using the rBMD method. Retesting of 647 isolates produced a range of telavancin MIC values from 0.015 µg/mL to 0.12 µg/mL with MIC 50/90 values of 0.06/0.06 µg/mL for the total pool of samples. For methicillin-resistant S. aureus (MRSA), MIC 50/90 values were 0.06/0.12 µg/mL. These values are up to 4-fold lower than MIC 50/90 values obtained using the original method. These results were used in part to justify lowering the telavancin breakpoints. All tested isolates remained susceptible to telavancin at the revised susceptibility breakpoint of ≤0.12 µg/mL. Overall, the clinical cure rate for microbiologically evaluable telavancin-treated patients was 78% for S. aureus, 76% for patients with MRSA, and 79% for patients with isolates with reduced susceptibility to vancomycin (MIC ≥1 µg/mL). Results from the rBMD method support the in vitro potency of telavancin against S. aureus. ATTAIN (NCT00107952 and NCT00124020). Theravance Biopharma Antibiotics, Inc.

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.

Identification of Candida parapsilosis Sensu Lato in Pediatric Patients and Antifungal Susceptibility Testing.

PubMed

Cattana, Maria Emilia; Dudiuk, Catiana; Fernández, Mariana; Rojas, Florencia; Alegre, Liliana; Córdoba, Susana; Garcia-Effron, Guillermo; Giusiano, Gustavo

2017-07-01

A total of 59 Candida parapsilosis sensu stricto and 1 Candida orthopsilosis recovered from catheters and blood cultures of pediatric patients from the northeastern region of Argentina were studied. Susceptibility to azoles, amphotericin B, and echinocandins was tested by the broth microdilution method. According to CLSI clinical breakpoints, >91% of the strains were azole susceptible, whereas 15% showed high amphotericin B MICs. Copyright © 2017 American Society for Microbiology.

Native Brazilian plants against nosocomial infections: a critical review on their potential and the antimicrobial methodology.

PubMed

H Moreno, Paulo Roberto; da Costa-Issa, Fabiana Inácio; Rajca-Ferreira, Agnieszka K; Pereira, Marcos A A; Kaneko, Telma M

2013-01-01

The growing incidences of drug-resistant pathogens have increased the attention on several medicinal plants and their metabolites for antimicrobial properties. These pathogens are the main cause of nosocomial infections which led to an increasing mortality among hospitalized patients. Taking into consideration those factors, this paper reviews the state-of-the-art of the research on antibacterial agents from native Brazilian plant species related to nosocomial infections as well as the current methods used in the investigations of the antimicrobial activity and points out the differences in techniques employed by the authors. The antimicrobial assays most frequently used were broth microdilution, agar diffusion, agar dilution and bioautography. The broth microdilution method should be the method of choice for testing new antimicrobial agents from plant extracts or isolated compounds due to its advantages. At the moment, only a small part of the rich Brazilian flora has been investigated for antimicrobial activity, mostly with unfractionated extracts presenting a weak or moderate antibacterial activity. The combination of crude extract with conventional antibiotics represents a largely unexploited new form of chemotherapy with novel and multiple mechanisms of action that can overcome microbial resistance that needs to be further investigated. The antibacterial activity of essential oil vapours might also be an interesting alternative treatment of hospital environment due to their ability in preventing biofilm formation. However, in both alternatives more studies should be done on their mode of action and toxicological effects in order to optimize their use.

Screening Togolese medicinal plants for few pharmacological properties

PubMed Central

Karou, Simplice D.; Tchacondo, Tchadjobo; Tchibozo, Micheline Agassounon Djikpo; Anani, Kokou; Ouattara, Lassina; Simpore, Jacques; de Souza, Comlan

2012-01-01

Background: Terminalia macroptera Guill. et Perr. (Combretaceae), Sida alba L. (Malvaceae), Prosopis africana Guill et Perr. Taub. (Mimosaceae), Bridelia ferruginea Benth. (Euphorbiaceae), and Vetiveria nigritana Stapf. (Asteraceae) are traditionally used in Togolese folk medicine to treat several diseases including microbial infections. Objective: This study aimed to investigate the antimicrobial, antioxidant, and hemolytic properties of the crude extracts of the above-mentioned plants. Materials and Methods: The antimicrobial and the antioxidant activities were assayed using the NCCLS microdilution method and the DPPH free radical scavenging, respectively. Human A+ red blood cells were used to perform the hemolytic assay. Phenolics were further quantified in the extracts using spectrophotometric methods. Results: Minimal inhibitory concentrations in the range of 230-1800 μg/ml were recorded in the NCCLS broth microdilution for both bacterial and fungal strains with methanol extracts. The DPPH radical scavenging assay yielded interesting antioxidant activities of the extracts of P. africana and T. macroptera (IC50 values of 0.003 ± 0.00 μg/ml and 0.05 ± 0.03 μg/ml, respectively). These activities were positively correlated with the total phenolic contents and negatively correlated with the proanthocyanidin content of the extracts. The hemolytic assay revealed that great hemolysis occurred with the methanol extracts of T. macroptera, S. longepedunculata, and B. ferruginea. Conclusion: These results support in part the use of the selected plants in the treatment of microbial infections. In addition, the plant showed an interesting antioxidant activity that could be useful in the management of oxidative stress. PMID:22518084

Potential utility of a peptide deformylase inhibitor (NVP PDF-713) against oxazolidinone-resistant or streptogramin-resistant Gram-positive organism isolates.

PubMed

Jones, Ronald N; Moet, Gary J; Sader, Helio S; Fritsche, Thomas R

2004-05-01

To evaluate the potency of a novel peptide deformylase inhibitor, NVP PDF-713, against Gram-positive organisms having resistances to linezolid or quinupristin/dalfopristin. A total of 45 strains from three genera (six species groups) were tested by reference broth microdilution methods. The mechanism of resistance to the oxazolidinone was determined by sequencing of the gene encoding the ribosomal target. NVP PDF-713 retained activity against linezolid-resistant staphylococci (MIC range 0.25-2 mg/L), Streptococcus oralis (MIC 0.5 mg/L), Enterococcus faecalis (MIC range 2-4 mg/L) and Enterococcus faecium (MIC range 0.5-4 mg/L). Quinupristin/dalfopristin-resistant E. faecium (MIC range 1-2 mg/L) and staphylococci (MIC range 0.12-2 mg/L) were also inhibited by NVP PDF-713. Many (10 of 13 strains) of the linezolid-resistant enterococci were resistant to vancomycin and these clinical strains had a G2576U ribosomal target mutation. NVP PDF-713 appears to be a promising clinical candidate among the peptide deformylase inhibitors for the treatment of infections caused by Gram-positive organisms that possess resistances to oxazolidinones or streptogramin combinations.

Antibacterial and antioxidant cassane diterpenoids from Caesalpinia benthamiana.

PubMed

Dickson, Rita A; Houghton, Peter J; Hylands, Peter J

2007-05-01

Bioactivity-guided fractionation of the light petroleum extract of Caesalpinia benthamiana (=Mezoneuron benthamianum) root bark has led to the isolation of two cassane diterpenoids, designated as benthaminin 1 and 2. A third compound, a deoxy form of caesaldekarin C (also referred to as methyl vouacapenate) which has previously been isolated from Caesalpinia major, C. bonducella, Vouacapoua americana and V. macropetala, was also isolated, together with beta-sitosterol and stigmastenone. The antibacterial and antioxidant activities of these cassane diterpenoids have been assessed using the microdilution assay method and DPPH spectrophotometric and TBA lipid peroxidation assays. Benthaminin 1 was the more active antibacterial compound with MIC values of 47.8 microM for both Staphylococcus aureus and Micrococcus flavus. Benthaminin 2 was the more active antioxidant compound and showed IC50 values of 42.7 microM and 74.2 microM for the DPPH and TBA assays, respectively. Deoxycaesaldekarin C possessed both antibacterial and antioxidant activities. The presence of methyl ester and methyl functional groups as well as an unsaturated furan ring appears to confer antibacterial activity. On the other hand, the relatively stronger antioxidant activity of benthaminin 2 may be associated with the presence of an exocyclic methylene function.

In Vitro Susceptibilities of Malassezia Species to a New Triazole, Albaconazole (UR-9825), and Other Antifungal Compounds

PubMed Central

Garau, Margarita; Pereiro, Jr., Manolo; del Palacio, Amalia

2003-01-01

The in vitro activity of the new triazole albaconazole (UR-9825) in comparison with those of flucytosine, fluconazole, ketoconazole, itraconazole, and voriconazole against 70 strains of Malassezia spp. was determined by a microdilution method using a colorimetric indicator for metabolic activity. Albaconazole showed an in vitro profile similar to those of the different antifungals tested (MIC ≤ 0.06 μg/ml for all the strains). PMID:12821494

Study of the anti-MRSA activity of Rhizoma coptidis by chemical fingerprinting and broth microdilution methods.

PubMed

Luo, Jiao-Yang; Yan, Dan; Yang, Mei-Hua

2014-05-01

Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogenic bacterium that causes both hospital- and community-acquired infections, and for which single-drug treatments are becoming less efficient. Rhizoma coptidis has been used for more than two thousand years in China to treat diarrhea, fever, and jaundice. In this study, the anti-MRSA activity of Rhizoma coptidis is examined and its effective components sought. The mecA and norA genes were determined by PCR amplification and sequencing. Drug susceptibility of Staphylococcus aureus ATCC43300 was performed using the VITEK2 compact system. The chemical fingerprint of Rhizoma coptidis was investigated using HPLC and preparative liquid chromatography, and the anti-MRSA activity was determined using an improved broth microdilution method. The drug susceptibility test revealed that the penicillin-binding protein phenotype of the strain changed in comparison to penicillin-sensitive Staphylococcus aureus. Ten batches of Rhizoma coptidis showed anti-MRSA activity on the norA-negative Staphylococcus aureus strain, as well as the strain that contained a norA gene. The spectrum-effect relationship revealed that the berberine alkaloids were the effective components, within which berberine, coptisine, palmatine, epiberberine, and jatrorrhizine were the major components. This study lays a foundation for in vivo studies of Rhizoma coptidis and for the development of multi-component drugs. Copyright © 2014 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

Antibiotic Resistance among Clinical Ureaplasma Isolates Recovered from Neonates in England and Wales between 2007 and 2013

PubMed Central

Chalker, Victoria J.; Jones, Lucy C.; Maxwell, Nicola C.; Spiller, O. Brad

2015-01-01

Ureaplasma spp. are associated with numerous clinical sequelae with treatment options being limited due to patient and pathogen factors. This report examines the prevalence and mechanisms of antibiotic resistance among clinical strains isolated from 95 neonates, 32 women attending a sexual health clinic, and 3 patients under investigation for immunological disorders, between 2007 and 2013 in England and Wales. MICs were determined by using broth microdilution assays, and a subset of isolates were compared using the broth microdilution method and the Mycoplasma IST2 assay. The underlying molecular mechanisms for resistance were determined for all resistant isolates. Three isolates carried the tet(M) tetracycline resistance gene (2.3%; confidence interval [CI], 0.49 to 6.86%); two isolates were ciprofloxacin resistant (1.5%; CI, 0.07 to 5.79%) but sensitive to levofloxacin and moxifloxacin, while no resistance was seen to any macrolides tested. The MIC values for chloramphenicol were universally low (2 μg/ml), while inherently high-level MIC values for gentamicin were seen (44 to 66 μg/ml). The Mycoplasma IST2 assay identified a number of false positives for ciprofloxacin resistance, as the method does not conform to international testing guidelines. While antibiotic resistance among Ureaplasma isolates remains low, continued surveillance is essential to monitor trends and threats from importation of resistant clones. PMID:26459899

Antibiotic Resistance among Clinical Ureaplasma Isolates Recovered from Neonates in England and Wales between 2007 and 2013.

PubMed

Beeton, Michael L; Chalker, Victoria J; Jones, Lucy C; Maxwell, Nicola C; Spiller, O Brad

2016-01-01

Ureaplasma spp. are associated with numerous clinical sequelae with treatment options being limited due to patient and pathogen factors. This report examines the prevalence and mechanisms of antibiotic resistance among clinical strains isolated from 95 neonates, 32 women attending a sexual health clinic, and 3 patients under investigation for immunological disorders, between 2007 and 2013 in England and Wales. MICs were determined by using broth microdilution assays, and a subset of isolates were compared using the broth microdilution method and the Mycoplasma IST2 assay. The underlying molecular mechanisms for resistance were determined for all resistant isolates. Three isolates carried the tet(M) tetracycline resistance gene (2.3%; confidence interval [CI], 0.49 to 6.86%); two isolates were ciprofloxacin resistant (1.5%; CI, 0.07 to 5.79%) but sensitive to levofloxacin and moxifloxacin, while no resistance was seen to any macrolides tested. The MIC values for chloramphenicol were universally low (2 μg/ml), while inherently high-level MIC values for gentamicin were seen (44 to 66 μg/ml). The Mycoplasma IST2 assay identified a number of false positives for ciprofloxacin resistance, as the method does not conform to international testing guidelines. While antibiotic resistance among Ureaplasma isolates remains low, continued surveillance is essential to monitor trends and threats from importation of resistant clones. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

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.

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.

Determination of the antibiofilm, antiadhesive, and anti-MRSA activities of seven Salvia species

PubMed Central

Al-Bakri, Amal G.; Othman, Ghadeer; Afifi, Fatma U.

2010-01-01

Background: Several Salvia species are indigenous to Jordan and are widely used as beverages and spices and for their medicinal properties. The objective of the study was to establish the antimicrobial activities, including the antiadhesive and antibiofilm effects of seven different Salvia species. Materials and Methods: Methods used for planktonic culture included agar diffusion, broth microdilution, and minimal biocidal concentration determination while viable count was used for the determination of the antibiofilm and antiadhesion activities. Overnight cultures of reference strains of Candida albicans, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus and clinical strains of methicillin-resistant S. aureus (MRSA) were used as test microorganisms. Results: An antimicrobial activity toward planktonic cultures demonstrated a significant bacteriocidal activity (≥4 log cycle reduction) for the S. triloba extract against S. aureus including MRSA. Its volatile oil exhibited an antimicrobial activity covering all tested microorganisms with the exception of P. aeruginosa. S. triloba extract and volatile oil were successful in preventing and controlling the biofilm, demonstrating antiadhesion and antibiofilm activities, respectively. Conclusion: These reported activities for S. triloba extract and volatile oil allows their listing as potential antibiofilm and anti-MRSA natural agents. This might suggest their use as an antiseptic in the prophylaxis and treatment of S. aureus-associated skin infections. The antimicrobial activity of the other tested Salvia species was negligible. PMID:21120026

Synergism between hydrogen peroxide and seventeen acids against five agri-food-borne fungi and one yeast strain.

PubMed

Martin, H; Maris, P

2012-12-01

The objective of this study was to evaluate fungicidal efficacy of hydrogen peroxide administered in combination with 17 mineral and organic acids authorized for use in the food industry. The assays were performed on a 96-well microplate using a microdilution technique based on the checkerboard titration method. The six selected strains (one yeast and five fungi) were reference strains and strains representative of contaminating fungi found in the food industry. Each synergistic hydrogen peroxide/acid combination found after fifteen minutes contact time at 20 °C in distilled water was then tested in conditions simulating four different use conditions. Twelve combinations were synergistic in distilled water, eleven of these remained synergistic with one or more of the four mineral and organic interfering substances selected. Hydrogen peroxide/formic acid combination remained effective against four strains and was never antagonistic against the other two fungi. Combinations with propionic acid and acetic acid stayed synergistic against two strains. Those with oxalic acid and lactic acid kept their synergism only against Candida albicans. No synergism was detected against Penicillium cyclopium. Synergistic combinations of disinfectants were revealed, among them the promising hydrogen peroxide/formic acid combination. A rapid screening method developed in our laboratory for bacteria was adapted to fungi and used to reveal the synergistic potential of disinfectants and/or sanitizers combinations. © 2012 The Society for Applied Microbiology.

Polymyxin B Etest Fails to Distinguish Carbapenem-resistant Enterobacteriaceae with Elevated Polymyxin B MICs

PubMed Central

Kulengowski, Brandon; Brignola, Matthew; Gallagher, Chanah; Rutter, W Cliff; Ribes, Julie A; Burgess, David S

2017-01-01

Abstract Background Polymyxins are being revitalized to combat carbapenem-resistant Enterobacteriaceae (CRE). However, evaluating the activity of these agents by traditional broth dilution methods is not practical for busy clinical laboratories. We compared polymyxin B (PMB) activity utilizing two quantitative susceptibility testing methods, Etest® and broth microdilution (BMD), against CRE isolates from patients at an academic medical center. Methods PMB activity against 70 recent CRE clinical isolates was determined by BMD and Etest® according to CLSI guidelines. P. aeruginosa ATCC® 27853 was used as a quality control strain. The CLSI PMB susceptibility breakpoint of non-fermenting gram-negative bacteria (<2 mg/L) was used. Essential agreement between methods was defined as an MIC measured within 1 log2 dilution. Categorical agreement was defined between methods as classification of isolates in the same susceptibility category (susceptible or resistant). Major and very major error rates were calculated, and McNemar’s test was used for determining a difference between methods. Results CRE isolates were primarily Enterobacter spp. (43%), followed by K. pneumoniae (41%) and E. coli (9%). Essential agreement between testing methods was low (9%), but categorical agreement was 81% (P = 0.0002). Although false non-susceptibility was never observed by Etest® (BMD as reference), the rate of very major errors by Etest® was high (19%). Etest® miscalled 87% of PMB-resistant CRE. Conclusion Etest® reporting of false susceptibility may result in inappropriate antibiotic utilization and treatment failure clinically. We do not recommend using Etest® for PMB susceptibility testing for routine patient care. Disclosures All authors: No reported disclosures.

In vitro drug susceptibility of 40 international reference rapidly growing mycobacteria to 20 antimicrobial agents

PubMed Central

Pang, Hui; Li, Guilian; Wan, Li; Jiang, Yi; Liu, Haican; Zhao, Xiuqin; Zhao, Zhongfu; Wan, Kanglin

2015-01-01

Rapidly growing mycobacteria (RGM) are human pathogens that are relatively easily identified by acid-fast staining but are proving difficult to treat in the clinic. In this study, we performed susceptibility testing of 40 international reference RGM species against 20 antimicrobial agents using the cation-adjusted Mueller-Hinton (CAMH) broth microdilution based on the minimum inhibitory concentration (MIC) assay recommended by the guidelines of the Clinical and Laboratory Standards Institute (CLSI). The results demonstrated that RGM organisms were resistant to the majority of first-line antituberculous agents but not to second-line fluoroquinolones or aminoglycosides. Three drugs (amikacin, tigecycline and linezolid) displayed potent antimycobacterial activity against all tested strains. Capreomycin, levofloxacin and moxifloxacin emerged as promising candidates for the treatment of RGM infections, and cefoxitin and meropenem were active against most strains. Mycobacterium chelonae (M. chelonae), M. abscessus, M. bolletii, M. fortuitum, M. boenickei, M. conceptionense, M. pseudoshottsii, M. septicum and M. setense were the most resistant RGM species. These results provide significant insight into the treatment of RGM species and will assist optimization of clinical criteria. PMID:26629031

Development of Similar Broth Microdilution Methods to Determine the Antimicrobial Susceptibility of Flavobacterium columnare and F. psychrophilum.

PubMed

Gieseker, Charles M; Crosby, Tina C; Mayer, Tamara D; Bodeis, Sonya M; Stine, Cynthia B

2016-03-01

Flavobacterium columnare and F. psychrophilum are major fish pathogens that cause diseases that may require antimicrobial therapy. Choice of appropriate treatment is dependent upon determining the antimicrobial susceptibility of isolates. Therefore we optimized methods for broth microdilution testing of F. columnare and F. psychrophilum to facilitate standardizing an antimicrobial susceptibility test. We developed adaptations to make reproducible broth inoculums and confirmed the proper incubation time and media composition. We tested the stability of potential quality-control bacteria and compared test results between different operators. Log phase occurred at 48 h for F. columnare and 72-96 h for F. psychrophilum, confirming the test should be incubated at 28°C for approximately 48 h and at 18°C for approximately 96 h, respectively. The most consistent susceptibility results were achieved with plain, 4-g/L, dilute Mueller-Hinton broth supplemented with dilute calcium and magnesium. Supplementing the broth with horse serum did not improve growth. The quality-control strains, Escherichia coli ATCC 25922 and Aeromonas salmonicida subsp. salmonicida ATCC 33658, yielded stable minimal inhibitory concentrations (MIC) against all seven antimicrobials tested after 30 passes at 28°C and 15 passes at 18°C. In comparison tests, most MICs of the isolates agreed 100% within one drug dilution for ampicillin, florfenicol, and oxytetracycline. The agreement was lower with the ormetoprim-sulfdimethoxine combination, but there was at least 75% agreement for all but one isolate. These experiments have provided methods to help standardize antimicrobial susceptibility testing of these nutritionally fastidious aquatic bacteria. Received June 24, 2015; accepted October 2, 2015.

Comparison of agar dilution and antibiotic gradient strip test with broth microdilution for susceptibility testing of swine Brachyspira species.

PubMed

Mirajkar, Nandita S; Gebhart, Connie J

2016-03-01

Production-limiting diseases in swine caused by Brachyspira are characterized by mucohemorrhagic diarrhea (B. hyodysenteriae and "B. hampsonii") or mild colitis (B. pilosicoli), while B. murdochii is often isolated from healthy pigs. Emergence of novel pathogenic Brachyspira species and strains with reduced susceptibility to commonly used antimicrobials has reinforced the need for standardized susceptibility testing. Two methods are currently used for Brachyspira susceptibility testing: agar dilution (AD) and broth microdilution (BMD). However, these tests have primarily been used for B. hyodysenteriae and rarely for B. pilosicoli. Information on the use of commercial susceptibility testing products such as antibiotic gradient strips is lacking. Our main objective was to validate and compare the susceptibility results, measured as the minimum inhibitory concentration (MIC), of 6 antimicrobials for 4 Brachyspira species (B. hyodysenteriae, "B. hampsonii", B. pilosicoli, and B. murdochii) by BMD and AD (tiamulin, valnemulin, lincomycin, tylosin, and carbadox) or antibiotic gradient strip (doxycycline) methods. In general, the results of a high percentage of all 4 Brachyspira species differed by ±1 log2 dilution or less by BMD and AD for tiamulin, valnemulin, lincomycin, and tylosin, and by BMD and antibiotic gradient strip for doxycycline. The carbadox MICs obtained by BMD were 1-5 doubling dilutions different than those obtained by AD. BMD for Brachyspira was quicker to perform with less ambiguous interpretation of results when compared with AD and antibiotic gradient strip methods, and the results confirm the utility of BMD in routine diagnostics. © 2016 The Author(s).

Irreproducible and uninterpretable Polymyxin B MICs for Enterobacter cloacae and Enterobacter aerogenes.

PubMed

Landman, David; Salamera, Julius; Quale, John

2013-12-01

Carbapenem-resistant Enterobacter species are emerging nosocomial pathogens. As with most multidrug-resistant Gram-negative pathogens, the polymyxins are often the only therapeutic option. In this study involving clinical isolates of E. cloacae and E. aerogenes, susceptibility testing methods with polymyxin B were analyzed. All isolates underwent testing by the broth microdilution (in duplicate) and agar dilution (in duplicate) methods, and select isolates were examined by the Etest method. Selected isolates were also examined for heteroresistance by population analysis profiling. Using a susceptibility breakpoint of ≤2 μg/ml, categorical agreement by all four dilution tests (two broth microdilution and two agar dilution) was achieved in only 76/114 (67%) of E. cloacae isolates (65 susceptible, 11 resistant). Thirty-eight (33%) had either conflicting or uninterpretable results (multiple skip wells, i.e., wells that exhibit no growth although growth does occur at higher concentrations). Of the 11 consistently resistant isolates, five had susceptible MICs as determined by Etest. Heteroresistant subpopulations were detected in eight of eight isolates tested, with greater percentages in isolates with uninterpretable MICs. For E. aerogenes, categorical agreement between the four dilution tests was obtained in 48/56 (86%), with conflicting and/or uninterpretable results in 8/56 (14%). For polymyxin susceptibility testing of Enterobacter species, close attention must be paid to the presence of multiple skip wells, leading to uninterpretable results. Susceptibility also should not be assumed based on the results of a single test. Until the clinical relevance of skip wells is defined, interpretation of polymyxin susceptibility tests for Enterobacter species should be undertaken with extreme caution.

Irreproducible and Uninterpretable Polymyxin B MICs for Enterobacter cloacae and Enterobacter aerogenes

PubMed Central

Landman, David; Salamera, Julius

2013-01-01

Carbapenem-resistant Enterobacter species are emerging nosocomial pathogens. As with most multidrug-resistant Gram-negative pathogens, the polymyxins are often the only therapeutic option. In this study involving clinical isolates of E. cloacae and E. aerogenes, susceptibility testing methods with polymyxin B were analyzed. All isolates underwent testing by the broth microdilution (in duplicate) and agar dilution (in duplicate) methods, and select isolates were examined by the Etest method. Selected isolates were also examined for heteroresistance by population analysis profiling. Using a susceptibility breakpoint of ≤2 μg/ml, categorical agreement by all four dilution tests (two broth microdilution and two agar dilution) was achieved in only 76/114 (67%) of E. cloacae isolates (65 susceptible, 11 resistant). Thirty-eight (33%) had either conflicting or uninterpretable results (multiple skip wells, i.e., wells that exhibit no growth although growth does occur at higher concentrations). Of the 11 consistently resistant isolates, five had susceptible MICs as determined by Etest. Heteroresistant subpopulations were detected in eight of eight isolates tested, with greater percentages in isolates with uninterpretable MICs. For E. aerogenes, categorical agreement between the four dilution tests was obtained in 48/56 (86%), with conflicting and/or uninterpretable results in 8/56 (14%). For polymyxin susceptibility testing of Enterobacter species, close attention must be paid to the presence of multiple skip wells, leading to uninterpretable results. Susceptibility also should not be assumed based on the results of a single test. Until the clinical relevance of skip wells is defined, interpretation of polymyxin susceptibility tests for Enterobacter species should be undertaken with extreme caution. PMID:24088860

Activity of a long-acting echinocandin, CD101, determined using CLSI and EUCAST reference methods, against Candida and Aspergillus spp., including echinocandin- and azole-resistant isolates.

PubMed

Pfaller, Michael A; Messer, Shawn A; Rhomberg, Paul R; Jones, Ronald N; Castanheira, Mariana

2016-10-01

The objective of this study was to evaluate the in vitro activity of CD101, a novel echinocandin with a long serum elimination half-life, and comparator (anidulafungin and caspofungin) antifungal agents against a collection of Candida and Aspergillus spp. isolates. CD101 and comparator agents were tested against 106 Candida spp. and 67 Aspergillus spp. isolates, including 27 isolates of Candida harbouring fks hotspot mutations and 12 itraconazole non-WT Aspergillus, using CLSI and EUCAST reference susceptibility broth microdilution (BMD) methods. Against WT and fks mutant Candida albicans, Candida glabrata and Candida tropicalis, the activity of CD101 [MIC90 = 0.06, 0.12 and 0.03 mg/L, respectively (CLSI method values)] was comparable to that of anidulafungin (MIC90 = 0.03, 0.12 and 0.03 mg/L, respectively) and caspofungin (MIC90 = 0.12, 0.25 and 0.12 mg/L, respectively). WT Candida krusei isolates were very susceptible to CD101 (MIC = 0.06 mg/L). CD101 activity (MIC50/90 = 1/2 mg/L) was comparable to that of anidulafungin (MIC50/90 = 2/2 mg/L) against Candida parapsilosis. CD101 (MIC mode = 0.06 mg/L for C. glabrata) was 2- to 4-fold more active against fks hotspot mutants than caspofungin (MIC mode = 0.5 mg/L). CD101 was active against Aspergillus fumigatus, Aspergillus terreus, Aspergillus niger and Aspergillus flavus (MEC90 range = ≤0.008-0.03 mg/L). The essential agreement between CLSI and EUCAST methods for CD101 was 92.0%-100.0% among Candida spp. and 95.0%-100.0% among Aspergillus spp. The activity of CD101 is comparable to that of other members of the echinocandin class for the prevention and treatment of serious fungal infections. Similar results for CD101 activity versus Candida and Aspergillus spp. may be obtained with either CLSI or EUCAST BMD methods. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy.

Screening Togolese medicinal plants for few pharmacological properties.

PubMed

Karou, Simplice D; Tchacondo, Tchadjobo; Tchibozo, Micheline Agassounon Djikpo; Anani, Kokou; Ouattara, Lassina; Simpore, Jacques; de Souza, Comlan

2012-04-01

Terminalia macroptera Guill. et Perr. (Combretaceae), Sida alba L. (Malvaceae), Prosopis africana Guill et Perr. Taub. (Mimosaceae), Bridelia ferruginea Benth. (Euphorbiaceae), and Vetiveria nigritana Stapf. (Asteraceae) are traditionally used in Togolese folk medicine to treat several diseases including microbial infections. This study aimed to investigate the antimicrobial, antioxidant, and hemolytic properties of the crude extracts of the above-mentioned plants. The antimicrobial and the antioxidant activities were assayed using the NCCLS microdilution method and the DPPH free radical scavenging, respectively. Human A+ red blood cells were used to perform the hemolytic assay. Phenolics were further quantified in the extracts using spectrophotometric methods. Minimal inhibitory concentrations in the range of 230-1800 μg/ml were recorded in the NCCLS broth microdilution for both bacterial and fungal strains with methanol extracts. The DPPH radical scavenging assay yielded interesting antioxidant activities of the extracts of P. africana and T. macroptera (IC(50) values of 0.003 ± 0.00 μg/ml and 0.05 ± 0.03 μg/ml, respectively). These activities were positively correlated with the total phenolic contents and negatively correlated with the proanthocyanidin content of the extracts. The hemolytic assay revealed that great hemolysis occurred with the methanol extracts of T. macroptera, S. longepedunculata, and B. ferruginea. These results support in part the use of the selected plants in the treatment of microbial infections. In addition, the plant showed an interesting antioxidant activity that could be useful in the management of oxidative stress.

In Vitro Activities of Gemifloxacin versus Five Quinolones and Two Macrolides against 271 Spanish Isolates of Legionella pneumophila: Influence of Charcoal on Susceptibility Test Results

PubMed Central

García, M. T.; Pelaz, C.; Giménez, M. J.; Aguilar, L.

2000-01-01

The MICs at which 90% of isolates are inhibited for gemifloxacin, trovafloxacin, and grepafloxacin were low (≤0.01 μg/ml) for 271 Legionella isolates when they were determined by the broth microdilution method but increased (≥6 dilutions) when they were determined by the agar dilution method. This was due to the charcoal in the agar dilution medium, as shown by the progressive decrease in the MICs when the charcoal concentrations decreased. As free drug is the active fraction, charcoal binding should be considered. PMID:10898695

Wild-Type MIC Distributions and Epidemiological Cutoff Values for Caspofungin and Aspergillus spp. for the CLSI Broth Microdilution Method (M38-A2 Document)▿

PubMed Central

Espinel-Ingroff, A.; Fothergill, A.; Fuller, J.; Johnson, E.; Pelaez, T.; Turnidge, J.

2011-01-01

Clinical breakpoints have not been established for mold testing. Epidemiologic cutoff values (ECVs) are available for six Aspergillus spp. and the triazoles, but not for caspofungin. Wild-type (WT) minimal effective concentration (MEC) distributions (organisms in a species-drug combination with no acquired resistance mechanisms) were defined in order to establish ECVs for six Aspergillus spp. and caspofungin. The number of available isolates was as follows: 1,691 A. fumigatus, 432 A. flavus, 192 A. nidulans, 440 A. niger, 385 A. terreus, and 75 A. versicolor isolates. CLSI broth microdilution MEC data gathered in five independent laboratories in Canada, Europe, and the United States were aggregated for the analyses. ECVs expressed in μg/ml that captured 95% and 99% of the modeled wild-type population were for A. fumigatus 0.5 and 1, A. flavus 0.25 and 0.5, A. nidulans 0.5 and 0.5, A. niger 0.25 and 0.25, A. terreus 0.25 and 0.5, and A. versicolor 0.25 and 0.5. Although caspofungin ECVs are not designed to predict the outcome of therapy, they may aid in the detection of strains with reduced antifungal susceptibility to this agent and acquired resistance mechanisms. PMID:21422219

Determination of the antibiofilm, antiadhesive, and anti-MRSA activities of seven Salvia species.

PubMed

Al-Bakri, Amal G; Othman, Ghadeer; Afifi, Fatma U

2010-10-01

Several Salvia species are indigenous to Jordan and are widely used as beverages and spices and for their medicinal properties. The objective of the study was to establish the antimicrobial activities, including the antiadhesive and antibiofilm effects of seven different Salvia species. Methods used for planktonic culture included agar diffusion, broth microdilution, and minimal biocidal concentration determination while viable count was used for the determination of the antibiofilm and antiadhesion activities. Overnight cultures of reference strains of Candida albicans, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus and clinical strains of methicillin-resistant S. aureus (MRSA) were used as test microorganisms. An antimicrobial activity toward planktonic cultures demonstrated a significant bacteriocidal activity (≥4 log cycle reduction) for the S. triloba extract against S. aureus including MRSA. Its volatile oil exhibited an antimicrobial activity covering all tested microorganisms with the exception of P. aeruginosa. S. triloba extract and volatile oil were successful in preventing and controlling the biofilm, demonstrating antiadhesion and antibiofilm activities, respectively. These reported activities for S. triloba extract and volatile oil allows their listing as potential antibiofilm and anti-MRSA natural agents. This might suggest their use as an antiseptic in the prophylaxis and treatment of S. aureus-associated skin infections. The antimicrobial activity of the other tested Salvia species was negligible.

Composition and antimicrobial activity of the essential oils of Laserpitium latifolium L. and L. ochridanum Micevski (Apiaceae).

PubMed

Popović, Višnja B; Petrović, Silvana D; Milenković, Marina T; Drobac, Milica M; Couladis, Maria A; Niketić, Marjan S

2015-01-01

The chemical composition and antimicrobial activity of essential oils of Laserpitium latifolium and L. ochridanum were investigated. The essential oils were isolated by steam distillation and characterized by GC-FID and GC/MS analyses. All essential oils were distinguished by high contents of monoterpenes, and α-pinene was the most abundant compound in the essential oils of L. latifolium underground parts and fruits (contents of 44.4 and 44.0%, resp.). The fruit essential oil was also rich in sabinene (26.8%). Regarding the L. ochridanum essential oils, the main constituents were limonene in the fruit oil (57.7%) and sabinene in the herb oil (25.9%). The antimicrobial activity of these essential oils as well as that of L. ochridanum underground parts, whose composition was reported previously, was tested by the broth-microdilution method against four Gram-positive and three Gram-negative bacteria and two Candida albicans strains. Except the L. latifolium underground-parts essential oil, the other investigated oils showed a high antimicrobial potential against Staphylococcus aureus, S. epidermidis, Micrococcus luteus, or Candida albicans (minimal inhibitory concentrations of 13.0-73.0 μg/ml), comparable to or even higher than that of thymol, which was used as reference compound. Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.

Construction of a Simple, Inexpensive Multiple Enzyme-Linked Immunosorbent Assay Microdilution Plate Washer

PubMed Central

Stobbs, L. W.

1990-01-01

In this paper, plans are given for the construction of an inexpensive enzyme-linked immunosorbent assay plate washer from readily available materials. The wash unit uses an intermittent wash cycle based on a wash manifold cycling over the microdilution plates for a predetermined time. Laboratory tests showed that the unit provided reliable, rapid washing of plates with tap water, with no detectable contamination between wells. Substrate absorbance values for test samples from machine-washed plates were equal to or greater than absorbance values for corresponding samples from plates washed manually by an accepted protocol, by using either enzyme-linked immunosorbent assay wash buffer or tap water. Images PMID:16348216

Update of contemporary antimicrobial resistance rates across China: reference testing results for 12 medical centers (2011).

PubMed

Jones, Ronald N; Castanheira, Mariana; Hu, Bijie; Ni, Yuxing; Lin, Stephen S F; Mendes, Rodrigo E; Wang, Yao

2013-11-01

Antimicrobial resistance (R) surveillance across Asia and especially in China has documented unique patterns and mechanisms. This 2011 study reports results for 2278 isolates from 12 hospitals in China (94-216 strains/site); most from bacteremia (20.4%), pneumonias (29.1%), or skin and skin structure infections (20.9%). Samples were tested by reference broth microdilution methods, interpreted by published susceptibility (S) breakpoints. The most common species were Staphylococcus aureus (343, 45.8% MRSA), Escherichia coli (EC; 288), Pseudomonas aeruginosa (PSA; 221), Klebsiella spp. (KSP; 208), acinetobacters (ACB; 178), enterobacters (155), Streptococcus pneumoniae (SPN; 154, 46.8% penicillin-S), and enterococci (ENT; 137). Among 849 Gram-positive (GP) cocci, linezolid, tigecycline (TIG), daptomycin, and vancomycin provided best antimicrobial coverage (≥99.7% S). Resistance patterns of concern were 0.3% VISA, 15.4% teicoplanin non-S coagulase-negative staphylococci, 1.5% vancomycin-R ENT (all Enterococcus faecium), 1.9% levofloxacin-R β-haemolytic streptococci, and 35.1 and 12.7% ceftriaxone-non-S rates for SPN and viridans group streptococci, respectively. For Gram-negative bacilli, R among Enterobacteriaceae was highest against β-lactams (extended spectrum β-lactamase-phenotype strains at 73.6 and 42.8% in EC and KSP, respectively; carbapenem-R was only 2.1-4.3% with KPC and IMP type enzymes detected in KSP). The widest spectrum agents were cefoperazone/sulbactam (79.5-86.1%), piperacillin/tazobactam (88.9-92.0%), TIG (98.6-100%), amikacin (AMK; 91.8-93.7%), and meropenem (95.7-97.1% S). PSA was most inhibited by AMK (90.5% S) and colistin (COL; 99.5%), with cefepime (67.9%) best among the tested β-lactams. Only COL (100% S) and TIG (MIC90, 2 μg/mL) showed significant potencies against ACB. In conclusion, R among pathogens from 12 Chinese hospitals illustrates several agents active against GP pathogens, but more serious R problems were noted among Enterobacteriaceae, PSA, and ACB. Combination treatment for the latter multidrug-R strains appears necessary, guided by local antibiograms and national surveillance results applying reference methods. © 2013.

In Vitro Interaction of Terbinafine with Itraconazole against Clinical Isolates of Scedosporium prolificans

PubMed Central

Meletiadis, Joseph; Mouton, Johan W.; Rodriguez-Tudela, Juan L.; Meis, Jacques F. G. M.; Verweij, Paul E.

2000-01-01

In order to develop new approaches for the chemotherapy of invasive infections caused by Scedosporium prolificans, the in vitro interaction between itraconazole and terbinafine against 20 clinical isolates was studied using a checkerboard microdilution method. Itraconazole and terbinafine alone were inactive against most isolates, but the combination was synergistic against 95 and 85% of isolates after 48 and 72 h of incubation, respectively. Antagonism was not observed. The MICs obtained with the terbinafine-itraconazole combination were within levels that can be achieved in plasma. PMID:10639389

Antifungal Activity of Decyl Gallate against Several Species of Pathogenic Fungi

PubMed Central

de Paula e Silva, Ana Carolina Alves; Costa-Orlandi, Caroline Barcelos; Gullo, Fernanda Patrícia; Sangalli-Leite, Fernanda; de Oliveira, Haroldo Cesar; da Silva, Julhiany de Fátima; Rossi, Suélen Andrea; Benaducci, Tatiane; Wolf, Vanessa Gonçalves; Regasini, Luis Octávio; Petrônio, Maicon Segalla; Silva, Dulce Helena Siqueira; Bolzani, Vanderlan S.; Mendes-Giannini, Maria José Soares

2014-01-01

This work aims to demonstrate that the gallic acid structure modification to the decyl gallate (G14) compound contributed to increase the antifungal activity against several species of pathogenic fungi, mainly, Candida spp., Cryptococcus spp., Paracoccidioides spp., and Histoplasma capsulatum, according to standardized microdilution method described by Clinical Laboratory Standard Institute (CLSI) documents. Moreover this compound has a particularly good selectivity index value, which makes it an excellent candidate for broad-spectrum antifungal prototype and encourages the continuation of subsequent studies for the discovery of its mechanism of action. PMID:25505923

Antibacterial activities of the methanol extracts of ten Cameroonian vegetables against Gram-negative multidrug-resistant bacteria

PubMed Central

2013-01-01

Background Many edible plants are used in Cameroon since ancient time to control microbial infections. This study was designed at evaluating the antibacterial activities of the methanol extracts of ten Cameroonian vegetables against a panel of twenty nine Gram negative bacteria including multi-drug resistant (MDR) strains. Methods The broth microdilution method was used to determine the Minimal Inhibitory Concentrations (MIC) and the Minimal Bactericidal Concentrations (MBC) of the studied extracts. When chloramphenicol was used as a reference antibiotic, the MICs were also determined in the presence of Phenylalanine-Arginine β-Naphtylamide (PAβN), an efflux pumps inhibitor (EPI). The phytochemical screening of the extracts was performed using standard methods. Results All tested extracts exhibited antibacterial activities, with the MIC values varying from 128 to 1024 mg/L. The studied extracts showed large spectra of action, those from L. sativa, S. edule, C. pepo and S. nigrum being active on all the 29 bacterial strains tested meanwhile those from Amaranthus hybridus, Vernonia hymenolepsis, Lactuca.carpensis and Manihot esculenta were active on 96.55% of the strains used. The plant extracts were assessed for the presence of large classes of secondary metabolites: alkaloids, anthocyanins, anthraquinones, flavonoids, phenols, saponins, steroids, tannins and triterpenes. Each studied plant extract was found to contain compounds belonging to at least two of the above mentioned classes. Conclusion These results confirm the traditional claims and provide promising baseline information for the potential use of the tested vegetables in the fight against bacterial infections involving MDR phenotypes. PMID:23368430

A colorimetric broth microdilution method for assessment of Helicobacter pylori sensitivity to antimicrobial agents.

PubMed

Knezevic, Petar; Aleksic Sabo, Verica; Simin, Natasa; Lesjak, Marija; Mimica-Dukic, Neda

2018-04-15

Helicobacter pylori is a major infective etiological agent of the upper gastrointestinal tract diseases. The bacterium exhibits resistance to various conventional antibiotics, being usually challenging for eradication. Since there is an urge to consider alternative therapeutic strategies, the aim of the study was to examine selected essential oils of plants belonging to families Cupressaceae (Juniperus communis) and Lamiaceae (Hyssopus officinalis, Salvia officinalis, Melissa officinalis, Lavandula angustifolia, Ocimum basilicum and Thymus serpyllum) against H. pylori, using an improved microdilution broth method. The oils were examined in concentration range from 0.03 to 4 μL/mL. The method comprises Brain-heart infusion broth supplemented with yeast extract, horse serum and IsoVitaleX. After 3 day incubation, an equal volume of double strengthen Christensen's urea was added into each well and incubated for additional 4 h. In wells with present H. pylori, the medium changed color from yellow to purple, allowing MIC determination even without a microtitre plate reader. The microtitre format method is convenient as it is less expensive, easier to perform and requires less amount of an anti-H. pylori agent. The improved method enhances specificity to H. pylori, as fast urease activity is almost an exclusive property of this bacterium. The application of the second step incubation with Christensen's urea decreases the possibility of false positive/negative results due to contaminant growth or commonly poor H. pylori growth. Among the examined oils, J. communis, H. officinalis and O. basilicum were not active with the highest applied concentrations, while the most active was T. serpyllum, with MIC 2.0-4.0 μL/mL. This is the first report on essential oils activity of T. serpyllum and H. officinalis against H. pylori. Copyright © 2018 Elsevier B.V. All rights reserved.

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.

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.

In vitro antimicrobial activity of benzoyl peroxide against Propionibacterium acnes assessed by a novel susceptibility testing method.

PubMed

Okamoto, Kazuaki; Ikeda, Fumiaki; Kanayama, Shoji; Nakajima, Akiko; Matsumoto, Tatsumi; Ishii, Ritsuko; Umehara, Masatoshi; Gotoh, Naomasa; Hayashi, Naoki; Iyoda, Takako; Matsuzaki, Kaoru; Matsumoto, Satoru; Kawashima, Makoto

2016-06-01

Benzoyl peroxide (BPO), a therapeutic agent for acne vulgaris, was assessed for in vitro antimicrobial activity against Propionibacterium acnes using a novel broth microdilution testing that improved BPO solubility. We searched for a suitable culture medium to measure the minimum inhibitory concentration (MIC) of BPO against P. acnes and finally found the Gifu anaerobic medium (GAM) broth supplemented with 0.1(v/v)% glycerol and 2(v/v)% Tween 80, in which BPO dissolved up to 1250 μg/mL and P. acnes grew well. The MICs and minimum bactericidal concentrations (MBCs) of BPO against 44 clinical isolates of P. acnes collected from Japanese patients with acne vulgaris were determined by our testing method using the supplemented GAM broth. The MICs of BPO were 128 or 256 μg/mL against all isolates of P. acnes regardless of susceptibility to nadifloxacin or clindamycin. The MBCs of BPO were also 128 or 256 μg/mL against the same isolates. Moreover, BPO at the MIC showed a rapid bactericidal activity against P. acnes ATCC11827 in time-kill assay. In conclusion, we could develop a novel assay for the MIC and MBC determinations of BPO against P. acnes, which is reliable and reproducible as a broth microdilution testing and the present results suggest that BPO has a potent bactericidal activity against P. acnes. Copyright © 2016 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Rapid Automated Antimicrobial Susceptibility Testing of Streptococcus pneumoniae by Use of the bioMerieux VITEK 2

PubMed Central

Jorgensen, James H.; Barry, Arthur L.; Traczewski, M. M.; Sahm, Daniel F.; McElmeel, M. Leticia; Crawford, Sharon A.

2000-01-01

The VITEK 2 is a new automated instrument for rapid organism identification and susceptibility testing. It has the capability of performing rapid susceptibility testing of Streptococcus pneumoniae with specially configured cards that contain enriched growth medium and antimicrobial agents relevant for this organism. The present study compared the results of testing of a group of 53 challenge strains of pneumococci with known resistance properties and a collection of clinical isolates examined in two study phases with a total of 402 and 416 isolates, respectively, with a prototype of the VITEK 2. Testing was conducted in three geographically separate laboratories; the challenge collection was tested by all three laboratories, and the unique clinical isolates were tested separately by the individual laboratories. The VITEK 2 results of tests with 10 antimicrobial agents were compared to the results generated by the National Committee for Clinical Laboratory Standards reference broth microdilution MIC test method. Excellent interlaboratory agreement was observed with the challenge strains. The overall agreement within a single twofold dilution of MICs defined by the VITEK 2 and reference method with the clinical isolates was 96.3%, although there were a number of off-scale MICs that could not be compared. The best agreement with the clinical isolates was achieved with ofloxacin and chloramphenicol (100%), and the lowest level of agreement among those drugs with sufficient on-scale MICs occurred with trimethoprim-sulfamethoxazole (89.7%). Overall there were 1.3% very major, 6.6% minor, and no major interpretive category errors encountered with the clinical isolates, although >80% of the minor interpretive errors involved only a single log2 dilution difference. The mean time for generation of susceptibility results with the clinical isolates was 8.1 h. The VITEK 2 provided rapid, reliable susceptibility category determinations with both the challenge and clinical isolates examined in this study. PMID:10921932

In Vitro Antifungal Activity of KP-103, a Novel Triazole Derivative, and Its Therapeutic Efficacy against Experimental Plantar Tinea Pedis and Cutaneous Candidiasis in Guinea Pigs

PubMed Central

Tatsumi, Yoshiyuki; Yokoo, Mamoru; Arika, Tadashi; Yamaguchi, Hideyo

2001-01-01

The in vitro activity of KP-103, a novel triazole derivative, against pathogenic fungi that cause dermatomycoses and its therapeutic efficacy against plantar tinea pedis and cutaneous candidiasis in guinea pigs were investigated. MICs were determined by a broth microdilution method with morpholinepropanesulfonic acid-buffered RPMI 1640 medium for Candida species and with Sabouraud dextrose broth for dermatophytes and by an agar dilution method with medium C for Malassezia furfur. KP-103 was the most active of all the drugs tested against Candida albicans (geometric mean [GM] MIC, 0.002 μg/ml), other Candida species including Candida parapsilosis and Candida glabrata (GM MICs, 0.0039 to 0.0442 μg/ml), and M. furfur (GM MIC, 0.025 μg/ml). KP-103 (1% solution) was highly effective as a treatment for guinea pigs with cutaneous candidiasis and achieved mycological eradication in 8 of the 10 infected animals, whereas none of the imidazoles tested (1% solutions) was effective in even reducing the levels of the infecting fungi. KP-103 was as active as clotrimazole and neticonazole but was less active than lanoconazole and butenafine against Trichophyton rubrum (MIC at which 80% of isolates are inhibited [MIC80], 0.125 μg/ml) and Trichophyton mentagrophytes (MIC80, 0.25 μg/ml). However, KP-103 (1% solution) exerted therapeutic efficacy superior to that of neticonazole and comparable to those of lanoconazole and butenafine, yielding negative cultures for all samples from guinea pigs with plantar tinea pedis tested. This suggests that KP-103 has better pharmacokinetic properties in skin tissue than the reference drugs. Because the in vitro activity of KP-103, unlike those of the reference drugs, against T. mentagrophytes was not affected by hair as a keratinic substance, its excellent therapeutic efficacy seems to be attributable to good retention of its antifungal activity in skin tissue, in addition to its potency. PMID:11302816

Comparative activity of ceftobiprole against Gram-positive and Gram-negative isolates from Europe and the Middle East: the CLASS study.

PubMed

Rossolini, Gian M; Dryden, Matthew S; Kozlov, Roman S; Quintana, Alvaro; Flamm, Robert K; Läuffer, Jörg M; Lee, Emma; Morrissey, Ian; CLASS Study Group

2011-01-01

to assess the in vitro activity of ceftobiprole and comparators against a recent collection of Gram-positive and Gram-negative pathogens, in order to detect potential changes in susceptibility patterns, and to evaluate the Etest assay for ceftobiprole susceptibility testing. contemporary Gram-positive and Gram-negative isolates (excluding extended-spectrum β-lactamase-producing isolates) from across Europe and the Middle East were collected, and their susceptibility to ceftobiprole, vancomycin, teicoplanin, linezolid, ceftazidime and cefepime was assessed using the Etest method. Quality testing [using Etest and broth microdilution (BMD)] was conducted at a central reference laboratory. some 5041 Gram-positive and 4026 Gram-negative isolates were included. Against Gram-positive isolates overall, ceftobiprole had the lowest MIC50 (0.5 mg/L), compared with 1 mg/L for its comparators (vancomycin, teicoplanin and linezolid). Against methicillin-resistant Staphylococcus aureus, all four agents had a similar MIC90 (2 mg/L), but ceftobiprole had a 4-fold better MIC90 (0.5 mg/L) against methicillin-susceptible strains. Only 38 Gram-positive isolates were confirmed as ceftobiprole resistant. Among Gram-negative strains, 86.9%, 91.7% and 95.2% were susceptible to ceftobiprole, ceftazidime and cefepime, respectively. Pseudomonas aeruginosa was less susceptible to all three antimicrobials than any other Gram-negative pathogen. There was generally good agreement between local Etest results and those obtained at the reference laboratory (for ceftobiprole: 86.8% with Gram-negatives; and 94.7% with Gram-positives), as well as between results obtained by BMD and Etest methods (for ceftobiprole: 98.2% with Gram-negatives; and 98.4% with Gram-positives). ceftobiprole exhibits in vitro activity against a wide range of Gram-positive and Gram-negative pathogens, including multidrug-resistant strains. No changes in its known susceptibility profile were identified.

Antimicrobial and antioxidant activities of triterpenoid and phenolic derivatives from two Cameroonian Melastomataceae plants: Dissotis senegambiensis and Amphiblemma monticola.

PubMed

Nzogong, Raissa Tioyem; Ndjateu, Fabrice Sterling Tchantchou; Ekom, Steve Endeguele; Fosso, Jules-Arnaud Mboutchom; Awouafack, Maurice Ducret; Tene, Mathieu; Tane, Pierre; Morita, Hiroyuki; Choudhary, Muhammad Iqbal; Tamokou, Jean-de-Dieu

2018-05-16

Antimicrobial resistance is a serious threat against humankind and the search for new therapeutics is needed. This study aims to investigate the antimicrobial and antioxidant activities of ethanol extracts and compounds isolated from Dissotis senegambiensis and Amphiblemma monticola, two Cameroonian Melastomataceae species traditionally used for the treatment of fever, malaria and infectious diseases. The plant extracts were prepared by maceration in ethanol. Standard chromatographic and spectroscopic methods were used to isolate and identify fourteen compounds from the two plant species [1-6 (from D. senegambiensis), 3, 4 and 7-14 (from A. monticola)]. A two-fold serial micro-dilution method was used to determine the minimum inhibitory concentration (MIC) against four bacterial strains including two resistant bacterial strains, methicillin resistant S. aureus (MRSA3) and methicillin resistant S. aureus (MRSA4) and three yeast strains. The fractionation of EtOH extracts afforded fourteen compounds belonging to triterpenoid and phenolic derivatives. The ethanol extracts, compounds 3, 5-8, 10 and the mixture of 10 + 12 were active against all the tested bacterial and fungal species. Compound 7 (MIC = 16-32 μg/mL) and 10 (MIC = 8-16 μg/mL) displayed the largest antibacterial and antifungal activities, respectively. Compounds 7, 10 and the mixture of 10 + 12 showed prominent antibacterial activity against methicillin- resistant S. aureus (MRSA) which is in some cases equal to that of ciprofloxacin used as reference antibacterial drug. Compound 8 also showed high radical-scavenging activities and ferric reducing power when compared with vitamin C and butylated hydroxytoluene used as reference antioxidants. The tested samples were non-toxic to normal cells highlighting their good selectivity. The result of this investigation reveals the potential of D. senegambiensis and A. monticola as well as the most active compounds in the search for new antimicrobial and antioxidant agents. So, further investigations are needed.

MALDI-TOF MS typing of a nosocomial methicillin-resistant Staphylococcus aureus outbreak in a neonatal intensive care unit.

PubMed

Steensels, Deborah; Deplano, Ariane; Denis, Olivier; Simon, Anne; Verroken, Alexia

2017-08-01

The early detection of a methicillin-resistant Staphylococcus aureus (MRSA) outbreak is decisive to control its spread and rapidly initiate adequate infection control measures. Therefore, prompt determination of epidemiologic relatedness of clinical MRSA isolates is essential. Genetic typing methods have a high discriminatory power but their availability remains restricted. In this study, we aimed to challenge matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) as a typing tool of a nosocomial MRSA outbreak in a neonatal intensive care unit. Over a 2-year period, 15 MRSA isolates were recovered from patients (n = 14) and health care workers (n = 1) at the neonatal intensive care unit. Five reference strains were included for comparison. Identification was performed by MALDI-TOF MS and susceptibility profiles determined by automated broth microdilution. Typing analysis by MALDI-TOF MS included mean spectrum profiles and subsequent dendrogram creation using BioNumerics software. Results were compared with spa typing and pulsed-field gel electrophoresis (PFGE). Our study showed good concordance (93%) between PFGE, spa typing, and MALDI-TOF MS for the outbreak-related MRSA strains. MALDI-TOF MS typing showed excellent typeability and discriminatory power but showed poor reproducibility. This study is one of the first to document the potential usefulness of MALDI-TOF MS with standardized data analysis as a typing tool for investigating a nosocomial MRSA outbreak. A concordance of 93% compared to reference typing techniques was observed. However, because of poor reproducibility, long-term follow-up of prospective isolated strains is not practical for routine use. Further studies are needed to confirm our observations.

Inhibitory effect of 1,2,4-triazole-ciprofloxacin hybrids on Haemophilus parainfluenzae and Haemophilus influenzae biofilm formation in vitro under stationary conditions.

PubMed

Kosikowska, Urszula; Andrzejczuk, Sylwia; Plech, Tomasz; Malm, Anna

2016-10-01

Haemophilus parainfluenzae and Haemophilus influenzae, upper respiratory tract microbiota representatives, are able to colonize natural and artificial surfaces as biofilm. The aim of the present study was to assay the effect of ten 1,2,4-triazole-ciprofloxacin hybrids on planktonic or biofilm-forming haemophili cells in vitro under stationary conditions on the basis of MICs (minimal inhibitory concentrations) and MBICs (minimal biofilm inhibitory concentrations). In addition, anti-adhesive properties of these compounds were examined. The reference strains of H. parainfluenzae and H. influenzae were included. The broth microdilution microtiter plate (MTP) method with twofold dilution of the compounds, or ciprofloxacin (reference agent) in 96-well polystyrene microplates, was used. The optical density (OD) reading was made spectrophotometrically at a wavelength of 570 nm (OD570) both to measure bacterial growth and to detect biofilm-forming cells under the same conditions with 0.1% crystal violet. The following values of parameters were estimated for 1,2,4-triazole-ciprofloxacin hybrids - MIC = 0.03-15.63 mg/L, MBIC = 0.03-15.63 mg/L, MBIC/MIC = 0.125-8, depending on the compound, and for ciprofloxacin - MIC = 0.03-0.06 mg/L, MBIC = 0.03-0.12 mg/L, MBIC/MIC = 1-2. The observed strong anti-adhesive properties (95-100% inhibition) of the tested compounds were reversible during long-term incubation at subinhibitory concentrations. Thus, 1,2,4-triazole-ciprofloxacin hybrids may be considered as starting compounds for designing improved agents not only against planktonic but also against biofilm-forming Haemophilus spp. cells. Copyright © 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Antibacterial activity and antibiotic modulating potential of the essential oil obtained from Eugenia jambolana in association with led lights.

PubMed

Pereira, Nara L F; Aquino, Pedro E A; Júnior, José G A S; Cristo, Janyketchuly S; Vieira Filho, Marcos A; Moura, Flávio F; Ferreira, Najla M N; Silva, Maria K N; Nascimento, Eloiza M; Correia, Fabrina M A; Cunha, Francisco A B; Boligon, Aline A; Coutinho, Henrique D M; Ribeiro-Filho, Jaime; Matias, Edinardo F F; Guedes, Maria I F

2017-09-01

Bacterial resistance has risen as an important health problem with impact on the pharmaceutical industry because many antibiotics have become ineffective, which has affected their commercialization. The Brazilian biodiversity is marked by a vast variety of natural products with significant therapeutic potential, which could bring new perspectives in the treatment of infections caused by resistant microorganisms. The present study aimed to evaluate the antibacterial effect of the essential oil obtained from Eugenia jambolana (EjEO) using the method of microdilution method to determine the Minimum Inhibitory Concentration (MIC). The modulatory effect of this oil on antibiotic activity was determined using both the broth microdilution and gaseous contact methods. The antibacterial effect of the association of the gaseous contact and the use of a LED unit with red and blue lights was also determined. The chemical components of the EjEO were characterized by HPLC, which revealed the presence of α-pinene as a major constituent. The EjEO presented a MIC≥128μg/mL against S. aureus and ≥1024μg/mL against E. coli. The combination of the EjEO with antibiotics presented synergism against E. coli and antagonism against S. aureus. An antagonistic effect was obtained from the association of EjEO with amikacin and erythromycin by the method of gaseous contact. On the other hand, the association of EjEO with ciprofloxacin presented a synergistic effect against S. aureus and E. coli exposed to LED lights. A similar effect was observed in the association of the EjEO with norfloxacin presented synergism against S. aureus in the same conditions. In conclusion, our results demonstrated that the essential oil obtained from Eugenia jambolana interfere with the action of antibiotics against bacteria exposed to LED lights. Thus, further researches are required to elucidate the mechanisms underlying these effects, which could open new perspectives in the development of new antibacterial therapies. Copyright © 2017 Elsevier B.V. All rights reserved.

Antifungal activities of diphenyl diselenide and ebselen against echinocandin-susceptible and -resistant strains of Candida parapsilosis.

PubMed

Chassot, Francieli; Pozzebon Venturini, Tarcieli; Baldissera Piasentin, Fernanda; Morais Santurio, Janio; Estivalet Svidzinski, Terezinha Inez; Hartz Alves, Sydney

2016-10-01

We evaluated the in vitro antifungal activity of diphenyl diselenide and ebselen against echinocandin-susceptible and -resistant strains of Candida parapsilosis using the broth microdilution method. Diphenyl diselenide (MIC range =1-8 µg/mL) and ebselen (MIC range =0.25-4 µg/mL) showed in vitro activity against echinocandin-susceptible isolates. However, ebselen also showed the highest antifungal activity against echinocandin-resistant strains (MIC range =0.06-4 µg/mL). This study demonstrated that the antifungal potential of diphenyl diselenide and ebselen deserves further investigation using in vivo experimental protocols.

Antimicrobial Susceptibility Testing, Drug Resistance Mechanisms, and Therapy of Infections with Nontuberculous Mycobacteria

PubMed Central

Nash, Kevin A.; Wallace, Richard J.

2012-01-01

Summary: Within the past 10 years, treatment and diagnostic guidelines for nontuberculous mycobacteria have been recommended by the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA). Moreover, the Clinical and Laboratory Standards Institute (CLSI) has published and recently (in 2011) updated recommendations including suggested antimicrobial and susceptibility breakpoints. The CLSI has also recommended the broth microdilution method as the gold standard for laboratories performing antimicrobial susceptibility testing of nontuberculous mycobacteria. This article reviews the laboratory, diagnostic, and treatment guidelines together with established and probable drug resistance mechanisms of the nontuberculous mycobacteria. PMID:22763637

In Vitro Antifungal Susceptibility Profiles of 12 Antifungal Drugs against 55 Trichophyton schoenleinii Isolates from Tinea Capitis Favosa Patients in Iran, Turkey, and China

PubMed Central

Deng, Shuwen; Ansari, Saham; Rafati, Haleh; Taghizadeh-Armaki, Mojtaba; Nasrollahi-Omran, Ayatollah; Tolooe, Ali; Zhan, Ping; Liao, Wanqing; van der Lee, Henrich A.; Verweij, Paul E.

2016-01-01

ABSTRACT Trichophyton schoenleinii is an anthropophilic dermatophyte mainly causing tinea favosa of the scalp in certain regions of the world, especially Africa and Asia. We investigated the in vitro susceptibilities of 55 T. schoenleinii isolates collected over the last 30 years from Iran, Turkey, and China to 12 antifungals using the CLSI broth microdilution method. Our results revealed that terbinafine and ketoconazole were the most potent antifungal agents among those tested, independently of the geographic regions where strains were isolated. PMID:27956429

In Vitro Antifungal Susceptibility Profiles of 12 Antifungal Drugs against 55 Trichophyton schoenleinii Isolates from Tinea Capitis Favosa Patients in Iran, Turkey, and China.

PubMed

Deng, Shuwen; Ansari, Saham; Ilkit, Macit; Rafati, Haleh; Hedayati, Mohammad T; Taghizadeh-Armaki, Mojtaba; Nasrollahi-Omran, Ayatollah; Tolooe, Ali; Zhan, Ping; Liao, Wanqing; van der Lee, Henrich A; Verweij, Paul E; Seyedmousavi, Seyedmojtaba

2017-02-01

Trichophyton schoenleinii is an anthropophilic dermatophyte mainly causing tinea favosa of the scalp in certain regions of the world, especially Africa and Asia. We investigated the in vitro susceptibilities of 55 T. schoenleinii isolates collected over the last 30 years from Iran, Turkey, and China to 12 antifungals using the CLSI broth microdilution method. Our results revealed that terbinafine and ketoconazole were the most potent antifungal agents among those tested, independently of the geographic regions where strains were isolated. Copyright © 2017 American Society for Microbiology.

In vitro comparison of antimicrobial activity of aqueous decoction of Coriandrum sativum, and Dentol Drop with chlorhexidine on Streptococcus mutans

PubMed Central

Moradian, Hamid; Bazargani, Abdollah; Rafiee, Azade; Nazarialam, Ali

2013-01-01

Background and objectives Dental caries is still remained as a major health problem. This problem has created a new interest to search for new antimicrobial agents from various sources including medicinal plants. Since limited data is available so far regarding the antibacterial effect of Coriandrum sativum seed and Dentol Drop against Streptococcus mutans, this study aims to assess this activity. Materials and Methods This experimental study was conducted in Shiraz University of Medical Sciences. In vitro comparison of antimicrobial activity of aqueous decoction of Coriandrum sativum seed and Dentol drop with chlorhexidine against Streptococcus mutans was evaluated using disk diffusion and broth microdilution assays. Positive and negative controls were considered. The data was statistically analyzed by applying Kruskal-Wallis and Tukey post-hoc test to compare the groups using SPSS software (version 17). Results Dentol drop showed a remarkable antibacterial activity, in comparison with chlorhexidine, against S. mutans in the disk diffusion (p value = 0.005), and broth microdilution assays (p value = 0.0001). Based on the results of this study, Coriandrum sativum seed did not posses any antibacterial property. Conclusion Coriandrum sativum seed showed no anti-Streptococcus mutans activity. Dentol drop exhibited a remarkable antibacterial activity against S. mutans when tested in vitro. Dentol drop can be further studied as a preventive measure for dental caries. PMID:24475330

Comparative evaluation of antibacterial activity of caffeic acid phenethyl ester and PLGA nanoparticle formulation by different methods

NASA Astrophysics Data System (ADS)

Arasoglu, Tülin; Derman, Serap; Mansuroglu, Banu

2016-01-01

The aim of the present study was to evaluate the antimicrobial activity of nanoparticle and free formulations of the CAPE compound using different methods and comparing the results in the literature for the first time. In parallel with this purpose, encapsulation of CAPE with the PLGA nanoparticle system (CAPE-PLGA-NPs) and characterization of nanoparticles were carried out. Afterwards, antimicrobial activity of free CAPE and CAPE-PLGA-NPs was determined using agar well diffusion, disk diffusion, broth microdilution and reduction percentage methods. P. aeroginosa, E. coli, S. aureus and methicillin-resistant S. aureus (MRSA) were chosen as model bacteria since they have different cell wall structures. CAPE-PLGA-NPs within the range of 214.0 ± 8.80 nm particle size and with an encapsulation efficiency of 91.59 ± 4.97% were prepared using the oil-in-water (o-w) single-emulsion solvent evaporation method. The microbiological results indicated that free CAPE did not have any antimicrobial activity in any of the applied methods whereas CAPE-PLGA-NPs had significant antimicrobial activity in both broth dilution and reduction percentage methods. CAPE-PLGA-NPs showed moderate antimicrobial activity against S. aureus and MRSA strains particularly in hourly measurements at 30.63 and 61.25 μg ml-1 concentrations (both p < 0.05), whereas they failed to show antimicrobial activity against Gram-negative bacteria (P. aeroginosa and E. coli, p > 0.05). In the reduction percentage method, in which the highest results of antimicrobial activity were obtained, it was observed that the antimicrobial effect on S. aureus was more long-standing (3 days) and higher in reduction percentage (over 90%). The appearance of antibacterial activity of CAPE-PLGA-NPs may be related to higher penetration into cells due to low solubility of free CAPE in the aqueous medium. Additionally, the biocompatible and biodegradable PLGA nanoparticles could be an alternative to solvents such as ethanol, methanol or DMSO. Consequently, obtained results show that the method of selection is extremely important and will influence the results. Thus, broth microdilution and reduction percentage methods can be recommended as reliable and useful screening methods for determination of antimicrobial activity of PLGA nanoparticle formulations used particularly in drug delivery systems compared to both agar well and disk diffusion methods.

Validation of Vitek 2 Nonfermenting Gram-Negative Cards and Vitek 2 Version 4.02 Software for Identification and Antimicrobial Susceptibility Testing of Nonfermenting Gram-Negative Rods from Patients with Cystic Fibrosis▿

PubMed Central

Otto-Karg, Ines; Jandl, Stefanie; Müller, Tobias; Stirzel, Beate; Frosch, Matthias; Hebestreit, Helge; Abele-Horn, Marianne

2009-01-01

Accurate identification and antimicrobial susceptibility testing (AST) of nonfermenters from cystic fibrosis patients are essential for appropriate antimicrobial treatment. This study examined the ability of the newly designed Vitek 2 nonfermenting gram-negative card (NGNC) (new gram-negative identification card; bioMérieux, Marcy-l'Ètoile, France) to identify nonfermenting gram-negative rods from cystic fibrosis patients in comparison to reference methods and the accuracy of the new Vitek 2 version 4.02 software for AST compared to the broth microdilution method. Two hundred twenty-four strains for identification and 138 strains for AST were investigated. The Vitek 2 NGNC identified 211 (94.1%) of the nonfermenters correctly. Among morphologically atypical microorganisms, five strains were misidentified and eight strains were determined with low discrimination, requiring additional tests which raised the correct identification rate to 97.8%. Regarding AST, the overall essential agreement of Vitek 2 was 97.6%, and the overall categorical agreement was 92.9%. Minor errors were found in 5.1% of strains, and major and very major errors were found in 1.6% and 0.3% of strains, respectively. In conclusion, the Vitek NGNC appears to be a reliable method for identification of morphologically typical nonfermenters and is an improvement over the API NE system and the Vitek 2 GNC database version 4.01. However, classification in morphologically atypical nonfermenters must be interpreted with care to avoid misidentification. Moreover, the new Vitek 2 version 4.02 software showed good results for AST and is suitable for routine clinical use. More work is needed for the reliable testing of strains whose MICs are close to the breakpoints. PMID:19710272

Determination of antifungal susceptibility patterns among the environmental isolates of Aspergillus fumigatus in Iran

PubMed Central

Mohammadi, Faezeh; Dehghan, Parvin; Nekoeian, Shahram; Hashemi, Seyed Jamal

2016-01-01

Background: In recent years, triazole-resistant environmental isolates of Aspergillus fumigatus have emerged in Europe and Asia. Azole resistance has been reported in patients who are treated with long-term azole therapy or exposure of the fungus spores to the azole fungicides used in agriculture. To date, a wide range of mutations in A. fumigatus have been described conferring azole-resistance, which commonly involves modifications in the cyp51A gene. We investigated antifungal susceptibility pattern of environmental isolates of A. fumigatus. Materials and Methods: In this study, 170 environmental samples collected from indoors surfaces of three hospitals in Iran. It was used β-tubulin gene to confirm the all of A. fumigatus isolates, which was identified by conventional methods. Furthermore, the antifungal susceptibility of itraconazole, voriconazole, and posaconazole was investigated using broth microdilution test, according to European Committee on Antimicrobial Susceptibility testing reference method. Results: From a total of 158 environmental molds fungi obtained from the hospitals, 58 isolates were identified as A. fumigatus by amplification of expected size of β-tubulin gene (~500 bp). In this study, in vitro antifungal susceptibility testing has shown that there were not high minimum inhibitory concentration values of triazole antifungals in all of the 58 environmental isolates of A. fumigatus. Conclusion: Our findings demonstrated that there was not azole-resistant among environmental isolates of A. fumigatus. Medical triazoles compounds have structural similarity with triazole fungicide compounds in agriculture, therefore, resistance development through exposure to triazole fungicide compounds in the environment is important but it sounds there is not a serious health problem in drug resistance in environmental isolates in Iran. PMID:27656605

Vancomycin AUC/MIC ratio and 30-day mortality in patients with Staphylococcus aureus bacteremia.

PubMed

Holmes, Natasha E; Turnidge, John D; Munckhof, Wendy J; Robinson, J Owen; Korman, Tony M; O'Sullivan, Matthew V N; Anderson, Tara L; Roberts, Sally A; Warren, Sanchia J C; Gao, Wei; Howden, Benjamin P; Johnson, Paul D R

2013-04-01

A ratio of the vancomycin area under the concentration-time curve to the MIC (AUC/MIC) of ≥ 400 has been associated with clinical success when treating Staphylococcus aureus pneumonia, and this target was recommended by recently published vancomycin therapeutic monitoring consensus guidelines for treating all serious S. aureus infections. Here, vancomycin serum trough levels and vancomycin AUC/MIC were evaluated in a "real-world" context by following a cohort of 182 patients with S. aureus bacteremia (SAB) and analyzing these parameters within the critical first 96 h of vancomycin therapy. The median vancomycin trough level at this time point was 19.5 mg/liter. There was a significant difference in vancomycin AUC/MIC when using broth microdilution (BMD) compared with Etest MIC (medians of 436.1 and 271.5, respectively; P < 0.001). Obtaining the recommended vancomycin target AUC/MIC of ≥ 400 using BMD was not associated with lower 30-day all-cause or attributable mortality from SAB (P = 0.132 and P = 0.273, respectively). However, an alternative vancomycin AUC/MIC of >373, derived using classification and regression tree analysis, was associated with reduced mortality (P = 0.043) and remained significant in a multivariable model. This study demonstrated that we obtained vancomycin trough levels in the target therapeutic range early during the course of therapy and that obtaining a higher vancomycin AUC/MIC (in this case, >373) within 96 h was associated with reduced mortality. The MIC test method has a significant impact on vancomycin AUC/MIC estimation. Clinicians should be aware that the current target AUC/MIC of ≥ 400 was derived using the reference BMD method, so adjustments to this target need to be made when calculating AUC/MIC ratio using other MIC testing methods.

Vancomycin AUC/MIC Ratio and 30-Day Mortality in Patients with Staphylococcus aureus Bacteremia

PubMed Central

Turnidge, John D.; Munckhof, Wendy J.; Robinson, J. Owen; Korman, Tony M.; O'Sullivan, Matthew V. N.; Anderson, Tara L.; Roberts, Sally A.; Warren, Sanchia J. C.; Gao, Wei; Howden, Benjamin P.; Johnson, Paul D. R.

2013-01-01

A ratio of the vancomycin area under the concentration-time curve to the MIC (AUC/MIC) of ≥400 has been associated with clinical success when treating Staphylococcus aureus pneumonia, and this target was recommended by recently published vancomycin therapeutic monitoring consensus guidelines for treating all serious S. aureus infections. Here, vancomycin serum trough levels and vancomycin AUC/MIC were evaluated in a “real-world” context by following a cohort of 182 patients with S. aureus bacteremia (SAB) and analyzing these parameters within the critical first 96 h of vancomycin therapy. The median vancomycin trough level at this time point was 19.5 mg/liter. There was a significant difference in vancomycin AUC/MIC when using broth microdilution (BMD) compared with Etest MIC (medians of 436.1 and 271.5, respectively; P < 0.001). Obtaining the recommended vancomycin target AUC/MIC of ≥400 using BMD was not associated with lower 30-day all-cause or attributable mortality from SAB (P = 0.132 and P = 0.273, respectively). However, an alternative vancomycin AUC/MIC of >373, derived using classification and regression tree analysis, was associated with reduced mortality (P = 0.043) and remained significant in a multivariable model. This study demonstrated that we obtained vancomycin trough levels in the target therapeutic range early during the course of therapy and that obtaining a higher vancomycin AUC/MIC (in this case, >373) within 96 h was associated with reduced mortality. The MIC test method has a significant impact on vancomycin AUC/MIC estimation. Clinicians should be aware that the current target AUC/MIC of ≥400 was derived using the reference BMD method, so adjustments to this target need to be made when calculating AUC/MIC ratio using other MIC testing methods. PMID:23335735

Antibacterial activities of the methanol extracts of Albizia adianthifolia, Alchornea laxiflora, Laportea ovalifolia and three other Cameroonian plants against multi-drug resistant Gram-negative bacteria.

PubMed

Tchinda, Cedric F; Voukeng, Igor K; Beng, Veronique P; Kuete, Victor

2017-05-01

In the last 10 years, resistance in Gram-negative bacteria has been increasing. The present study was designed to evaluate the in vitro antibacterial activities of the methanol extracts of six Cameroonian medicinal plants Albizia adianthifolia , Alchornea laxiflora , Boerhavia diffusa , Combretum hispidum , Laportea ovalifolia and Scoparia dulcis against a panel of 15 multidrug resistant Gram-negative bacterial strains. The broth microdilution was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the extracts. The preliminary phytochemical screening of the extracts was conducted according to the reference qualitative phytochemical methods. Results showed that all extracts contained compounds belonging to the classes of polyphenols and triterpenes, other classes of chemicals being selectively distributed. The best antibacterial activities were recorded with bark and root extracts of A. adianthifolia as well as with L. ovalifolia extract, with MIC values ranging from 64 to 1024 μg/mL on 93.3% of the fifteen tested bacteria. The lowest MIC value of 64 μg/mL was recorded with A. laxiflora bark extract against Enterobacter aerogenes EA289. Finally, the results of this study provide evidence of the antibacterial activity of the tested plants and suggest their possible use in the control of multidrug resistant phenotypes.

In Vitro Activity of Tea Tree Oil Vaginal Suppositories against Candida spp. and Probiotic Vaginal Microbiota.

PubMed

Di Vito, Maura; Mattarelli, Paola; Modesto, Monica; Girolamo, Antonietta; Ballardini, Milva; Tamburro, Annunziata; Meledandri, Marcello; Mondello, Francesca

2015-10-01

The aim of this work is to evaluate the in vitro microbicidal activity of vaginal suppositories (VS) containing tea tree oil (TTO-VS) towards Candida spp. and vaginal probiotics. A total of 20 Candida spp. strains, taken from patients with vaginitis and from an established type collection, including reference strains, were analysed by using the CLSI microdilution method. To study the action of VS towards the beneficial vaginal microbiota, the sensitivity of Bifidobacterium animalis subsp. lactis (DSM 10140) and Lactobacillus spp. (Lactobacillus casei R-215 and Lactobacillus acidophilus R-52) was tested. Both TTO-VS and TTO showed fungicidal activity against all strains of Candida spp. whereas placebo-VS or the Aloe gel used as controls were ineffective. The study of fractional fungicidal concentrations (FFC) showed synergistic interaction with the association between Amphotericin B and TTO (0.25 to 0.08 µg/ml, respectively) against Candida albicans. Instead, the probiotics were only affected by TTO concentration ≥ 4% v/v, while, at concentrations < 2% v/v, they remained viable. TTO-VS exhibits, in vitro, a selective fungicidal action, slightly affecting only the Bifidobacteriun animalis strain growth belonging to the vaginal microbiota. In vivo studies are needed to confirm the efficacy to prevent acute or recurrent vaginal candidiasis. Copyright © 2015 John Wiley & Sons, Ltd.

In vitro antifungal activity of topical and systemic antifungal drugs against Malassezia species.

PubMed

Carrillo-Muñoz, Alfonso Javier; Rojas, Florencia; Tur-Tur, Cristina; de Los Ángeles Sosa, María; Diez, Gustavo Ortiz; Espada, Carmen Martín; Payá, María Jesús; Giusiano, Gustavo

2013-09-01

The strict nutritional requirements of Malassezia species make it difficult to test the antifungal susceptibility. Treatments of the chronic and recurrent infections associated with Malassezia spp. are usually ineffective. The objective of this study was to obtain in vitro susceptibility profile of 76 clinical isolates of Malassezia species against 16 antifungal drugs used for topical or systemic treatment. Isolates were identified by restriction fragment length polymorphism. Minimal inhibitory concentrations (MIC) were obtained by a modified microdilution method based on the Clinical Laboratory Standards Institute reference document M27-A3. The modifications allowed a good growth of all tested species. High in vitro antifungal activity of most tested drugs was observed, especially triazole derivatives, except for fluconazole which presented the highest MICs and widest range of concentrations. Ketoconazole and itraconazole demonstrated a great activity. Higher MICs values were obtained with Malassezia furfur indicating a low susceptibility to most of the antifungal agents tested. Malassezia sympodialis and Malassezia pachydermatis were found to be more-susceptible species than M. furfur, Malassezia globosa, Malassezia slooffiae and Malassezia restricta. Topical substances were also active but provide higher MICs than the compounds for systemic use. The differences observed in the antifungals activity and interspecies variability demonstrated the importance to studying the susceptibility profile of each species to obtain reliable information for defining an effective treatment regimen. © 2013 Blackwell Verlag GmbH.

Chemical Composition, Antioxidant and Antimicrobial Activities of Thymus capitata Essential Oil with Its Preservative Effect against Listeria monocytogenes Inoculated in Minced Beef Meat

PubMed Central

El Abed, Nariman; Kaabi, Belhassen; Smaali, Mohamed Issam; Chabbouh, Meriem; Habibi, Kamel; Mejri, Mondher; Marzouki, Mohamed Nejib; Ben Hadj Ahmed, Sami

2014-01-01

The chemical composition, antioxidant and antimicrobial activities, and the preservative effect of Thymus capitata essential oil against Listeria monocytogenes inoculated in minced beef meat were evaluated. The essential oil extracted was chemically analyzed by gas chromatography-mass spectrometry. Nineteen components were identified, of which carvacrol represented (88.89%) of the oil. The antioxidant activity was assessed in vitro by using both the DPPH and the ABTS assays. The findings showed that the essential oil exhibited high antioxidant activity, which was comparable to the reference standards (BHT and ascorbic acid) with IC50 values of 44.16 and 0.463 μg/mL determined by the free-radical scavenging DPPH and ABTS assays, respectively. Furthermore, the essential oil was evaluated for its antimicrobial activity using disc agar diffusion and microdilution methods. The results demonstrated that the zone of inhibition varied from moderate to strong (15–80 mm) and the minimum inhibition concentration values ranged from 0.32 to 20 mg/mL. In addition, essential oil evaluated in vivo against Listeria monocytogenes showed clear and strong inhibitory effect. The application of 0.25 or 1% (v/w) essential oil of T. capitata to minced beef significantly reduced the L. monocytogenes population when compared to those of control samples (P-value  <0.01). PMID:24719640

In vitro evaluation of antimicrobial features of sugammadex.

PubMed

Hanci, Volkan; Vural, Ahmet; Hanci, Sevgi Yılmaz; Ali Kiraz, Hasan; Omür, Dilek; Unver, Ahmet

2014-01-01

Drugs administered by intravenous routes may be contaminated during several stages of production or preparation. Sugammadex is a modified gamma cyclodextrin. While research into the antibacterial effects of varieties of cyclodextrin is available, there are no studies focusing on the antibacterial effects of sugammadex. This study investigates the in vitro antimicrobial activity of sugammadex. The in vitro antimicrobial activity of sugammadex was investigated using the broth microdilution method. The pH of the test solution was determined using a pH meter. The test microorganisms included Staphylococcus aureus ATCC 29213, Enterococcus fecalis ATCC 29212, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. In the second phase of the study 100mg/mL sugammadex (50μg) was contaminated with test microorganisms (50μg), including S. aureus ATCC 29213, E. fecalis ATCC 29212, E. coli ATCC 25922 and P. aeruginosa ATCC 27853, left to incubate for 24h and then the bacterial production in sugammadex was evaluated. The pH of the test solutions ranged between 7.25 and 6.97. Using the microdilution method, sugammadex had no antibacterial effect on S. aureus, E. fecalis, E. coli and P. aeruginosa at any concentration. In the second phase of the study bacterial production was observed after 24h in 100mg/mL sugammadex contaminated with the test microorganisms S. aureus, E. fecalis, E. coli and P. aeruginosa. Sugammadex had no antimicrobial effect on the test microorganisms, S. aureus, E. fecalis, E. coli and P. aeruginosa. Care should be taken that sterile conditions are maintained in the preparation of sugammadex; that the same sugammadex preparation not be used for more than one patient; and that storage conditions are adhered to after sugammadex is put into the injector. Copyright © 2013 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

Lemongrass-Incorporated Tissue Conditioner Against Candida albicans Culture

PubMed Central

Amornvit, Pokpong; Srithavaj, Theerathavaj

2014-01-01

Background: Tissue conditioner is applied popularly with dental prosthesis during wound healing process but it becomes a reservoir of oral microbiota, especially Candida species after long-term usage. Several antifungal drugs have been mixed with this material to control fungal level. In this study, lemongrass essential oil was added into COE-COMFORT tissue conditioner before being determined for anti-Candida efficacy. Materials and Methods: Lemongrass (Cymbopogon citratus) essential oil was primarily determined for antifungal activity against C. albicans American type culture collection (ATCC) 10231 and MIC (minimum inhibitory concentration) value by agar disk diffusion and broth microdilution methods, respectively. COE-COMFORT tissue conditioner was prepared as recommended by the manufacturer after a fixed volume of the oil at its MIC or higher concentrations were mixed thoroughly in its liquid part. Antifungal efficacy of the tissue conditioner with/without herb was finally analyzed. Results: Lemongrass essential oil displayed potent antifungal activity against C. albicans ATCC 10231and its MIC value was 0.06% (v/v). Dissimilarly, the tissue conditioner containing the oil at MIC level did not cease the growth of the tested fungus. Both reference and clinical isolates of C. albicans were completely inhibited after exposed to the tissue conditioner containing at least 0.25% (v/v) of the oil (approximately 4-time MIC). The tissue conditioner without herb or with nystatin was employed as negative or positive control, respectively. Conclusion: COE-COMFORT tissue conditioner supplemented with lemongrass essential oil obviously demonstrated another desirable property as in vitro anti-Candida efficacy to minimize the risk of getting Candidal infection. PMID:25177638

Application of Enrofloxacin and Orbifloxacin Disks Approved in Japan for Susceptibility Testing of Representative Veterinary Respiratory Pathogens

PubMed Central

HARADA, Kazuki; USUI, Masaru; ASAI, Tetsuo

2014-01-01

ABSTRACT In this study, susceptibilities of Pasteurella multocida, Mannheimia haemolytica and Actinobacillus pleuropneumoniae to enrofloxacin and orbifloxacin were tested using an agar diffusion method with the commercial disks and a broth microdilution method. Good correlation between the 2 methods for enrofloxacin and orbifloxacin was observed for P. multocida (r = −0.743 and −0.818, respectively), M. haemolytica (r = −0.739 and −0.800, respectively) and A. pleuropneumoniae (r = −0.785 and −0.809, respectively). Based on the Clinical and Laboratory Standards Institute interpretive criteria for enrofloxacin, high-level categorical agreement between the 2 methods was found for P. multocida (97.9%), M. haemolytica (93.8%) and A. pleuropneumoniae (92.0%). Our findings indicate that the tested commercial disks can be applied for susceptibility testing of veterinary respiratory pathogens. PMID:25008965

In Vitro Antifungal Susceptibility Testing of Candida Isolates with the EUCAST Methodology, a New Method for ECOFF Determination.

PubMed

Meletiadis, J; Curfs-Breuker, I; Meis, J F; Mouton, J W

2017-04-01

The in vitro susceptibilities of 1,099 molecularly identified clinical Candida isolates against 8 antifungal drugs were determined using the EUCAST microdilution method. A new simple, objective, and mathematically solid method for determining epidemiological cutoff values (ECOFFs) was developed by derivatizing the MIC distribution and determining the derivatized ECOFF (dECOFF) as the highest MIC with the maximum second derivative. The dECOFFs were similar (95% agreement within 1 dilution) to the EUCAST ECOFFs. Overall, low non-wild-type/resistance rates were found. The highest rates were found for azoles with C. parapsilosis (2.7 to 9.8%), C. albicans (7%), and C. glabrata (1.7 to 2.3%) and for echinocandins with C. krusei (3.3%), C. albicans (1%), and C. tropicalis (1.7%). Copyright © 2017 American Society for Microbiology.

In vitro activity of daptomycin and comparator agents against Staphylococcus aureus isolates from intravenous drug users with right endocarditis.

PubMed

Sanchez-Porto, Antonio; Casanova-Roman, Manuel; Casas-Ciria, Javier; Santaella, Maria Jose; Sanchez-Morenilla, Immaculada; Eiros-Bouza, Jose Maria

2010-06-01

There is an increasing need for alternative agents in endocarditis, especially with the increasing incidence of vancomycin-intermediate Staphylococcus aureus (VISA). We evaluated the in vitro activity of daptomycin and several comparator agents against 33 non-duplicate clinical Staphylococcus aureus isolates from intravenous drug users with right endocarditis. Wider microdilution panels were used for all the comparator agents and daptomycin. Daptomycin was also tested using E-test strips. E-test strips were used to confirm the vancomycin MICs. Methicillin-resistant Staphylococcus aureus (MRSA isolates with vancomycin MICs ≥ 2 g/mL were screened using the E-test GRD. In all, 30 isolates were methicillin-susceptible (MSSA) and 3 MRSA. The three MRSA isolates exhibited a false vancomycin MIC >2 g/mL determined by Wider microdilution panels. They were screened using the E-test GRD and they were GRD negative. Their final MIC was 2 g/mL. Three MSSA and three MRSA isolates had a vancomycin MIC of 2 g/mL. Four MSSA isolates had a vancomycin MIC of 1.5 g/mL, daptomycin MIC90 0.25 g/mL, linezolid MIC90 2 g/mL. As regards daptomycin, wider microdilution panels and E-test strips yielded the same results. Our findings suggest that daptomycin and linezolid are a viable alternative for treating right endocarditis and bacteraemia caused by MSSA, MRSA and hVISA.

Antimicrobial activity of honey from the stingless bee Trigona carbonaria determined by agar diffusion, agar dilution, broth microdilution and time-kill methodology.

PubMed

Boorn, K L; Khor, Y-Y; Sweetman, E; Tan, F; Heard, T A; Hammer, K A

2010-05-01

The aim of this study was to determine the spectrum of antimicrobial activity of 11 samples of stingless bee honey compared to medicinal, table and artificial honeys. Activity was assessed by agar diffusion, agar dilution, broth microdilution and time-kill viability assays. By agar dilution, minimum inhibitory concentration (MIC) ranges were 4% to >10% (w/v) for Gram-positive bacteria, 6% to >16% (w/v) for Gram-negative bacteria and 6% to >10% (w/v) for Candida spp. By broth microdilution, all organisms with the exception of Candida albicans and Candida glabrata were inhibited at 3 log for Pseudomonas aeruginosa and <1 log for C. albicans. Similar treatment with each control honey resulted in decreases of <1 log for all organisms. Stingless bee honey has broad-spectrum antibacterial activity although activity against Candida was limited. Stingless bee honey samples varied in activity and the basis for this remains to be determined. Stingless bee honey had similar activity to medicinal honey and may therefore have a role as a medicinal agent.

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.

In vitro antimycobacterial activities of Physalis angulata L.

PubMed

Pietro, R C; Kashima, S; Sato, D N; Januário, A H; França, S C

2000-07-01

The HIV-tuberculosis co-infection has caused an impact on tuberculosis epidemiology all over the world and the efficacies of the therapeutic schemes traditionally prescribed in the treatment of tuberculosis, such as isoniazid, rifampicin and pyrazinamide, have decreased due to the appearance of multidrug-resistant M. tuberculosis strains (MDR). This work is part of research on natural antimicrobial agents from plant extracts through bioassay-guided fractionation, by in vitro determination of the minimum inhibitory concentration (MIC) using the microdilution method with Alamar blue oxidation-reduction dye. Crude CHCl3 Physalis angulata extracts and physalin-containing fractions displayed antimycobacterial activity against Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium kansasii, Mycobacterium malmoense and Mycobacterium intracellulare.

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

Synthesis, antibacterial and cytotoxic activities of new biflorin-based hydrazones and oximes.

PubMed

da S Souza, Luciana G; Almeida, Macia C S; Lemos, Telma L G; Ribeiro, Paulo R V; de Brito, Edy S; Silva, Vera L M; Silva, Artur M S; Braz-Filho, Raimundo; Costa, José G M; Rodrigues, Fábio F G; Barreto, Francisco S; de Moraes, Manoel O

2016-01-15

Biflorin 1 is a biologically active quinone, isolated from Capraria biflora. Five new biflorin-based nitrogen derivatives were synthesized, of which two were mixtures of (E)- and (Z)- isomers: (Z)-2a, (Z)-2b, (Z)-3a, (Z)- and (E)-3b, (Z)- and (E)-3c. The antibacterial activity was investigated using the microdilution method for determining the minimum inhibitory concentration (MIC) against six bacterial strains. Tests have shown that these derivatives have potential against all bacterial strains. The cytotoxic activity was also evaluated against three strains of cancer cells, but none of the derivatives showed activity. Copyright © 2015. Published by Elsevier Ltd.

The Effect of Citrus Essential Oils and Their Constituents on Growth of Xanthomonas citri subsp. citri.

PubMed

Mirzaei-Najafgholi, Hossein; Tarighi, Saeed; Golmohammadi, Morteza; Taheri, Parissa

2017-04-14

Citrus bacterial canker (CBC) caused by Xanthomonas citri subsp. citri ( Xcc ), is the most devastating of the citrus diseases worldwide. During our study, we found that Essential oils (EOs) of some citrus cultivars are effective on Xcc . Therefore, it prompted us to determine the plant metabolites responsible for the antibacterial properties. We obtained EOs from some locally cultivated citrus by using a Clevenger apparatus and their major constituents were identified by gas chromatography/mass spectrometry (GC-MS). The effect of Citrus aurantium , C. aurantifolia , Fortunella sp. EOs and their major constituents were evaluated against Xcc -KVXCC1 using a disk diffusion assay. Minimal inhibitory and bactericidal concentration of the EOs and their constituents were determined using the broth microdilution method. C. aurantium , C. aurantifolia Eos, and their major constituents including citral, linalool, citronellal, geraniol, α-terpineol, and linalyl acetate indicated antibacterial effects against Xcc . The C. aurantifolia EO and citral showed the highest antibacterial activity among the tested EOs and constituents with inhibition zones of 15 ± 0.33 mm and 16.67 ± 0.88 mm, respectively. Synergistic effects of the constituents were observed between α-terpineol-citral, citral-citronellal, citral-geraniol, and citronellal-geraniol by using a microdilution checkerboard assay. Transmission electron microscopy revealed that exposure of Xcc cells to citral caused cell wall damage and altered cytoplasmic density. We introduced C. aurantifolia and C. aurantium EOs, and their constituents citral, α-terpineol, citronellal, geraniol, and linalool as possible control agents for CBC.

Aqueous Ethanol Ignition and Engine Studies, Phase I

DOT National Transportation Integrated Search

2010-09-01

Our objectives were to design a micro-dilution tunnel for monitoring engine emissions, measure ignition temperature and heat release from ethanol-water-air mixtures on platinum, and initiate a computational fluid dynamics model of a catalytic igniter...

The ability of selected plant essential oils to enhance the action of recommended antibiotics against pathogenic wound bacteria.

PubMed

Sienkiewicz, Monika; Łysakowska, Monika; Kowalczyk, Edward; Szymańska, Grażyna; Kochan, Ewa; Krukowska, Jolanta; Olszewski, Jurek; Zielińska-Bliźniewska, Hanna

2017-03-01

The aim of this work was to characterize the ability of essential oils to support antibiotics against pathogenic bacteria in wounds. Gram-positive and Gram-negative bacteria obtained from wound infections were identified according to standard microbiological methods. Essential oils were analysed by GC-FID-MS. The susceptibility of bacteria to antibiotics, essential oils and their combination was assessed using the disc-diffusion method. The Minimal Inhibitory Concentration and Minimum Bactericidal Concentration of the essential oils were established by the micro-dilution broth method. Although cinnamon, clove, thyme and lavender essential oils were found to have the greatest antibacterial activity when used alone, the greatest additive and synergistic effects against pathogenic wound bacteria in combination with recommended antibiotics were demonstrated by basil, clary sage and rosemary oils. Copyright © 2016 Elsevier Ltd and ISBI. All rights reserved.

Prevalence and transmission of antimicrobial resistance among Aeromonas populations from a duckweed aquaculture based hospital sewage water recycling system in Bangladesh.

PubMed

Rahman, Mokhlasur; Huys, Geert; Kühn, Inger; Rahman, Motiur; Möllby, Roland

2009-10-01

In order to investigate the influence of a duckweed aquaculture based hospital sewage water recycling plant on the prevalence and dissemination of antibiotic resistance, we made use of an existing collection of 1,315 Aeromonas isolates that were previously typed by the biochemical fingerprinting PhP-AE system. In these treatment plant, hospital raw sewage water is first collected in a settlement pond (referred to as sewage water in this study) and is then transferred to a lagoon, where the duckweed (Lemnaceae) is grown (referred to as lagoon). The duckweed is harvested and used as feed for the fish in a separate pond (referred to as fish pond). From this collection, representatives of 288 PhP types were subjected to antibiotic susceptibility testing for eight antimicrobials by broth microdilution method. The overall resistance rates among Aeromonas isolates from the treatment plant were highest for ampicillin (87%) and erythromycin (79%) followed by cephalothin (58%), nalidixic acid (52%), streptomycin (51%), tetracycline (31%), chloramphenicol (13%) and gentamicin (8%). A significantly lower prevalence of antibiotic resistance was found in Aeromonas from environmental control water, patient stool samples, duckweed and fish compared to sewage water isolates. The prevalence of resistance in the sewage water was not significantly reduced compared to the lagoon water and fish pond. Throughout the treatment system, the frequencies of resistant strains were found to diminish during the sewage water purification process, i.e. in the lagoon where sewage water is used to grow the duckweed. However, the frequency of resistant strains again increased in the fish pond where sewage grown duckweed is used for aquaculture. Among the selected isolates, two multiresistant clonal groups of Aeromonas caviae HG4 were identified that exhibited indistinguishable PhP and amplified fragment length polymorphism fingerprints and shared a common plasmid of approximately 5 kb. Representatives of both groups were recovered from almost every part of the sewage treatment plant but not in the control ponds nor in human samples, which suggests that specific multiresistant Aeromonas clones are able to persist and spread throughout the entire purification process.

Validation of VITEK 2 Version 4.01 Software for Detection, Identification, and Classification of Glycopeptide-Resistant Enterococci

PubMed Central

Abele-Horn, Marianne; Hommers, Leif; Trabold, René; Frosch, Matthias

2006-01-01

We evaluated the ability of the new VITEK 2 version 4.01 software to identify and detect glycopeptide-resistant enterococci compared to that of the reference broth microdilution method and to classify them into the vanA, vanB, vanC1, and vanC2 genotypes. Moreover, the accuracy of antimicrobial susceptibility testing with agents with improved potencies against glycopeptide-resistant enterococci was determined. A total of 121 enterococci were investigated. The new VITEK 2 software was able to identify 114 (94.2%) enterococcal strains correctly to the species level and to classify 119 (98.3%) enterococci correctly to the glycopeptide resistance genotype level. One Enterococcus casseliflavus strain and six Enterococcus faecium vanA strains with low-level resistance to vancomycin were identified with low discrimination, requiring additional tests. One of the vanA strains was misclassified as the vanB type, and one glycopeptide-susceptible E. facium wild type was misclassified as the vanA type. The overall essential agreements for antimicrobial susceptibility testing results were 94.2% for vancomycin, 95.9% for teicoplanin, 100% for quinupristin-dalfopristin and moxifloxacin, and 97.5% for linezolid. The rates of minor errors were 9% for teicoplanin and 5% for the other antibiotic agents. The identification and susceptibility data were produced within 4 h to 6 h 30 min and 8 h 15 min to 12 h 15 min. In conclusion, use of VITEK 2 version 4.01 software appears to be a reliable method for the identification and detection of glycopeptide-resistant enterococci as well as an improvement over the use of the former VITEK 2 database. However, a significant reduction in the detection time would be desirable. PMID:16390951

In vitro antifungal susceptibility of clinical species belonging to Aspergillus genus and Rhizopus oryzae.

PubMed

Kachuei, R; Khodavaisy, S; Rezaie, S; Sharifynia, S

2016-03-01

Among filamentous fungal pathogens, Aspergillus spp. and zygomycetes account for highest rates of morbidity and mortality among immunocompromised patients. Recently developed antifungal drugs offer the potential to improve management and therapeutic outcomes of fungal infections. The aim of this study was to analyse the in vitro activities of voriconazole, itraconazole, amphotericin B and caspofungin against clinical isolates of Aspergillus spp. and Rhizopus oryzae. The in vitro antifungal susceptibility of 54 isolates belonging to different clinical isolates of Aspergillus spp. and R. oryzae was tested for four antifungal agents using a microdilution reference method (CLSI, M38-A2). All isolates were identified by typical colony and microscopic characteristics, and also characterized by molecular methods. Caspofungin (MEC range: 0.008-0.25 and MEC50: 0.0023μg/mL) was the most active drug in vitro against Aspergillus spp., followed by voriconazole (MIC range: 0.031-8 and MIC50: 0.5μg/mL), itraconazole (MIC range: 0.031-16 and MIC50: 0.25μg/mL), and amphotericin B (MIC range: 0.125-4 and MIC50: 0.5μg/mL), in order of decreasing activity. The caspofungin, voriconazole, and itraconazole demonstrated poor in vitro activity against R. oryzae isolates evaluated, followed by amphotericin B. This study demonstrates that caspofungin had good antifungal activity and azole agents had better activity than amphotericin B against Aspergillus species. Although, azole drugs are considered ineffective against R. oryzae. This result is just from a small scale in vitro susceptibility study and we did not take other factors into consideration. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Seagrass as a potential source of natural antioxidant and anti-inflammatory agents.

PubMed

Yuvaraj, N; Kanmani, P; Satishkumar, R; Paari, A; Pattukumar, V; Arul, V

2012-04-01

Halophila spp. is a strong medicine against malaria and skin diseases and is found to be very effective in early stages of leprosy. Seagrasses are nutraceutical in nature and therefore of importance as food supplements. The antibacterial, antioxidant, and anti-inflammatory activities of Halophila ovalis R. Br. Hooke (Hydrocharitaceae) methanol extract were investigated and the chemical constituents of purified fractions were analyzed. Plant materials were collected from Pondicherry coastal line, and antimicrobial screening of crude extract, and purified fractions was carried out by the disc diffusion method and the minimum inhibitory concentration (MICs) of the purified fractions and reference antibiotics were determined by microdilution method. Antioxidant and anti-inflammatory activities were investigated in vitro. Chemical constituents of purified fractions V and VI were analyzed by gas chromatography-mass spectrometry (GC-MS), and the phytochemicals were quantitatively determined. Methanol extract inhibited the growth of Bacillus cereus at a minimum inhibitory concentration of 50 µg/mL and other Gram-negative pathogens at 75 µg/ml, except Vibrio vulnificus. Reducing power and total antioxidant level increased with increasing extract concentration. H. ovalis exhibited strong scavenging activity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radicals at IC(50) of 0.13 and 0.65 mg/mL, respectively. Methanol extract of H. ovalis showed noticeable anti-inflammatory activity at IC(50) of 78.72 µg/mL. The GC-MS analysis of H. ovalis revealed the presence of triacylglycerols as major components in purified fractions. Quantitative analysis of phytochemicals revealed that phenols are rich in seagrass H. ovalis. These findings demonstrated that the methanol extract of H. ovalis exhibited appreciable antibacterial, noticeable antioxidant, and anti-inflammatory activities, and thus could be use as a potential source for natural health products.

Species Identification and In Vitro Antifungal Susceptibility of Aspergillus terreus Species Complex Clinical Isolates from a French Multicenter Study.

PubMed

Imbert, S; Normand, A C; Ranque, S; Costa, J M; Guitard, J; Accoceberry, I; Bonnal, C; Fekkar, A; Bourgeois, N; Houzé, S; Hennequin, C; Piarroux, R; Dannaoui, E; Botterel, F

2018-05-01

Aspergillus section Terrei is a species complex currently comprised of 14 cryptic species whose prevalence in clinical samples as well as antifungal susceptibility are poorly known. The aims of this study were to investigate A. Terrei clinical isolates at the species level and to perform antifungal susceptibility analyses by reference and commercial methods. Eighty-two clinical A. Terrei isolates were collected from 8 French university hospitals. Molecular identification was performed by sequencing parts of beta-tubulin and calmodulin genes. MICs or minimum effective concentrations (MECs) were determined for 8 antifungal drugs using both EUCAST broth microdilution (BMD) methods and concentration gradient strips (CGS). Among the 79 A. Terrei isolates, A. terreus stricto sensu ( n = 61), A. citrinoterreus ( n = 13), A. hortai ( n = 3), and A. alabamensis ( n = 2) were identified. All strains had MICs of ≥1 mg/liter for amphotericin B, except for two isolates (both A. hortai ) that had MICs of 0.25 mg/liter. Four A. terreus isolates were resistant to at least one azole drug, including one with pan-azole resistance, yet no mutation in the CYP51A gene was found. All strains had low MECs for the three echinocandins. The essential agreements (EAs) between BMD and CGS were >90%, except for those of amphotericin B (79.7%) and itraconazole (73.4%). Isolates belonging to the A section Terrei identified in clinical samples show wider species diversity beyond the known A. terreus sensu stricto Azole resistance inside the section Terrei is uncommon and is not related to CYP51A mutations here. Finally, CGS is an interesting alternative for routine antifungal susceptibility testing. Copyright © 2018 American Society for Microbiology.

Performance of Vitek 2 for Antimicrobial Susceptibility Testing of Staphylococcus spp. and Enterococcus spp.

PubMed Central

Bobenchik, April M.; Hindler, Janet A.; Giltner, Carmen L.; Saeki, Sandra

2014-01-01

Vitek 2 (bioMérieux, Inc., Durham, NC) is a widely used commercial antimicrobial susceptibility testing system. We compared MIC results obtained by Vitek 2 to those obtained by the Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) reference method for 134 staphylococcal and 84 enterococcal clinical isolates. Nineteen agents were evaluated, including all those available on Vitek 2 for testing staphylococci and enterococci. The resistance phenotypes tested included methicillin-resistant Staphylococcus aureus (MRSA) (n = 58), S. aureus with inducible clindamycin resistance (ICR) (n = 30), trimethoprim-sulfamethoxazole-resistant MRSA (n = 10), vancomycin-resistant Enterococcus (n = 37), high-level gentamicin-resistant Enterococcus (n = 15), linezolid-resistant Enterococcus (n = 5), and daptomycin-nonsusceptible Enterococcus faecalis (n = 6). For the staphylococci, there was 98.9% categorical agreement (CA). There was one very major error (VME) for gentamicin in a Staphylococcus hominis isolate, six VMEs for inducible clindamycin in S. aureus isolates, and two major errors (ME) for daptomycin in an S. aureus and a Staphylococcus epidermidis isolate. For enterococci, there was 97.3% CA. Two VMEs were observed for daptomycin in isolates of E. faecalis and 2 ME, 1 for high-level gentamicin resistance and 1 for nitrofurantoin, in E. faecium isolates. Overall, there was 98.3% CA and 99% essential agreement for the testing of staphylococci and enterococci by the Vitek 2. With the exception of detecting ICR in S. aureus, Vitek 2 performed reliably for antimicrobial susceptibility testing of staphylococci and enterococci. PMID:24478467

LEADER Program Results for 2009: an Activity and Spectrum Analysis of Linezolid Using 6,414 Clinical Isolates from 56 Medical Centers in the United States▿†

PubMed Central

Farrell, David J.; Mendes, Rodrigo E.; Ross, James E.; Sader, Helio S.; Jones, Ronald N.

2011-01-01

The LEADER Program monitors the in vitro activity of linezolid in sampled U.S. medical centers using reference broth microdilution methods with supporting molecular investigations in a central laboratory design. This report summarizes data obtained in 2009, the 6th consecutive year of this longitudinal study. A total of 6,414 isolates from 56 medical centers in all nine Census regions across the United States participated in 2009. For the six leading species/groups, the following linezolid MIC90 values were observed: Staphylococcus aureus, 2 μg/ml; coagulase-negative staphylococci (CoNS), 1 μg/ml; Enterococcus spp., 2 μg/ml; Streptococcus pneumoniae, 1 μg/ml; viridans group streptococci, 1 μg/ml; and beta-hemolytic streptococci, 1 μg/ml. Linezolid resistance was only 0.34% overall, with no evidence of significant increase in the LEADER Program since 2006. The predominant linezolid resistant mechanism found was a G2576T mutation in the 23S rRNA. L3/L4 riboprotein mutations were also found. The mobile multidrug-resistant cfr gene was found in four strains (two S. aureus strains and one strain each of S. epidermidis and S. capitis) from four different states, suggesting persistence but a lack of dissemination. Linezolid continues to exhibit excellent activity and spectrum, and this study documents the need for continued monitoring of emerging mechanisms of resistance over a wide geographic area. PMID:21670176

In vitro antifungal susceptibility of Malassezia pachydermatis from dogs with and without skin lesions.

PubMed

Cafarchia, Claudia; Figueredo, Luciana A; Iatta, Roberta; Montagna, Maria Teresa; Otranto, Domenico

2012-03-23

Canine Malassezia dermatitis is frequently treated with systemic ketoconazole (KTZ) and itraconazole (ITZ). However, no information is available on the antifungal susceptibility to azoles and allilamine of Malassezia pachydermatis isolates from dogs with or without skin lesions. The present study was designed to evaluate the in vitro antifungal susceptibility of M. pachydermatis strains from dogs with or without skin lesions to KTZ, ITZ, miconazole (MICO), fluconazole (FLZ), posaconazole (POS), voriconazole (VOR) and terbinafine (TER) using the Clinical and Laboratory Standards Institute reference Broth Microdilution Method (CLSI M27-A2). The association between the susceptibility to antifungal compounds and the origin of M. pachydermatis, from skin with or without lesions has been also assessed. A total of 62 M. pachydermatis strains from healthy dogs (i.e., Group A=30) or with skin lesions (i.e., Group B=32) were tested. ITZ, KTZ and POS showed the highest activity against M. pachydermatis strains, whereas MICO TER and FLZ the lowest. A higher number of Malassezia resistant strains were registered among isolates from Group B than those from Group A. This study indicates that M. pachydermatis strains were susceptible to ITZ, KTZ, and POS. However, dogs with lesions may harbour strains with low susceptibility to antifungal agents and displaying cross-resistance phenomena to azole. The antifungal therapy in Malassezia infections requires careful appraisal of choice of drugs especially in cases of unresponsiveness to antifungal treatment or recurrent infections. Copyright © 2011 Elsevier B.V. All rights reserved.

Multilocus Sequence Typing of Serially Collected Isolates of Cryptococcus from HIV-Infected Patients in South Africa

PubMed Central

Van Wyk, Marelize; Govender, Nelesh P.; Litvintseva, Anastasia P.

2014-01-01

Patients with cryptococcal meningitis in sub-Saharan Africa frequently relapse following treatment. The natural history and etiology of these recurrent episodes warrant investigation. Here, we used multilocus sequence typing (MLST) to compare the molecular genotypes of strains of Cryptococcus neoformans and Cryptococcus gattii isolated from serial episodes of cryptococcal meningitis that were separated by at least 110 days. The most common MLST genotypes among the isolates were the dominant global clinical genotypes (M5 and M4) of molecular type VNI, as well as the VNI genotypes apparently restricted to southern Africa. In addition, there was considerable genetic diversity among these South African isolates, as 15% of the patients had unique genotypes. Eleven percent of the patients were reinfected with a genetically different strain following their initial diagnosis and treatment. However, the majority of serial episodes (89%) were caused by strains with the same genotype as the original strain. These results indicate that serial episodes of cryptococcosis in South Africa are frequently associated with persistence or relapse of the original infection. Using a reference broth microdilution method, we found that the serial isolates of 11% of the patients infected with strains of C. neoformans var. grubii with identical genotypes exhibited ≥4-fold increases in the MICs to fluconazole. Therefore, these recurrent episodes may have been precipitated by inadequate induction or consolidation of antifungal treatment and occasionally may have been due to increased resistance to fluconazole, which may have developed during the chronic infection. PMID:24648562

Antimicrobial activities of the methanol extract and compounds from Artocarpus communis (Moraceae)

PubMed Central

2011-01-01

Background Artocarpus communis is used traditionally in Cameroon to treat several ailments, including infectious and associated diseases. This work was therefore designed to investigate the antimicrobial activities of the methanol extract (ACB) and compounds isolated from the bark of this plant, namely peruvianursenyl acetate C (1), α-amyrenol or viminalol (2), artonin E (4) and 2-[(3,5-dihydroxy)-(Z)-4-(3-methylbut-1-enyl)phenyl]benzofuran-6-ol (5). Methods The liquid microdilution assay was used in the determination of the minimal inhibitory concentration (MIC) and the minimal microbicidal concentration (MMC), against seven bacterial and one fungal species. Results The MIC results indicated that ACB as well as compounds 4 and 5 were able to prevent the growth of all tested microbial species. All other compounds showed selective activities. The lowest MIC value of 64 μg/ml for the crude extract was recorded on Staphylococcus aureus ATCC 25922 and Escherichia coli ATCC 8739. The corresponding value of 32 μg/ml was recorded with compounds 4 and 5 on Pseudomonas aeruginosa PA01 and compound 5 on E. coli ATCC 8739, their inhibition effect on P. aeruginosa PA01 being more than that of chloramphenicol used as reference antibiotic. Conclusion The overall results of this study provided supportive data for the use of A. communis as well as some of its constituents for the treatment of infections associated with the studied microorganisms. PMID:21612612

Differences in the antimicrobial susceptibility profiles of Moraxella bovis, M. bovoculi and M. ovis

PubMed Central

Maboni, Grazieli; Gressler, Leticia T.; Espindola, Julia P.; Schwab, Marcelo; Tasca, Caiane; Potter, Luciana; de Vargas, Agueda Castagna

2015-01-01

The aim of this study was to determine the differences in the antimicrobial susceptibility profiles of Moraxella bovis, M. bovoculi and M. ovis. Thirty-two strains of Moraxella spp. isolated from cattle and sheep with infectious keratoconjunctivitis were tested via broth microdilution method to determine their susceptibility to ampicillin, cefoperazone, ceftiofur, cloxacillin, enrofloxacin, florfenicol, gentamicin, neomycin, oxytetracycline and penicillin. The results demonstrated that Moraxella spp. strains could be considered sensitive for most of the antimicrobials tested in this study, but differences between the antimicrobial susceptibility profiles of these three Moraxella species were found. M. bovis might differ from other species due to the higher MIC and MBC values it presented. PMID:26273272

Antifungal Susceptibility Testing of Malassezia spp. with an Optimized Colorimetric Broth Microdilution Method.

PubMed

Leong, Cheryl; Buttafuoco, Antonino; Glatz, Martin; Bosshard, Philipp P

2017-06-01

Malassezia is a genus of lipid-dependent yeasts. It is associated with common skin diseases such as pityriasis versicolor and atopic dermatitis and can cause systemic infections in immunocompromised individuals. Owing to the slow growth and lipid requirements of these fastidious yeasts, convenient and reliable antifungal drug susceptibility testing assays for Malassezia spp. are not widely available. Therefore, we optimized a broth microdilution assay for the testing of Malassezia that is based on the CLSI and EUCAST assays for Candida and other yeasts. The addition of ingredients such as lipids and esculin provided a broth medium formulation that enabled the growth of all Malassezia spp. and could be read, with the colorimetric indicator resazurin, by visual and fluorescence readings. We tested the susceptibility of 52 strains of 13 Malassezia species to 11 commonly used antifungals. MIC values determined by visual readings were in good agreement with MIC values determined by fluorescence readings. The lowest MICs were found for the azoles itraconazole, posaconazole, and voriconazole, with MIC 90 values of 0.03 to 1.0 μg/ml, 0.06 to 0.5 μg/ml, and 0.03 to 2.0 μg/ml, respectively. All Malassezia spp. were resistant to echinocandins and griseofulvin. Some Malassezia spp. also showed high MIC values for ketoconazole, which is the most widely recommended topical antifungal to treat Malassezia skin infections. In summary, our assay enables the fast and reliable susceptibility testing of Malassezia spp. with a large panel of different antifungals. Copyright © 2017 American Society for Microbiology.

Antifungal Susceptibility Testing of Malassezia spp. with an Optimized Colorimetric Broth Microdilution Method

PubMed Central

Leong, Cheryl; Buttafuoco, Antonino

2017-01-01

ABSTRACT Malassezia is a genus of lipid-dependent yeasts. It is associated with common skin diseases such as pityriasis versicolor and atopic dermatitis and can cause systemic infections in immunocompromised individuals. Owing to the slow growth and lipid requirements of these fastidious yeasts, convenient and reliable antifungal drug susceptibility testing assays for Malassezia spp. are not widely available. Therefore, we optimized a broth microdilution assay for the testing of Malassezia that is based on the CLSI and EUCAST assays for Candida and other yeasts. The addition of ingredients such as lipids and esculin provided a broth medium formulation that enabled the growth of all Malassezia spp. and could be read, with the colorimetric indicator resazurin, by visual and fluorescence readings. We tested the susceptibility of 52 strains of 13 Malassezia species to 11 commonly used antifungals. MIC values determined by visual readings were in good agreement with MIC values determined by fluorescence readings. The lowest MICs were found for the azoles itraconazole, posaconazole, and voriconazole, with MIC90 values of 0.03 to 1.0 μg/ml, 0.06 to 0.5 μg/ml, and 0.03 to 2.0 μg/ml, respectively. All Malassezia spp. were resistant to echinocandins and griseofulvin. Some Malassezia spp. also showed high MIC values for ketoconazole, which is the most widely recommended topical antifungal to treat Malassezia skin infections. In summary, our assay enables the fast and reliable susceptibility testing of Malassezia spp. with a large panel of different antifungals. PMID:28381607

Increasing rate of daptomycin non-susceptible strains of Staphylococcus aureus in patients with atopic dermatitis.

PubMed

Błażewicz, Izabela; Jaśkiewicz, Maciej; Piechowicz, Lidia; Neubauer, Damian; Nowicki, Roman J; Kamysz, Wojciech; Barańska-Rybak, Wioletta

2017-12-01

Daptomycin is a cyclic lipopeptide that is bactericidal against Staphylococcus aureus , including methicillin-resistant S. aureus (MRSA), vancomycin-intermediate S. aureus (VISA) and vancomycin-resistant S. aureus (VRSA) strains. Daptomycin exerts its antimicrobial effect by a calcium-dependent interaction with the cytoplasmic membrane resulting in depolarization, ion loss and rapid cell death. Unfortunately, loss of daptomycin susceptibility in S. aureus in the clinical setting has been noted. To evaluate the susceptibility profile to daptomycin among S. aureus strains isloted from patients with atopic dermatitis (AD). Another point was to correlate the results obtained by broth microdilution method and Etest, which is commonly applied in clinical setting. One hundred patients with the diagnosis of atopic dermatitis were microbiologically assessed for the carriage of S. aureus . Antimicrobial susceptibility tests were performed using broth-microdilution (BMD) and Etests for daptomycin. Staphylococcus aureus strains were isolated from the majority of our patients, either from the skin (73%) or the anterior nares (75%). Six of the 100 nasal swabs (6%) and 5 of the 100 skin swabs (5%) were positive for methicillin-resistant Staphylococcus aureus (MRSA). A total of 81 of 148 (54.7%) daptomycin non-susceptible isolates of S. aureus were identified by BMD. Only 19 of 81 were also classified as non-susceptible by Etest. Clinicians and microbiologists should be aware of the possibility of the emergence of daptomycin non-susceptibility (or increase in minimal inhibitory concentration) during prolonged therapy and closely monitor the susceptibility of persisting isolates that might be recovered during therapy.

Activity of Ceftazidime-Avibactam against Fluoroquinolone-Resistant Enterobacteriaceae and Pseudomonas aeruginosa

PubMed Central

Pitart, C.; Marco, F.; Keating, T. A.; Nichols, W. W.

2015-01-01

Ceftazidime-avibactam and comparator antibiotics were tested by the broth microdilution method against 200 Enterobacteriaceae and 25 Pseudomonas aeruginosa strains resistant to fluoroquinolones (including strains with the extended-spectrum β-lactamase [ESBL] phenotype and ceftazidime-resistant strains) collected from our institution. The MICs and mechanisms of resistance to fluoroquinolone were also studied. Ninety-nine percent of fluoroquinolone-resistant Enterobacteriaceae strains were inhibited at a ceftazidime-avibactam MIC of ≤4 mg/liter (using the susceptible CLSI breakpoint for ceftazidime alone as a reference). Ceftazidime-avibactam was very active against ESBL Escherichia coli (MIC90 of 0.25 mg/liter), ESBL Klebsiella pneumoniae (MIC90 of 0.5 mg/liter), ceftazidime-resistant AmpC-producing species (MIC90 of 1 mg/liter), non-ESBL E. coli (MIC90 of ≤0.125 mg/liter), non-ESBL K. pneumoniae (MIC90 of 0.25 mg/liter), and ceftazidime-nonresistant AmpC-producing species (MIC90 of ≤0.5 mg/liter). Ninety-six percent of fluoroquinolone-resistant P. aeruginosa strains were inhibited at a ceftazidime-avibactam MIC of ≤8 mg/liter (using the susceptible CLSI breakpoint for ceftazidime alone as a reference), with a MIC90 of 8 mg/liter. Additionally, fluoroquinolone-resistant mutants from each species tested were obtained in vitro from two strains, one susceptible to ceftazidime and the other a β-lactamase producer with a high MIC against ceftazidime but susceptible to ceftazidime-avibactam. Thereby, the impact of fluoroquinolone resistance on the activity of ceftazidime-avibactam could be assessed. The MIC90 values of ceftazidime-avibactam for the fluoroquinolone-resistant mutant strains of Enterobacteriaceae and P. aeruginosa were ≤4 mg/liter and ≤8 mg/liter, respectively. We conclude that the presence of fluoroquinolone resistance does not affect Enterobacteriaceae and P. aeruginosa susceptibility to ceftazidime-avibactam; that is, there is no cross-resistance. PMID:25753646

Antibacterial activity against Clostridium genus and antiradical activity of the essential oils from different origin.

PubMed

Kačániová, Miroslava; Vukovič, Nenad; Horská, Elena; Salamon, Ivan; Bobková, Alica; Hleba, Lukáš; Fiskelová, Martina; Vatľák, Alexander; Petrová, Jana; Bobko, Marek

2014-01-01

In the present study, the antimicrobial and antiradical activities of 15 essential oils were investigated. The antimicrobial activities were determined by using agar disc diffusion and broth microdilution methods against Clostridium genus and antioxidant properties of essential oils by testing their scavenging effect on DPPH radicals activities. We determined the antibacterial activity of Clostridium butyricum, Clostridium hystoliticum, Clostridium intestinale, Clostridium perfringens and Clostridium ramosum. We obtained the original commercial essential oils samples of Lavandula angustifolia, Carum carvi, Pinus montana, Mentha piperita, Foeniculum vulgare Mill., Pinus sylvestris, Satureia montana, Origanum vulgare L. (2 samples), Pimpinella anisum, Rosmarinus officinalis L., Salvia officinalis L., Abies alba Mill., Chamomilla recutita L. Rausch and Thymus vulgaris L. produced in Slovakia (Calendula a.s., Nova Lubovna, Slovakia). The results of the disk diffusion method showed very high essential oils activity against all tested strains of microorganisms. The best antimicrobial activity against C. butyricum was found at Pimpinella anisum, against C. hystoliticum was found at Pinus sylvestris, against C. intestinale was found at Satureia hortensis L., against C. perfringens was found at Origanum vulgare L. and against C. ramosum was found at Pinus sylvestris. The results of broth microdilution assay showed that none of the essential oils was active against C. hystoliticum. The best antimicrobial activity against C. butyricum was found at Abies alba Mill., against C. intestinale was found at Abies alba Mill., against C. perfringens was found at Satureia montana and against C. ramosum was found at Abius alba and Carum carvi. Antioxidant DPPH radical scavenging activity was determined at several solutions of oil samples (50 μL.mL(-1)-0.39 μL.mL(-1)) and the best scavenging effect for the highest concentration (50 μL.mL(-1)) was observed. The antioxidant properties were different in particular plant species. The highest% of inhibition after 30 min. of reaction was observed at Origanum vulgare (93%), Satureia montana (90.66%) and Lavandula augustifolia (90.22%).

Investigations of kanuka and manuka essential oils for in vitro treatment of disease and cellular inflammation caused by infectious microorganisms.

PubMed

Chen, Chien-Chia; Yan, Sui-Hing; Yen, Muh-Yong; Wu, Pei-Fang; Liao, Wei-Ting; Huang, Tsi-Shu; Wen, Zhi-Hong; David Wang, Hui-Min

2016-02-01

Diseases caused by infectious and inflammatory microorganisms are among the most common and most severe nosocomial diseases worldwide. Therefore, developing effective agents for treating these illnesses is critical. In this study, essential oils from two tea tree species, kanuka (Kunzea ericoides) and manuka (Leptospermum scoparium), were evaluated for use in treating diseases and inflammation caused by microorganism infection. Isolates of clinically common bacteria and fungi were obtained from American Type Culture Collection and from Kaohsiung Veterans General Hospital. Minimum inhibitory concentrations for Trichosporon mucoides, Malassezia furfur, Candida albicans, and Candida tropicalis were determined by the broth microdilution method with Sabouraud dextrose broth. The antibacterial susceptibility of Staphylococcus aureus, Streptococcus sobrinus, Streptococcus mutans, and Escherichia coli were determined by the broth microdilution method. A human acute monocytic leukemia cell line (THP-1) was cultured to test the effects of the essential oils on the release of the two inflammatory cytokines, tumor necrosis factor-α and interleukin-4. Multiple analyses of microorganism growth confirmed that both essential oils significantly inhibited four fungi and the four bacteria. The potent fungicidal properties of the oils were confirmed by minimum inhibitory concentrations ranging from 0.78% to 3.13%. The oils also showed excellent bactericidal qualities with 100% inhibition of the examined bacteria. In THP-1 cells, both oils lowered tumor necrosis factor-α released after lipopolysaccharide stimulation. Finally, the antimicrobial and anti-inflammatory effects of the oils were obtained without adversely affecting the immune system. These results indicate that the potent antimicroorganism and anti-inflammation properties of kanuka and manuka essential oils make them strong candidates for use in treating infections and immune-related disease. The data confirm the potential use of kanuka and manuka extracts as pharmaceutical antibiotics, medical cosmetology agents, and food supplements. Copyright © 2014. Published by Elsevier B.V.

Prevalence and Antimicrobial Resistance of Campylobacter Isolated from Dressed Beef Carcasses and Raw Milk in Tanzania

PubMed Central

Kashoma, Isaac P.; Kassem, Issmat I.; John, Julius; Kessy, Beda M.; Gebreyes, Wondwossen; Kazwala, Rudovick R.

2016-01-01

Campylobacter species are commonly transmitted to humans through consumption of contaminated foods such as milk and meat. The aim of this study was to investigate the prevalence, antimicrobial resistance, and genetic determinants of resistance of Campylobacter isolated from raw milk and beef carcasses in Tanzania. The antimicrobial resistance genes tested included blaOXA-61 (ampicillin), aph-3-1 (aminoglycoside), tet(O) (tetracycline), and cmeB (multi-drug efflux pump). The prevalence of Campylobacter was 9.5% in beef carcasses and 13.4% in raw milk, respectively. Using multiplex-polymerase chain reaction (PCR), we identified 58.1% of the isolates as Campylobacter jejuni, 30.7% as Campylobacter coli, and 9.7% as other Campylobacter spp. One isolate (1.6%) was positive for both C. jejuni and C. coli specific PCR. Antimicrobial susceptibility testing using the disk diffusion assay and the broth microdilution method showed resistance to: ampicillin (63% and 94.1%), ciprofloxacin (9.3% and 11.8%), erythromycin (53.7% and 70.6%), gentamicin (0% and 15.7%), streptomycin (35.2% and 84.3%), and tetracycline (18.5% and 17.7%), respectively. Resistance to azithromycin (42.6%), nalidixic acid (64.8%), and chloramphenicol (13%) was determined using the disk diffusion assay only, while resistance to tylosin (90.2%) was quantified using the broth microdilution method. The blaOXA-61 (52.6% and 28.1%), cmeB (26.3% and 31.3%), tet(O) (26.3% and 31.3%), and aph-3-1 (5.3% and 3.0%) were detected in C. coli and C. jejuni. These findings highlight the extent of antimicrobial resistance in Campylobacter occurring in important foods in Tanzania. The potential risks to consumers emphasize the need for adequate control approaches, including the prudent use of antimicrobials to minimize the spread of antimicrobial-resistant Campylobacter. PMID:26153978

Prevalence and Antimicrobial Resistance of Campylobacter Isolated from Dressed Beef Carcasses and Raw Milk in Tanzania.

PubMed

Kashoma, Isaac P; Kassem, Issmat I; John, Julius; Kessy, Beda M; Gebreyes, Wondwossen; Kazwala, Rudovick R; Rajashekara, Gireesh

2016-01-01

Campylobacter species are commonly transmitted to humans through consumption of contaminated foods such as milk and meat. The aim of this study was to investigate the prevalence, antimicrobial resistance, and genetic determinants of resistance of Campylobacter isolated from raw milk and beef carcasses in Tanzania. The antimicrobial resistance genes tested included blaOXA-61 (ampicillin), aph-3-1 (aminoglycoside), tet(O) (tetracycline), and cmeB (multi-drug efflux pump). The prevalence of Campylobacter was 9.5% in beef carcasses and 13.4% in raw milk, respectively. Using multiplex-polymerase chain reaction (PCR), we identified 58.1% of the isolates as Campylobacter jejuni, 30.7% as Campylobacter coli, and 9.7% as other Campylobacter spp. One isolate (1.6%) was positive for both C. jejuni and C. coli specific PCR. Antimicrobial susceptibility testing using the disk diffusion assay and the broth microdilution method showed resistance to: ampicillin (63% and 94.1%), ciprofloxacin (9.3% and 11.8%), erythromycin (53.7% and 70.6%), gentamicin (0% and 15.7%), streptomycin (35.2% and 84.3%), and tetracycline (18.5% and 17.7%), respectively. Resistance to azithromycin (42.6%), nalidixic acid (64.8%), and chloramphenicol (13%) was determined using the disk diffusion assay only, while resistance to tylosin (90.2%) was quantified using the broth microdilution method. The blaOXA-61 (52.6% and 28.1%), cmeB (26.3% and 31.3%), tet(O) (26.3% and 31.3%), and aph-3-1 (5.3% and 3.0%) were detected in C. coli and C. jejuni. These findings highlight the extent of antimicrobial resistance in Campylobacter occurring in important foods in Tanzania. The potential risks to consumers emphasize the need for adequate control approaches, including the prudent use of antimicrobials to minimize the spread of antimicrobial-resistant Campylobacter.

Evaluation of the toxicity and antimicrobial activity of hydroethanolic extract of Arrabidaea chica (Humb. & Bonpl.) B. Verl.

PubMed

Mafioleti, Luciano; da Silva Junior, Iberê Ferreira; Colodel, Edson Moleta; Flach, Adriana; Martins, Domingos Tabajara de Oliveira

2013-11-25

Arrabidaea chica (Bignoniaceae) is a vine native to the Amazon Rainforest, popularly known as "crajiru" and whose infusion and decoction of the leaves are used to treat diseases such as gastric ulcers, inflammations, infections, anemia, herpes, jaundice among others. It is also used as a natural dye. This work aimed to evaluate the in vitro and in vivo toxicity, antimicrobial activity including analysis of chemical constitution of the hydroethanolic extract of the leaves of Arrabidaea chica (HEAc). Acute and subchronic toxicity of HEAc was evaluated in mice and rats, respectively, and by Alamar blue (cytotoxicity assay) using CHO-K1 cells. Antimicrobial activity of HEAc was tested by broth microdilution method using a panel of bacteria and yeast of clinical interest. The preliminary phytochemical analysis of HEAc was performed by electrospray ionization mass spectrometry [ESI(+)-MS]. Secondary metabolites were quantified by colorimetric methods. When administered in vivo at doses up to 3000 mg/kg v.o., HEAc did not cause any signs and symptoms of acute toxicity in mice and no cytotoxicity in CHO-K1 cells. Administration for 30 days caused leukocytosis (200 mg/kg) and reversible reductions in non-dose dependent of body weight, total weight gain and feed intake in rats given 200mg/kg and 500 mg/kg of HEAc, but were not accompanied by behavioral and clinical changes (laboratory and histopathological) that may have demonstrated evidences of subchronic toxicity HEAc demonstrated a pronounced activity against Helicobacter pylori (MIC=12.5 μg/mL) and moderate activity against Enterococcus faecalis (MIC=100 μg/mL) in broth microdilution. Preliminary phytochemical analysis of HEAc by colorimetric methods revealed that mainly the presence of phenolic compounds (16.6%), especially flavones and flavonols (4.02%). [ESI(+)-MS] fingerprint analyses of HEAc revealed the presence of 3-deoxyanthocyanidins and kaempferol. Our data provide evidence that HEAc is safe and can be useful in infections related to Helicobacter pylori and Enterococcus faecalis. Phytochemical analysis revealed the predominant presence of flavones and flavonols, possibly involved in the antimicrobial action of HEAc. © 2013 Elsevier Ireland Ltd. All rights reserved.

ANTIFUNGAL POTENTIAL OF PLANT SPECIES FROM BRAZILIAN CAATINGA AGAINST DERMATOPHYTES

PubMed Central

BIASI-GARBIN, Renata Perugini; DEMITTO, Fernanda de Oliveira; do AMARAL, Renata Claro Ribeiro; FERREIRA, Magda Rhayanny Assunção; SOARES, Luiz Alberto Lira; SVIDZINSKI, Terezinha Inez Estivalet; BAEZA, Lilian Cristiane; YAMADA-OGATTA, Sueli Fumie

2016-01-01

Trichophyton rubrum and Trichophyton mentagrophytes complex, or Trichophyton spp. are the main etiologic agents of dermatophytosis, whose treatment is limited by the high cost of antifungal treatments, their various side effects, and the emergence of resistance amongst these species. This study evaluated the in vitro antidermatophytic activity of 23 crude extracts from nine plant species of semiarid vegetation (caatinga) found in Brazil. The extracts were tested at concentrations ranging from 1.95 to 1,000.0 mg/mL by broth microdilution assay against the reference strains T. rubrum ATCC 28189 and T. mentagrophytesATCC 11481, and 33 clinical isolates of dermatophytes. All plants showed a fungicidal effect against both fungal species, with MIC/MFC values of the active extracts ranging from 15.6 to 250.0 µg/mL. Selected extracts of Eugenia uniflora (AcE), Libidibia ferrea (AE), and Persea americana (AcE) also exhibited a fungicidal effect against all clinical isolates of T. rubrum and T. mentagrophytes complex. This is the first report of the antifungal activity of Schinus terebinthifolius, Piptadenia colubrina, Parapiptadenia rigida, Mimosa ophthalmocentra, and Persea americana against both dermatophyte species. PMID:27007561

ANTIFUNGAL POTENTIAL OF PLANT SPECIES FROM BRAZILIAN CAATINGA AGAINST DERMATOPHYTES.

PubMed

Biasi-Garbin, Renata Perugini; Demitto, Fernanda de Oliveira; Amaral, Renata Claro Ribeiro do; Ferreira, Magda Rhayanny Assunção; Soares, Luiz Alberto Lira; Svidzinski, Terezinha Inez Estivalet; Baeza, Lilian Cristiane; Yamada-Ogatta, Sueli Fumie

2016-01-01

Trichophyton rubrum and Trichophyton mentagrophytes complex, or Trichophyton spp. are the main etiologic agents of dermatophytosis, whose treatment is limited by the high cost of antifungal treatments, their various side effects, and the emergence of resistance amongst these species. This study evaluated the in vitro antidermatophytic activity of 23 crude extracts from nine plant species of semiarid vegetation (caatinga) found in Brazil. The extracts were tested at concentrations ranging from 1.95 to 1,000.0 mg/mL by broth microdilution assay against the reference strains T. rubrum ATCC 28189 and T. mentagrophytes ATCC 11481, and 33 clinical isolates of dermatophytes. All plants showed a fungicidal effect against both fungal species, with MIC/MFC values of the active extracts ranging from 15.6 to 250.0 µg/mL. Selected extracts of Eugenia uniflora (AcE), Libidibia ferrea (AE), and Persea americana (AcE) also exhibited a fungicidal effect against all clinical isolates of T. rubrum and T. mentagrophytes complex. This is the first report of the antifungal activity of Schinus terebinthifolius, Piptadenia colubrina, Parapiptadenia rigida, Mimosa ophthalmocentra, and Persea americana against both dermatophyte species.

Argentinean propolis from Zuccagnia punctata Cav. (Caesalpinieae) exudates: phytochemical characterization and antifungal activity.

PubMed

Agüero, María Belén; Gonzalez, Mariela; Lima, Beatriz; Svetaz, Laura; Sánchez, Marianela; Zacchino, Susana; Feresin, Gabriela Egly; Schmeda-Hirschmann, Guillermo; Palermo, Jorge; Wunderlin, Daniel; Tapia, Alejandro

2010-01-13

This paper reports the in vitro antifungal activity of propolis extracts from the province of Tucuman (Argentina) as well as the identification of their main antifungal compounds and botanical origin. The antifungal activity was determined by the microdilution technique, using reference microorganisms and clinical isolates. All dermatophytes and yeasts tested were strongly inhibited by different propolis extracts (MICs between 16 and 125 microg mL(-1)). The most susceptible species were Microsporum gypseum, Trichophyton mentagrophytes, and Trichophyton rubrum. The main bioactive compounds were 2',4'-dihydroxy-3'-methoxychalcone 2 and 2',4'-dihydroxychalcone 3. Both displayed strong activity against clinical isolates of T. rubrum and T. mentagrophytes (MICs and MFCs between 1.9 and 2.9 microg mL(-1)). Additionally, galangin 5, pinocembrin 6, and 7-hydroxy-8-methoxyflavanone 9 were isolated from propolis samples and Zuccagnia punctata exudates, showing moderate antifungal activity. This is the first study matching the chemical profile of Z. punctata Cav. exudates with their corresponding propolis, giving strong evidence on the botanical origin of the studied propolis.

Antibacterial properties studies of trunk barks of Terminalia ivorensis, a commercial and medicinal species on some methicillin-resistant Staphylococci species strains.

PubMed

Coulibaly, K; Zirihi, G N; Guessennd-Kouadio, N; Oussou, K R; Dosso, M

2014-09-01

Methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis and coagulase-negative Staphylococcus infections are a worldwide concern. Terminalia ivorensis, of Combretaceae family plant, is widely used traditional medicinal in Côte d'Ivoire to treat dermal diseases (affection in which Staphylococci are implied) including local inflammation and also to treat voice-loss. This study focused to investigate the effect in vitro of the extracts of trunk barks of Terminalia ivorensis on some methicillin/oxacillin-resistant strains of Staphylococcus aureus, S. epidermidis, coagulase-negative S. and reference strain of S. aureus ATCC 25923. Antibacterial activity of aqueous, 70% ethanolic 70% and aqueous residue extracts was assessed using agar disc-diffusion method and liquid medium microdilution method in 96 multi-well micro-titer plates. This method led us to determine minimum inhibition concentration (M.I.C.) and minimum bactericidal concentration (M.B.C.). The presence of chemical groups major was detected qualitatively. Aqueous and 70% ethanolic 70% extracts showed significant activity against all the bacteria except aqueous residue when compared with the standard antibiotic oxacillin (5 µg/ml). M.I.C. for aqueous and 70% ethanolic 70% extracts ranged from 0,83-16,67 mg/ml and 0,156-13,33 mg/ml respectively. Viable cell determination revealed the bactericidal nature of the two barks extracts. The 70% ethanolic 70% extract exhibited the highest activity according to the M.B.C. values. The phytochemical analysis indicates the presence of tannins, saponins, flavonoids, terpen/sterols, coumarins, polyphenols and traces of alkaloid. The in-vitro antibacterial efficacy shown by the barks of this plant and his lushness in chimical compounds, would justify use of this one in the traditional treatment of some diseases of microbial origin. These compounds could be suggested to provide alternative solution to the development of new therapeutic agents.

Screening of crude extracts of six medicinal plants used in South-West Nigerian unorthodox medicine for anti-methicillin resistant Staphylococcus aureus activity

PubMed Central

Akinyemi, Kabir O; Oladapo, Olukayode; Okwara, Chidi E; Ibe, Christopher C; Fasure, Kehinde A

2005-01-01

Background Six Nigerian medicinal plants Terminalia avicennioides, Phylantus discoideus, Bridella ferruginea, Ageratum conyzoides, Ocimum gratissimum and Acalypha wilkesiana used by traditional medical practitioners for the treatment of several ailments of microbial and non-microbial origins were investigated for in vitro anti-methicillin Resistant Staphylococcus aureus (MRSA) activity. Methods Fresh plant materials were collected from the users. Water and ethanol extracts of the shredded plants were obtained by standard methods. The Bacterial cultures used were strains of MRSA isolated from patients. MRSA was determined by the reference broth microdilution methods using the established National Committee for Clinical Laboratory Standards break points. Staphylococcus aureus NCIB 8588 was used as a standard strain. Susceptibility testing and phytochemical screening of the plant extracts were performed by standard procedures. Controls were maintained for each test batch. Results Both water and ethanol extracts of T. avicennioides, P. discoideus, O. gratissimum, and A. wilkesiana were effective on MRSA. The Minimum Inhibition Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the ethanol extracts of these plants range from 18.2 to 24.0 mcg/ml and 30.4 to 37.0 mcg/ml respectively. In contrast, MIC range of 30.6 to 43.0 mcg/ml and 55.4 to 71.0 mcg/ml were recorded for ethanol and water extracts of B. ferruginea, and A. conyzoides respectively. Higher MBC values were obtained for the two plants. These concentrations were too high to be considered active in this study. All the four active plants contained at least trace amount of anthraquinones. Conclusion Our results offer a scientific basis for the traditional use of water and ethanol extracts of A. wilkesiana, O. gratissimum, T. avicennioides and P. discoideus against MRSA-associated diseases. However, B. ferruginea and A. conyzoides were ineffective in vitro in this study; we therefore suggest the immediate stoppage of their traditional use against MRSA-associated diseases in Lagos, Nigeria. PMID:15762997

Antimicrobial activity of chemically modified dextran derivatives.

PubMed

Tuchilus, Cristina G; Nichifor, Marieta; Mocanu, Georgeta; Stanciu, Magdalena C

2017-04-01

Cationic amphiphilic dextran derivatives with a long alkyl group attached to the reductive end of the polysaccharide chain and quaternary ammonium groups attached as pendent groups to the main dextran backbone were synthesized and tested for their antimicrobial properties against several bacteria and fungi strains. Dependence of antimicrobial activity on both polymer chemical composition (dextran molar mass, length of end alkyl group and chemical structure of ammonium groups) and type of microbes was highlighted by disc-diffusion method (diameter of inhibition zone) and broth microdilution method (minimum inhibitory concentrations). Polymers had antimicrobial activity for all strains studied, except for Pseudomonas aeruginosa ATCC 27853. The best activity against Staphylococcus aureus (Minimun Inhibitory Concentration 60μg/mL) was provided by polymers obtained from dextran with lower molecular mass (Mn=4500), C 12 H 25 or C 18 H 37 end groups, and N,N-dimethyl-N-benzylammonium pendent groups. Copyright © 2017 Elsevier Ltd. All rights reserved.

Susceptibility of Acinetobacter Strains Isolated from Deployed U.S. Military Personnel▿

PubMed Central

Hawley, Joshua S.; Murray, Clinton K.; Griffith, Matthew E.; McElmeel, M. Leticia; Fulcher, Letitia C.; Hospenthal, Duane R.; Jorgensen, James H.

2007-01-01

The susceptibilities of 142 Acinetobacter baumannii-calcoaceticus complex isolates (95 from wounded U.S. soldiers deployed overseas) to 13 antimicrobial agents were determined by broth microdilution. The most active antimicrobial agents (≥95% of isolates susceptible) were colistin, polymyxin B, and minocycline. PMID:17043112

Management of cosmetic embarrassment caused by Malassezia spp. with fruticose lichen Cladia using phylogenetic approach.

PubMed

Pandey, Anand; Mishra, Rohit K; Tiwari, Amit K; Kumar, Awadhesh; Bajaj, A K; Dikshit, Anupam

2013-01-01

During anti-Malassezia screening of plants by CLSI broth microdilution method, Cladia aggregata (Swartz) Nyl. (family Cladoniaceae), a fruticose lichen from Sikkim (northeast Himalayan region), has been found effective at minimum inhibitory concentrations (mg/mL) of 2.72, 0.63, and 1.28 against yeast-like fungi namely, M. furfur, M. globosa and M. sympodialis, respectively. These test pathogens are responsible for pityriasis versicolor (PV) and seborrheic dermatitis (SD) in humans. We tried to establish the reason for variable MICs against various Malassezia spp. using bioinformatical tools, thereby reducing the cost of the experimentation. This is the first report on anti-Malassezia activity of C. aggregata and thus can serve as a potential source for the development of cosmaceuticals.

In vitro combination of antifungal agents against Malassezia pachydermatis.

PubMed

Schlemmer, Karine B; de Jesus, Francielli P K; Loreto, Erico S; Farias, Julia B; Alves, Sydney H; Ferreiro, Laerte; Santurio, Janio M

2018-06-19

The yeast Malassezia pachydermatis is a common commensal and occasional opportunistic pathogen of theskin microbiota of animals and humans. In this study, the susceptibility of M. pachydermatis isolates to fluconazole (FLC), itraconazole (ITZ), ketoconazole (KTZ), clotrimazole (CLZ), and miconazole (MCZ) alone and in combination with terbinafine (TRB), nystatin (NYS), and caspofungin (CSP) was evaluated in vitro based on the M27-A3 technique and the checkerboard microdilution method using Sabouraud dextrose broth with 1% tween 80 (SDB). Based on the mean FICI values, the main synergies observed were combinations of ITZ+CSP and CLZ+CSP (55.17%). The most significant combinations deserve in vivo evaluations because might provide effective alternative treatments against M. pachydermatis due to their synergistic interactions.

Serological diagnosis of neurobrucellosis.

PubMed Central

Sanchez-Sousa, A; Torres, C; Campello, M G; Garcia, C; Parras, F; Cercenado, E; Baquero, F

1990-01-01

The presence of antibodies was determined in the serum and cerebrospinal fluid in six patients with neurobrucellosis using the Rose Bengal test, the microdilution agglutination test, and the Coombs' test. Four of the patients were followed up for more than three months. The Rose Bengal test and the microagglutination test were positive in cerebrospinal fluid in five of the six cases at some stage. The Coombs' test was positive in cerebrospinal fluid in every patient and in one was the only positive serological test. Cerebrospinal fluid positivity is not excluded by low titres or negative results of antibodies in the serum for any of the three methods. A Coombs' test or some equivalent must always be made on the cerebrospinal fluid to diagnose neurobrucellosis. PMID:2312754

In vitro synergism between berberine and miconazole against planktonic and biofilm Candida cultures.

PubMed

Wei, Guo-Xian; Xu, Xin; Wu, Christine D

2011-06-01

To investigate the antimycotic activity of the plant alkaloid berberine (BBR), alone and in combination with antifungal azoles, against planktonic and biofilm Candida cultures. The minimum inhibitory concentrations (MICs) of BBR, miconazole (MCZ), and fluconazole (FLC) towards Candida albicans, Candida glabrata, Candida kefyr, Candida krusei, Candida parapsilosis, and Candida tropicalis were determined by a microdilution method. For C. albicans, the synergistic effects of BBR combined with MCZ or FLC were examined in a paper disc agar diffusion assay and checkerboard microdilution assay. The effect of the BBR/MCZ combination was further investigated in a C. albicans biofilm formation model with a dual-chamber flow cell. The effect on metabolic activity of biofilm cells was established using 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT)/menadione. Berberine inhibited the growth of various Candida species (MICs 0.98-31.25mg/L) in the following order of susceptibility: C. krusei > C. kefyr > C. glabrata > C. tropicalis > C. parapsilosis and C. albicans. Synergism between BBR and MCZ or FLC was observed in the disc diffusion assay as well as in suspension showing an FIC index <0.5 (∑FIC=0.19). Whilst neither BBR (16 mg/L) nor MCZ (0.8 mg/L) alone significantly inhibited biofilm formation of C. albicans, their combination reduced biofilm formation by >91% after 24 h, as established from the reduction in surface area coverage (P<0.01). The BBR/MCZ combination also exhibited synergy against the metabolic activity of pre-formed C. albicans biofilms in polystyrene microtiter plates (∑FIC=0.25). Berberine exhibits synergistic effects with commonly used antimycotic drugs against C. albicans, either in planktonic or in biofilm growth phases. Published by Elsevier Ltd.

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

Resistance of Bacteroides isolates recovered among clinical samples from a major Costa Rican hospital between 2000 and 2008 to ß-lactams, clindamycin, metronidazole, and chloramphenicol.

PubMed

Cordero-Laurent, E; Rodríguez, C; Rodríguez-Cavallini, E; Gamboa-Coronado, M M; Quesada-Gómez, C

2012-12-01

To assess the susceptibility of 100 isolates of Bacteroides spp. recovered in a major Costa Rican hospital between 2000 and 2008 to several ß-lactams, chloramphenicol, clindamycin and metronidazole. Susceptibility to amoxicillin, amoxicillin with clavulanic acid, piperacillin, piperacillin with tazobactam, ticarcillin, ticarcillin with clavulanic acid, cefoxitin, cefotetan, imipenem, chloramphenicol, clindamycin, and metronidazole was determined with the ATB ANA® system. In addition, minimum inhibitory concentrations (MIC) of clindamycin and metronidazole were determined with the broth microdilution method because these drugs are the treatment of choice for anaerobic infections in Costa Rica. Reference strains ATCC® 25285 and ATCC® 29741 were employed as indicated. According to the ATB ANA® system, 93 isolates were resistant to at least one antibiotic. Resistance to ß-lactams was common. By contrast, resistance to ß-lactams supplemented with ß-lactamase inhibitors was rare. All of the strains were inhibited by imipenem and chloramphenicol. By a broth microdilución test, resistance to clindamycin was 20%, with MIC ranging from 64 mg/L to 256 mg/L; all of the strains were susceptible to metronidazole. The high MIC for clindamycin obtained for the majority of the resistant strains is highly suggestive of the presence of mechanisms of acquired resistance among the isolates, therefore surveillance studies are required to determine its efficacy. The low resistance to metronidazole observed underlines its value as a first-line drug. On the other hand, imipenem could be used to treat infections that do not respond well to metronidazole or clindamycin.

Genotyping and In Vitro Antifungal Susceptibility Testing of Fusarium Isolates from Onychomycosis in India.

PubMed

Gupta, Chhavi; Jongman, Marit; Das, Shukla; Snehaa, K; Bhattacharya, S N; Seyedmousavi, S; van Diepeningen, Anne D

2016-08-01

Onychomycosis refers to fungal infection of the nail and is commonly caused by dermatophytes, while yeasts and non-dermatophytic molds (NDM) are increasingly recognized as pathogens in nail infections. The present study was done to delineate molecular epidemiology of Fusarium onychomycosis in India. Five hundred nail samples of Indian patients clinically suspected of onychomycosis were subjected to direct microscopy and fungal culture. Representative Fusarium isolates were further identified to species level by multi-locus sequencing for internal transcribed spacer, translation elongation factor 1 alpha (tef1-α) and RNA polymerase II subunit (rpb2) regions (primer pairs: ITS1/ITS4, EF1/EF2, 5f2/7cr, respectively). These representative strains were also tested for in vitro antifungal susceptibility by the broth microdilution method. Members of the genus Fusarium proved to be the most common NDM responsible for onychomycosis. The Fusarium spp. responsible for onychomycosis belonged to the Fusarium solani species complex (F. keratoplasticum and F. falciforme) and Fusarium fujikuroi species complex (F. proliferatum, F. acutatum and F. sacchari). Antifungal susceptibility results indicated that amphotericin B was the most effective antifungal across all isolates (MIC ranging 0.5-2 mg/L), followed by voriconazole (MIC ranging 1-8 µg/ml). However, a large variation was shown in susceptibility to posaconazole (MIC ranging 0.5 to >16 µg/ml). To conclude, we identified different Fusarium spp. responsible for onychomycosis in India with variation within species in susceptibility to antifungal agents, showing that fusariosis requires correct and prompt diagnosis as well as antifungal susceptibility testing.

[In vitro antibacterial activity of Curcuma longa (Zingiberaceae) against nosocomial bacteria in Montería, Colombia].

PubMed

Méndez Álvarez, Nelson; Angulo Ortíz, Alberto; Contreras Martínez, Orfa

2016-09-01

Bacterial resistance is a growing health problem worldwide that has serious economic and social impacts, compromising public health, and the therapeutic action of current antibiotics. Therefore, the search for new compounds with antimicrobial properties is relevant in modern studies, particularly against bacteria of clinical interest. In the present study, in vitro antibacterial activity of the ethanol extract and essential oil of Curcuma longa (Zingiberaceae) was evaluated against nosocomial bacteria, using the microdilution method. Escherichia coli strains, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus sp. were used, Salmonella sp. and Bacillus sp., isolated from nosocomial infections in a hospital in the city of Monteria and reference strains of S. aureus ATCC 43300, S. aureus ATCC 29213, S. aureus ATCC 25923, P. aeruginosa ATCC 27853, E. coli ATCC 25922 and K. pneumonia ATCC 700603. The ethanol extract antibacterial profile was more efficient at higher concentrations (1 000 ppm), obtaining significant percentages of reduction of more than 50 % against K. pneumoniae ATCC 700603 and a clinical isolate of E. coli; while compared to Bacillus clinical isolate, was more active than the essential oil. For the rest of microorganisms, the reduction percentages obtained at a concentration of 1 000 ppm varied between 17 and 42 % with ethanolic extract, and 8 to 43 % with essential oil. At concentrations of 100 and 500 ppm antibacterial activity of the extracts was lower. The results indicated that the ethanolic extract and essential oil of C. longa rhizomes have active compounds with antibacterial properties that could be used in future research as a therapeutic alternative for the treatment of infections caused by nosocomial pathogens.

In Vitro Susceptibilities of Mycoplasma hyopneumoniae Field Isolates

PubMed Central

Vicca, J.; Stakenborg, T.; Maes, D.; Butaye, P.; Peeters, J.; de Kruif, A.; Haesebrouck, F.

2004-01-01

The in vitro susceptibilities of 21 Mycoplasma hyopneumoniae field isolates were determined using a broth microdilution technique. One isolate showed acquired resistance to lincomycin, tilmicosin, and tylosin, while five isolates were resistant to flumequine and enrofloxacin. Acquired resistance against these antimicrobials in M. hyopneumoniae field isolates was not reported previously. PMID:15504886

In vitro avarol does affect the growth of Candida sp.

PubMed

Pejin, Boris; Ciric, Ana; Markovic, Dejan; Tommonaro, Giuseppina; Sokovic, Marina

2016-09-01

This work extends in vitro screening of antimicrobial activity of avarol, the marine natural product firstly isolated from the Mediterranean sponge Dysidea avara. Its anticandidial activity was evaluated by microdilution method against eight Candida strains, two ATCC and six clinical ones. At a different extent this compound was proven to be active against all the strains tested (MIC 0.8-6.0 μg/mL and MFC 1.6-12.0 μg/mL, respectively). According to the best of our knowledge, this is the first report on avarol activity towards any yeast strain which may be of relevance for Alzheimer's disease. Indeed, avarol derivatives showing moderate AChE activity should be screened for anticandidial activity both in vitro and in vivo.

3-Bromopyruvate: a novel antifungal agent against the human pathogen Cryptococcus neoformans.

PubMed

Dyląg, Mariusz; Lis, Paweł; Niedźwiecka, Katarzyna; Ko, Young H; Pedersen, Peter L; Goffeau, Andre; Ułaszewski, Stanisław

2013-05-03

We have investigated the antifungal activity of the pyruvic acid analogue: 3-bromopyruvate (3-BP). Growth inhibition by 3-BP of 110 strains of yeast-like and filamentous fungi was tested by standard spot tests or microdilution method. The human pathogen Cryptococcus neoformans exhibited a low Minimal Inhibitory Concentration (MIC) of 0.12-0.15 mM 3-BP. The high toxicity of 3-BP toward C. neoformans correlated with high intracellular accumulation of 3-BP and also with low levels of intracellular ATP and glutathione. Weak cytotoxicity towards mammalian cells and lack of resistance conferred by the PDR (Pleiotropic Drug Resistance) network in the yeast Saccharomyces cerevisiae, are other properties of 3-BP that makes it a novel promising anticryptococcal drug. Copyright © 2013 Elsevier Inc. All rights reserved.

Antimicrobial activity of some medicinal barks used in Peruvian Amazon.

PubMed

Kloucek, P; Svobodova, B; Polesny, Z; Langrova, I; Smrcek, S; Kokoska, L

2007-05-04

The aim of this study was to evaluate the antimicrobial activity of six barks traditionally used in Callería District (Ucayali Department, Peru) for treating conditions likely to be associated with microorganisms. Ethanol extracts of stem barks of Abuta grandifolia (Menispermaceae), Dipteryx micrantha (Leguminosae), Cordia alliodora (Boraginaceae), Naucleopsis glabra (Moraceae), Pterocarpus rohrii (Leguminosae), and root bark of Maytenus macrocarpa (Celastraceae) were tested against nine bacteria and one yeast using the broth microdilution method. All plants possessed significant antimicrobial effect, however, the extract of Naucleopsis glabra exhibited the strongest activity against Gram-positive bacteria (MICs ranging from 62.5 to 125 microg/ml), while the broadest spectrum of action was shown by the extract of Maytenus macrocarpa, which inhibited all the strains tested with MICs ranging from 125 to 250 microg/ml.

Epidemiology and antifungal susceptibilities of yeast isolates causing invasive infections across urban Beijing, China.

PubMed

Guo, Li-Na; Xiao, Meng; Cao, Bin; Qu, Fen; Zhan, Yu-Liang; Hu, Yun-Jian; Wang, Xin-Ru; Liang, Guo-Wei; Gu, Hai-Tong; Qi, Jun; Yuan, Hui; Min, Rong; Wang, Fei-Yan; Liu, Lin-Juan; Wang, Hai-Bin; Jiang, Wei; Duan, Xue-Guang; Xu, Wen-Jian; Yu, Yan-Hua; Su, Jian-Rong; Zhang, Jian-Zhong; Nong, Jin-Qing; Liu, Shu-Mei; Li, Jun; Liu, Jun-Ting; Yue, Zhi-Gang; Yang, Duo; Guo, Jie; Zhao, Rui; Zhang, Ya-Nan; Yang, Xi-Ming; Liu, Xiao-Qing; Hsueh, Po-Ren; Xu, Ying-Chun

2017-09-01

To investigate the species distribution and antifungal susceptibility profiles of yeast isolates causing invasive infections across Beijing. A total of 1201 yeast isolates recovered from blood and other sterile body fluids were correctly identified by matrix-assisted laser desorption/ionization TOF MS supplemented by DNA sequencing. Antifungal susceptibility testing was performed according to the Clinical and Laboratory Standards Institute broth microdilution method. Candida (95.5%) remained the most common yeast species isolated; Candida albicans (38.8%) and Candida parapsilosis (22.6%) were the leading species of candidemia. Azole resistances were mainly observed in Candida glabrata and Candida tropicalis isolates. This study outlined the epidemiologic data of invasive yeast infections and highlighted the need for continuous monitoring of azole resistances among C. glabrata and C. tropicalis isolates in Beijing.

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).

Management of Cosmetic Embarrassment Caused by Malassezia spp. with Fruticose Lichen Cladia Using Phylogenetic Approach

PubMed Central

Pandey, Anand; Mishra, Rohit K.; Tiwari, Amit K.; Kumar, Awadhesh; Bajaj, A. K.; Dikshit, Anupam

2013-01-01

During anti-Malassezia screening of plants by CLSI broth microdilution method, Cladia aggregata (Swartz) Nyl. (family Cladoniaceae), a fruticose lichen from Sikkim (northeast Himalayan region), has been found effective at minimum inhibitory concentrations (mg/mL) of 2.72, 0.63, and 1.28 against yeast-like fungi namely, M. furfur, M. globosa and M. sympodialis, respectively. These test pathogens are responsible for pityriasis versicolor (PV) and seborrheic dermatitis (SD) in humans. We tried to establish the reason for variable MICs against various Malassezia spp. using bioinformatical tools, thereby reducing the cost of the experimentation. This is the first report on anti-Malassezia activity of C. aggregata and thus can serve as a potential source for the development of cosmaceuticals. PMID:24069589

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.

Chemical composition, anti-biofilm activity and potential cytotoxic effect on cancer cells of Rosmarinus officinalis L. essential oil from Tunisia.

PubMed

Jardak, Marwa; Elloumi-Mseddi, Jihene; Aifa, Sami; Mnif, Sami

2017-10-02

Rosmarinus officinalis L. from Tunisia, popularly known as rosemary, is of a considerable importance for its medicinal uses and aromatic value. The aim of this study was to examine the chemical composition of Rosmarinus officinalis essential oil (ROEO) and to evaluate its antibiofilm activity on biofilm-forming bacterium and its anticancer activity on cancer cell lines. The chemical composition of Rosmarinus officinalis essential oil (ROEO) was analyzed by GC-MS and its antibacterial activity was evaluated by micro-dilution method. The antibofilm activity of ROEO was evaluated using the crystal violet test and the cytotoxicity activity was determined by the MTT assay. In this research, thirty-six compounds were identified in ROEO using GC-MS analyses. The main components were 1,8-cineole (23.56%), camphene (12.78%), camphor (12.55%) and β-pinene (12.3%). The antibacterial activity of ROEO was evaluated by micro-dilution method. The oil exhibited inhibition and bactericidal effect against two strains: Staphylococcus aureus ATCC 9144 and Staphylococcus epidermidis S61. It was found that the minimum inhibitory concentration (MIC) obtained for S. aureus and S. epidermidis ranged from 1.25 to 2.5 and from 0.312 to 0.625 μl ml -1 , respectively and the minimum bactericidal concentration (MBC) were in the order of 5 and 2.5 μl ml -1 , respectively. Furthermore, this oil showed a S. epidermidis biofilm inhibition more than 57% at a concentration of 25 μl ml -1 . The eradication of 67% of the established biofilm was observed at a concentration of 50 μl ml -1 of ROEO, whereas the dose of 25 μl ml -1 removed only 38% of preformed biofilm. ROEO strongly inhibited the proliferation of Hela and MCF-7 cells with IC 50 values of 0.011 and 0.253 μl ml -1 , respectively. Our results demonstrate that ROEO could have a potential role in the treatment of diseases related to infection by microorganisms or proliferation of cancer cells.

Evaluation of a New System, VITEK 2, for Identification and Antimicrobial Susceptibility Testing of Enterococci

PubMed Central

Garcia-Garrote, Fernando; Cercenado, Emilia; Bouza, Emilio

2000-01-01

We evaluated the new automated VITEK 2 system (bioMérieux) for the identification and antimicrobial susceptibility testing of enterococci. The results obtained with the VITEK 2 system were compared to those obtained by reference methods: standard identification by the scheme of Facklam and Sahm [R. R. Facklam and D. F. Sahm, p. 308–314, in P. R. Murray et al., ed., Manual of Clinical Microbiology, 6th ed., 1995] and with the API 20 STREP system and, for antimicrobial susceptibility testing, broth microdilution and agar dilution methods by the procedures of the National Committee for Clinical Laboratory Standards. The presence of vanA and vanB genes was determined by PCR. A total of 150 clinical isolates were studied, corresponding to 60 Enterococcus faecalis, 55 Enterococcus faecium, 26 Enterococcus gallinarum, 5 Enterococcus avium, 2 Enterococcus durans, and 2 Enterococcus raffinosus isolates. Among those isolates, 131 (87%) were correctly identified to the species level with the VITEK 2 system. Approximately half of the misidentifications were for E. faecium with low-level resistance to vancomycin, identified as E. gallinarum or E. casseliflavus; however, a motility test solved the discrepancies and increased the agreement to 94%. Among the strains studied, 66% were vancomycin resistant (57 VanA, 16 VanB, and 26 VanC strains), 23% were ampicillin resistant (MICs, ≥16 μg/ml), 31% were high-level gentamicin resistant, and 45% were high-level streptomycin resistant. Percentages of agreement for susceptibility and resistance to ampicillin, vancomycin, and teicoplanin and for high-level gentamicin resistance and high-level streptomycin resistance were 93, 95, 97, 97, and 96%, respectively. The accuracy of identification and antimicrobial susceptibility testing of enterococci with the VITEK 2 system, together with the significant reduction in handling time, will have a positive impact on the work flow of the clinical microbiology laboratory. PMID:10834961

In Vitro Antifungal Susceptibility of Neoscytalidium dimidiatum Clinical Isolates from Malaysia.

PubMed

James, Jasper Elvin; Santhanam, Jacinta; Lee, Mei Chen; Wong, Choon Xian; Sabaratnam, Parameswari; Yusoff, Hamidah; Tzar, Mohd Nizam; Razak, Mohd Fuat Abdul

2017-04-01

Neoscytalidium dimidiatum is an opportunistic fungus causing cutaneous infections mostly, which are difficult to treat due to antifungal resistance. In Malaysia, N. dimidiatum is associated with skin and nail infections, especially in the elderly. These infections may be mistaken for dermatophyte infections due to similar clinical appearance. In this study, Neoscytalidium isolates from cutaneous specimens, identified using morphological and molecular methods (28 Neoscytalidium dimidiatum and 1 Neoscytalidium sp.), were evaluated for susceptibility towards antifungal agents using the CLSI broth microdilution (M38-A2) and Etest methods. Amphotericin B, voriconazole, miconazole and clotrimazole showed high in vitro activity against all isolates with MIC ranging from 0.0313 to 1 µg/mL. Susceptibility towards fluconazole and itraconazole was noted in up to 10% of isolates, while ketoconazole was inactive against all isolates. Clinical breakpoints for antifungal drugs are not yet available for most filamentous fungi, including Neoscytalidium species. However, the results indicate that clinical isolates of N. dimidiatum in Malaysia were sensitive towards miconazole, clotrimazole, voriconazole and amphotericin B, in vitro.

Synthesis, characterization, antibacterial activities and carbonic anhydrase enzyme inhibitor effects of new arylsulfonylhydrazone and their Ni(II), Co(II) complexes

NASA Astrophysics Data System (ADS)

Özdemir, Ümmühan Özmen; Arslan, Fatma; Hamurcu, Fatma

2010-01-01

Ethane sulfonic acide hydrazide ( esh: CH 3CH 2SO 2NHNH 2) derivatives as 5-methylsalicyl-aldehydeethanesulfonylhydrazone ( 5msalesh), 5-methyl-2-hydroxyacetophenoneethane sulfonylhydrazone ( 5mafesh) and their Ni(II), Co(II) complexes have been synthesized for the first time. The structure of these compounds has been investigated by elemental analysis, FT-IR, 1H NMR, 13C NMR, LC/MS, UV-vis spectrophotometric method, magnetic susceptibility, thermal studies and conductivity measurements. The antibacterial activities of synthesized compounds were studied against Gram positive bacteria; Staphylococcus aureus, Bacillus subtilis, Bacillus magaterium and Gram negative bacteria; Salmonella enteritidis, Escherichia coli by using the microdilution broth method. The biological activity screening showed that ligands have more activity than complexes against the tested bacteria. The inhibition activities of these compounds on carbonic anhydrase II (CA II) have been investigated by comparing IC 50 and Ki values and it has been found that 5msalesh and its complexes have more enzyme inhibition efficiency than other compounds.

Tuned apatitic materials: Synthesis, characterization and potential antimicrobial applications

NASA Astrophysics Data System (ADS)

Fierascu, Irina; Fierascu, Radu Claudiu; Somoghi, Raluca; Ion, Rodica Mariana; Moanta, Adriana; Avramescu, Sorin Marius; Damian, Celina Maria; Ditu, Lia Mara

2018-04-01

Inorganic antimicrobial materials can be viable for multiple applications (related to its use for new buildings with special requirements related to microbiological loading, such as hospital buildings and for consolidation of cultural heritage constructions); also the use of substituted hydroxyapatites for protection of stone artefacts against environmental factors (acidic rain) and biodeterioration it's an option to no longer use of toxic substances. This paper presents methods of synthesis and characterization of the material from the point of view of the obtained structures and final applications. The materials were characterized in terms of composition and morphology (using X-ray Diffraction, X-ray Fluorescence, Inductively coupled plasma-atomic emission spectrometry, Fourier Transform Infrared Spectroscopy, X-ray Photoelectron Spectroscopy, Surface area and pore size determination). Antimicrobial activity was tested against filamentous fungi strains and pathogenic bacteria strains, using both spot on lawn qualitative method (on agar medium) and serial microdilution quantitative method (in broth medium). Further, it was evaluated the anti-biofilm activity of the tested samples toward the most important microbial strains implicated in biofilm development, using crystal violet stained biofilms microtiter assay, followed by spectrophotometric quantitative evaluation.

Antimicrobial susceptibility monitoring of mastitis pathogens isolated from acute cases of clinical mastitis in dairy cows across Europe: VetPath results.

PubMed

Thomas, Valérie; de Jong, Anno; Moyaert, Hilde; Simjee, Shabbir; El Garch, Farid; Morrissey, Ian; Marion, Hervé; Vallé, Michel

2015-07-01

VetPath is an ongoing pan-European antimicrobial susceptibility monitoring programme collecting pathogens from diseased cattle, pigs and poultry not recently treated with antibiotics. Non-replicate milk samples were collected from cows with acute clinical mastitis in eight countries. Escherichia coli, Staphylococcus aureus and Streptococcus uberis were isolated by standardised methods. Antimicrobial susceptibility was determined in a central laboratory by CLSI broth microdilution methodology; results were interpreted using clinical breakpoints where available. Among E. coli (n=280), resistance to tetracycline (14.3%) and cefapirin (11.1%) were most common. Resistance to other β-lactam antibiotics was absent (ceftiofur) or very low (cefalexin, amoxicillin/clavulanic acid). The MIC90 of enrofloxacin and marbofloxacin was 0.03 and 0.06μg/mL, respectively, with 0.7% of strains displaying a deviating high MIC. Staphylococcus aureus (n=250) were susceptible to most antibiotics tested, although 36.0% were resistant to penicillin G. For other β-lactam antibiotics where a CLSI breakpoint was available, no resistance was detected. Tetracycline resistance was low (5.2%). Streptococcus uberis (n=282) were susceptible to all β-lactam antibiotics, although 29.8% were intermediately susceptible to penicillin G; 18.8% of strains were resistant to erythromycin and 28.7% to tetracycline. This European study shows that bacteria associated with acute clinical mastitis are susceptible to most antibiotics with the exception of penicillin G against S. aureus, and erythromycin and tetracycline against S. uberis. The results of this study should serve as a reference baseline. This work also highlights the urgent need to set additional clinical breakpoints for antibiotics frequently used to treat mastitis. Copyright © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

A multicenter surveillance of antimicrobial resistance in Serratia marcescens in Taiwan.

PubMed

Liou, Bo-Huang; Duh, Ruay-Wang; Lin, Yi-Tsung; Lauderdale, Tsai-Ling Yang; Fung, Chang-Phone

2014-10-01

Serratia marcescens is an important nosocomial pathogen and the characteristic property of resistance conferred by extended-spectrum beta-lactamase or a novel AmpC cephalosporinase was not unusual in Taiwan. This study investigated the trends in antimicrobial resistance in S. marcescens from a nationwide surveillance in Taiwan. S. marcescens isolates were collected biennially between 2002 and 2010 from medical centers and regional hospitals throughout Taiwan, as part of the Taiwan Surveillance of Antimicrobial Resistance program. Minimal inhibitory concentrations were determined by the Clinical and Laboratory Standards Institute reference broth microdilution method. A total of 403 nonduplicate S. marcescens isolates were collected, mostly from respiratory samples (157, 39.0%), followed by the urinary tract samples (90, 22.3%). Overall, 99.3% isolates were susceptible to imipenem, 93.8% to ceftazidime, 89.2% to minocycline, 87.8% to amikacin, 86.8% to cefepime, 82.9% to aztreonam, 73.2% to ceftriaxone, 72.7% to levofloxacin, 63.8% to ciprofloxacin, 60.8% to trimethoprim/sulfamethoxazole (TMP/SMX), and 59.6% to gentamicin. A significantly increased susceptibility rate after 2004 was observed for the following antibiotics: amikacin (73.8% vs. 97.1%), gentamicin (40.0% vs. 72.4%), ciprofloxacin (53.8% vs. 70.4%), ceftriaxone (53.8% vs. 86.0%), cefepime (74.4% vs. 95.1%), aztreonam (72.5% vs. 89.7%), and TMP/SMX (41.3% vs. 73.7%). In this 8-year study, the susceptibility of S. marcescens to ceftazidime and imipenem remained consistently high in Taiwan. S. marcescens isolates demonstrated relatively higher resistance to ciprofloxacin and levofloxacin, and therefore continued surveillance of antimicrobial resistance, especially for fluoroquinolone, is warranted. Copyright © 2013. Published by Elsevier B.V.

Synergistic effects of tacrolimus and azole antifungal compounds in fluconazole-susceptible and fluconazole-resistant Candida glabrata isolates.

PubMed

Denardi, Laura Bedin; Mario, Débora Alves Nunes; Loreto, Érico Silva; Santurio, Janio Morais; Alves, Sydney Hartz

2015-03-01

In vitro interaction between tacrolimus (FK506) and four azoles (fluconazole, ketoconazole, itraconazole and voriconazole) against thirty clinical isolates of both fluconazole susceptible and -resistant Candida glabrata were evaluated by the checkerboard microdilution method. Synergistic, indifferent or antagonism interactions were found for combinations of the antifungal agents and FK506. A larger synergistic effect was observed for the combinations of FK506 with itraconazole and voriconazole (43%), followed by that of the combination with ketoconazole (37%), against fluconazole-susceptible isolates. For fluconazole-resistant C. glabrata , a higher synergistic effect was obtained from FK506 combined with ketoconazole (77%), itraconazole (73%), voriconazole (63%) and fluconazole (60%). The synergisms that we observed in vitro , notably against fluconazole-resistant C. glabrata isolates, are promising and warrant further analysis of their applications in experimental in vivo studies.

Synthesis and antimicrobial activities of new higher amino acid Schiff base derivatives of 6-aminopenicillanic acid and 7-aminocephalosporanic acid

NASA Astrophysics Data System (ADS)

Özdemir (nee Güngör), Özlem; Gürkan, Perihan; Özçelik, Berrin; Oyardı, Özlem

2016-02-01

Novel β-lactam derivatives (1c-3c) (1d-3d) were produced by using 6-aminopenicillanic acid (6-APA), 7-aminocephalosporanic acid (7-ACA) and the higher amino acid Schiff bases. The synthesized compounds were characterized by elemental analysis, IR, 1H/13C NMR and UV-vis spectra. Antibacterial activities of all the higher amino acid Schiff bases (1a-3a) (1b-3b) and β-lactam derivatives were screened against three gram negative bacteria (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Acinetobacter baumannii RSKK 02026), three gram positive bacteria (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 07005, Bacillus subtilis ATCC 6633) and their drug-resistant isolates by using broth microdilution method. Two fungi (Candida albicans and Candida krusei) were used for antifungal activity.

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

Composition and antimicrobial activity of Marrubium incanum Desr. (Lamiaceae) essential oil.

PubMed

Petrović, Silvana; Pavlović, Milica; Maksimović, Zoran; Milenković, Marina; Couladis, Maria; Tzakouc, Olga; Niketić, Marjan

2009-03-01

The essential oil from the aerial parts of Marrubium incanum Desr. (Lamiaceae), obtained by hydrodistillation, was analyzed by GC and GC-MS. Forty-six compounds were identified, representing 96.3% of the total oil. The main components of the oil were (E)-caryophyllene (27.0%), germacrene D (26.2%) and bicyclogermacrene (11.5%). The microbial growth inhibitory properties of the isolated essential oil were determined using the agar diffusion and broth microdilution method against seven bacterial species (Staphylococcus aureus ATCC 25923, S. epidermidis ATCC 12228, Micrococcus flavus ATCC 10240, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Klebsiella pneumoniae NCIMB 9111, and Pseudomonas aeruginosa ATCC 27853), and two strains of the yeast Candida albicans (ATCC 10259 and ATCC24433). The essential oil showed activity against all the microorganisms tested, but differences in microbial susceptibility were registered.

Species identification and susceptibility to 17 antibiotics of coagulase-negative staphylococci isolated from clinical specimens.

PubMed

Marsik, F J; Brake, S

1982-04-01

A total of 299 isolates of gram-positive, catalase-positive, coagulase-negative cocci were isolated from a variety of specimens collected from patients at a large university hospital, and 281 (94%) were identified as staphylococci by established methods. Using the scheme of Kloos and Schleifer, we determined the species of the coagulase-negative staphylococci. Staphylococcus epidermidis was the cause of all bacteremias and the most commonly isolated species from bone, joint, and wound infections. Staphylococcus haemolyticus was the second most common isolate from wound infections, and Staphylococcus saprophyticus was the most commonly isolated species from urinary tract infections. Antibiograms to 17 antimicrobial agents were performed by a microdilution technique, and the results revealed that S. epidermidis was resistant to a water spectrum of antimicrobial agents than the other species of staphylococci were.

Species identification and susceptibility to 17 antibiotics of coagulase-negative staphylococci isolated from clinical specimens.

PubMed Central

Marsik, F J; Brake, S

1982-01-01

A total of 299 isolates of gram-positive, catalase-positive, coagulase-negative cocci were isolated from a variety of specimens collected from patients at a large university hospital, and 281 (94%) were identified as staphylococci by established methods. Using the scheme of Kloos and Schleifer, we determined the species of the coagulase-negative staphylococci. Staphylococcus epidermidis was the cause of all bacteremias and the most commonly isolated species from bone, joint, and wound infections. Staphylococcus haemolyticus was the second most common isolate from wound infections, and Staphylococcus saprophyticus was the most commonly isolated species from urinary tract infections. Antibiograms to 17 antimicrobial agents were performed by a microdilution technique, and the results revealed that S. epidermidis was resistant to a water spectrum of antimicrobial agents than the other species of staphylococci were. PMID:7068839

Antibacterial, antifungal, and antiviral activities of the lipophylic extracts of Pistacia vera.

PubMed

Ozçelik, Berrin; Aslan, Mustafa; Orhan, Ilkay; Karaoglu, Taner

2005-01-01

In the present study, antibacterial, antifungal, and antiviral properties of 15 lipohylic extracts obtained from different parts (leaf, branch, stem, kernel, shell skins, seeds) of Pistacia vera were screened against both standard and the isolated strains of Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, Candida albicans and C. parapsilosis by microdilution method. Both Herpes simplex (DNA) and Parainfluenza viruses (RNA) were used for the determination of antiviral activity of the P. vera extracts by using Vero cell line. Ampicilline, ofloxocine, ketoconazole, fluconazole, acyclovir and oseltamivir were used as the control agents. The extracts showed little antibacterial activity between the range of 128-256 microg/ml concentrations whereas they had noticeable antifungal activity at the same concentrations. Kernel and seed extracts showed significant antiviral activity compared to the rest of the extracts as well as the controls.

In Vitro Activities of 35 Double Combinations of Antifungal Agents against Scedosporium apiospermum and Scedosporium prolificans▿

PubMed Central

Cuenca-Estrella, Manuel; Alastruey-Izquierdo, Ana; Alcazar-Fuoli, Laura; Bernal-Martinez, Leticia; Gomez-Lopez, Alicia; Buitrago, Maria J.; Mellado, Emilia; Rodriguez-Tudela, Juan L.

2008-01-01

Activities of 35 combinations of antifungal agents against Scedosporium spp. were analyzed by a checkerboard microdilution design and the summation of fractional concentration index. An average indifferent effect was detected apart from combinations of azole agents and echinocandins against Scedosporium apiospermum. Antagonism was absent for all antifungal combinations against both species. PMID:18195067

Clinical Trichophyton rubrum Strain Exhibiting Primary Resistance to Terbinafine

PubMed Central

Mukherjee, Pranab K.; Leidich, Steven D.; Isham, Nancy; Leitner, Ingrid; Ryder, Neil S.; Ghannoum, Mahmoud A.

2003-01-01

The in vitro antifungal susceptibilities of six clinical Trichophyton rubrum isolates obtained sequentially from a single onychomycosis patient who failed oral terbinafine therapy (250 mg/day for 24 weeks) were determined by broth microdilution and macrodilution methodologies. Strain relatedness was examined by random amplified polymorphic DNA (RAPD) analyses. Data obtained from both broth micro- and macrodilution assays were in agreement and revealed that the six clinical isolates had greatly reduced susceptibilities to terbinafine. The MICs of terbinafine for these strains were >4 μg/ml, whereas they were <0.0002 μg/ml for the susceptible reference strains. Consistent with these findings, the minimum fungicidal concentrations (MFCs) of terbinafine for all six strains were >128 μg/ml, whereas they were 0.0002 μg/ml for the reference strain. The MIC of terbinafine for the baseline strain (cultured at the initial screening visit and before therapy was started) was already 4,000-fold higher than normal, suggesting that this is a case of primary resistance to terbinafine. The results obtained by the broth macrodilution procedure revealed that the terbinafine MICs and MFCs for sequential isolates apparently increased during the course of therapy. RAPD analyses did not reveal any differences between the isolates. The terbinafine-resistant isolates exhibited normal susceptibilities to clinically available antimycotics including itraconazole, fluconazole, and griseofulvin. However, these isolates were fully cross resistant to several other known squalene epoxidase inhibitors, including naftifine, butenafine, tolnaftate, and tolciclate, suggesting a target-specific mechanism of resistance. This is the first confirmed report of terbinafine resistance in dermatophytes. PMID:12499173

Antimicrobial activity and determination of bioactive components from marine Alcaligenes faecalis extract against a sulfate-reducing bacteria

NASA Astrophysics Data System (ADS)

AbdSharad, Ali; Usup, Gires; Sahrani, Fathul Karim; Ahmad, Asmat

2016-11-01

Biogenic souring and microbial-influenced corrosion is a common scenario in petroleum reservoir. The serious threat normally comes from sulfate-reducing bacteria (SRB). Alcaligenes faecalis was tested in this study for the ability to inhibit the growth of SRB. Ethyl acetate extraction of A. faecalis grown in marine broth was carried out to produce crude ethyl acetate of A. faecalis (CEAF). CEAF was diluted at concentrations 0.2-12.8 mg/mL and was tested for anti-microbial activity by microdilution susceptibility tests in 96-wells plate. CEAF was then analyzed by Gas Chromatography Mass Spectrometry (GC-MS). The microdilution susceptibility tests showed that the crude have anti- microbial activities on SRB. CEAF showed immediate killing effect against SRB in liquid medium which suggest the presence of active chemical compounds with antimicrobial activity. The GC-MS analysis showed the presence of 20 different chemical compounds in CEAF, The major components in CEAF can be related to antimicrobial, antifungal, antioxidant, pesticide, metabolism, toxicity, anticancer and corrosion inhibition activities. In conclusion, crude ethyl acetate extract of A. faecalis has the ability to inhibit SRB growth.

[Do different interpretative methods used for evaluation of checkerboard synergy test affect the results?].

PubMed

Ozseven, Ayşe Gül; Sesli Çetin, Emel; Ozseven, Levent

2012-07-01

In recent years, owing to the presence of multi-drug resistant nosocomial bacteria, combination therapies are more frequently applied. Thus there is more need to investigate the in vitro activity of drug combinations against multi-drug resistant bacteria. Checkerboard synergy testing is among the most widely used standard technique to determine the activity of antibiotic combinations. It is based on microdilution susceptibility testing of antibiotic combinations. Although this test has a standardised procedure, there are many different methods for interpreting the results. In many previous studies carried out with multi-drug resistant bacteria, different rates of synergy have been reported with various antibiotic combinations using checkerboard technique. These differences might be attributed to the different features of the strains. However, different synergy rates detected by checkerboard method have also been reported in other studies using the same drug combinations and same types of bacteria. It was thought that these differences in synergy rates might be due to the different methods of interpretation of synergy test results. In recent years, multi-drug resistant Acinetobacter baumannii has been the most commonly encountered nosocomial pathogen especially in intensive-care units. For this reason, multidrug resistant A.baumannii has been the subject of a considerable amount of research about antimicrobial combinations. In the present study, the in vitro activities of frequently preferred combinations in A.baumannii infections like imipenem plus ampicillin/sulbactam, and meropenem plus ampicillin/sulbactam were tested by checkerboard synergy method against 34 multi-drug resistant A.baumannii isolates. Minimum inhibitory concentration (MIC) values for imipenem, meropenem and ampicillin/sulbactam were determined by the broth microdilution method. Subsequently the activity of two different combinations were tested in the dilution range of 4 x MIC and 0.03 x MIC in 96-well checkerboard plates. The results were obtained separately using the four different interpretation methods frequently preferred by researchers. Thus, it was aimed to detect to what extent the rates of synergistic, indifferent and antagonistic interactions were affected by different interpretation methods. The differences between the interpretation methods were tested by chi-square analysis for each combination used. Statistically significant differences were detected between the four different interpretation methods for the determination of synergistic and indifferent interactions (p< 0.0001). Highest rates of synergy were observed with both combinations by the method that used the lowest fractional inhibitory concentration index of all the non-turbid wells along the turbidity/non-turbidity interface. There was no statistically significant difference between the four methods for the detection of antagonism (p> 0.05). In conclusion although there is a standard procedure for checkerboard synergy testing it fails to exhibit standard results owing to different methods of interpretation of the results. Thus, there is a need to standardise the interpretation method for checkerboard synergy testing. To determine the most appropriate method of interpretation further studies investigating the clinical benefits of synergic combinations and additionally comparing the consistency of the results obtained from the other standard combination tests like time-kill studies, are required.

Effect of Polysorbate 80 on Oritavancin Binding to Plastic Surfaces: Implications for Susceptibility Testing▿

PubMed Central

Arhin, Francis F.; Sarmiento, Ingrid; Belley, Adam; McKay, Geoffrey A.; Draghi, Deborah C.; Grover, Parveen; Sahm, Daniel F.; Parr, Thomas R.; Moeck, Gregory

2008-01-01

Oritavancin, a semisynthetic lipoglycopeptide with activity against gram-positive bacteria, has multiple mechanisms of action, including the inhibition of cell wall synthesis and the perturbation of the membrane potential. Approved guidelines for broth microdilution MIC assays with dalbavancin, another lipoglycopeptide, require inclusion of 0.002% polysorbate 80. To investigate the potential impact of polysorbate 80 on oritavancin susceptibility assays, we quantified the recovery of [14C]oritavancin from susceptibility assay plates with and without polysorbate 80 and examined the effect of the presence of polysorbate 80 on the oritavancin MICs for 301 clinical isolates from the genera Staphylococcus, Enterococcus, and Streptococcus. In the absence of polysorbate 80, [14C]oritavancin was rapidly lost from solution in susceptibility assay test plates: 9% of the input drug was recovered in broth at 1 h when [14C]oritavancin was tested at 1 μg/ml. Furthermore, proportionately greater losses were observed at lower oritavancin concentrations, suggesting saturable binding of oritavancin to surfaces. The inclusion of 0.002% polysorbate 80 or 2% lysed horse blood permitted the recovery of 80 to 100% [14C]oritavancin at 24 h for all drug concentrations tested. Concordantly, oritavancin MIC90s for streptococcal isolates, as determined in medium containing 2% lysed horse blood, were identical with and without polysorbate 80. In stark contrast, polysorbate 80 reduced the oritavancin MIC90s by 16- to 32-fold for clinical isolates of enterococci and staphylococci, which are typically cultured without blood. The results presented here provide evidence that the MIC data for oritavancin in the current literature significantly underestimate the potency of oritavancin in vitro. Moreover, the combination of data from MIC and [14C]oritavancin recovery studies supports the revision of the oritavancin broth microdilution method to include polysorbate 80 throughout the assay. PMID:18299406

Antibacterial, antifungal and antioxidant activity of Olea africana against pathogenic yeast and nosocomial pathogens.

PubMed

Masoko, Peter; Makgapeetja, David M

2015-11-17

Olea africana leaves are used by Bapedi people to treat different ailments. The use of these leaves is not validated, therefore the aim of this study is to validate antimicrobial properties of this plant. The ground leaves were extracted using solvents of varying polarity (hexane, chloroform, dichloromethane (DCM), ethyl acetate, acetone, ethanol, methanol, butanol and water). Thin layer chromatography (TLC) was used to analyse the chemical constituents of the extracts. The TLC plates were developed in three different solvent systems, namely, benzene/ethanol/ammonium solution (BEA), chloroform/ethyl acetate/formic acid (CEF) and ethyl acetate/methanol/water (EMW). The micro-dilution assay and bioautography method were used to evaluate the antibacterial activity of the extracts against Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis and Staphylococcus aureus and the antifungal activity against Candida albicans and Cryptococcus neoformans. Methanol was the best extractant, yielding a larger amount of plant material whereas hexane yielded the least amount. In phytochemical analyses, more compounds were observed in BEA, followed by EMW and CEF. Qualitative 2, 2- diphenylpacryl-1-hydrazyl (DPPH) assay displayed that all the extracts had antioxidant activity. Antioxidant compounds could not be separated using BEA solvent system while with CEF and EMW enabled antioxidant compounds separation. The minimum inhibitory concentrations (MIC) values against test bacteria ranged between 0.16 and 2.50 mg/mL whereas against fungi, MIC ranged from 0.16 to 0.63 mg/mL. Bioautography results demonstrated that more than one compound was responsible for antimicrobial activity in the microdilution assay as the compounds were located at different Rf values. The results indicate that leaf extracts of Olea africana contain compounds with antioxidant, antibacterial and antifungal activities. Therefore, further studies are required to isolate the active compounds and perform other tests such as cytotoxicity. Olea africana may be a potential source of antimicrobial compounds.

Anti-anaerobic activity of levofloxacin alone and combined with clindamycin and metronidazole.

PubMed

Credito, K L; Jacobs, M R; Appelbaum, P C

2000-11-01

Microdilution MICs of levofloxacin against twelve anaerobes ranged between 0.5-8.0 microg/ml and those of clindamycin and metronidazole between 0.008-2.0 and 0.25->16.0 microg/ml, respectively. Combination of levofloxacin with clindamycin and/or metronidazole in time-kill tests led to synergy at levofloxacin concentrations at or below the MIC in 7/12 strains.

[In vitro activity of voriconazole and three other antifungal agents against dermatophytes].

PubMed

Serrano-Martino, María del Carmen; Chávez-Caballero, Mónica; Valverde-Conde, Anastasio; Claro, Rosa María; Pemán, Javier; Martín-Mazuelos, Estrella

2003-11-01

The increase in infections due to dermatophytes in recent years led us to study the effectiveness of new antifungal formulations against these microorganisms. The in vitro activity of a new antifungal agent, voriconazole, was compared with three other antifungal agents, itraconazole, fluconazole and terbinafine, against 120 dermatophytes belonging to four species (61 Trichophyton mentagrophytes, 34 Microsporum canis, 13 M. gypseum and 12 T. rubrum). A broth microdilution method was used following the recommendations of the NCCLS document M38-P with some modifications. Terbinafine was the most active agent against the dermatophytes studied (MIC90 < or = 0.03 mg/ml), followed by voriconazole (MIC90, 0.25 micro g/ml) and itraconazole (MIC90, 0.5 micro g/ml). Fluconazole was the least active antifungal agent. The most susceptible species was M. canis. Voriconazole was found to have effective activity against dermatophytes.

Chemical compositions and antibacterial activity of the leaf and stem oils of Piper porphyrophyllum (Lindl.) N.E. Br.

PubMed Central

Salleh, Wan Mohd Nuzul Hakimi Wan; Ahmad, Farediah; Sirat, Hasnah Mohd; Yen, Khong Heng

2012-01-01

The essential oils obtained by hydrodistillation from the fresh leaf and stem of Piper porphyrophyllum N.E. Br. were analyzed by GC and GC/MS. Thirty four constituents were identified in the leaf oil, while thirty eight constituents were identified in the stems oil. The most abundant components in the leaf oil included bicyclogermacrene (14.7 %), α-copaene (13.2 %) and β-phellandrene (9.5 %) while sabinene (15.5 %), bicyclogermacrene (12.3 %) and α-copaene (8.1 %) were the main constituents in the stem oil. The evaluation of antibacterial activity by using micro-dilution method revealed that both oils were moderately active against all the Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis) and Gram-negative bacteria (Pseudomonas aeruginosa, Pseudomonas putida and Escherichia coli) with minimum inhibitory concentration (MIC) values in the range 125-1000 µg/ml. PMID:27418915

Antimicrobial and antifungal activities of the extracts and essential oils of Bidens tripartita.

PubMed

Tomczykowa, Monika; Tomczyk, Michał; Jakoniuk, Piotr; Tryniszewska, Elzbieta

2008-01-01

The aim of this study was to determine the antibacterial and antifungal properties of the extracts, subextracts and essential oils of Bidens tripartita flowers and herbs. In the study, twelve extracts and two essential oils were investigated for activity against different Gram-positive Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, Gram-negative bacteria Escherichia coli, E. coli (beta-laktamase+), Klebsiella pneumoniae (ESBL+), Pseudomonas aeruginosa and some fungal organisms Candida albicans, C. parapsilosis, Aspergillus fumigatus, A. terreus using a broth microdilution and disc diffusion methods. The results obtained indicate antimicrobial activity of the tested extracts (except butanolic extracts), which however did not inhibit the growth of fungi used in this study. Bacteriostatic effect of both essential oils is insignificant, but they have strong antifungal activity. These results support the use of B. tripartita to treat a microbial infections and it is indicated as an antimicrobial and antifungal agent, which may act as pharmaceuticals and preservatives.

[Fluconazole and itraconazole susceptibility testing with clinical yeast isolates and algae of the genus Prototheca by means of the Etest].

PubMed

Blaschke-Hellmessen, R

1996-01-01

Preliminary own results suggest, that the Etest (produced by AB BIODISK, Solna, Sweden) performed on casitone medium meets the requirements of a routine test of yeast susceptibility to fluconazole and itraconazole. Testing of 46 clinical yeast isolates, of 5 strains of Exophiala dermatitidis and 4 strains of algae of the genus Prototheca revealed species-, genus- and strain-specific variations of the susceptibility to fluconazole and itraconazole. Candida glabrata was less susceptible to both triazoles than the other Candida species with exception of Candida krusei. Exophiala dermatitidis was highly susceptible to itraconazole. Prototheca wickerhamii and P. zopfii were resistant to both triazoles. Casitone medium is most appropriate for the determination of susceptibility to fluconazole and itraconazole by the Etest. The results of the Etest were comparable with those of a breakpoint test (microdilution method).

In Vitro Anti-Toxoplasma gondii and Antimicrobial Activity of Amides Derived from Cinnamic Acid.

PubMed

Silveira, Graziela Rangel; Campelo, Karoline Azerêdo; Lima, Gleice Rangel Silveira; Carvalho, Lais Pessanha; Samarão, Solange Silva; Vieira-da-Motta, Olney; Mathias, Leda; Matos, Carlos Roberto Ribeiro; Vieira, Ivo José Curcino; Melo, Edesio José Tenório de; Maria, Edmilson José

2018-03-28

Most cinnamic acids, their esters, amides, aldehydes, and alcohols present several therapeutic actions through anti-inflammatory, antitumor, and inhibitory activity against a great variety of microorganisms. In this work, eight amines derived from cinnamic acid were synthesized and tested against host cells infected with Toxoplasma gondii and the bacteria Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis, and three strains of Staphylococcus aureus . Compounds 3 and 4 showed the best result against intracellular T. gondii , presenting antiparasitic activity at low concentrations (0.38 and 0.77 mM). The antibacterial activity of these compounds was also evaluated by the agar microdilution method, and amides 2 and 5 had a minimum inhibitory concentration of 250 µg mL -1 against two strains of S. aureus (ATCC 25923 and bovine strain LSA 88). These also showed synergistic action along with a variety of antibiotics, demonstrating that amines derived from cinnamic acid have potential as pharmacological agents.

Antimicrobial susceptibility of Actinobacillus pleuropneumoniae isolates from clinical outbreaks of porcine respiratory diseases.

PubMed

Kucerova, Z; Hradecka, H; Nechvatalova, K; Nedbalcova, K

2011-05-12

Limited data regarding the susceptibility of Actinobacillus pleuropneumoniae to antimicrobials has been published during recent years. Accordingly, the aim of the present study was to investigate the distribution of MICs for the isolates of A. pleuropneumoniae from diseased pigs in the Czech Republic between 2007 and 2009. A total of 242 isolates were tested for susceptibility to 16 antimicrobial agents by a broth microdilution method. A low degree of resistance was observed for florfenicol (0.8%), amoxicillin and clavulanic acid (0.8%), tilmicosin (1.2%), tiamulin (1.7%) and ampicillin (3.3%), whereas resistance to tetracycline was detected more frequently, 23.9% of isolates. Interestingly, resistance to florfenicol has not yet been reported in any study investigating antimicrobial resistance of A. pleuropneumoniae. By PCR the presence of the floR gene was confirmed in all florfenicol resistant isolates. Copyright © 2011 Elsevier B.V. All rights reserved.

Evaluation of antimicrobial activity of extracts of Tibouchina candolleana (melastomataceae), isolated compounds and semi-synthetic derivatives against endodontic bacteria.

PubMed

Dos Santos, Fernanda M; de Souza, Maria Gorete; Crotti, Antônio E Miller; Martins, Carlos H G; Ambrósio, Sérgio R; Veneziani, Rodrigo C S; E Silva, Márcio L Andrade; Cunha, Wilson R

2012-04-01

This work describes the phytochemical study of the extracts from aerial parts of Tibouchina candolleana as well as the evaluation of the antimicrobial activity of extracts, isolated compounds, and semi-synthetic derivatives of ursolic acid against endodontic bacteria. HRGC analysis of the n-hexane extract of T. candolleana allowed identification of β-amyrin, α-amyrin, and β-sitosterol as major constituents. The triterpenes ursolic acid and oleanolic acid were isolated from the methylene chloride extract and identified. In addition, the flavonoids luteolin and genistein were isolated from the ethanol extract and identified. The antimicrobial activity was investigated via determination of the minimum inhibitory concentration (MIC) using the broth microdilution method. Amongst the isolated compounds, ursolic acid was the most effective against the selected endodontic bacteria. As for the semi-synthetic ursolic acid derivatives, only the methyl ester derivative potentiated the activity against Bacteroides fragilis.

Evaluation of antimicrobial activity of extracts of Tibouchina candolleana (melastomataceae), isolated compounds and semi-synthetic derivatives against endodontic bacteria

PubMed Central

dos Santos, Fernanda M.; de Souza, Maria Gorete; Crotti, Antônio E. Miller; Martins, Carlos H. G.; Ambrósio, Sérgio R.; Veneziani, Rodrigo C. S.; e Silva, Márcio L. Andrade; Cunha, Wilson R.

2012-01-01

This work describes the phytochemical study of the extracts from aerial parts of Tibouchina candolleana as well as the evaluation of the antimicrobial activity of extracts, isolated compounds, and semi-synthetic derivatives of ursolic acid against endodontic bacteria. HRGC analysis of the n-hexane extract of T. candolleana allowed identification of β-amyrin, α-amyrin, and β-sitosterol as major constituents. The triterpenes ursolic acid and oleanolic acid were isolated from the methylene chloride extract and identified. In addition, the flavonoids luteolin and genistein were isolated from the ethanol extract and identified. The antimicrobial activity was investigated via determination of the minimum inhibitory concentration (MIC) using the broth microdilution method. Amongst the isolated compounds, ursolic acid was the most effective against the selected endodontic bacteria. As for the semi-synthetic ursolic acid derivatives, only the methyl ester derivative potentiated the activity against Bacteroides fragilis. PMID:24031892

Antimicrobial susceptibility pattern of Brachyspira intermedia isolates from European layers.

PubMed

Verlinden, Marc; Boyen, Filip; Pasmans, Frank; Garmyn, An; Haesebrouck, Freddy; Martel, An

2011-09-01

A broth microdilution method was used to determine the antimicrobial susceptibility of 20 Brachyspira intermedia isolates obtained from different layer flocks in Belgium and The Netherlands between 2008 and 2010. The antimicrobial agents used were tylosin, tilmicosin, tiamulin, valnemulin, doxycycline, and lincomycin. The minimal inhibitory concentration (MIC) distribution patterns of tylosin, tilmicosin, lincomycin, and doxycycline were bimodal, demonstrating acquired resistance against doxycycline in three strains, against the macrolides in two strains, and against lincomycin in one strain. The MICs of tiamulin and valnemulin showed a monomodal distribution, but with tailing toward the higher MIC values, possibly suggesting low-level acquired resistance in six isolates. Sequencing revealed a G1058C mutation in the 16S rRNA gene in all doxycycline-resistant strains. The strain resistant to tylosin, tilmicosin, and lincomycin had an A2058T mutation in the 23S rRNA gene.

Streptococcus pneumoniae: distribution of serotypes and antimicrobial susceptibility in patients with cancer.

PubMed

Soto-Noguerón, Araceli; Carnalla-Barajas, María Noemí; Cornejo-Juárez, Patricia; Volkow-Fernández, Patricia; Velázquez-Meza, María Elena; Echániz-Aviles, Gabriela

2018-01-01

To describe the distribution of pneumococcal serotypes causing infectious diseases in patients with hematological malignancies and solid tumors and their antimicrobial susceptibility before and after introduction of pneumococcal conjugate vaccine (PCV7) in Mexico. Consecutive pneumococcal isolates from hospitalized patients from the SIREVA-network were serotyped using the Quellung reaction and antimicrobial susceptibility was performed using the broth microdilution method. A total of 175 pneumococcal isolates were recovered, 105 from patients with hematological malignancies and 70 with solid tumors. Serotypes 19A (22.7%), 19F (20.4%), and 35B (17.7%) were the most frequent isolates in the first group and serotypes 3 (27.2%) and 19A (28.6%) in the second group. No decreased susceptibility to beta-lactams or TMP/SMX was observed after introduction of PCV7. An increase in non-vaccine types is observed without significate changes in antimicrobial susceptibility after introduction of PCV7.

Antioxidant Content, Antioxidant Activity, and Antibacterial Activity of Five Plants from the Commelinaceae Family

PubMed Central

Tan, Joash Ban Lee; Yap, Wei Jin; Tan, Shen Yeng; Lim, Yau Yan; Lee, Sui Mae

2014-01-01

Commelinaceae is a family of herbaceous flowering plants with many species used in ethnobotany, particularly in South America. However, thus far reports of their bioactivity are few and far between. The primary aim of this study was to quantify the antioxidant and antibacterial activity of five Commelinaceae methanolic leaf extracts. The antioxidant content was evaluated by the total phenolic content (TPC), total tannin content (TTC), and total flavonoid content (TFC) assays. The antioxidant activities measured were DPPH free radical scavenging (FRS), ferric reducing power (FRP), and ferrous ion chelating (FIC); of the five plants, the methanolic leaf extract of Tradescantia zebrina showed the highest antioxidant content and activity, and exhibited antibacterial activity against six species of Gram-positive and two species of Gram-negative bacteria in a range of 5–10 mg/mL based on the broth microdilution method. PMID:26785239

Multidrug resistant bacteria are sensitive to Euphorbia prostrata and six others Cameroonian medicinal plants extracts.

PubMed

Voukeng, Igor K; Beng, Veronique P; Kuete, Victor

2017-07-25

Multidrug resistant (MDR) bacteria are responsible for therapeutic failure and there is an urgent need for novels compounds efficient on them. Eleven methanol extracts from seven Cameroonian medicinal plants were tested for their antibacterial activity using broth micro-dilution method against 36 MDR bacterial strains including Escherichia coli, Enterobacter aerogenes, Enterobacter cloacae, Klebsiella pneumoniae, Providencia stuartii, Pseudomonas aeruginosa and Staphylococcus aureus. Euphorbia prostrata extract was found active against all the 36 tested bacteria including Gram-negative phenotypes over-expressing efflux pumps such as P. aeruginosa PA124, E. aerogenes CM64 and E. coli AG102. E. prostrata had minimal inhibitory concentrations values between 128 and 256 µg/mL on 55.55% of the studied microorganisms. Other plants extract displayed selective antibacterial activity. Results obtained in this study highlight the antibacterial potential of the tested plants and the possible use of E. prostrata to combat bacterial infections including MDR phenotypes.

CHROMagar Candida Medium for Direct Susceptibility Testing of Yeast from Blood Cultures

PubMed Central

Tan, Grace L.; Peterson, Ellena M.

2005-01-01

An evaluation was performed on 95 blood cultures positive for Candida spp. to determine the correlation of direct susceptibility testing of fluconazole versus both standardized disk diffusion and MIC methods. For direct testing, an aliquot taken from BD BACTEC Plus and/or BD BACTEC Lytic/10 bottles (Becton Dickinson [BD], Sparks, MD) positive by gram stain for yeast was subcultured to CHROMagar Candida (BD), and a 25-μg fluconazole disk (BD) was placed on the plate. The area of growth inhibition surrounding the disk was measured at 24 and 48 h. In addition, a subculture of the isolate was tested by a microdilution MIC using YeastOne (TREK Diagnostics Systems Inc., OH) and disk diffusion (NCCLS M44-A) using a standardized inoculum plated onto CHROMagar Candida as well as Mueller-Hinton agar to which 2% glucose and 0.5 μg/ml methylene blue dye was added (MH-GMB). The categorical interpretation derived from the MIC was used as the reference to which the disk diffusion results were compared. There were a total of 41 Candida albicans, 23 Candida glabrata, 20 Candida parapsilosis, 9 Candida tropicalis, and 1 each of Candida krusei and Candida lusitaniae tested. At 24 h there was full agreement among the methods for all C. albicans, C. tropicalis, C. lusitaniae, and C. krusei isolates. For the C. parapsilosis isolates at 24 h there was one very major discrepancy using the direct CHROMagar and one major error with the standardized MH-GMB. The majority of the errors were seen at 24 h with the C. glabrata isolates. Of the 23 C. glabrata isolates at 24 h by direct CHROMagar, there were 10 minor and 1 very major error; by MH-GMB there were 12 minor and 2 very major errors; and by standardized CHROMagar Candida there were 13 minor and 2 major errors. There were no very major errors with C. glabrata when all plates were read at 48 h. At 24 h by the direct and standardized CHROMagar the majority of C. glabrata isolates were more resistant, whereas by MH-GMB they were more susceptible than the reference MIC interpretation. In summary, subculturing yeast directly from blood cultures onto CHROMagar to which a fluconazole disk has been added may provide a presumptive identification at 24 h and, with the exception of C. glabrata, was able to predict the susceptibility to fluconazole with the majority of Candida isolates examined in this evaluation. PMID:15814992

Adherence of staphylococcus aureus to catheter tubing inhibition by quaternary ammonium compounds

PubMed Central

Iyamba, Jean-Marie Liesse; Okombe, Daniel Tassa; Zakanda, Francis Nsimba; Malongo, Trésor Kimbeni; Unya, Joseph Welo; Lukukula, Cyprien Mbundu; Kikuni, Ntondo za Balega Takaisi

2016-01-01

Introduction S. aureus is a Gram positive bacterium which is responsible for a wide range of infections. This pathogen has also the ability to adhere to biotic or abiotic surface such as central venous catheter (CVC) and to produce a biofilm. The aim of this study was to evaluate the effect of hexadecyltrimethyl ammonium bromide (HTAB) and Hexadecylbetainate chloride (HBC) on Staphylococcus aureus adherence to the catheter tubing and on bacteria growth. Methods Broth microdilution method was used to determine the Minimal Inhibitory Concentration (MIC). The detection of slime production was done by Congo Red Agar method, and the adherence of bacteria to the catheter tubing was evaluated by the enumeration of bacteria on plate counts. Results The results of this study showed that the MICs of HTAB were ranged from 0.125 to 0.5 µg/mL, and those of HBC fluctuated between 2 to 8 µg/mL. HTAB and HBC inhibited bacteria adhesion on the surface of the catheter tubing. Conclusion This study showed that HTAB and HBC can prevent the adherence of S. aureus strains to the surface of catheter tubing, suggesting that they could be used to prevent the risk of catheter related bloodstream infections. PMID:28250874

ANTIMICROBIAL AND ANTIBIOFILM EFFECTS OF EXTRACTS FROM TRAPA NATANS L., EVALUATION OF TOTAL PHENOLIC AND FLAVONOID CONTENTS AND GC-MS ANALYSIS.

PubMed

Radojevic, Ivana D; Vasic, Sava M; Dekic, Milan S; Radulovic, Niko S; Delic, Gorica T; Durdevic, Jelena S; Comic, Ljiljana R

2016-11-01

Research conducted in this study shows the applied in vitro antimicrobial and antibiofilm activity of the four extracts isolated from Trapa natans L. leaves. In this study, different methods were used (microdilution, tissue culture plate, different colorimetric methods, GC-FID and GC-MS analysis). While the water extract didn't show antibacterial activity, the acetone extract showed the strongest one. The same activity in the case of Pseudomonas aeruginosa (MIC was 313 μg/mL) was better than the activity of controls and it matched with antibiofilm activity. The effect of extracts was better on G+ bacteria (MICs were <78-625 μg/mL). For ethanol and ethyl acetate extracts all BIC values were better than MICs. Extracts showed a significant effect on Aspergillus restrictus (MICs were < 78/156 μg/mL). The GC and GC-MS analysis of the ethyl acetate extract revealed the identification of 22 compounds with (all E)-squalene (20.2%), n-alkanes and norlignan hinokiresinol among the most abundant ones. This is the first time that T. natans was studied using these methods.

Chromosomally Encoded mcr-5 in Colistin non-susceptible Pseudomonas aeruginosa.

PubMed

Snesrud, Erik; Maybank, Rosslyn; Kwak, Yoon I; Jones, Anthony R; Hinkle, Mary K; Mc Gann, Patrick

2018-05-29

Whole genome sequencing (WGS) of historical Pseudomonas aeruginosa clinical isolates identified a chromosomal copy of mcr-5 within a Tn 3 -like transposon in P. aeruginosa MRSN 12280. The isolate was non-susceptible to colistin by broth microdilution and genome analysis revealed no mutations known to confer colistin resistance. To the best of our knowledge, this is the first report of mcr in colistin non-susceptible P. aeruginosa .

Twenty-Five Year Epidemiology of Invasive Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates Recovered at a Burn Center

DTIC Science & Technology

2009-01-01

elements and tend to carry resis- tance determinants in addition to mecA. In addition to varying antimicrobial resistance, the presence of certain...Antimicrobial susceptibility testing BMD testing was performed using CLSI criteria to determine antimicrobial susceptibility, broth microdilution performed...minocycline, trimethoprim –sul- famethoxazole, ciprofloxacin, rifampin, tigecycline and gen- tamicin. Wells containing daptomycin were supplemented with 50 mg

Methicillin-Resistant Staphylococcus aureus in Wound Cultures Recovered from a Combat Support Hospital in Iraq

DTIC Science & Technology

2010-07-01

analyzed. Antimicrobial resistance testing was determined by broth microdilution and the BD Phoenix Automated Microbiology System. The genotypic pattern was... trimethoprim -sulfamethoxazole (94%), and clindamy- cin (94%). Of agents not typically recommended as monotherapy, 98% of isolates were susceptible to rifampin...was van- comycin (Table 1). The most active oral antistaphylococcal agents were tetracycline (95.2% of isolates susceptible) and trimethoprim

In vitro comparison of antimicrobial activity of aqueous decoction of Coriandrum sativum, and Dentol Drop with chlorhexidine on Streptococcus mutans.

PubMed

Moradian, Hamid; Bazargani, Abdollah; Rafiee, Azade; Nazarialam, Ali

2013-09-01

Dental caries is still remained as a major health problem. This problem has created a new interest to search for new antimicrobial agents from various sources including medicinal plants. Since limited data is available so far regarding the antibacterial effect of Coriandrum sativum seed and Dentol Drop against Streptococcus mutans, this study aims to assess this activity. This experimental study was conducted in Shiraz University of Medical Sciences. In vitro comparison of antimicrobial activity of aqueous decoction of Coriandrum sativum seed and Dentol drop with chlorhexidine against Streptococcus mutans was evaluated using disk diffusion and broth microdilution assays. Positive and negative controls were considered. The data was statistically analyzed by applying Kruskal-Wallis and Tukey post-hoc test to compare the groups using SPSS software (version 17). Dentol drop showed a remarkable antibacterial activity, in comparison with chlorhexidine, against S. mutans in the disk diffusion (p value = 0.005), and broth microdilution assays (p value = 0.0001). Based on the results of this study, Coriandrum sativum seed did not posses any antibacterial property. Coriandrum sativum seed showed no anti-Streptococcus mutans activity. Dentol drop exhibited a remarkable antibacterial activity against S. mutans when tested in vitro. Dentol drop can be further studied as a preventive measure for dental caries.

Performance of Vitek 2 for Antimicrobial Susceptibility Testing of Acinetobacter baumannii, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia with Vitek 2 (2009 FDA) and CLSI M100S 26th Edition Breakpoints

PubMed Central

Bobenchik, April M.; Deak, Eszter; Hindler, Janet A.; Charlton, Carmen L.

2016-01-01

ABSTRACT The performances of Vitek 2 AST-GN69 and AST-XN06 cards were compared to Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution (BMD) for 99 isolates of Pseudomonas aeruginosa, 26 Acinetobacter baumannii isolates, and 11 Stenotrophomonas maltophilia isolates. In total, 15 antimicrobials were evaluated, with 11 for P. aeruginosa, 14 for A. baumannii, and 2 for S. maltophilia. Categorical agreement (CA) was assessed using both Vitek 2 breakpoints and 2016 CLSI M100S 26th edition breakpoints. The essential agreement values for P. aeruginosa, A. baumannii, and S. maltophilia were 99.5%, 99.2%, and 100%, respectively. The CA values for P. aeruginosa, A. baumannii, and S. maltophilia were 94.1%, 92.7%, and 95.5%, respectively, by the Vitek 2 breakpoints, and 93.4%, 92.3%, and 95.5%, respectively, by the CLSI breakpoints. Overall, the Vitek 2 performance was comparable to that of BMD using both Vitek 2 breakpoints and 2016 CLSI M100S 26th edition breakpoints. Improved performance was noted for the reformulated piperacillin-tazobactam and imipenem found on the AST-GN69 card, with no very major or major errors noted when using the CLSI breakpoints. PMID:27881616

Antibiotic susceptibility of 259 Listeria monocytogenes strains isolated from food, food-processing plants and human samples in Germany.

PubMed

Noll, Matthias; Kleta, Sylvia; Al Dahouk, Sascha

2017-12-26

The objective of this study was to evaluate the susceptibility of 259 Listeria monocytogenes strains isolated from food and food-processing environments and patient samples in Germany to 14 antibiotics widely used in veterinary and human medicine. L. monocytogenes strains were isolated mainly from milk and milk products and classified according to their molecular serotypes IIa (n=112), IIb (n=41), IIc (n=36), IVa (n=1), IVb (n=66), and IVb-v1 (n=3). Susceptibility tests were performed by using the automated 96-well based microdilution system Micronaut-S. Ampicillin, benzylpenicillin, ceftriaxone, ciprofloxacin, daptomycin, erythromcyin, gentamicin, linezolid, meropenem, rifampicin, tetracycline, tigecycline, trimethoprim/sulfamethoxazole and vancomycin were tested in at least five different concentrations. Among the 259 strains under study, 145 strains revealed multidrug-resistance (resistance to ≥3 antibiotics) and predominantly belonged to serotype IV (59%). Strains were mainly resistant to daptomycin, tigecycline, tetracycline, ciprofloxacin, ceftriaxone, trimethropim/sulfamethoxazole and gentamicin. Antibiotic resistance in general and multidrug-resistance in particular were more prevalent in L. monocytogenes strains isolated in Germany compared to similar reference stocks from other European countries and the USA but similar to stocks from China. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Antibacterial activity of ethanolic extracts of some Vietnamese medicinal plants against Helicobacter pylori

NASA Astrophysics Data System (ADS)

Ngan, Luong Thi My; Dung, Pham Phuong; Nhi, Nguyen Vang Thi Yen; Hoang, Nguyen van Minh; Hieu, Tran Trung

2017-09-01

Helicobacter pylori is one of the most common human infectious bacteria. The infection is highly associated with a number of the most important disease of the upper gastrointestinal tract, including gastritis, duodenitis, peptic ulceration, and gastric cancer. In addition, widespread use of antimicrobial agents has resulted in the development of antibiotic resistance. Metabolites of plants, particularly higher plants, have been suggested as alternative potential sources for antibacterial products due to their safe. This study aimed to evaluate antibacterial activities of crude ethanolic extracts of seventeen Vietnamese medicinal plants toward one reference strain and three clinical isolates of Helicobacter pylori using broth micro-dilution bioassay. The antibacterial activities of these extracts were also compared with those of seven antibiotics, amoxicillin, clarithromycin, erythromycin, levofloxacin, azithromycin, tetracycline, and metronidazole. The extracts of Ampelopsis cantoniensis and Cleistocalyx operculatus showed highest antibacterial activity with MIC (MBC) values of 0.31 - 0.97 (2.5 - 5) mg/mL, followed by the extracts of Hedyotis diffusa and Ardisia silvestris with MIC (MBC) values of 1.04 - 1.94 (7.5 - 10) mg/mL. The remaining plant extracts exhibited moderate, low and very low or no active to the H. pylori strains. Further studies are needed to determine the active compounds from the extracts that showed high antibacterial activity against H. pylori.

Antimicrobial activity of some essential oils against oral multidrug-resistant Enterococcus faecalis in both planktonic and biofilm state

PubMed Central

Benbelaïd, Fethi; Khadir, Abdelmounaïm; Abdoune, Mohamed Amine; Bendahou, Mourad; Muselli, Alain; Costa, Jean

2014-01-01

Objective To evaluate some essential oils in treatment of intractable oral infections, principally caused by biofilm of multidrug-resistant Enterococcus faecalis (E. faecalis), such as persistent endodontic infections in which their treatment exhibits a real challenge for dentists. Methods Ten chemically analyzed essential oils by gas chromatography-mass spectrometry were evaluated for antimicrobial activity against sensitive and resistant clinical strains of E. faecalis in both planktonic and biofilm state using two methods, disk diffusion and broth micro-dilution. Results Studied essential oils showed a good antimicrobial activity and high ability in E. faecalis biofilm eradication, whether for sensitive or multidrug-resistant strains, especially those of Origanum glandulosum and Thymbra capitata with interesting minimum inhibitory concentration, biofilm inhibitory concentration, and biofilm eradication concentration values which doesn't exceed 0.063%, 0.75%, and 1.5%, respectively. Conclusions Findings of this study indicate that essential oils extracted from aromatic plants can be used in treatment of intractable oral infections, especially caused by biofilm of multidrug-resistant E. faecalis. PMID:25182948

Ultraviolet light and laser irradiation enhances the antibacterial activity of glucosamine-functionalized gold nanoparticles

PubMed Central

Govindaraju, Saravanan; Ramasamy, Mohankandhasamy; Baskaran, Rengarajan; Ahn, Sang Jung; Yun, Kyusik

2015-01-01

Here we report a novel method for the synthesis of glucosamine-functionalized gold nanoparticles (GlcN-AuNPs) using biocompatible and biodegradable glucosamine for antibacterial activity. GlcN-AuNPs were prepared using different concentrations of glucosamine. The synthesized AuNPs were characterized for surface plasmon resonance, surface morphology, fluorescence spectroscopy, and antibacterial activity. The minimum inhibitory concentrations (MICs) of the AuNPs, GlcN-AuNPs, and GlcN-AuNPs when irradiated by ultraviolet light and laser were investigated and compared with the MIC of standard kanamycin using Escherichia coli by the microdilution method. Laser-irradiated GlcN-AuNPs exhibited significant bactericidal activity against E. coli. Flow cytometry and fluorescence microscopic analysis supported the cell death mechanism in the presence of GlcN-AuNP-treated bacteria. Further, morphological changes in E. coli after laser treatment were investigated using atomic force microscopy and transmission electron microscopy. The overall results of this study suggest that the prepared nanoparticles have potential as a potent antibacterial agent for the treatment of a wide range of disease-causing bacteria. PMID:26345521

Detailed solvent, structural, quantum chemical study and antimicrobial activity of isatin Schiff base

NASA Astrophysics Data System (ADS)

Brkić, Dominik R.; Božić, Aleksandra R.; Marinković, Aleksandar D.; Milčić, Miloš K.; Prlainović, Nevena Ž.; Assaleh, Fathi H.; Cvijetić, Ilija N.; Nikolić, Jasmina B.; Drmanić, Saša Ž.

2018-05-01

The ratios of E/Z isomers of sixteen synthesized 1,3-dihydro-3-(substituted phenylimino)-2H-indol-2-one were studied using experimental and theoretical methodology. Linear solvation energy relationships (LSER) rationalized solvent influence of the solvent-solute interactions on the UV-Vis absorption maxima shifts (νmax) of both geometrical isomers using the Kamlet-Taft equation. Linear free energy relationships (LFER) in the form of single substituent parameter equation (SSP) was used to analyze substituent effect on pKa, NMR chemical shifts and νmax values. Electron charge density was obtained by the use of Quantum Theory of Atoms in Molecules, i.e. Bader's analysis. The substituent and solvent effect on intramolecular charge transfer (ICT) were interpreted with the aid of time-dependent density functional (TD-DFT) method. Additionally, the results of TD-DFT calculations quantified the efficiency of ICT from the calculated charge-transfer distance (DCT) and amount of transferred charge (QCT). The antimicrobial activity was evaluated using broth microdilution method. 3D QSAR modeling was used to demonstrate the influence of substituents effect as well as molecule geometry on antimicrobial activity.

Composition and antimicrobial activities of Lippia multiflora Moldenke, Mentha x piperita L. and Ocimum basilicum L. essential oils and their major monoterpene alcohols alone and in combination.

PubMed

Bassolé, Imaël Henri Nestor; Lamien-Meda, Aline; Bayala, Balé; Tirogo, Souleymane; Franz, Chlodwig; Novak, Johannes; Nebié, Roger Charles; Dicko, Mamoudou Hama

2010-11-03

Essential oils from leaves of Lippia multiflora, Mentha x piperita and Ocimum basilicum from Burkina Faso were analysed by GC-FID and GC-MS. Major components were p-cymene, thymol, b-caryophyllene, carvacrol and carvone for L. multiflora, menthol and iso-menthone for M. x piperita and, linalool and eugenol for O. basilicum. The essential oils and their major monoterpene alcohols were tested against nine bacterial strains using the disc diffusion and broth microdilution methods. The essential oils with high phenolic contents were the most effective antimicrobials. The checkerboard method was used to quantify the efficacy of paired combinations of essential oils and their major components. The best synergetic effects among essential oils and major components were obtained with combinations involving O. basilicum essential oil and eugenol, respectively. As phenolic components are characterized by a strong spicy aroma, this study suggests that the selection of certain combinations of EOs could help to reduce the amount of essential oils and consequently reduce any adverse sensory impact in food.

Fusarium sacchari, a cause of mycotic keratitis among sugarcane farmers - a series of four cases from North India.

PubMed

Bansal, Yashik; Chander, Jagdish; Kaistha, Neelam; Singla, Nidhi; Sood, Sunandan; van Diepeningen, Anne D

2016-11-01

The two most common filamentous fungi causing mycotic keratitis are Aspergillus and Fusarium spp. Around 70 Fusarium spp. are involved in causing human infections. In this study, four cases of keratitis in sugarcane farmers in India are being reported, caused by the sugar cane pathogen Fusarium sacchari, a species of the Fusarium fujikuroi species complex. Fusarial keratitis was established by potassium hydroxide/Calcofluor white wet mounts and fungal culture of corneal scrapings on conventional media. Final identification was done by genetic sequencing at CBS-KNAW, Utrecht, The Netherlands. The antifungal susceptibility testing was done using broth microdilution method as per CLSI document M38-A2. Four cases of F. sacchari keratitis were identified. Three of them had trauma with sugarcane leaves, whereas one sugarcane farmer reported trauma by vegetative matter. The morphological similarities among various Fusarium species warrant use of molecular methods for identification of cryptic species. A wide distribution of sugarcane farming could be the possible explanation for emergence of F. sacchari keratitis in India. © 2016 Blackwell Verlag GmbH.

Chemical composition of Argentinean propolis collected in extreme regions and its relation with antimicrobial and antioxidant activities.

PubMed

Vera, Nancy; Solorzano, Eliana; Ordoñez, Roxana; Maldonado, Luis; Bedascarrasbure, Enrique; Isla, María I

2011-06-01

This paper reveals, for the first time, the functional properties of propolis from an extreme region of Argentine (El Rincón, Province of Catamarca, Argentina), as well as the isolation and identification of bioactive compounds. The antioxidant activity was determined by the ABTS method and beta-carotene bleaching. The antibacterial activity was determined on methicillin resistant Staphylococcus aureus (MRSA) by the microdilution method and bioautographic assays. Twelve compounds were isolated and identified by NMR spectroscopy. The main bioactive compounds were 2',4'-dihydroxy-3'-methoxychalcone (3), 2',4'-dihydroxychalcone (9), 2',4',4-trihydroxy-6'- methoxychalcone (8), 5-hydroxy-4',7-dimethoxyflavone (4), 4',5-dihydroxy-3,7,8-trimethoxyflavone (10) and 7-hydroxy- 5,8-dimethoxyflavone (11). All compounds were active against clinical isolates (MIC50 10 microg/mL) and displayed antioxidant activity (SC50 values of 20 microg/mL). The MIC and SC50 values of the isolated compounds were lower than those obtained with crude propolis extracts, chloroform sub-extracts and isolated fractions.

Evaluation of the antifungal activity and modulation between Cajanus cajan (L.) Millsp. leaves and roots ethanolic extracts and conventional antifungals

PubMed Central

Brito, Samara A.; Rodrigues, Fabíola F. G.; Campos, Adriana R.; da Costa, José G. M.

2012-01-01

Background: The use and investigation of natural products with antimicrobial activity from vegeral source have been reported by several researchers. Cajanus cajan (Fabaceae) is a multiple use specie mainly as human food. In popular medicine, diverse parts of the plant are used as sedative and to treat cough, hepatitis, and diabetes. Materials and Methods: This study shows the characterization of secondary metabolites present in ehtanolic extracts from leaves and roots of Cajanus cajan by phytochemical prospection. The evaluation of the antifungal activity was performed by the microdilution method, and from the subinhibitory concentrations (MIC 1/8) the modulatory activity of antifungical (fluconazole and ketoconazole) was analyzed by the direct contact assay against C. albicans ATCC40006, Candida krusei ATCC 6538 and Candida tropicalis ATCC 40042. Results: The results showed the presence of tannins, flavonoids, and alkaloids in both extracts as the clinically relevant antifungal activity. The modulatory potential is presented by the antifungal tested against yeasts. Conclusion: The extracts studied here have demonstrated to be a new therapeutic source to treat these microorganism-associated diseases. PMID:22701281

The effect of clary sage oil on staphylococci responsible for wound infections

PubMed Central

Głowacka, Anna; Poznańska-Kurowska, Katarzyna; Kaszuba, Andrzej; Urbaniak, Anna; Kowalczyk, Edward

2015-01-01

Introduction The spreading of bacterial antibiotic resistance among clinical strains of pathogenic bacteria has made investigators to search for other active antibacterial agents which could provide a valuable complement to the existing therapies. Aim To determine the antibacterial activity of clary sage oil (Salvia sclarea L.) against Staphylococcus clinical strains which were isolated from patients with wound infections. Material and methods A comprehensive evaluation of Staphylococcus clinical strain resistance to antibiotics was performed. The constituents of clary sage oil were assayed by GC-FID-MS analysis. The minimal inhibitory concentration (MIC) of the tested essential oil against staphylococci by the micro-dilution broth method was determined. Results The clary sage oil was active against Staphylococcus aureus, S. epidermidis and S. xylosus with MIC values ranging from 3.75 to 7.00 µl/ml. Conclusions The results of the in vitro tests encourage to use formulations containing sage oil as the active natural antimicrobial agent. Because of its antimicrobial properties clary sage oil may be applied to treat wounds and skin infections. PMID:25821423

Methodological comparisons for antimicrobial resistance surveillance in feedlot cattle

PubMed Central

2013-01-01

Background The purpose of this study was to objectively compare methodological approaches that might be utilized in designing an antimicrobial resistance (AMR) surveillance program in beef feedlot cattle. Specifically, four separate comparisons were made to investigate their potential impact on estimates for prevalence of AMR. These included investigating potential differences between 2 different susceptibility testing methods (broth microdilution and disc diffusion), between 2 different target bacteria (non-type-specific E. coli [NTSEC] and Mannheimia haemolytica), between 2 strategies for sampling feces (individual samples collected per rectum and pooled samples collected from the pen floor), and between 2 strategies for determining which cattle to sample (cattle that were culture-positive for Mannheimia haemolytica and those that were culture-negative). Results Comparing two susceptibility testing methods demonstrated differences in the likelihood of detecting resistance between automated disk diffusion (BioMIC®) and broth microdilution (Sensititre®) for both E. coli and M. haemolytica. Differences were also detected when comparing resistance between two bacterial organisms within the same cattle; there was a higher likelihood of detecting resistance in E. coli than in M. haemolytica. Differences in resistance prevalence were not detected when using individual animal or composite pen sampling strategies. No differences in resistance prevalences were detected in E. coli recovered from cattle that were culture-positive for M. haemolytica compared to those that were culture-negative, suggesting that sampling strategies which targeted recovery of E. coli from M. haemolytica-positive cattle would not provide biased results. Conclusions We found that for general purposes, the susceptibility test selected for AMR surveillance must be carefully chosen considering the purpose of the surveillance since the ability to detect resistance appears to vary between these tests depending upon the population where they are applied. Continued surveillance of AMR in M. haemolytica recovered by nasopharyngeal swab is recommended if monitoring an animal health pathogen is an objective of the surveillance program as results of surveillance using fecal E. coli cannot be extrapolated to this important respiratory pathogen. If surveillance of E. coli was pursued in the same population, study populations could target animals that were culture-positive for M. haemolytica without biasing estimates for AMR in E. coli. Composite pen-floor sampling or sampling of individuals per-rectum could possibly be used interchangeably for monitoring resistance in E. coli. PMID:24144185

Inhibitory Effects of Pterodon emarginatus Bean Oil and Extract on Staphylococcus aureus

PubMed Central

Mendes, V. S.; Sant'Anna, J. B.; Oliveira, S. C. C.; Maldonade, Iriani Rodrigues; Machado, Eleuza Rodrigues

2017-01-01

Background: Pterodon emarginatus is a tree of the Brazilian Savannah. The beans of this tree are used in folk medicine as anti-inflammatory preparations, especially for infections caused by Staphylococcus aureus. These bacteria can cause simple infections or serious illnesses such as pneumonia, meningitis, endocarditis, toxic shock syndrome, septicemia, and others. Objective: This study had the goal of verifying the effect of the essential oil (OE) from P. emarginatus on the inhibition of S. aureus in culture medium, i.e., “ in vitro” tests. Materials and Methods: The vegetable material was cut and crushed with a press. The OE was obtained by extraction using hexane, alcohol, and water. The P. emarginatus extracts obtained were used to evaluate the antimicrobial effect on S. aureus (ATCC 25923) by tests of well diffusion, disc diffusion, and microdilution. The strain used in the assays was maintained in brain heart infusion broth and nutrient agar until testing. Afterward, the bacteria were spread on agar plates with Mueller-Hinton agar medium. In the wells and on the paper discs, the OE suspensions were placed in the following volumes: 10, 15, 20, 25, 30, 40, and 80 μL and subsequently they were incubated at 35°C ± 2°C. After 24 h, the number of colony-forming unit was determined. Results: Pure OE and hydroalcoholic extract inhibited the growth of S. aureus, while aqueous extract had no effect on bacterial growth in all microbial methods used. Conclusion: Thus, the present study showed the potential of sucupira-based extracts against S. aureus growth, opening new perspectives for the evaluation of these bioactive compounds as phytopharmaceutical products. SUMMARY Plant extract act as antimicrobials to prevent and reduce bacterial contaminationBeans of Pterodon emarginatus has antibacterial propertiesExtraction with different solvents might implicate on the rate of bacterial deathThe effect of different microbiological methods (well diffusion, disc diffusion and microdilution) was evaluated on reducing CFUThe results showed by MBC that concentrations superior to 10% (v/v) using AC and 7.5% (v/v) using OE were necessary to eliminate colonies formedAccording to data of MIC, at 2.5% of AC and OE was enough to kill S. aureusThe well diffusion technique demonstrated better performance than disc diffusion test for OE and AC extractsHydroalcoholic and oil extracts of sucupira beans had highest effect against Staphylococcus aureusAqueous extract had no effect on bacterial growth in all microbial methods testedThe sucupira-based extracts is a promising source as herbal drug due to therapeutic value Abbreviations Used: OE: Essencial oil; AC: Hydroalcoholic oil extract; AQ: Aqueous extracts; MIC: Minimum inhibitory concentration; MBC: Minimum bactericidal concentration; CFU: Colony formed unit. PMID:29263627

Antistaphylococcal activity of dalbavancin, an experimental glycopeptide.

PubMed

Lin, Gengrong; Credito, Kim; Ednie, Lois M; Appelbaum, Peter C

2005-02-01

Dalbavancin, tested against 146 staphylococci, was more potent than other drugs tested, with an MIC at which 50% of staphylococci were inhibited of 0.03 microg/ml and an MIC at which 90% of staphylococci were inhibited of 0.06 microg/ml by microdilution. For all strains, MICs of vancomycin, linezolid, ranbezolid, oritavancin, daptomycin, and quinupristin-dalfopristin were

Susceptibility of Oral Bacteria to an Antimicrobial Decapeptide

DTIC Science & Technology

2003-01-01

coccus mitis ATCC 15913, Streptococcus oralis ATCC 35037T, Lactoba- cillus salivarius ATCC 29602, Lactobacillus acidophilus ATCC 43571 and...exhibited an ED99 (the dose at which 99% killing was observed after 15 min at 37 8C) of 6.25 gml1 against selected strains of Lactobacillus salivarius...broth microdilution assay. Growth of the cariogenic bacteria S.mutansATCC 25175T, S. sobrinus and L. acidophilus was also inhibited effectively by Fig

Evaluation of paper gradient concentration strips for antifungal combination testing of Candida spp.

PubMed

Siopi, Maria; Siafakas, Nikolaos; Zerva, Loukia; Meletiadis, Joseph

2015-11-01

In vitro combination testing with broth microdilution chequerboard (CHEQ) method is widely used although it is time-consuming, cumbersome and difficult to apply in routine setting of clinical microbiology laboratory. A new gradient concentration paper strip method, the Liofilchem(®) MIC test strips (MTS), provides an alternative easy and fast method enabling the simultaneous diffusion of both drugs in combination. We therefore tested a polyene+azole and an azole+echinocandin combination against 18 Candida isolates with the CHEQ method based on EUCAST guidelines and the MTS method in research and routine settings. Fractional inhibitory concentration (FIC) indices were calculated after 24 and 48 h of incubation based on complete and prominent (FIC-2) growth inhibition endpoints. Reproducibility and agreement within 1 twofold dilution was assessed. The FICs of the two methods were correlated quantitatively with t-test and Pearson analysis and qualitatively with Chi-squared test. The reproducibility of the CHEQ and MTS method was 88-100% and their agreement was 80% with 62-77% of MTS FICs being higher than the corresponding CHEQ FICs. A statistically significant Pearson correlation (r = 0.86, P = 0.0003) and association (χ(2) = 17.05, df = 4, P = 0.002) was found between MTS FIC and CHEQ FIC-2 after 24 h. Categorical agreement was 63% with no very major or major errors. All MTS synergistic interactions were also synergistic with the CHEQ method. © 2015 Blackwell Verlag GmbH.

Anti-inflammatory, antioxidant, and antimicrobial activities of Cocos nucifera var. typica

PubMed Central

2013-01-01

Background Teas from the husk fiber of Cocos nucifera are used in the folk medicine to treat arthritis and other inflammatory processes. Some works show that some varieties have biological activities. However, one of the main variety of the species, C. nucifera var. typica, known in Brazil as “gigante”, was not studied yet. Thus, this study evaluates if this variety has the anti-inflammatory and antimicrobial activities already reported in other varieties. Methods C. nucifera aqueous crude extract (10, 50, and 100 mg/kg) and the reference drugs morphine (1 mg/kg) and acetylsalicylic acid (100 mg/kg) were evaluated in models of inflammation (formalin-induced licking and subcutaneous air pouch). The antioxidant activity was evaluated by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) photometric assay and compared with those of the standards (quercetin, rutin, and ascorbic acid). The extract was also screened against Candida albicans, Escherichia coli, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus (MRSA), in the agar diffusion method. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined by the broth micro-dilution assay. Activities of combinations of the extract and antibiotics (methicillin or vancomycin) against MRSA were evaluated using checkerboard assays. Results The extract significantly inhibited the time that the animals spent licking the formalin-injected paws (second phase). The extract also inhibited the inflammatory process induced by subcutaneous carrageenan injection by reducing cell migration, protein extravasation, and TNF-α production. Additionally, the extract showed an antioxidant potential in vitro as good as standards in their antioxidant activity. The extract was active only against S. aureus and MRSA. MIC and the bactericidal concentrations were identical (1,024 μg/ml). The extract and methicillin acted synergistically against the clinical MRSA isolate, whereas an indifferent effect was detected when the extract was combined with vancomycin. Conclusions The extract exhibits anti-inflammatory activity through the inhibition of the cell migration. The mixture of extract constituents and methicillin could lead to the development of a new combination antibiotic against MRSA infections. PMID:23680079

Antimicrobial susceptibility of animal and human isolates of Clostridium difficile by broth microdilution.

PubMed

Pirš, Tina; Avberšek, Jana; Zdovc, Irena; Krt, Brane; Andlovic, Alenka; Lejko-Zupanc, Tatjana; Rupnik, Maja; Ocepek, Matjaž

2013-09-01

A total of 188 human (n = 92) and animal (n = 96) isolates of Clostridium difficile of different PCR ribotypes were screened for susceptibility to 30 antimicrobials using broth microdilution. When comparing the prevalence of antimicrobial resistance, the isolates of animal origin were significantly more often resistant to oxacillin, gentamicin and trimethoprim/sulfamethoxazole (P<0.01). The most significant difference between the animal and human populations (P = 0.0006) was found in the level of imipenem resistance, with a prevalence of 53.3 % in isolates of human origin and 28.1 % in isolates of animal origin. Overall, the results show similar MICs for the majority of tested antimicrobials for isolates from human and animal sources, which were collected from the same geographical region and in the same time interval. This supports the hypothesis that C. difficile could be transmissible between human and animal hosts. Resistant isolates have been found in all animal species tested, including food and companion animals, and also among non-toxigenic isolates. The isolates of the most prevalent PCR ribotype 014/020 had low resistance rates for moxifloxacin, erythromycin, rifampicin and daptomycin, but a high resistance rate for imipenem. Multiresistant strains were found in animals and humans, belonging to PCR ribotypes 012, 017, 027, 045, 046, 078 and 150, and also to non-toxigenic strains of PCR ribotypes 010 and SLO 080.

Analysis by UPLC-MS-QTOF and antifungal activity of guava (Psidium guajava L.).

PubMed

Bezerra, Camila Fonseca; Rocha, Janaína Esmeraldo; Nascimento Silva, Maria Karollyna do; de Freitas, Thiago Sampaio; de Sousa, Amanda Karine; Dos Santos, Antônia Thassya Lucas; da Cruz, Rafael Pereira; Ferreira, Maciel Horácio; da Silva, Josefa Carolaine Pereira; Machado, Antonio Judson Targino; Carneiro, Joara Nályda Pereira; Sales, Débora Lima; Coutinho, Henrique Douglas Melo; Ribeiro, Paulo Riceli Vasconcelos; de Brito, Edy Sousa; Morais-Braga, Maria Flaviana Bezerra

2018-05-08

Psidium guajava L. is a plant widely used for food and in folk medicine all over the world. Studies have shown that guava leaves have antifungal properties. In this study, Flavonoid and Tannic fractions were tested to investigate their chemical composition and antifungal potential in vitro.21 compounds in the two fractions, presenting a higher content of phenolic compounds. The antifungal assays were performed against Candida albicans, Candida tropicalis and Candida krusei by microdilution to determine the IC 50 and the cell viability curve. Minimal Fungicidal Concentration(MFC) and the inhibitory effects of the association of the fractions with Fluconazole, as well as the assays used to verify any morphological changes were performed in microculture chambers based on the concentrations from the microdilution. The IC 50 of the isolated fractions and the fractions associated with each other were calculated, varying from 69.29 to 3444.62 μg/mL and the fractions associated with fluconazole varied from 925.56 to 1.57 μg/mL, it was clear that the association of the natural product with the antifungal presented a synergism. The fractions affected pleomorphism capacity and have a potential antifungal activity as they caused fungal inhibition in isolated use, potentiated the action of Fluconazole, reducing its concentration and impeding morphological transition, one of the virulence factors of the genus. Copyright © 2018 Elsevier Ltd. All rights reserved.

Direct Antimicrobial Susceptibility Testing of Gram-Negative Bacilli in Blood Cultures by an Electrochemical Method

PubMed Central

Huang, Ay Huey; Wu, Jiunn Jong; Weng, Yu Mei; Ding, Hwia Cheng; Chang, Tsung Chain

1998-01-01

Nonfastidious aerobic gram-negative bacilli (GNB) are commonly isolated from blood cultures. The feasibility of using an electrochemical method for direct antimicrobial susceptibility testing of GNB in positive blood cultures was evaluated. An aliquot (10 μl) of 1:10-diluted positive blood cultures containing GNB was inoculated into the Bactometer module well (bioMérieux Vitek, Hazelwood, Mo.) containing 1 ml of Mueller-Hinton broth supplemented with an antibiotic. Susceptibility tests were performed in a breakpoint broth dilution format, with the results being categorized as resistant, intermediate, or susceptible. Seven antibiotics (ampicillin, cephalothin, gentamicin, amikacin, cefamandole, cefotaxime, and ciprofloxacin) were used in this study, with each agent being tested at the two interpretive breakpoint concentrations. The inoculated modules were incubated at 35°C, and the change in impedance in each well was continuously monitored for 24 h by the Bactometer. The MICs of the seven antibiotics for each blood isolate were also determined by the standardized broth microdilution method. Of 146 positive blood cultures (1,022 microorganism-antibiotic combinations) containing GNB tested by the direct method, the rates of very major, major, and minor errors were 0, 1.1, and 2.5%, respectively. The impedance method was simple; no centrifugation, preincubation, or standardization of the inocula was required, and the susceptibility results were normally available within 3 to 6 h after inoculation. The rapid method may allow proper antimicrobial treatment almost 30 to 40 h before the results of the standard methods are available. PMID:9738038

Evaluation of in-vitro antibiotic susceptibility of different morphological forms of Borrelia burgdorferi.

PubMed

Sapi, Eva; Kaur, Navroop; Anyanwu, Samuel; Luecke, David F; Datar, Akshita; Patel, Seema; Rossi, Michael; Stricker, Raphael B

2011-01-01

Lyme disease is a tick-borne illness caused by the spirochete Borrelia burgdorferi. Although antibiotic therapy is usually effective early in the disease, relapse may occur when administration of antibiotics is discontinued. Studies have suggested that resistance and recurrence of Lyme disease might be due to formation of different morphological forms of B. burgdorferi, namely round bodies (cysts) and biofilm-like colonies. Better understanding of the effect of antibiotics on all morphological forms of B. burgdorferi is therefore crucial to provide effective therapy for Lyme disease. Three morphological forms of B. burgdorferi (spirochetes, round bodies, and biofilm-like colonies) were generated using novel culture methods. Minimum inhibitory concentration and minimum bactericidal concentration of five antimicrobial agents (doxycycline, amoxicillin, tigecycline, metronidazole, and tinidazole) against spirochetal forms of B. burgdorferi were evaluated using the standard published microdilution technique. The susceptibility of spirochetal and round body forms to the antibiotics was then tested using fluorescent microscopy (BacLight™ viability staining) and dark field microscopy (direct cell counting), and these results were compared with the microdilution technique. Qualitative and quantitative effects of the antibiotics against biofilm-like colonies were assessed using fluorescent microscopy and dark field microscopy, respectively. Doxycycline reduced spirochetal structures ∼90% but increased the number of round body forms about twofold. Amoxicillin reduced spirochetal forms by ∼85%-90% and round body forms by ∼68%, while treatment with metronidazole led to reduction of spirochetal structures by ∼90% and round body forms by ∼80%. Tigecycline and tinidazole treatment reduced both spirochetal and round body forms by ∼80%-90%. When quantitative effects on biofilm-like colonies were evaluated, the five antibiotics reduced formation of these colonies by only 30%-55%. In terms of qualitative effects, only tinidazole reduced viable organisms by ∼90%. Following treatment with the other antibiotics, viable organisms were detected in 70%-85% of the biofilm-like colonies. Antibiotics have varying effects on the different morphological forms of B. burgdorferi. Persistence of viable organisms in round body forms and biofilm-like colonies may explain treatment failure and persistent symptoms following antibiotic therapy of Lyme disease.

Identification and Antimicrobial Susceptibility Testing of Anaerobic Bacteria: Rubik’s Cube of Clinical Microbiology?

PubMed Central

Gajdács, Márió; Spengler, Gabriella; Urbán, Edit

2017-01-01

Anaerobic bacteria have pivotal roles in the microbiota of humans and they are significant infectious agents involved in many pathological processes, both in immunocompetent and immunocompromised individuals. Their isolation, cultivation and correct identification differs significantly from the workup of aerobic species, although the use of new technologies (e.g., matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, whole genome sequencing) changed anaerobic diagnostics dramatically. In the past, antimicrobial susceptibility of these microorganisms showed predictable patterns and empirical therapy could be safely administered but recently a steady and clear increase in the resistance for several important drugs (β-lactams, clindamycin) has been observed worldwide. For this reason, antimicrobial susceptibility testing of anaerobic isolates for surveillance purposes or otherwise is of paramount importance but the availability of these testing methods is usually limited. In this present review, our aim was to give an overview of the methods currently available for the identification (using phenotypic characteristics, biochemical testing, gas-liquid chromatography, MALDI-TOF MS and WGS) and antimicrobial susceptibility testing (agar dilution, broth microdilution, disk diffusion, gradient tests, automated systems, phenotypic and molecular resistance detection techniques) of anaerobes, when should these methods be used and what are the recent developments in resistance patterns of anaerobic bacteria. PMID:29112122

Identification and Antimicrobial Susceptibility Testing of Anaerobic Bacteria: Rubik's Cube of Clinical Microbiology?

PubMed

Gajdács, Márió; Spengler, Gabriella; Urbán, Edit

2017-11-07

Anaerobic bacteria have pivotal roles in the microbiota of humans and they are significant infectious agents involved in many pathological processes, both in immunocompetent and immunocompromised individuals. Their isolation, cultivation and correct identification differs significantly from the workup of aerobic species, although the use of new technologies (e.g., matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, whole genome sequencing) changed anaerobic diagnostics dramatically. In the past, antimicrobial susceptibility of these microorganisms showed predictable patterns and empirical therapy could be safely administered but recently a steady and clear increase in the resistance for several important drugs (β-lactams, clindamycin) has been observed worldwide. For this reason, antimicrobial susceptibility testing of anaerobic isolates for surveillance purposes or otherwise is of paramount importance but the availability of these testing methods is usually limited. In this present review, our aim was to give an overview of the methods currently available for the identification (using phenotypic characteristics, biochemical testing, gas-liquid chromatography, MALDI-TOF MS and WGS) and antimicrobial susceptibility testing (agar dilution, broth microdilution, disk diffusion, gradient tests, automated systems, phenotypic and molecular resistance detection techniques) of anaerobes, when should these methods be used and what are the recent developments in resistance patterns of anaerobic bacteria.

Anti-inflammatory, antioxidant, and antimicrobial activities of Cocos nucifera var. typica.

PubMed

Silva, Rafaela Ribeiro; Oliveira e Silva, Davi; Fontes, Humberto Rollemberg; Alviano, Celuta Sales; Fernandes, Patricia Dias; Alviano, Daniela Sales

2013-05-16

Teas from the husk fiber of Cocos nucifera are used in the folk medicine to treat arthritis and other inflammatory processes. Some works show that some varieties have biological activities. However, one of the main variety of the species, C. nucifera var. typica, known in Brazil as "gigante", was not studied yet. Thus, this study evaluates if this variety has the anti-inflammatory and antimicrobial activities already reported in other varieties. C. nucifera aqueous crude extract (10, 50, and 100 mg/kg) and the reference drugs morphine (1 mg/kg) and acetylsalicylic acid (100 mg/kg) were evaluated in models of inflammation (formalin-induced licking and subcutaneous air pouch). The antioxidant activity was evaluated by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) photometric assay and compared with those of the standards (quercetin, rutin, and ascorbic acid). The extract was also screened against Candida albicans, Escherichia coli, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus (MRSA), in the agar diffusion method. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined by the broth micro-dilution assay. Activities of combinations of the extract and antibiotics (methicillin or vancomycin) against MRSA were evaluated using checkerboard assays. The extract significantly inhibited the time that the animals spent licking the formalin-injected paws (second phase). The extract also inhibited the inflammatory process induced by subcutaneous carrageenan injection by reducing cell migration, protein extravasation, and TNF-α production. Additionally, the extract showed an antioxidant potential in vitro as good as standards in their antioxidant activity. The extract was active only against S. aureus and MRSA. MIC and the bactericidal concentrations were identical (1,024 μg/ml). The extract and methicillin acted synergistically against the clinical MRSA isolate, whereas an indifferent effect was detected when the extract was combined with vancomycin. The extract exhibits anti-inflammatory activity through the inhibition of the cell migration. The mixture of extract constituents and methicillin could lead to the development of a new combination antibiotic against MRSA infections.

In vitro antimicrobial activity of ozenoxacin against methicillin-susceptible Staphylococcus aureus, methicillin-resistant S. aureus and Streptococcus pyogenes isolated from clinical cutaneous specimens in Japan.

PubMed

Kanayama, Shoji; Ikeda, Fumiaki; Okamoto, Kazuaki; Nakajima, Akiko; Matsumoto, Tatsumi; Ishii, Ritsuko; Amano, Ayako; Matsuzaki, Kaoru; Matsumoto, Satoru

2016-10-01

Ozenoxacin, a novel non-fluorinated topical quinolone, was assessed for in vitro antimicrobial activity against each 50 isolates of methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), and Streptococcus pyogenes according to the broth microdilution method recommended by the Clinical and Laboratory Standards Institute. The isolates used in this study were recovered from cutaneous specimens of Japanese adult and pediatric patients who visited hospitals in 2014. The MIC90s of ozenoxacin against MSSA, MRSA and S. pyogenes isolates from adult patients were ≤0.06, 4 and ≤0.06 μg/mL, respectively. The MIC90s of ozenoxacin against MSSA and S. pyogenes isolates from pediatric patients were equal to those against the adult isolates. On the other hand, the MIC90s of ozenoxacin against the pediatric MRSA isolates was 0.12 μg/mL, and was 32 times lower than that against the adult isolates. The antimicrobial activity of ozenoxacin against MSSA, MRSA and S. pyogenes was equal to or greater than those of 7 reference antimicrobial agents had been used for the treatment of skin infections. The MICs of ozenoxacin was highly correlated with those of nadifloxacin and levofloxacin in the 50 MRSA isolates (r(2) = 0.906 and 0.833, respectively). However, ozenoxacin kept the potent antimicrobial activity with the MIC ranging from 1 to 4 μg/mL even against MRSA low susceptible (MIC: >64 μg/mL) to nadifloxacin or levofloxacin. Ozenoxacin could represent the first-in-class non-fluorinated quinolone for the topical treatment of various superficial skin infections caused by MSSA, MRSA and S. pyogenes. Copyright © 2016 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Antimicrobial susceptibility and genetic characterization of Escherichia coli recovered from frozen game meat.

PubMed

Mateus-Vargas, Rafael H; Atanassova, Viktoria; Reich, Felix; Klein, Günter

2017-05-01

The increasing number of antimicrobial resistant Enterobacteriaceae both in veterinary and human medicine, the dissemination of these bacteria in several environments and their possible repercussions on human health is causing concern. Game meat is usually seen as free of antimicrobial resistant bacteria. The objective of this study was to evaluate the current antimicrobial susceptibility status in generic Escherichia coli isolated from packed frozen game meat from a game handling establishment in Germany. A total of 229 E. coli isolates were obtained from cuts of red deer, roe deer and wild boar. The susceptibility to 12 antimicrobial agents was evaluated by a broth microdilution method according to ISO 20776-1:2006. Minimal Inhibitory Concentration (MIC) values were compared to breakpoints and cut-off values published by the EUCAST. Isolates showing MICs above the reference values were further studied for associated resistance determinants and phylogrouping by PCR. Overall, 16 E. coli isolates (7.0%) showed resistance (microbiological or clinical) to at least one antimicrobial agent tested. Clinical resistance was recorded to ampicillin (5/229) and chloramphenicol (4/229), whereas the MIC of 9 isolates exceeded the epidemiological cut-off value for doxycycline. One of the ampicillin-resistant isolates showed resistance to the β-lactam antibiotic derivatives tested, cephalosporines and aztreonam. Three of 9 non-wild-type isolates for doxycycline were positive for tet (B) genes. The ß-lactam-resistant isolate was found to harbour bla CTX-M-1 gene. These data show a low prevalence of resistant E. coli in packed game meat compared to studies on conventional meat. Although isolates obtained in this study may also be originating from the processing environment and not necessarily from animals, based on our results, it is important to monitor the development of antimicrobial resistance in game animals and products in order to identify future threats for the consumers. Copyright © 2016 Elsevier Ltd. All rights reserved.

Azole-synergistic anti-candidal activity of altenusin, a biphenyl metabolite of the endophytic fungus Alternaria alternata isolated from Terminalia chebula Retz.

PubMed

Phaopongthai, Jatuporn; Wiyakrutta, Suthep; Meksuriyen, Duangdeun; Sriubolmas, Nongluksna; Suwanborirux, Khanit

2013-12-01

In this study, a tropical endophytic fungus, Alternaria alternata Tche-153 was isolated from a Thai medicinal plant Terminalia chebula Rezt. The ethyl acetate extract prepared from the fermentation broth exhibited significant ketoconazole-synergistic activity against Candida albicans. Bioassay-directed fractionation of the ethyl acetate extract led to the isolation of altenusin (1), isoochracinic acid (2), and altenuic acid (3) together with 2,5-dimethyl-7-hydroxychromone (4). Using the disc diffusion method and the microdilution chequerboard technique, only altenusin (1) in combination with each of three azole drugs, ketoconazole, fluconazole or itraconazole at their low sub-inhibitory concentrations exhibited potent synergistic activity against C. albicans with the fractional inhibitory concentration index range of 0.078 to 0.188. This first discovery of altenusin (1) as a new azole-synergistic prototype possessing a biphenyl structure is of significance for further development of new azole-synergists to treat invasive candidiasis.

Antibacterial and glucosyltransferase enzyme inhibitory activity of helmyntostachyszelanica

NASA Astrophysics Data System (ADS)

Kuspradini, H.; Putri, AS; Mitsunaga, T.

2018-04-01

Helminthostachyszeylanica is a terrestrial, herbaceous, fern-like plant of southeastern Asia and Australia, commonly known as tunjuk-langit. This kind of plant have a medicinal properties such as treatment of malaria, dysentery and can be eaten with betel in the treatment of whooping cough. To evaluate the scientific basis for the use of the plant, the antimicrobial activities of extracts of the stem and leaves were evaluated. The bacteria used in this study is Streptococcus sobrinus, a species of gram-positive, that may be associated with human dental caries. The dried powdered plant parts were extracted using methanol and 50% aqueous extract and screened for their antibacterial effects of Streptococcus sobrinus using the 96 well-plate microdilution broth method. The inhibitory activities of its related enzyme were also determined. The plant extracts showed variable antibacterial and Glucosyltransferase enzyme inhibitory activity while some extracts could not cause any inhibition. It was shown that 50% ethanolics of Helminthostachyzeylanica stem have a potency as anti dental caries agents.

Zn(II), Ni(II), Cu(II) and Pb(II) complexes of tridentate asymmetrical Schiff base ligands: Synthesis, characterization, properties and biological activity

NASA Astrophysics Data System (ADS)

Şahin, Mustafa; Koçak, Nuriye; Erdenay, Damla; Arslan, Uğur

2013-02-01

New asymmetrical tridentate Schiff base ligands were synthesized using 1,2-phenylenediamine, 4-methyl-1,2-phenylenediamine, 2-hydroxy-1-napthaldehyde, 9-anthracenecarboxaldehyde. Schiff base ligands and their metal complexes were synthesised and characterized by using FT-IR, 1H NMR, 13C NMR, UV-Vis, XRD, ESR, elemental analysis and fluorescence studies. The antimicrobial activity of the ligands and their metal complexes were studied against Staphylococcus aureus ATCC 29213, S. aureus ATCC 25923, Streptococcus mutans RSHM 676, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853. The determination of the antibacterial activity was done using the broth microdilution methods. In general, it has been determined that the studied compounds have MIC values similar to Gram-positive and Gram-negative bacteria. It has been found that Ni, Pb, Zn derivatives of HL1A and ZnL2A has lower MIC values than ampicillin for P. aeruginosa ATCC 27853 strain.

Antibiotic resistance assessment in S. aureus strains isolated from raw sheep's milk cheese.

PubMed

Spanu, V; Virdis, S; Scarano, C; Cossu, F; De Santis, E P L; Cosseddu, A M

2010-06-01

In vitro activities of 16 antibiotics were tested against 36 Staphylococcus aureus (SA) strains isolated from raw sheep's milk cheese from six dairies. The minimum inhibitory concentration (MIC) was determined using a broth microdilution method (CLSI). All 36 isolates were analyzed for the presence of the accessory gene regulator gene, agr (I-IV), and genes encoding resistance to methicillin (mecA), erythromycin (ermA), penicillin (blaZ), and vancomycin (vanA-B). The isolates were also analyzed for similarities in pulsed-field gel electrophoresis (PFGE) patterns. SA strains showed resistance to ampicillin (36.1%), penicillin (33.3%), tetracycline (11.1%), and cloxacillin (2.8%) but were susceptible (>or=94.4%) to 12 out of 16 tested antimicrobials. The overall susceptibility of the strains to oxacillin, vancomycin, and erythromycin was confirmed by the absence of the mecA, vanA-B, and ermA genes. The PFGE results showed that 32 strains belonged to 10 different clusters (P1-P10) while four strains were untypeable.

Antibacterial and antifungal activities of different parts of Tribulus terrestris L. growing in Iraq

PubMed Central

Al-Bayati, Firas A.; Al-Mola, Hassan F.

2008-01-01

Antimicrobial activity of organic and aqueous extracts from fruits, leaves and roots of Tribulus terrestris L., an Iraqi medicinal plant used as urinary anti-infective in folk medicine, was examined against 11 species of pathogenic and non-pathogenic microorganisms: Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Corynebacterium diphtheriae, Escherichia coli, Proteus vulgaris, Serratia marcescens, Salmonella typhimurium, Klebsiella pneumoniae, Pseudomonas aeruginosa and Candida albicans using microdilution method in 96 multiwell microtiter plates. All the extracts from the different parts of the plant showed antimicrobial activity against most tested microorganisms. The most active extract against both Gram-negative and Gram-positive bacteria was ethanol extract from the fruits with a minimal inhibitory concentration (MIC) value of 0.15 mg/ml against B. subtilis, B. cereus, P. vulgaris and C. diphtheriae. In addition, the same extract from the same plant part demonstrated the strongest antifungal activity against C. albicans with an MIC value of 0.15 mg/ml. PMID:18257138

Evaluation of Antifungal Effect of Silver Nanoparticles Against Microsporum canis, Trichophyton mentagrophytes and Microsporum gypseum

PubMed Central

Ayatollahi Mousavi, Seyyed Amin; Salari, Samira; Hadizadeh, Sanaz

2015-01-01

Background Dermatophytosis is the common cutaneous infections in humans and animals, which is caused by the keratinophylic fungus called dermatophytes. In recent years, drugs resistance in pathogenic fungi, including dermatophyte strains to the current antifungals have been increased. Objectives The aim of this study was to evaluate the antifungal efficacy of AgNPs against Microsporum canis, Trichophyton mentagrophytes , and Microsporum gypseum. Materials and Methods The antifungal susceptibility of nanosilver particles compared with griseofulvin (GR). Its efficacy was investigated against three strains of dermatophytes by both agar dilution and broth microdilution test (BMD). Results The average minimum inhibitory concentration (MIC) AgNPs on M. canis, T. mentagrophytes and M. gypseum were 200, 180 and 170 μg.mL-1, respectively. Whereas these strains showed MIC of 25, 100 and 50 μg.mL-1 for GR. Conclusions Our finding indicated that the AgNPs was less active than GR but it had anti-dermatophytic effect. PMID:28959308

Trachyspermum ammi (L.) sprague: chemical composition of essential oil and antimicrobial activities of respective fractions.

PubMed

Moein, Mahmoodreza R; Zomorodian, Kamiar; Pakshir, Keyvan; Yavari, Farnoosh; Motamedi, Marjan; Zarshenas, Mohammad M

2015-01-01

Resistance to antibacterial agents has become a serious problem for global health. The current study evaluated the antimicrobial activities of essential oil and respective fractions of Trachyspermum ammi (L.) Sprague. Seeds of the essential oil were extracted and fractionated using column chromatography. All fractions were then analyzed by gas chromatography/mass spectrometry. Antifungal and antibacterial activities of the oil and its fractions were assessed using microdilution method. Compounds γ-terpinene (48.07%), ρ-cymene (33.73%), and thymol (17.41%) were determined as major constituents. The effect of fraction II was better than total essential oil, fraction I, and standard thymol. The greater effect of fraction II compared to standard thymol showed the synergistic effects of the ingredients in this fraction. As this fraction and also total oil were effective on the studied microorganism, the combination of these products with current antimicrobial agents could be considered as new antimicrobial compounds in further investigations. © The Author(s) 2014.

Functional Ginger Extracts from Supercritical Fluid Carbon Dioxide Extraction via In Vitro and In Vivo Assays: Antioxidation, Antimicroorganism, and Mice Xenografts Models

PubMed Central

Lee, Chih-Chen; Chiou, Li-Yu; Wang, Jheng-Yang; Chou, Sin-You; Lan, John Chi-Wei; Huang, Tsi-Shu; Huang, Kuo-Chuan

2013-01-01

Supercritical fluid carbon dioxide extraction technology was developed to gain the active components from a Taiwan native plant, Zingiber officinale (ginger). We studied the biological effects of ginger extracts via multiple assays and demonstrated the biofunctions in each platform. Investigations of ginger extracts indicated antioxidative properties in dose-dependant manners on radical scavenging activities, reducing powers and metal chelating powers. We found that ginger extracts processed moderate scavenging values, middle metal chelating levels, and slight ferric reducing powers. The antibacterial susceptibility of ginger extracts on Staphylococcus aureus, Streptococcus sobrinus, S. mutans, and Escherichia coli was determined with the broth microdilution method technique. The ginger extracts had operative antimicroorganism potentials against both Gram-positive and Gram-negative bacteria. We further discovered the strong inhibitions of ginger extracts on lethal carcinogenic melanoma through in vivo xenograft model. To sum up, the data confirmed the possible applications as medical cosmetology agents, pharmaceutical antibiotics, and food supplements. PMID:23983624

Synthesis and characterization of novel silver nanoparticles using Chamaemelum nobile extract for antibacterial application

NASA Astrophysics Data System (ADS)

Erjaee, Hoda; Rajaian, Hamid; Nazifi, Saeed

2017-06-01

The present study reports green synthesis of silver nanoparticles (AgNPs) at room temperature using aqueous Chamaemelum nobile extract for the first time. The effect of silver nitrate concentration, quantity of the plant extract and the reaction time on particle size was optimized and studied by UV-Vis spectroscopy and dynamic light scattering. The appearance of brownish color with λ max of 422 nm confirmed the formation of AgNPs. Synthesized nanoparticles were further characterized by Fourier transform infrared spectroscopy, x-ray diffraction and transmission electron microscopy. In addition, antimicrobial activity of the AgNPs against Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Bacillus subtilis was evaluated based on the inhibition zone using the disc-diffusion assay and measurement of minimal inhibition concentration and minimal bactericidal concentration by standard microdilution method. In conclusion, synthesis of nanoparticle with aqueous Chamaemelum nobile extract is simple, rapid, environmentally benign and inexpensive. Moreover, these synthesized nanoparticles exhibit significant antibacterial activity.

The effect of clary sage oil on staphylococci responsible for wound infections.

PubMed

Sienkiewicz, Monika; Głowacka, Anna; Poznańska-Kurowska, Katarzyna; Kaszuba, Andrzej; Urbaniak, Anna; Kowalczyk, Edward

2015-02-01

The spreading of bacterial antibiotic resistance among clinical strains of pathogenic bacteria has made investigators to search for other active antibacterial agents which could provide a valuable complement to the existing therapies. To determine the antibacterial activity of clary sage oil (Salvia sclarea L.) against Staphylococcus clinical strains which were isolated from patients with wound infections. A comprehensive evaluation of Staphylococcus clinical strain resistance to antibiotics was performed. The constituents of clary sage oil were assayed by GC-FID-MS analysis. The minimal inhibitory concentration (MIC) of the tested essential oil against staphylococci by the micro-dilution broth method was determined. The clary sage oil was active against Staphylococcus aureus, S. epidermidis and S. xylosus with MIC values ranging from 3.75 to 7.00 µl/ml. The results of the in vitro tests encourage to use formulations containing sage oil as the active natural antimicrobial agent. Because of its antimicrobial properties clary sage oil may be applied to treat wounds and skin infections.

Antibacterial activity of some bryophytes used traditionally for the treatment of burn infections.

PubMed

Singh, Meenakshi; Singh, Shweta; Nath, Virendra; Sahu, Vinay; Rawat, Ajay Kumar Singh

2011-05-01

Plagiochasma appendiculatum L. & L. (Aytoniaceae), Conocephalum conicum (L.) Necker (Conocephalaceae), Bryum argenteum Hedw. (Bryaceae), and Mnium marginatum (With.) P. Beauv. (Mniaceae) are bryophytes (liverworts and mosses) used by traditional healers for the treatment of burn, cuts, wounds, and skin disorders. This study evaluated the antibacterial activity of four bryophytes against some common bacteria responsible for burn infections. Different fractions of bryophytes were screened using the disc diffusion (qualitative) and broth microdilution (quantitative) methods, according to the guidelines of the National Committee for Clinical and Laboratory Standards. Chloroform fractions of liverworts were more active against Gram negative strains while butanol fractions of mosses had significant activity against Gram positive bacteria. Staphylococcus aureus was the most sensitive strain of those tested with the butanol fraction of M. marginatum (moss), with the strongest inhibition zone of 102.92% and minimum inhibitory concentration of 30 μg mL(-1). Our findings support the use of the bryophytes in traditional medicine for burn infections because of their significant antibacterial activity.

Molecular typing and antimicrobial susceptibility of Clostridium perfringens from broiler chickens.

PubMed

Gharaibeh, Saad; Al Rifai, Rami; Al-Majali, Ahmad

2010-12-01

Clostridium perfringens (Cp) causes necrotic enteritis disease in commercial poultry. Antimicrobials are used to control and treat this disease and sometimes clinical outbreaks do not respond well to certain treatments. This study was designed to isolate Cp from clinical cases, type these isolates by multiplex PCR, and determine their antimicrobial susceptibility by micro-dilution method. A total of 67 Cp isolates were obtained from 155 broiler chicken flocks. All isolates were classified as type A and non-enterotoxin producers. Lincomycin, erythromycins, and tilmicosin showed very high minimal inhibitory concentration (MIC) 50 of ≥256 μg/ml. However, tylosin, amoxicillin, ampicillin, penicillin, florfenicol, danofloxacin, enrofloxacin, chlortetracycline, doxycycline, and oxytetracycline had variable MIC₅₀ of 64, 0.5, 1, 1, 8, 4, 8, 4, 8, 0.5 μg/ml, respectively. It is recommended that Cp infections in Jordan be treated with either penicillins or tetracyclines especially amoxicillin and oxytetracycline. Copyright © 2010 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.

Assessment of antinociceptive, antipyretic and antimicrobial activity of Piper cubeba L. essential oil in animal models.

PubMed

Mothana, Ramzi; Alsaid, Mansour; Khaled, Jamal M; Alharbi, Naiyf S; Alatar, Abdulrahman; Raish, Mohammad; Al-Yahya, Mohammed; Rafatullah, Syed; Parvez, Mohammad Khalid; Ahamad, Syed Rizwan

2016-03-01

This study was designed to investigate the possible antiniciceptive, antipyretic and antimicrobial activities of the essential oil obtained from the fruits of Piper Cubeba (L.). To assess the antinociceptive and antipyretic activities, three doses (150, 300 and 600 mg/kg, i.p.) were tested in acetic acid-induced abdominal writhing, tail flick reaction and hot-plate and Brewer's yeast-induced hyperpyrexia test models in animals. Moreover, the antimicrobial activity was examined using agar diffusion method and broth micro-dilution assay for minimum inhibitory concentrations (MIC). The Piper Cubeba essential oil (PCEO) showed a marked antinociception (17, 30 and 54%) and an increase in reaction time in mice in the flick tailed and hot-plate tests. The brewer's yeast induced hyperpyrexia was decreased in a dose dependent manner. PCEO also exhibited a strong antimicrobial potential. These findings confirm the traditional analgesic indications of P. cubeba oil and provide persuasive evidence and support its use in Arab traditional medicine.

Antifungal study of the resinous exudate and of meroterpenoids isolated from Psoralea glandulosa (Fabaceae).

PubMed

Madrid, Alejandro; Espinoza, Luis; González, Cesar; Mellado, Marco; Villena, Joan; Santander, Rocío; Silva, Viviana; Montenegro, Iván

2012-12-18

Psoralea glandulosa L. (Fabaceae) is a medicinal resinous shrub used in Chilean folk medicine as antiseptic in treatment of infections and skin diseases caused by bacteria and fungus. To evaluate the in vitro antifungal activity of the resin and the active components from P. glandulosa against clinical yeast isolates. Active compounds were obtained of the resinous exudate from aerial parts of P. glandulosa. Eight species of yeast were exposed to the resin and two major compounds. Minimum inhibitory concentration (MIC(80)) was determined according to the standard broth microdilution method. Bakuchiol and 3-hydroxy-bakuchiol demonstrated potent activity with the MIC(80) ranging from 4 to >16 and 0.125 to 16 μg/mL, respectively. The resin had some degree of antifungal activity. The overall results provided important information for the potential application of the 3-hydroxy-bakuchiol from P. glandulosa in the therapy of serious infection and skin diseases caused by clinical yeast. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

In vitro activity of josamycin against Streptococcus pyogenes isolated from patients with upper respiratory tract infections in France.

PubMed

Auzou, M; Caillon, J; Poyart, C; Weber, P; Ploy, M-C; Leclercq, R; Cattoir, V

2015-07-01

The primary objective of our study was to obtain susceptibility data for josamycin against Streptococcus pyogenes isolated from patients presenting with upper respiratory tract infections in France. The secondary objective was to characterize the molecular mechanism of resistance in macrolide-resistant isolates. MICs of erythromycin, clarithromycin, azithromycin, josamycin, and clindamycin were determined by the broth microdilution method. Resistance genes erm(B), erm(TR), and mef(A) were screened by PCR. The MIC50 and MIC90 of josamycin against 193 isolates of S. pyogenes were 0.12 and 0.25mg/L, respectively, with a resistance rate estimated at 4.7%. Resistance was due to the erm(B) gene whereas strains harboring erm(TR) or mef(A) remained susceptible. Josamycin was active against >95% of S. pyogenes isolated from patients with upper respiratory tract infections, and can be used as an alternative for the treatment of pharyngitis. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

In vitro inhibitory effects of farnesol and interactions between farnesol and antifungals against biofilms of Candida albicans resistant strains.

PubMed

Xia, Jinping; Qian, Fang; Xu, Wenqian; Zhang, Zhenzhen; Wei, Xin

2017-04-01

Antifungal resistance is a serious problem in clinical infections. Farnesol, which is a potential antifungal agent against biofilms formed by Candida albicans resistant strains (a fluconazole-resistant isolate derived from SC5314 and two clinical Candida resistant isolates), was investigated in this study. The inhibitory effects of farnesol on biofilms were examined by XTT assay. The morphological changes and biofilm thicknesses were analyzed by scanning electron microscopy and confocal laser scanning microscopy, respectively. Additionally, the checkerboard microdilution method was used to investigate the interactions between farnesol and antifungals (fluconazole, amphotericin B, caspofungin, itraconazole, terbinafine and 5-flurocytosine) against biofilms. The results showed decreased SMICs of farnesol and thinner biofilms in the farnesol-treated groups, indicating that farnesol inhibited the development of biofilms formed by the resistant strain. Furthermore, there were synergistic effects between farnesol and fluconazole/5-flurocytosine, while there were antagonistic effects between farnesol and terbinafine/itraconazole, respectively, on the biofilms formed by the resistant strains.

[Antimicrobial susceptibility patterns of Legionella isolates in the environment and in patients].

PubMed

Choi, Go Eun; Kang, Jeong Eun; Lee, Eun Yup; Chang, Chulhun L; Tateda, Kazuhiro; Yamaguchi, Keizo; Kim, Kyeong Hee; Kim, Jeong Man

2010-02-01

Antimicrobial susceptibility of Legionella spp. has rarely been studied in Korea. Therefore, we aimed to determine the susceptibility of Legionella spp. to various antibiotics. We assessed the antimicrobial susceptibility of 66 environmental and clinical Legionella isolates collected between January 2001 and December 2008 from Korea and Japan. The minimum inhibitory concentrations (MICs) of 6 antibiotics, namely, azithromycin, ciprofloxacin, clarithromycin, clindamycin, gatifloxacin, and gemifloxacin were determined by the broth microdilution method using buffered starch yeast extract broth. The MIC ranges of the 6 antibiotics used against the Legionella isolates were as follows: 0.004-0.062 microg/mL (azithromycin), 0.002-0.5 microg/mL (ciprofloxacin), 0.004-0.5 microg/mL (clarithromycin), 0.12-4 microg/mL (clindamycin), 0.002-0.12 microg/mL (gatifloxacin), and 0.008-1 microg/mL (gemifloxacin). Legionella spp. isolates from Korea and Japan were most susceptible to gatifloxacin. Azithromycin, clarithromycin, ciprofloxacin, and gemifloxacin were also effective for treating legionellosis.

Inhibition of the essential oil from Chenopodium ambrosioides L. and α-terpinene on the NorA efflux-pump of Staphylococcus aureus.

PubMed

de Morais Oliveira-Tintino, Cícera Datiane; Tintino, Saulo Relison; Limaverde, Paulo W; Figueredo, Fernando G; Campina, Fábia F; da Cunha, Francisco A B; da Costa, Roger H S; Pereira, Pedro Silvino; Lima, Luciene F; de Matos, Yedda M L S; Coutinho, Henrique Douglas Melo; Siqueira-Júnior, José P; Balbino, Valdir Q; da Silva, Teresinha Gonçalves

2018-10-01

This study was carried out to test the essential oil from C. ambrosioides leaves and its main constituent, α-Terpinene, in an antibacterial activity assay. As well, it was evaluated ability reduce resistance to norfloxacin and ethidium bromide was compared the Staphylococcus aureus 1199B whith 1199 wild type strain. The MIC of the C. ambrosioides essential oil and α-Terpinene were determined by microdilution method. The MIC of the essential oil and α-Terpinene presented a value ≥ 1024 μg/mL. However, when associated with antibacterials, the essential oil from C. ambrosioides leaves significantly reduced the MIC of antibiotics and ethidium bromide, characterizing an efflux pump inhibition. The C. ambrosioides essential oil, despite having no direct antibacterial activity against the S. aureus 1199B strain, showed a potentiating action when associated with antibacterial agents, this being attributed to an inhibition of efflux pumps. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evaluation of the antibacterial potential of Petroselinum crispum and Rosmarinus officinalis against bacteria that cause urinary tract infections

PubMed Central

Petrolini, Fernanda Villas Boas; Lucarini, Rodrigo; de Souza, Maria Gorete Mendes; Pires, Regina Helena; Cunha, Wilson Roberto; Martins, Carlos Henrique Gomes

2013-01-01

In this study we evaluated the antibacterial activity of the crude hydroalcoholic extracts, fractions, and compounds of two plant species, namely Rosmarinus officinalis and Petroselinum crispum, against the bacteria that cause urinary tract infection. The microdilution method was used for determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The crude hydroalcoholic extract of R. officinalis displayed in vitro activity against Gram-positive bacteria, with satisfactory MBC for the clinical isolate S. saprophyticus. The fractions and the pure compound rosmarinic acid did not furnish promising results for Gram-negative bacteria, whereas fractions 2, 3, and 4 gave encouraging results for Gram-positive bacteria and acted as bactericide against S. epidermidis as well as E. faecalis (ATCC 29212) and its clinical isolate. R. officinalis led to promising results in the case of Gram-positive bacteria, resulting in a considerable interest in the development of reliable alternatives for the treatment of urinary infections. PMID:24516424

Evaluation of the antibacterial potential of Petroselinum crispum and Rosmarinus officinalis against bacteria that cause urinary tract infections.

PubMed

Petrolini, Fernanda Villas Boas; Lucarini, Rodrigo; de Souza, Maria Gorete Mendes; Pires, Regina Helena; Cunha, Wilson Roberto; Martins, Carlos Henrique Gomes

2013-01-01

In this study we evaluated the antibacterial activity of the crude hydroalcoholic extracts, fractions, and compounds of two plant species, namely Rosmarinus officinalis and Petroselinum crispum, against the bacteria that cause urinary tract infection. The microdilution method was used for determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The crude hydroalcoholic extract of R. officinalis displayed in vitro activity against Gram-positive bacteria, with satisfactory MBC for the clinical isolate S. saprophyticus. The fractions and the pure compound rosmarinic acid did not furnish promising results for Gram-negative bacteria, whereas fractions 2, 3, and 4 gave encouraging results for Gram-positive bacteria and acted as bactericide against S. epidermidis as well as E. faecalis (ATCC 29212) and its clinical isolate. R. officinalis led to promising results in the case of Gram-positive bacteria, resulting in a considerable interest in the development of reliable alternatives for the treatment of urinary infections.

Chemical Composition and Antimicrobial Activities of Essential Oils from Nepeta cataria L. against Common Causes of Food-Borne Infections

PubMed Central

Zomorodian, Kamiar; Saharkhiz, Mohammad Jamal; Shariati, Samaneh; Pakshir, Keyvan; Rahimi, Mohammad Javad; Khashei, Reza

2012-01-01

Nepeta cataria L. is traditionally consumed as a food additive. The effects of three different harvest stages of N. cataria essential oils (EOs) against most common causes of food-borne infections were evaluated by broth microdilution method as recommended by the Clinical and Laboratory Standards Institute (CLSI). The chemical composition of the EOs from N. cataria has been analyzed by gas chromatography/mass spectrometry (GC/MS). The analysis of the EOs indicated that 4a-α,7-α,7a-β-nepetalactone (55–58%) and 4a-α,7-β,7a-α-nepetalactone (30–31.2%) were the major compounds of the EOs at all developmental stages. The results showed that the tested EOs exhibited antimicrobial activities against the food-borne pathogens at concentrations of 0.125–2 μL/mL. Based on these results, the EO of N. cataria can possibly be used in food products as a natural preservative agent. PMID:22779012

Cationic synthetic peptides: assessment of their antimicrobial potency in liquid preserved boar semen.

PubMed

Speck, Stephanie; Courtiol, Alexandre; Junkes, Christof; Dathe, Margitta; Müller, Karin; Schulze, Martin

2014-01-01

Various semen extender formulas are in use to maintain sperm longevity and quality whilst acting against bacterial contamination in liquid sperm preservation. Aminoglycosides are commonly supplemented to aid in the control of bacteria. As bacterial resistance is increasing worldwide, antimicrobial peptides (AMPs) received lively interest as alternatives to overcome multi-drug resistant bacteria. We investigated, whether synthetic cationic AMPs might be a suitable alternative for conventional antibiotics in liquid boar sperm preservation. The antibacterial activity of two cyclic AMPs (c-WWW, c-WFW) and a helical magainin II amide analog (MK5E) was studied in vitro against two Gram-positive and eleven Gram-negative bacteria. Isolates included ATCC reference strains, multi-resistant E. coli and bacteria cultured from boar semen. Using broth microdilution, minimum inhibitory concentrations were determined for all AMPs. All AMPs revealed activity towards the majority of bacteria but not against Proteus spp. (all AMPs) and Staphylococcus aureus ATCC 29213 (MK5E). We could also demonstrate that c-WWW and c-WFW were effective against bacterial growth in liquid preserved boar semen in situ, especially when combined with a small amount of gentamicin. Our results suggest that albeit not offering a complete alternative to traditional antibiotics, the use of AMPs offers a promising solution to decrease the use of conventional antibiotics and thereby limit the selection of multi-resistant strains.

Cationic Synthetic Peptides: Assessment of Their Antimicrobial Potency in Liquid Preserved Boar Semen

PubMed Central

Speck, Stephanie; Courtiol, Alexandre; Junkes, Christof; Dathe, Margitta; Müller, Karin; Schulze, Martin

2014-01-01

Various semen extender formulas are in use to maintain sperm longevity and quality whilst acting against bacterial contamination in liquid sperm preservation. Aminoglycosides are commonly supplemented to aid in the control of bacteria. As bacterial resistance is increasing worldwide, antimicrobial peptides (AMPs) received lively interest as alternatives to overcome multi-drug resistant bacteria. We investigated, whether synthetic cationic AMPs might be a suitable alternative for conventional antibiotics in liquid boar sperm preservation. The antibacterial activity of two cyclic AMPs (c-WWW, c-WFW) and a helical magainin II amide analog (MK5E) was studied in vitro against two Gram-positive and eleven Gram-negative bacteria. Isolates included ATCC reference strains, multi-resistant E. coli and bacteria cultured from boar semen. Using broth microdilution, minimum inhibitory concentrations were determined for all AMPs. All AMPs revealed activity towards the majority of bacteria but not against Proteus spp. (all AMPs) and Staphylococcus aureus ATCC 29213 (MK5E). We could also demonstrate that c-WWW and c-WFW were effective against bacterial growth in liquid preserved boar semen in situ, especially when combined with a small amount of gentamicin. Our results suggest that albeit not offering a complete alternative to traditional antibiotics, the use of AMPs offers a promising solution to decrease the use of conventional antibiotics and thereby limit the selection of multi-resistant strains. PMID:25148109

In vitro interactions between amphotericin B and hydrocortisone: potential implications for intrathecal therapy.

PubMed

Hodge, Greg; Cohen, Stuart H; Thompson, George R

2015-09-01

Fungal meningitis remains a severe and often lethal infection requiring aggressive antifungal therapy and in refractory cases the use of intrathecal amphotericin B (AmB). Administration of amphotericin B by this method may result in clinically apparent adverse reactions such as paresthesias, radiculitis, or myelopathy. Coadministration of hydrocortisone is therefore often given in an attempt to avoid these effects; however, the potential consequences of this approach on fungal growth or on drug synergy/antagonism had not previously been assessed. We used the checkerboard titration broth microdilution method to analyze interactions by fractional inhibitory concentration indices (FICIs). The combination of amphotericin B and hydrocortisone resulted in synergy or indifference against all isolates (Candida, Cryptococcus, and Coccidioides) during in vitro testing at low concentrations. Antagonism was observed using higher hydrocortisone concentrations (those not observed in vivo) suggesting possible steric hindrance or binding to AmB may occur at doses unlikely to be present during clinical care. Concurrent hydrocortisone and AmB administration should not be avoided due to in vitro antagonism concerns. © 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.

Antiproliferative and antibacterial activity of some glutarimide derivatives.

PubMed

Popović-Djordjević, Jelena B; Klaus, Anita S; Žižak, Željko S; Matić, Ivana Z; Drakulić, Branko J

2016-12-01

Antiproliferative and antibacterial activities of nine glutarimide derivatives (1-9) were reported. Cytotoxicity of compounds was tested toward three human cancer cell lines, HeLa, K562 and MDA-MB-453 by MTT assay. Compound 7 (2-benzyl-2-azaspiro[5.11]heptadecane-1,3,7-trione), containing 12-membered ketone ring, was found to be the most potent toward all tested cell lines (IC50 = 9-27 μM). Preliminary screening of antibacterial activity by a disk diffusion method showed that Gram-positive bacteria were more susceptible to the tested compounds than Gram-negative bacteria. Minimum inhibitory concentration (MIC) determined by a broth microdilution method confirmed that compounds 1, 2, 4, 6-8 and 9 inhibited the growth of all tested Gram-positive and some of the Gram-negative bacteria. The best antibacterial potential was achieved with compound 9 (ethyl 4-(1-benzyl-2,6-dioxopiperidin-3-yl)butanoate) against Bacillus cereus (MIC 0.625 mg/mL; 1.97 × 10(-3 )mol/L). Distinction between more and less active/inactive compounds was assessed from the pharmacophoric patterns obtained by molecular interaction fields.

Non Diphtheritic Corynebacteria: An Emerging Nosocomial Pathogen in Skin and Soft Tissue Infection

PubMed Central

Ravi, GS; Alex, Ann Mary; Mamatha, KR; Sunitha, L; Ramya, K Thangam

2015-01-01

Introduction Non-diphtheritic corynebacteria are normal inhabitants of skin and mucous membrane. When isolated from clinical specimens they are often considered as contaminants. Recent reports suggest their role as emerging nosocomial pathogens. Aim To speciate non-diphtheritic corynebacteria isolated from wound specimens, to correlate their clinical significance and to determine their invitro antimicrobial susceptibilities to 9 antimicrobial agents. Materials and Methods Twenty five non-diphtheritic corynebacteria from skin and soft tissue infections were selected for study. Isolates were identified by battery of tests and minimum inhibitory concentration (MIC) was detected by Clinical & Laboratory Standards Institute (CLSI) described broth microdilution method. MIC was interpreted according CLSI and British Society for Antimicrobial Chemotherapy (BSAC) guidelines. Results C. amycolatum was the predominant species (20%) followed by C. striatum (16%). Penicillin was least effective invitro followed by clindamycin and ciprofloxacin. Excellent activities were shown by vancomycin, linezolid and imipenem. Multidrug resistance was found in all the species. Conclusion Non-diphtheritic corynebacteria are potential nosocomial pathogens among acute/chronic complicated skin and soft tissue infection. Vancomycin or linezolid can be used empirically to treat such infections until the invitro susceptibility results are available. PMID:26816891

Graphene oxide-modified ZnO particles: synthesis, characterization, and antibacterial properties

PubMed Central

Zhong, Linlin; Yun, Kyusik

2015-01-01

Nanosized ZnO particles with diameters of 15 nm were prepared with a solution precipitation method at low cost and high yield. The synthesis of the particles was functionalized by the organic solvent dimethylformamide, and the particles were covalently bonded to the surface of graphene oxide. The morphology of the graphene oxide sheets and ZnO particles was confirmed with field emission scanning electron microscopy and biological atomic force microscopy. Fourier transform infrared spectroscopy and X-ray diffraction were used to analyze the physical and chemical properties of the ZnO/graphene oxide composites that differed from those of the individual components. Enhanced electrochemical properties were detected with cyclic voltammetry, with a redox peak of the composites at 0.025 mV. Excellent antibacterial activity of ZnO/graphene oxide composites was observed with a microdilution method in which minimum inhibitory concentrations of 6.25 µg/mL for Escherichia coli and Salmonella typhimurium, 12.5 µg/mL for Bacillus subtilis, and 25 µg/mL for Enterococcus faecalis. After further study of the antibacterial mechanism, we concluded that a vast number of reactive oxygen species formed on the surface of composites, improving antibacterial properties. PMID:26347126

Antifungal activity of essential oils of Croton species from the Brazilian Caatinga biome.

PubMed

Fontenelle, R O S; Morais, S M; Brito, E H S; Brilhante, R S N; Cordeiro, R A; Nascimento, N R F; Kerntopf, M R; Sidrim, J J C; Rocha, M F G

2008-05-01

To find new antifungal agents among essential oils from Brazilian Croton species. Plant leaves were steam distilled and the obtained essential oils were analyzed by gas chromatography/mass spectroscopy. The main constituents were estragole and anethole for Croton zehntneri, methyl-eugenol and bicyclogermacrene for Croton nepetaefolius and spathulenol and bicyclogermacrene for Croton argyrophylloides. The antifungal activity of essential oils was evaluated against Candida albicans, Candida tropicalis and Microsporum canis by the agar-well diffusion method and the minimum inhibitory concentration (MIC) by the broth microdilution method. Essential oils of Croton species demonstrated better activity against M. canis. Among the three plants C. argyrophylloides showed the best results, with MIC ranging from 9 to 19 microg ml(-1). The acute administration of the essential oil up to 3 g kg(-1) by the oral route to mice was devoid of overt toxicity. The studied essential oils are active in vitro against the dermatophyte M. canis and present relative lack of acute toxicity in vivo. Because of its antifungal activity and low toxicity, the essential oils of studied Croton species are promising sources for new phytotherapeutic agents to treat dermatophytosis.

Chemical composition and antimicrobial activity of essential oil from cones of Pinus koraiensis.

PubMed

Lee, Jeong-Ho; Yang, Hye-Young; Lee, Hong-Sub; Hong, Soon-Kwang

2008-03-01

The essential oil from the cones of Pinus koraiensis was prepared after removing the seeds, and its chemical composition analyzed using gas chromatography-mass spectrometry (GC-MS). Hydrodistillation of the P. koraiensis cones yielded 1.07% (v/w) of essential oil, which was almost three times the amount of essential oil extracted from the needles of the same plant. Moreover, the antimicrobial activities of the oil against the growth of Gram-positive bacteria, Gram-negative bacteria, and fungi were evaluated using the agar disc diffusion method and broth microdilution method. Eighty-seven components, comprising about 96.8% of the total oil, were identified. The most abundant oil components were limonene (27.90%), alpha-pinene (23.89%), beta-pinene (12.02%), 3-carene (4.95%), beta-myrcene (4.53%), isolongifolene (3.35%), (-)-bornyl acetate (2.02%), caryophyllene (1.71%), and camphene (1.54%). The essential oil was confirmed to have significant antimicrobial activities, especially against pathogenic fungal strains such as Candida glabrata YFCC 062 and Cryptococcus neoformans B 42419. Therefore, the present results indicate that the essential oil from the cones of Pinus koraiensis can be used in various ways as a nontoxic and environmentally friendly disinfectant.

Preparation and bactericide activity of gallic acid stabilized gold nanoparticles

NASA Astrophysics Data System (ADS)

Moreno-Álvarez, S. A.; Martínez-Castañón, G. A.; Niño-Martínez, N.; Reyes-Macías, J. F.; Patiño-Marín, N.; Loyola-Rodríguez, J. P.; Ruiz, Facundo

2010-10-01

In this work, gold nanoparticles with three different sizes (13.7, 39.4, and 76.7 nm) were prepared using a simple aqueous method with gallic acid as the reducing and stabilizing agent, the different sizes were obtained varying some experimental parameters as the pH of the reaction and the amount of the gallic acid. The prepared nanoparticles were characterized using X-ray diffraction, transmission electron microscopy, dynamic light scattering, and UV-Vis spectroscopy. Samples were identified as elemental gold and present spherical morphology, a narrow size distribution and good stabilization according to TEM and DLS results. The antibacterial activity of this gallic acid stabilized gold nanoparticles against S. mutans (the etiologic agent of dental caries) was assessed using a microdilution method obtaining a minimum inhibitory concentration of 12.31, 12.31, and 49.25 μg/mL for 13.7, 39.4, and 76.7 nm gold nanoparticles, respectively. The antibacterial assay showed that gold nanoparticles prepared in this work present a bactericide activity by a synergistic action with gallic acid. The MIC found for this nanoparticles are much lower than those reported for mixtures of gold nanoparticles and antibiotics.

Study of the impact of cranberry extract on the virulence factors and biofilm formation by Enterococcus faecalis strains isolated from urinary tract infections.

PubMed

Wojnicz, Dorota; Tichaczek-Goska, Dorota; Korzekwa, Kamila; Kicia, Marta; Hendrich, Andrzej B

2016-12-01

Drinking of cranberry fruit juice and application of commercial preparations containing the cranberry extracts are recommended in the prevention and treatment of urinary tract infections (UTIs), especially in women with recurrent UTIs. Many studies focus on the activity of cranberries against uropathogenic Escherichia coli (E. coli) strains. However, the knowledge of the cranberry effect on Gram-positive Enterococcus faecalis (E. faecalis) is limited. Therefore, the aim of our study was to establish the activity of commercial concentrated cranberry extract on the growth, virulence factors and biofilm formation of E. faecalis strains isolated from urine. Minimal inhibitory concentrations (MICs) of cranberry extract were determined by the broth microdilution method. Disc diffusion method was used to determine antimicrobial susceptibility. The impact of cranberry extract on bacterial survival, hydrophobicity, synthesis of lipase, lecithinase, DNase, hemolysin, gelatinase and biofilm mass was determined. Results show that cranberry extract inhibits the growth, enzymatic activities of bacteria and limits biofilm formation. The antibacterial activities of the studied cranberry extract confirm that it could be successfully used in prevention of UTIs caused by E. faecalis.

Chemical composition, antimicrobial and antioxidant potential of the essential oil of Guarea kunthiana A. Juss.

PubMed

Pandini, J A; Pinto, F G S; Scur, M C; Santana, C B; Costa, W F; Temponi, L G

2018-02-01

The essential oils are extracted from plant compounds and can present activities antimicrobial and antioxidant properties. The goals of the present study were: (a) to determine the chemical composition of the essential oil of Guarea kunthiana A. Juss using the method of gas chromatography coupled to mass spectrometry (GC-MS); (b) to evaluate the antimicrobial potential of this oil using the broth microdilution method against different microorganisms: five Gram-negative bacteria, four Gram-positive bacteria and a yeast and (c) to determine the antioxidant activity of the oil using the DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical assay. The GC-MS analyses allowed identifying 13 constituents, representing 96.52% of the essencial oil composition. The main compounds identified were α-zingiberene (34.48%), β-sesquiphellandrene (22.90%), and α-curcumene (16.17%). With respect to the antimicrobial activity, the essential oil was effective against all the microorganisms tested, except for the bacteria E. coli and K. pneumoniae, which were resistant to the action of the oil. From a general point of view, Gram-positive bacteria were more susceptible to the action of the essential oil than Gram-negative bacteria. The essential oil exhibited antioxidant potential.

Comparison of chemical composition and antibacterial activity of Nigella sativa seed essential oils obtained by different extraction methods.

PubMed

Kokoska, L; Havlik, J; Valterova, I; Sovova, H; Sajfrtova, M; Jankovska, I

2008-12-01

Nigella sativa L. seed essential oils obtained by hydrodistillation (HD), dry steam distillation (SD), steam distillation of crude oils obtained by solvent extraction (SE-SD), and supercritical fluid extraction (SFE-SD) were tested for their antibacterial activities, using the broth microdilution method and subsequently analyzed by gas chromatography and gas chromatography-mass spectrometry. The results showed that the essential oils tested differed markedly in their chemical compositions and antimicrobial activities. The oils obtained by HD and SD were dominated by p-cymene, whereas the major constituent identified in both volatile fractions obtained by SD of extracted oils was thymoquinone (ranging between 0.36 and 0.38 g/ml, whereas in oils obtained by HD and SD, it constituted only 0.03 and 0.05 g/ml, respectively). Both oils distilled directly from seeds showed lower antimicrobial activity (MICs > or = 256 and 32 microg/ml for HD and SD, respectively) than those obtained by SE-SD and SFE-SD (MICs > or = 4 microg/ml). All oil samples were significantly more active against gram-positive than against gram-negative bacteria. Thymoquinone exhibited potent growth-inhibiting activity against gram-positive bacteria, with MICs ranging from 8 to 64 microg/ml.

Molecular identification and antifungal susceptibility profile of Candida species isolated from patients with vulvovaginitis in Tehran, Iran

PubMed Central

Sharifynia, Somayeh; Falahati, Mehraban; Akhlaghi, Lame; Foroumadi, Alireza; Fateh, Roohollah

2017-01-01

Background: Rapid and accurate identification and evaluation of antifungal susceptibility pattern of Candida isolates are crucial to determine suitable antifungal drugs for the treatment of patients with vulvovaginitis candidiasis. Materials and Methods: Vaginal samples were collected from 150 women with suspicious vaginal candidiasis, and then cultured on Sabouraoud's Dextrose Agar with chloramphenicol to isolate Candida species. After identification of Candida isolates using polymerase chain reaction-restriction fragment length polymorphism technique, antifungal susceptibility testing of four azolic antifungal drugs was carried out using broth microdilution method according to the CLSI M27-A3. Results: Candida species were isolated from eighty suspected patients (61.79%). The most common pathogen was Candida albicans (63.75%). Resistance to fluconazole and ketoconazole was observed in 27.5% and 23.75% of Candida isolates, respectively, and only 2% of Candida isolates were resistant to miconazole. Interestingly, resistance to fluconazole in C. albicans was more than other Candida species. Conclusion: The results indicated that therapy should be selected according to the antifungal susceptibility tests for the prevention of treatment failure and miconazole therapy can be considered as the best therapeutic choice in the management of vulvovaginitis. PMID:29387119

Adherence of staphylococcus aureus to catheter tubing inhibition by quaternary ammonium compounds.

PubMed

Iyamba, Jean-Marie Liesse; Okombe, Daniel Tassa; Zakanda, Francis Nsimba; Malongo, Trésor Kimbeni; Unya, Joseph Welo; Lukukula, Cyprien Mbundu; Kikuni, Ntondo Za Balega Takaisi

2016-01-01

S. aureus is a Gram positive bacterium which is responsible for a wide range of infections. This pathogen has also the ability to adhere to biotic or abiotic surface such as central venous catheter (CVC) and to produce a biofilm. The aim of this study was to evaluate the effect of hexadecyltrimethyl ammonium bromide (HTAB) and Hexadecylbetainate chloride (HBC) on Staphylococcus aureus adherence to the catheter tubing and on bacteria growth. Broth microdilution method was used to determine the Minimal Inhibitory Concentration (MIC). The detection of slime production was done by Congo Red Agar method, and the adherence of bacteria to the catheter tubing was evaluated by the enumeration of bacteria on plate counts. The results of this study showed that the MICs of HTAB were ranged from 0.125 to 0.5 µg/mL, and those of HBC fluctuated between 2 to 8 µg/mL. HTAB and HBC inhibited bacteria adhesion on the surface of the catheter tubing. This study showed that HTAB and HBC can prevent the adherence of S. aureus strains to the surface of catheter tubing, suggesting that they could be used to prevent the risk of catheter related bloodstream infections.

Antifungal activity of Brazilian medicinal plants involved in popular treatment of mycoses.

PubMed

Cruz, M C S; Santos, P O; Barbosa, A M; de Mélo, D L F M; Alviano, C S; Antoniolli, A R; Alviano, D S; Trindade, R C

2007-05-04

A survey of medicinal plants used to treat common mycoses was done in the Curituba district, Sergipe State, Brazil. One hundred inhabitants were interviewed by health agents and traditional healers. Four different plants were the most cited (more than 50% of the citations): Ziziphus joazeiro, Caesalpinia pyramidalis, Bumelia sartorum and Hymenea courbaril. The aqueous extracts obtained following traditional methods and using different parts of these plants, were submitted to drop agar diffusion tests for primary antimicrobial screening. Only the water infusion extract of Ziziphus joazeiro and Caesalpinea pyramidalis presented a significant antifungal activity against Trichophyton rubrum, Candida guilliermondii, Candida albicans, Cryptococcus neoformans and Fonsecaea pedrosoi, when compared to the antifungal agent amphotericin B. The minimal inhibitory concentration (MIC) of the bioactive extracts was evaluated by the microdilution method. Best activity with a MIC of 6.5 microg/ml for both extracts was observed against Trichophyton rubrum and Candida guilliermondii. Ziziphus joazeiro and Caesalpinea pyramidalis extracts presented also low acute toxicity in murine models. The present study validates the folk use of these plant extracts and indicates that they can be effective potential candidates for the development of new strategies to treat fungal infections.

Antistaphylococcal Activity of Dalbavancin, an Experimental Glycopeptide

PubMed Central

Lin, Gengrong; Credito, Kim; Ednie, Lois M.; Appelbaum, Peter C.

2005-01-01

Dalbavancin, tested against 146 staphylococci, was more potent than other drugs tested, with an MIC at which 50% of staphylococci were inhibited of 0.03 μg/ml and an MIC at which 90% of staphylococci were inhibited of 0.06 μg/ml by microdilution. For all strains, MICs of vancomycin, linezolid, ranbezolid, oritavancin, daptomycin, and quinupristin-dalfopristin were ≤4.0 μg/ml. Dalbavancin was bactericidal at four times the MIC against all six strains tested. PMID:15673763

Etest Cannot Be Recommended for In Vitro Susceptibility Testing of Mucorales

PubMed Central

Caramalho, Rita; Maurer, Elisabeth; Binder, Ulrike; Araújo, Ricardo; Dolatabadi, Somayeh; Lass-Flörl, Cornelia

2015-01-01

Amphotericin B and posaconazole susceptibility patterns were determined for the most prevalent Mucorales, following EUCAST (European Committee on Antimicrobial Susceptibility Testing) broth microdilution guidelines. In parallel, Etest was performed and evaluated against EUCAST. The overall agreement of MICs gained with Etest and EUCAST was 75.1%; therefore, Etest cannot be recommended for antifungal susceptibility testing of Mucorales. Amphotericin B was the most active drug against Mucorales species in vitro, while the activities of posaconazole were more restricted. PMID:25845881

Bioassay Guided Fractionation of an Anti-Methicillin-Resistant Staphylococcus aureus Flavonoid From Bromus inermis Leyss Inflorescences

PubMed Central

Aliahmadi, Atousa; Mirzajani, Fateme; Ghassempour, Alireza; Sonboli, Ali

2014-01-01

Background: Plants are considered as promising sources of new antibacterial agents as well as bioassay guided fractionation. Objectives: In the present work, the antibacterial properties, especially against methicillin-resistant Staphylococcus aureus (MRSA), of Bromus inermis inflorescence was studied, using the bioassay guided fractionation as well as the bio-autographic method. Materials and Methods: The plant organic extract was prepared via maceration in methanol, followed by the fractionation using n-hexane. The extracts were subjected for minimum inhibitory concentrations (MICs) against some human pathogenic bacteria via standard broth micro-dilution assay. Thereafter, a bio-autographical method was applied using the high performance thin layer chromatography (HPTLC) coupled with agar overlay assays for the primary characterization and identification of bioactive substance (s). Results: Through the bioassay guided fractionation method, the greatest antibacterial activities were related to the n-hexane extract. It was also revealed that the effective anti-MRSA agent of the assessed plant was a relatively polar substance with an MIC value of about 8 μg/mL against the tested MRSA strain (in comparison with the MIC value of 32 μg/mL for chloramphenicol). Conclusions: As a result of the full range UV-Vis scanning of the responsible band in the HPTLC experiments (200-700 nm), the flavonoid was the most imaginable natural compound. PMID:25741430

Inhibitory Effects of Pterodon emarginatus Bean Oil and Extract on Staphylococcus aureus.

PubMed

Mendes, V S; Sant'Anna, J B; Oliveira, S C C; Maldonade, Iriani Rodrigues; Machado, Eleuza Rodrigues

2017-01-01

Pterodon emarginatus is a tree of the Brazilian Savannah. The beans of this tree are used in folk medicine as anti-inflammatory preparations, especially for infections caused by Staphylococcus aureus . These bacteria can cause simple infections or serious illnesses such as pneumonia, meningitis, endocarditis, toxic shock syndrome, septicemia, and others. This study had the goal of verifying the effect of the essential oil (OE) from P. emarginatus on the inhibition of S. aureus in culture medium, i.e., " in vitro " tests. The vegetable material was cut and crushed with a press. The OE was obtained by extraction using hexane, alcohol, and water. The P. emarginatus extracts obtained were used to evaluate the antimicrobial effect on S. aureus (ATCC 25923) by tests of well diffusion, disc diffusion, and microdilution. The strain used in the assays was maintained in brain heart infusion broth and nutrient agar until testing. Afterward, the bacteria were spread on agar plates with Mueller-Hinton agar medium. In the wells and on the paper discs, the OE suspensions were placed in the following volumes: 10, 15, 20, 25, 30, 40, and 80 μL and subsequently they were incubated at 35°C ± 2°C. After 24 h, the number of colony-forming unit was determined. Pure OE and hydroalcoholic extract inhibited the growth of S. aureus , while aqueous extract had no effect on bacterial growth in all microbial methods used. Thus, the present study showed the potential of sucupira-based extracts against S. aureus growth, opening new perspectives for the evaluation of these bioactive compounds as phytopharmaceutical products. Plant extract act as antimicrobials to prevent and reduce bacterial contaminationBeans of Pterodon emarginatus has antibacterial propertiesExtraction with different solvents might implicate on the rate of bacterial deathThe effect of different microbiological methods (well diffusion, disc diffusion and microdilution) was evaluated on reducing CFUThe results showed by MBC that concentrations superior to 10% (v/v) using AC and 7.5% (v/v) using OE were necessary to eliminate colonies formedAccording to data of MIC, at 2.5% of AC and OE was enough to kill S. aureus The well diffusion technique demonstrated better performance than disc diffusion test for OE and AC extractsHydroalcoholic and oil extracts of sucupira beans had highest effect against Staphylococcus aureus Aqueous extract had no effect on bacterial growth in all microbial methods testedThe sucupira-based extracts is a promising source as herbal drug due to therapeutic value Abbreviations Used: OE: Essencial oil; AC: Hydroalcoholic oil extract; AQ: Aqueous extracts; MIC: Minimum inhibitory concentration; MBC: Minimum bactericidal concentration; CFU: Colony formed unit.

Caryocar brasiliense supercritical CO2 extract possesses antimicrobial and antioxidant properties useful for personal care products

PubMed Central

2014-01-01

Background The cosmetic and pharmaceutical industries have an increasing interest in replacing synthetic antimicrobials in dermatological products due to increased microbial resistance to conventional antimicrobial agents. Pequi (Caryocar brasiliense) is a native fruit tree of the Brazilian Cerrado, specifically used in cosmetics, in the food industry, and for medicinal purposes. Leishmanicidal and antifungal activities have been reported previously. This study was designed to evaluate the antimicrobial and antioxidant activities of a C. brasiliense extract obtained by supercritical CO2 extraction. Methods The minimum inhibitory concentrations (MICs) against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus were determined by the classical microdilution method. Antiseptic activity against these organisms was evaluated by the plate diffusion method. The antioxidant potential of the extract was evaluated using a method based on the oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS). The extract’s chemical profile was analyzed for the presence of alkaloids, saponins, anthraquinones, steroids, tannins, flavonoids, and phenolic compounds according to standard colorimetric methods. Results The C. brasiliense supercritical CO2 extract exhibits antimicrobial activity against all bacteria tested. It also possesses antioxidant activity, when compared to a vitamin E standard. Conclusions The C. brasiliense supercritical CO2 extract may be useful for the development of personal care products, primarily for antiseptic skin products that inactivate, reduce, prevent, or arrest the growth of microorganisms with the inherent intent to mitigate or prevent disease as well as products that minimize damage caused by free radicals. PMID:24565304

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.

Automated reading of MIC microdilution trays containing fluorogenic enzyme substrates with the Sensititre Autoreader.

PubMed Central

Staneck, J L; Allen, S D; Harris, E E; Tilton, R C

1985-01-01

The Sensititre Autoreader is a microcomputer-driven instrument capable of automatically reading antimicrobial susceptibility microdilution trays. The instrument measures the fluorescence liberated by bacterial enzymatic activity on fluorogenic substrates as an indicator of growth in each well. A mathematical algorithm converts the fluorescent signals from an antimicrobial dilution series to an MIC endpoint. A three-center study evaluated the performance of the Autoreader in comparison with MIC determined visually in a duplicate set of control plates lacking fluorogenic substrate. Among 828 isolates of gram-negative bacilli tested against 17 antimicrobial agents, Autoreader 18-h MIC were within +/- 1 twofold dilution of control MIC values (agreement) in 95.3% of instances. In 3.5% of the instances, Autoreader values occurred +/- 2 half-step dilutions from control values (minor discrepancy), and in only 1.2% of instances did Autoreader values deviate from control values by greater than +/- 2 dilution steps (major discrepancy). Agreement, minor discrepancies, and major discrepancies were noted among 148 gram-positive cocci tested against 11 antimicrobial agents in 93.5, 4.8, and 1.7% of the instances, respectively. Over half of the major discrepancies noted with gram-negative bacilli occurred with Proteus mirabilis-beta-lactam combinations, a problem that was resolved when a lower initial inoculum was used. Inter-and intralaboratory reproducibility was excellent. Standard Sensititre susceptibility trays may be instrument read at 18 h reproducibly and accurately with only slight modification of conventional procedures to include fluorogenic enzyme substrates in the incubation broth. PMID:4031033

Pathogen occurrence and antimicrobial resistance trends among urinary tract infection isolates in the Asia-Western Pacific Region: report from the SENTRY Antimicrobial Surveillance Program, 1998-1999.

PubMed

Turnidge, John; Bell, Jan; Biedenbach, Douglas J; Jones, Ronald N

2002-07-01

Worldwide surveillance of antimicrobial resistance among urinary tract pathogens is useful to determine important trends and geographical variation for common Gram-positive and -negative species. The most common causative uropathogens often have intrinsic or acquired resistance mechanisms which include ESBL production among enteric bacilli, multi-drug resistant staphylococci and non-fermentative Gram-negative bacilli such as Pseudomonas aeruginosa and Acinetobacter spp. and vancomycin-resistant Enterococcus spp. This study evaluates pathogen frequency and the resistance rates among urinary tract infection (UTI) pathogens in 14 medical centres in the Asia-Pacific region between 1998 and 1999. The isolates were referred to a central monitor for reference NCCLS broth microdilution testing, identification confirmation and patient demographic analysis. Over 50% of the 958 pathogens were Escherichia coli and Klebsiella spp. followed by P. aeruginosa, Enterococcus spp. and Enterobacter spp. Susceptibility for the three enteric bacilli was high for carbapenems (100%), 'fourth-generation' cephalosporins (cefepime 94.9-98.6%) and amikacin (> or = 93.0%). Beta-lactamase inhibitor compounds were more active against E. coli (piperacillin/tazobactam; > 90% susceptible) than the other two enteric species and all other tested agents had a narrower spectra of activity. The rank order of anti-pseudomonal agents was amikacin (91.5% susceptible)> imipenem > piperacillin/tazobactam > tobramycin > ceftazidime and cefepime (77.4 and 76.4% susceptible, respectively). Susceptibility to quinolones for the P. aeruginosa isolates was only 63.2-67.0%. Only one vancomycin-intermediate Enterococcus spp. (van C phenotype) was detected among the 103 strains tested. Newer fluoroquinolones (gatifloxacin; MIC(50), mg/l) were more potent against enterococci than ciprofloxacin (MIC(50), 2 mg/l) and high-level resistance to aminoglycosides was common (41.7%). The data presented are compared to studies of similar design from other areas which are part of the SENTRY surveillance network.

Etest cannot be recommended for in vitro susceptibility testing of mucorales.

PubMed

Caramalho, Rita; Maurer, Elisabeth; Binder, Ulrike; Araújo, Ricardo; Dolatabadi, Somayeh; Lass-Flörl, Cornelia; Lackner, Michaela

2015-01-01

Amphotericin B and posaconazole susceptibility patterns were determined for the most prevalent Mucorales, following EUCAST (European Committee on Antimicrobial Susceptibility Testing) broth microdilution guidelines. In parallel, Etest was performed and evaluated against EUCAST. The overall agreement of MICs gained with Etest and EUCAST was 75.1%; therefore, Etest cannot be recommended for antifungal susceptibility testing of Mucorales. Amphotericin B was the most active drug against Mucorales species in vitro, while the activities of posaconazole were more restricted. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

In vitro activities of amoxicillin-clavulanate, doxycycline, ceftazidime, imipenem, and trimethoprim-sulfamethoxazole against biofilm of Brazilian strains of Burkholderia pseudomallei.

PubMed

Bandeira, Tereza de Jesus Pinheiro Gomes; Moreira, Camila Alencar; Brilhante, Raimunda Sâmia Nogueira; Castelo-Branco, Débora de Souza Collares Maia; Neto, Manoel Paiva de Araújo; Cordeiro, Rossana de Aguiar; Rodrigues, Terezinha de Jesus Santos; Rocha, Marcos Fábio Gadelha; Sidrim, José Júlio Costa

2013-11-01

This study aimed at investigating the in vitro activities of amoxicillin-clavulanate, doxycycline, ceftazidime, imipenem, and trimethoprim-sulfamethoxazole against Burkholderia pseudomallei in planktonic and biofilm forms, through broth microdilution and resazurin-based viability staining, respectively. In planktonic growth, the strains were susceptible to the drugs, while in biofilm growth, significantly higher antimicrobial concentrations were required, especially for ceftazidime and imipenem, surpassing the resistance breakpoints. These results highlight the importance of the routine evaluation of biofilm antimicrobial susceptibility.

Anti-Legionella activity of essential oil of Satureja cuneifolia.

PubMed

Dunkić, Valerija; Mikrut, Antonija; Bezić, Nada

2014-05-01

The essential oil of Satureja cuneifolia Ten. was characterized by a high concentration of the phenolic compounds carvacrol (21.3%) and thymol (9.2%). The in vitro activity of the essential oil against Legionela pneumophila serogroups (SG) I and 2-15 and Legionella spp. from different sources, using microdilution, showed that L. pneumofila is sensitive to the oil, with MICs ranging from 0.12 to 0.5%, v/v, and a MBC at 0.5 to 1%, v/v. The essential oil of S. cuneifolia was effective in the reduction of Legionellosis infections.

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.

Chemical Composition, Antimicrobial and Antioxidant Activities of Essential Oils from Two Avicennia schaueriana Stapf & Leechm. Ex Moldenke (Acanthaceae) Populations

PubMed Central

Machado, Kamilla N.; Kaneko, Telma M.; Young, Maria Cláudia M.; Murakami, Cynthia; Cordeiro, Inês; Moreno, Paulo Roberto H.

2017-01-01

Background: Avicennia schaueriana Stapf & Leechm. ex Moldenke (Acanthaceae) is a native species from the Brazilian mangroves presenting ecological and economic significance. This study compared the composition and the biological activities from the essential oils obtained from two A. schaueriana populations collected at Jureia-Itatins and Ilha do Cardoso. Methods: Essential oils were obtained by conventional means, and their compositions were analyzed by GC-MS. Screening assays for antimicrobial activity were carried out by the microdilution method and the antioxidant potential was assessed by the DPPH scavenging method. Results: The GC-MS analysis indicated that the Jureia oil (1) was composed mostly of the fatty acids palmitic (46.5%) and myristic (11.6%) acids, while the main components for the Ilha do Cardoso oil (2) were eugenol (19.7%), eugenol acetate (12.9%) and palmitic acid (15.1%). The oils showed an IC50 of 0.9 ± 0.011 mg/mL for 1 and 1.13 ± 0.028 mg/mL for 2 in the DPPH assay. The antimicrobial assay indicated MIC > 217 µg/mL for all tested microorganisms. Conclusions: The different essential oil composition may indicate the presence of chemotypes for A. schaueriana. The antioxidant activity of the oils was weak if compared with flavonoids. Despite the high MIC values, these oils presented some antibacterial potential against Pseudomonas aeruginosa. PMID:28930241

Chemical Composition, Antibacterial, Antibiofilm and Synergistic Properties of Essential Oils from Eucalyptus globulus Labill. and Seven Mediterranean Aromatic Plants.

PubMed

Vieira, Maria; Bessa, Lucinda J; Martins, M Rosário; Arantes, Sílvia; Teixeira, António P S; Mendes, Ângelo; Martins da Costa, Paulo; Belo, Anabela D F

2017-06-01

Essential oils (EOs) from Eucalyptus globulus Labill. ssp. globulus and from Mediterranean autochthonous aromatic plants - Thymus mastichina L., Mentha pulegium L., Rosmarinus officinalis L., Calamintha nepeta (L.) Savi ssp. nepeta, Cistus ladanifer L., Foeniculum vulgare L., Dittrichia viscosa (L.) Greuter ssp. viscosa - were extracted by hydrodistillation and characterized by GC-FID and NMR spectroscopy. EOs were evaluated for antimicrobial properties against several bacterial strains, using diverse methods, namely, the agar disc-diffusion method, the microdilution method, the crystal violet assay and the Live/Dead staining for assessment of biofilm formation. Potential synergy was assessed by a checkerboard method. EOs of R. officinalis and C. ladanifer showed a predominance in monoterpene hydrocarbons (> 60%); EOs of C. nepeta, M. pulegium, T. mastichina, E. globulus and F. vulgare were rich in oxygenated monoterpenes (62 - 96%) whereas EO of D. viscosa was mainly composed of oxygenated sesquiterpenes (54%). All EOs showed antimicrobial activity; M. pulegium and E. globulus generally had the strongest antimicrobial activity. EO of C. nepeta was the most promising in hampering the biofilm formation. The combinations D. viscosa/C. nepeta and E. globulus/T. mastichina were synergistic against Staphylococcus aureus. These results support the notion that EOs from the aromatic plants herein reported should be further explored as potential pharmaceuticals and/or food preservatives. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

Evaluation of the VITEK 2 System for the Identification and Susceptibility Testing of Three Species of Nonfermenting Gram-Negative Rods Frequently Isolated from Clinical Samples

PubMed Central

Joyanes, Providencia; del Carmen Conejo, María; Martínez-Martínez, Luis; Perea, Evelio J.

2001-01-01

VITEK 2 is a new automatic system for the identification and susceptibility testing of the most clinically important bacteria. In the present study 198 clinical isolates, including Pseudomonas aeruginosa (n = 146), Acinetobacter baumannii (n = 25), and Stenotrophomonas maltophilia (n = 27) were evaluated. Reference susceptibility testing of cefepime, cefotaxime, ceftazidime, ciprofloxacin, gentamicin, imipenem, meropenem, piperacillin, tobramycin, levofloxacin (only for P. aeruginosa), co-trimoxazole (only for S. maltophilia), and ampicillin-sulbactam and tetracycline (only for A. baumannii) was performed by microdilution (NCCLS guidelines). The VITEK 2 system correctly identified 91.6, 100, and 76% of P. aeruginosa, S. maltophilia, and A. baumannii isolates, respectively, within 3 h. The respective percentages of essential agreement (to within 1 twofold dilution) for P. aeruginosa and A. baumannii were 89.0 and 88.0% (cefepime), 91.1 and 100% (cefotaxime), 95.2 and 96.0% (ceftazidime), 98.6 and 100% (ciprofloxacin), 88.4 and 100% (gentamicin), 87.0 and 92.0% (imipenem), 85.0 and 88.0% (meropenem), 84.2 and 96.0% (piperacillin), and 97.3 and 80% (tobramycin). The essential agreement for levofloxacin against P. aeruginosa was 86.3%. The percentages of essential agreement for ampicillin-sulbactam and tetracycline against A. baumannii were 88.0 and 100%, respectively. Very major errors for P. aeruginosa (resistant by the reference method, susceptible with the VITEK 2 system [resistant to susceptible]) were noted for cefepime (0.7%), cefotaxime (0.7%), gentamicin (0.7%), imipenem (1.4%), levofloxacin (2.7%), and piperacillin (2.7%) and, for one strain of A. baumannii, for imipenem. Major errors (susceptible to resistant) were noted only for P. aeruginosa and cefepime (2.0%), ceftazidime (0.7%), and piperacillin (3.4%). Minor errors ranged from 0.0% for piperacillin to 22.6% for cefotaxime against P. aeruginosa and from 0.0% for piperacillin and ciprofloxacin to 20.0% for cefepime against A. baumannii. The VITEK 2 system provided co-trimoxazole MICs only for S. maltophilia; no very major or major errors were obtained for co-trimoxazole against this species. It is concluded that the VITEK 2 system allows the rapid identification of S. maltophilia and most P. aeruginosa and A. baumannii isolates. The VITEK 2 system can perform reliable susceptibility testing of many of the antimicrobial agents used against P. aeruginosa and A. baumannii. It would be desirable if new versions of the VITEK 2 software were able to determine MICs and the corresponding clinical categories of agents active against S. maltophilia. PMID:11526158

Identification and Antifungal Susceptibility Testing of Candida Species: A Comparison of Vitek-2 System with Conventional and Molecular Methods.

PubMed

Kaur, Ravinder; Dhakad, Megh Singh; Goyal, Ritu; Haque, Absarul; Mukhopadhyay, Gauranga

2016-01-01

Candida infection is a major cause of morbidity and mortality in immunocompromised patients; an accurate and early identification is a prerequisite need to be taken as an effective measure for the management of patients. The purpose of this study was to compare the conventional identification of Candida species with identification by Vitek-2 system and the antifungal susceptibility testing (AST) by broth microdilution method with Vitek-2 AST system. A total of 172 Candida isolates were subjected for identification by the conventional methods, Vitek-2 system, restriction fragment length polymorphism, and random amplified polymorphic DNA analysis. AST was carried out as per the Clinical and Laboratory Standards Institute M27-A3 document and by Vitek-2 system. Candida albicans (82.51%) was the most common Candida species followed by Candida tropicalis (6.29%), Candida krusei (4.89%), Candida parapsilosis (3.49%), and Candida glabrata (2.79%). With Vitek-2 system, of the 172 isolates, 155 Candida isolates were correctly identified, 13 were misidentified, and four were with low discrimination. Whereas with conventional methods, 171 Candida isolates were correctly identified and only a single isolate of C. albicans was misidentified as C. tropicalis . The average measurement of agreement between the Vitek-2 system and conventional methods was >94%. Most of the isolates were susceptible to fluconazole (88.95%) and amphotericin B (97.67%). The measurement of agreement between the methods of AST was >94% for fluconazole and >99% for amphotericin B, which was statistically significant ( P < 0.01). The study confirmed the importance and reliability of conventional and molecular methods, and the acceptable agreements suggest Vitek-2 system an alternative method for speciation and sensitivity testing of Candida species infections.

Outbreak of candidemia caused by fluconazole resistant Candida parapsilosis strains in an intensive care unit.

PubMed

Pinhati, Henrique Marconi Sampaio; Casulari, Luiz Augusto; Souza, Ana Carolina Remondi; Siqueira, Ricardo Andreotti; Damasceno, Camila Maria Gomes; Colombo, Arnaldo Lopes

2016-08-20

Candidemia is an increasing problem in tertiary care hospitals worldwide. Here, we report the first outbreak of candidemia caused by fluconazole-resistant C. parapsilosis (FRCP) strains in Brazil. This was a cross-sectional study of clinical and microbiological data of all candidemic episodes diagnosed from July 2011 to February 2012 in a 200-bed tertiary care hospital. Initial yeast identification and susceptibility testing were performed using the VITEK 2 - System. Isolates of Candida spp. resistant to fluconazole were sent to a reference laboratory (LEMI-UNIFESP) for further molecular identification and confirmation of resistance by CLSI microdilution test. A multivariate analysis was conducted to identify factors associated with FRCP infection. We identified a total of 40 critically ill patients with candidemia (15 women) with a median age of 70 years. The incidence of candidemia was 6 cases/1,000 patients admissions, including 28 cases (70 %) of infection with C. parapsilosis, 21 of which (75 %) were resistant to fluconazole. In only 19 % of FRCP candidemia cases had fluconazole been used previously. The results of our study indicated that diabetes is a risk factor for FRCP candidemia (p = 0.002). Overall, mortality from candidemia was 45 %, and mortality from episodes of FRCP infections was 42.9 %. The clustering of incident cases in the ICU and molecular typing of strains suggest horizontal transmission of FRCP. Accurate vigilant monitoring for new nosocomial strains of FRCP is required.

In Vitro Interactions between Non-Steroidal Anti-Inflammatory Drugs and Antifungal Agents against Planktonic and Biofilm Forms of Trichosporon asahii

PubMed Central

Cong, Lin; Lu, Xuelian

2016-01-01

Increasing drug resistance has brought enormous challenges to the management of Trichosporon spp. infections. The in vitro antifungal activities of non-steroidal anti-inflammatory drugs (NSAIDs) against Candida spp. and Cryptococcus spp. were recently discovered. In the present study, the in vitro interactions between three NSAIDs (aspirin, ibuprofen and diclofenac sodium) and commonly used antifungal agents (fluconazole, itraconazole, voriconazole, caspofungin and amphotericin B) against planktonic and biofilm cells of T. asahii were evaluated using the checkerboard microdilution method. The spectrophotometric method and the XTT reduction assay were used to generate data on biofilm cells. The fractional inhibitory concentration index (FICI) and the ΔE model were compared to interpret drug interactions. Using the FICI, the highest percentages of synergistic effects against planktonic cells (86.67%) and biofilm cells (73.33%) were found for amphotericin B/ibuprofen, and caspofungin/ibuprofen showed appreciable percentages (73.33% for planktonic form and 60.00% for biofilm) as well. We did not observe antagonism. The ΔE model gave consistent results with FICI (86.67%). Our findings suggest that amphotericin B/ibuprofen and caspofungin/ibuprofen combinations have potential effects against T. asahii. Further in vivo and animal studies to investigate associated mechanisms need to be conducted. PMID:27275608

In vitro and in vivo activities of posaconazole and amphotericin B in a murine invasive infection by Mucor circinelloides: poor efficacy of posaconazole.

PubMed

Salas, Valentina; Pastor, F Javier; Calvo, Enrique; Alvarez, Eduardo; Sutton, Deanna A; Mayayo, Emilio; Fothergill, Anette W; Rinaldi, Michael G; Guarro, Josep

2012-05-01

The in vitro susceptibility of 17 strains of Mucor circinelloides to amphotericin B and posaconazole was ascertained by using broth microdilution and disk diffusion methods and by determining the minimal fungicidal concentration (MFC). We evaluated the efficacy of posaconazole at 40 mg/kg of body weight/day and amphotericin B at 0.8 mg/kg/day in a neutropenic murine model of disseminated infection by M. circinelloides by using 6 different strains tested previously in vitro. In general, most of the posaconazole MICs were within the range of susceptibility or intermediate susceptibility, while the small inhibition zone diameters (IZDs) were indicative of nonsusceptibility for all isolates tested. The MFCs were ≥ 3 dilutions higher than the corresponding MICs. In contrast, amphotericin B showed good activity against all of the strains tested regardless of the method used. The in vivo studies demonstrated that amphotericin B was effective in prolonging survival and reducing the fungal load. Posaconazole showed poor in vivo efficacy with no correlation with the MIC values. The results suggested that posaconazole should be used with caution in the treatment of infections caused by Mucor circinelloides or by strains of Mucor not identified to the species level.

Phytochemical Composition, Antifungal and Antioxidant Activity of Duguetia furfuracea A. St.-Hill

PubMed Central

Pinho, Francisca Valéria Soares de Araújo; da Cruz, Litiele Cezar; Rodrigues, Nathane Rosa; Waczuk, Emily Pansera; Souza, Celestina Elba Sobral; da Costa, José Galberto Martins; Athayde, Margareth Linde; de Menezes, Irwin Rose Alencar

2016-01-01

Background. Duguetia furfuracea is popular plant used in popular medicine. Hypothesis/Purpose. This claim evaluated the phytochemical composition of the hydroethanolic extract (HEDF), fractions of Duguetia furfuracea, and antioxidant and antifungal activity. Methods. The chemical profile was carried out by HPLC-DAD. The total phenolic contents and flavonoid components were determined by Folin-Ciocalteu and aluminium chloride reaction. The antioxidant activity was measured by scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical and ferric reducing ability of plasma (FRAP) methods. The antifungal activity was determined by microdilution assay. Results. HPLC analysis revealed caffeic acid and rutin as major compounds (HEDF), caffeic acid and quercitrin (Mt-OH fraction), and quercitrin and isoquercitrin (Ac-OEt fraction). The highest levels of phenols and total flavonoids were found for Ac-OEt fraction, and the crude extract showed higher in vitro antioxidant potential. The antifungal activity showed synergic effect with fluconazole and EHDF against C. krusei, fluconazole and Mt-OH against C. krusei and C. tropicalis, and Ac-OE and fluconazole against C. albicans. Conclusion. The highest levels of phenols and total flavonoids were marked with antioxidant effect. This is the first report of bioactivity of the synergic effect of HEDF and fractions. More studies would be required to better clarify its mechanism of synergic action. PMID:27127550

Pharmacological and phytochemical screening of Palestinian traditional medicinal plants Erodium laciniatum and Lactuca orientalis.

PubMed

Jaradat, Nidal; AlMasri, Motasem; Zaid, Abdel Naser; Othman, Dua'a Ghazi

2017-09-01

Various epidemiological studies showed that herbal remedies containing polyphenols may protect against various diseases such as cancers, vascular diseases and inflammatory pathologies. Currently, such groups of bioactive compounds have become a subject of many antimicrobials and antioxidant investigations. Accordingly, the current study aimed to conduct biological and phytochemical screening for two Palestinian traditional medicinal plants, Erodium laciniatum and Lactuca orientalis. Current plants phytoconstituents and their antioxidant activities were evaluated by using standard phytochemical methods; meanwhile, antimicrobial activities were estimated by using several types of American Type Culture Collection and multidrug resistant clinical isolates by using agar diffusion well-variant, agar diffusion disc-variant and broth microdilution methods. Phytochemical screenings showed that L. orientalis and E. laciniatum contain mixtures of secondary and primary metabolites Moreover, total flavonoid, tannins and phenols content in E. laciniatum extract were higher than the L. orientalis extracts with almost the same antioxidant potentials. Additionally, both plants organic and aqueous extracts showed various potentials of antimicrobial activity Conclusions: Overall, the studied species have a mixture of phytochemicals, flavonoids, phenols and tannins also have antioxidant and antimicrobial activities which approved their folk uses in treatments of infectious and Alzheimer diseases and simultaneously can be used as therapeutic agents in the pharmaceutical industries.

Drug Susceptibility Testing of 31 Antimicrobial Agents on Rapidly Growing Mycobacteria Isolates from China

PubMed Central

Pang, Hui; Li, Guilian; Zhao, Xiuqin; Liu, Haican; Wan, Kanglin; Yu, Ping

2015-01-01

Objectives. Several species of rapidly growing mycobacteria (RGM) are now recognized as human pathogens. However, limited data on effective drug treatments against these organisms exists. Here, we describe the species distribution and drug susceptibility profiles of RGM clinical isolates collected from four southern Chinese provinces from January 2005 to December 2012. Methods. Clinical isolates (73) were subjected to in vitro testing with 31 antimicrobial agents using the cation-adjusted Mueller-Hinton broth microdilution method. The isolates included 55 M. abscessus, 11 M. fortuitum, 3 M. chelonae, 2 M. neoaurum, and 2 M. septicum isolates. Results. M. abscessus (75.34%) and M. fortuitum (15.07%), the most common species, exhibited greater antibiotic resistance than the other three species. The isolates had low resistance to amikacin, linezolid, and tigecycline, and high resistance to first-line antituberculous agents, amoxicillin-clavulanic acid, rifapentine, dapsone, thioacetazone, and pasiniazid. M. abscessus and M. fortuitum were highly resistant to ofloxacin and rifabutin, respectively. The isolates showed moderate resistance to the other antimicrobial agents. Conclusions. Our results suggest that tigecycline, linezolid, clofazimine, and cefmetazole are appropriate choices for M. abscessus infections. Capreomycin, sulfamethoxazole, tigecycline, clofazimine, and cefmetazole are potentially good choices for M. fortuitum infections. Our drug susceptibility data should be useful to clinicians. PMID:26351633

The Effect of Some Natural Essential Oils Against Bovine Mastitis Caused by Prototheca zopfii Isolates In Vitro.

PubMed

Grzesiak, Barbara; Kołodziej, Barbara; Głowacka, Anna; Krukowski, Henryk

2018-06-01

The aim of the study was to evaluate the effect of essential oils obtained from Thymus vulgaris L., Origanum vulgare L., Origanum majerana L., Mentha × piperita L. and Allium ursinum L. against Prototheca zopfii strains that cause inflammation of the udder (mastitis) in cows. The study was conducted on ten strains derived from milk samples. The microdilution method was used to determine the sensitivity of P. zopfii strains to the studied essential oils, and the disk diffusion method was used to determine the sensitivity to antifungal chemotherapeutics. The plates were incubated for 48 h at 37 °C under aerobic conditions. All strains of algae were sensitive to the essential oils marjoram, thyme and oregano and resistant to mint and garlic oils. MIC values ranged from 0.25 to 1 μl/ml. Marjoram oil demonstrated the greatest activity, and oregano oil the weakest. Among the antifungal agents tested, 90% of strains showed sensitivity to nystatin. One of the tested strains (71/IV) was resistant to all investigated antifungal agents. The tested essential oils are known to have anti-algae activity and can be used as natural agents for prophylaxis in animals, particularly in mastitis-affected cows.

1,2,4-triazole derivative with Schiff base; thiol-thione tautomerism, DFT study and antileishmanial activity

NASA Astrophysics Data System (ADS)

Süleymanoğlu, Nevin; Ustabaş, Reşat; Direkel, Şahin; Alpaslan, Yelda Bingöl; Ünver, Yasemin

2017-12-01

Thiol-thione tautomerism of 1,2,4-triazole derivative with Schiff base was investigated by spectroscopic methods and quantum mechanical calculations. Theoretical study of thiol-thione tautomeric forms of 1,2,4-triazole derivative with Schiff base; 1,2,4-triazole-thiol form, 1-((5-mercapto-4-(thiophene-2-ylmethyleneamino)-4H-1,2,4-triazole-3-yl)methyl)-3-(thiophene-2-ylmethyl)-4-(thiophene-2-ylmethyleneamino)-1H-1,2,4-triazole-5(4H)-one (I) and 1,2,4-triazole-thione form, 3-(thiophene-2-ylmethyl)-4-(thiophene-2-ylmethyleneamino)-1-((4-(thiophene-2-ylmethyleneamino)-5-thioxo-4,5-dihydro-1H-1,2,4-triazole-3-yl)methyl)-1H-1,2,4-triazole-5(4H)-one (II) was performed by the density functional theory (DFT) method with 6-311++G(d,p) basis set. Structural parameters were obtained and spectral parameters of NMR, FTIR and UV-vis were compared with experimental ones to determine structural details. In vitro antileishmanial activity was studied against Leishmania infantum promastigots by microdilution broth assay with Alamar Blue Dye. The results indicate that 1,2,4-triazole derivative exists in both thiol and thione form and, can be evaluated as antiparasitic in term of antileishmanial activity.

Pilot Screening to Determine Antimicrobial Synergies in a Multidrug-Resistant Bacterial Strain Library

PubMed Central

Kim, Si-Hyun; Park, Chulmin; Chun, Hye-Sun; Choi, Jae-Ki; Lee, Hyo-Jin; Cho, Sung-Yeon; Park, Sun Hee; Choi, Su-Mi; Choi, Jung-Hyun; Yoo, Jin-Hong

2016-01-01

With the rise in multidrug-resistant (MDR) bacterial infections, there has been increasing interest in combinations of ≥2 antimicrobial agents with synergistic effects. We established an MDR bacterial strain library to screen for in vitro antimicrobial synergy by using a broth microdilution checkerboard method and high-throughput luciferase-based bacterial cell viability assay. In total, 39 MDR bacterial strains, including 23 carbapenem-resistant gram-negative bacteria, 9 vancomycin-intermediate Staphylococcus aureus, and 7 vancomycin-resistant Enterococcus faecalis, were used to screen for potential antimicrobial synergies. Synergies were more frequently identified with combinations of imipenem plus trimethoprim–sulfamethoxazole for carbapenem-resistant Acinetobacter baumannii in the library. To verify this finding, we tested 34 A. baumannii clinical isolates resistant to both imipenem and trimethoprim–sulfamethoxazole by the checkerboard method. The imipenem plus trimethoprim–sulfamethoxazole combination showed synergy in the treatment of 21 (62%) of the clinical isolates. The results indicate that pilot screening for antimicrobial synergy in the MDR bacterial strain library could be valuable in the selection of combination therapeutic regimens to treat MDR bacterial infections. Further studies are warranted to determine whether this screening system can be useful to screen for the combined effects of conventional antimicrobials and new-generation antimicrobials or nonantimicrobials. PMID:26974861

Enhanced Cellular Cytotoxicity and Antibacterial Activity of 18-β-Glycyrrhetinic Acid by Albumin-conjugated PLGA Nanoparticles.

PubMed

Darvishi, B; Manoochehri, S; Esfandyari-Manesh, M; Samadi, N; Amini, M; Atyabi, F; Dinarvand, R

2015-12-01

The aim of the present work was to encapsulate 18-β-Glycyrrhetinic acid (GLA) in albumin conjugated poly(lactide-co-glycolide) (PLGA) nanoparticles by a modified nanoprecipitation method. Nanoparticles (NPs) were prepared by different drug to polymer ratios, human serum albumin (HSA) content, dithiothreitol (as producer of free thiol groups) content, and acetone (as non-solvent in nanoprecipitation). NPs with a size ranging from 126 to 174 nm were achieved. The highest entrapment efficiency (89.4±4.2%) was achieved when the ratio of drug to polymer was 1:4. The zeta potential of NPs was fairly negative (-8 to -12). Fourier transform infrared spectroscopy and differential scanning calorimetry proved the conjugation of HSA to PLGA NPs. In vitro release profile of NPs showed 2 phases: an initial burst for 4 h (34-49%) followed by a slow release pattern up to the end. The antibacterial effects of NPs against Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa were studied by microdilution method. The GLA-loaded NPs showed more antibacterial effect than pure GLA (2-4 times). The anticancer MTT test revealed that GLA-loaded NPs were approximately 9 times more effective than pure GLA in Hep G2 cells. © Georg Thieme Verlag KG Stuttgart · New York.

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

Great horsetail (Equisetum telmateia Ehrh.): Active substances content and biological effects

PubMed Central

Radojevic, Ivana D.; Stankovic, Milan S.; Stefanovic, Olgica D.; Topuzovic, Marina D.; Comic, Ljiljana R.; Ostojic, Aleksandar M.

2012-01-01

This paper deals with the antioxidant and antimicrobial activity, total phenolic content and concentrations of flavonoids of Equisetum telmateia extracts. Total phenolic content was determined with Folin-Ciocalteu reagent and it ranged between 129.0 to 262.7 mg GA/g. The concentration of flavonoids in various extracts of E. telmateia was determined using spectrophotometric method with aluminum chloride and obtained results varied from 112.6 to 199.8 mg RU/g. Antioxidant activity was monitored spectrophotometrically and expressed in terms of IC50 (µg/ml), and its values ranged from 33.4 to 982.2 µg/ml. The highest phenolic content, concentrations of flavonoids and capacity to neutralize DPPH radicals were found in the acetone extract. In vitro antimicrobial activity was determined using microdilution method. Minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) were also determined. Testing was performed on 22 microorganisms, including 15 strains of bacteria (standard and clinical strains) and 7 species of fungi. There were statistically significant differences in activity between the extracts of E. telmateia. Different effects were noticed against the bacteria and the methanol extract appeared to be most efficient. All the extracts showed significant antibacterial activity against G+ bacteria and weak to moderate activity against other microorganisms. PMID:27350768

Potential application of synthesized ferrocenylimines compounds for the elimination of bacteria in water

NASA Astrophysics Data System (ADS)

Ikhile, M. I.; Barnard, T. G.; Ngila, J. C.

2017-08-01

This work reports a study towards a search for environmentally friendly water disinfectant. The most common method for water treatment is based on chlorine which had a wide application over the years as a water disinfectant, but suffer the disadvantage of reacting with natural organic matter to form disinfection by products. In this study, the potential application of novel ferrocenylimines compounds, namely 4-ferrocenylaniline (1), N-(3-bromo-2-hydroxylbenzylidene)-4-ferrocenylimine (2) and N-(3-bromo-5-chlorosalicyl)-4-ferrocenylimine (3) for the elimination of bacteria in water was investigated by evaluating their antibacterial properties against twelve different bacterial strains using microdilution method in sterile 96 well micro titer plates. The in vitro antibacterial activity revealed that the ferrocenylimines compound exhibit higher antibacterial activity than ferrocene, which is one of the starting materials towards the synthesis of this novel ferrocenylimines compounds. The most active ferrocenylimines compound was compound 3 with a minimal inhibitory concentration (MIC) value of 0.30 mg/ml against S. sonnei. In addition, all the ferrocenylimines compounds possessed excellent antibacterial activity against B. cereus with the same MIC value of 0.31 mg/ml. The results obtained so far show great potential in the three tested ferrocenylimines compounds for use in water treatment in killing bacteria in water.

Comparison of the treatment efficacy between tigecycline plus high-dose cefoperazone-sulbactam and tigecycline monotherapy against ventilator-associated pneumonia caused by extensively drug-resistant Acinetobacter baumannii.

PubMed

Qin, Youfa; Zhang, Jie; Wu, Lei; Zhang, Dailong; Fu, Lunjiao; Xue, Xiaoyan

2018-03-01

The present study examined the effect of high-dose cefoperazone-sulbactam combined with tigecycline against ventilator-associated pneumonia (VAP) caused by extensively drug-resistant Acinetobacter baumannii(XDR-AB). 42 patients with VAP due to XDR-AB infection were randomized into two groups: the TIG group (received tigecycline injection) and the TIG+CFS group (received tigecycline and cefoperazone-sulbactam (1 : 1) injection). Pulsed field gel electrophoresis (PFGE) was used for genotyping the isolated XDR-AB. The microdilution method was used to test the minimum inhibitory concentration (MIC) of cefoperazone-sulbactam or tigecycline in vitro and the combined effect was determined with the checkerboard method. The total combined effectiveness rate (including all patients who demonstrated an improved condition) was significantly higher in the TIG+CFS group (85.7%) compared with the TIG group (47.6%) (p = 0.010). No significant differences were noted with regard to the adverse reactions between the two groups. The 42 isolated XDR-AB strains were classified into four types. The MIC of the two drugs in combination was significantly lower than that of each drug used alone (p < 0.05). High dose of cefoperazone-sulbactam can improve the antimicrobial activity of tigecycline against XDR-AB.
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Antimicrobial activity of crude epicarp and seed extracts from mature avocado fruit (Persea americana) of three cultivars.

PubMed

Raymond Chia, Teck Wah; Dykes, Gary A

2010-07-01

The epicarp and seed of Persea Americana Mill. var. Hass (Lauraceae), Persea Americana Mill. var. Shepard, and Persea americana Mill. var Fuerte cultivars of mature avocados (n = 3) were ground separately and extracted with both absolute ethanol and distilled water. Extracts were analyzed for antimicrobial activity using the microtiter broth microdilution assay against four Gram-positive bacteria, six Gram-negative bacteria, and one yeast. Antimicrobial activity against two molds was determined by the hole plate method. The ethanol extracts showed antimicrobial activity (104.2-416.7 microg/mL) toward both Gram-positive and Gram-negative bacteria (except Escherichia coli), while inhibition of the water extracts was only observed for Listeria monocytogenes (93.8-375.0 microg/mL) and Staphylococcus epidermidis (354.2 microg/mL). The minimum concentration required to inhibit Zygosaccharomyces bailii was 500 microg/mL for the ethanol extracts, while no inhibition was observed for the water extracts. No inhibition by either ethanol or water extracts was observed against Penicillium spp. and Aspergillus flavus.

Ambroxol Hydrochloride Combined with Fluconazole Reverses the Resistance of Candida albicans to Fluconazole.

PubMed

Li, Xiuyun; Zhao, Yuanhao; Huang, Xin; Yu, Cuixiang; Yang, Yilei; Sun, Shujuan

2017-01-01

In this study, we found that ambroxol hydrochloride (128 μg/mL) exhibits synergistic antifungal effects in combination with fluconazole (2 μg/mL) against resistant planktonic Candida albicans ( C. albicans ) cells. This combination also exhibited synergistic effects against resistant C. albicans biofilms in different stages (4, 8, and 12 h) according to the microdilution method. In vitro data were further confirmed by the success of this combination in treating Galleria mellonella infected by resistant C. albicans . With respect to the synergistic mechanism, our result revealed that ambroxol hydrochloride has an effect on the drug transporters of resistant C. albicans , increasing the uptake and decreasing the efflux of rhodamine 6G, a fluorescent alternate of fluconazole. This is the first study to investigate the in vitro and in vivo antifungal effects, as well as the possible synergistic mechanism of ambroxol hydrochloride in combination with fluconazole against resistant C. albicans . The results show the potential role for this drug combination as a therapeutic alternative to treat resistant C. albicans and provide insights into the development of antifungal targets and new antifungal agents.

Synergistic Activity of Econazole-Nitrate and Chelerythrine against Clinical Isolates of Candida albicans.

PubMed

Chen, Zhibao; Li, Xinran; Wu, Xiuping; Wang, Wei; Wang, Wendong; Xin, Mingxun; Shen, Fengge; Liu, Lihui; Liang, Junchao; Li, Lei; Yu, Lu

2014-01-01

The aim of this investigation was to assess the in-vitro interaction of two antifungal agents, econazole-nitrate and chelerythrine, against ten fluconazole-resistant clinical isolates and one ATCC type strain 10231 of Candida albicans. The checkerboard microdilution method was performed according to the recommendations of the National Committee for Clinical Laboratory Standards, and the results were determined by visual examination. The interaction intensity was tested in all isolates using the fractional inhibitory concentration index (FICI). These experiments showed synergism between econazole-nitrate and chelerythrine in antifungal activity against C. albicans, and no antagonistic activity was observed in any of the strains tested. Moreover, time-kill curves were performed with selected strains to confirm the positive interactions. The similarity between the results of the FICI values and the time-kill curves revealed that chelerythrine greatly enhances the antifungal effects of econazole-nitrate against isolates of C. albicans. This synergistic effect may markedly reduce the dose of econazole-nitrate required to treat candidiasis, thereby decreasing the econazole-nitrate toxic side effects. This novel synergism might provide a potential combination treatment against fungal infections.

Non Diphtheritic Corynebacteria: An Emerging Nosocomial Pathogen in Skin and Soft Tissue Infection.

PubMed

Rudresh, Shoorashetty Manohar; Ravi, G S; Alex, Ann Mary; Mamatha, K R; Sunitha, L; Ramya, K Thangam

2015-12-01

Non-diphtheritic corynebacteria are normal inhabitants of skin and mucous membrane. When isolated from clinical specimens they are often considered as contaminants. Recent reports suggest their role as emerging nosocomial pathogens. To speciate non-diphtheritic corynebacteria isolated from wound specimens, to correlate their clinical significance and to determine their invitro antimicrobial susceptibilities to 9 antimicrobial agents. Twenty five non-diphtheritic corynebacteria from skin and soft tissue infections were selected for study. Isolates were identified by battery of tests and minimum inhibitory concentration (MIC) was detected by Clinical & Laboratory Standards Institute (CLSI) described broth microdilution method. MIC was interpreted according CLSI and British Society for Antimicrobial Chemotherapy (BSAC) guidelines. C. amycolatum was the predominant species (20%) followed by C. striatum (16%). Penicillin was least effective invitro followed by clindamycin and ciprofloxacin. Excellent activities were shown by vancomycin, linezolid and imipenem. Multidrug resistance was found in all the species. Non-diphtheritic corynebacteria are potential nosocomial pathogens among acute/chronic complicated skin and soft tissue infection. Vancomycin or linezolid can be used empirically to treat such infections until the invitro susceptibility results are available.

A Biosurfactant-Sophorolipid Acts in Synergy with Antibiotics to Enhance Their Efficiency

PubMed Central

Joshi-Navare, Kasturi; Prabhune, Asmita

2013-01-01

Sophorolipids (SLs), biosurfactants with antimicrobial properties, have been tried to address the problem of antibiotic resistance. The synergistic action of SL and antibiotics was checked using standard microdilution and spread plate methods. With Staphylococcus aureus, SL-tetracycline combination achieved total inhibition before 4 h of exposure while tetracycline alone couldnot achieve total inhibition till the end of 6 h. The inhibition caused by exposure of bacterium to SL-tetracycline mixture was ~25% more as compared to SL alone. In spite of known robustness of gram-negative bacteria, SL-cefaclor mixture proved to be efficient against Escherichia coli which showed ~48% more inhibition within 2 h of exposure as compared to cefaclor alone. Scanning electron microscopy of the cells treated with mixture revealed bacterial cell membrane damage and pore formation. Moreover, SLs being a type of asymmetric bola, they are expected to form self-assemblies with unique functionality. This led to the speculation that SLs being amphiphilic in nature can span through the structurally alike cell membrane and facilitate the entry of drug molecules. PMID:24089681

Antibacterial activity-guided purification and identification of a novel C-20 oxygenated ent-kaurane from Rabdosia serra (MAXIM.) HARA.

PubMed

Lin, Lianzhu; Zhu, Dashuai; Zou, Linwu; Yang, Bao; Zhao, Mouming

2013-08-15

The objective of this work was to conduct an activity-guided isolation of antibacterial compounds from Rabdosia serra. The ethanol extracts of R. serra leaf and stem were partitioned sequentially into petroleum ether, ethyl acetate, butanol and water fractions, respectively. The ethanol extract of leaf evidenced broad-spectrum antibacterial activity against gram-positive bacterial, including Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, and Listeria monocytogenes. The ethyl acetate fractions of leaf and stem exhibited strong inhibition against gram-positive bacteria, and were then purified further. On the basis of antibacterial assay-guided purification, three phenolic compounds (rosmarinic acid, methyl rosmarinate and pedalitin) and four C-20 oxygenated ent-kauranes (effusanin E, lasiodin, rabdosichuanin D and a new compound namely effusanin F) were obtained, whose contents were determined by HPLC analysis. The broth microdilution method confirmed the important inhibition potential of C-20 oxygenated ent-kauranes with low minimum inhibitory concentration (MIC) values. Effusanin E, lasiodin and effusanin F could be useful for the development of new antibacterial agents. Copyright © 2013 Elsevier Ltd. All rights reserved.

Characterization of the Salmonella enterica Serotype Isangi Isolated from Patients for the First Time in China.

PubMed

Li, Xin-Peng; Gao, Ri-Hong; Hou, Pei-Bin; Ren, Yan-Yan; Zhang, Hua-Ning; Jiang, Kui-Ying; Chen, Yu-Zhen; Qi, Zi-Gang; Xu, Min; Bi, Zhen-Wang

2017-08-01

No studies have reported the isolation of serotype Salmonella Isangi from cases of salmonellosis in mainland China. We investigated an outbreak of foodborne disease with salmonella and collected the samples from the patients and surplus foods. Salmonella strains were isolated and the serotype was identified according to the Kauffmann-White scheme. The relatedness of the isolates was determined using pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). Antimicrobial susceptibility was conducted by the broth microdilution method. There were 74 diners in the case, 33 of which got ill, with an attack rate of 44.6% (33/74). A total of 24 samples were collected from the outbreak cases, six Salmonella Isangi strains were isolated and susceptible to all tested drugs. PFGE and WGS analysis suggested that the pathogen dissemination through a single or limited vector(s), the steamed fish and mixed food (fry spicy chicken, braised pork ribs, and goose leg), may be the source of infection or be cross-contaminated. We first report the characteristics of an outbreak and molecular strain relatedness of Salmonella Isangi in mainland China.

Anti-leptospiral activities of an endemic plant Glyptopetalum calocarpum (Kurz.) Prain used as a medicinal plant by Nicobarese of Andaman and Nicobar Islands.

PubMed

Chander, M Punnam; Kumar, K Vinod; Shriram, A N; Vijayachari, P

2015-01-01

Leaves of an endemic plant Glyptopetalum calocarpum are used by Nicobarese tribes of Andaman and Nicobar Islands, India, to prepare traditional medicine for treating fever. In the present investigation, pharmacologically active compounds were isolated from this plant and their antimicrobial efficacy was evaluated against the leptospiral strains. The anti-leptospiral activity of six plant-derived compounds was determined by both microdilution and macrodilution methods. Two out of six compounds, namely lupenone and stigmasterol, showed anti-leptospiral activity. The minimum inhibitory concentrations of the two compounds tested against pathogenic leptospiral strains belonging to 10 serovars were in the range of 100-200 μg/mL. The range of minimum bactericidal concentrations was 400-800 μg/mL. Compounds lupenone, stigmasterol, lupeol, β-amyrin and β-amyrin acetate had negligible or no haemolytic activity, exhibiting IC50 values of greater than 5 mg/mL. Further in vivo studies are needed to investigate the pharmacological and toxicological properties of G. calocarpum before it can be considered as a new anti-leptospiral agent.

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.

Buwchitin: a ruminal peptide with antimicrobial potential against Enterococcus faecalis

NASA Astrophysics Data System (ADS)

Oyama, Linda B.; Crochet, Jean-Adrien; Edwards, Joan E.; Girdwood, Susan E.; Cookson, Alan R.; Fernandez-Fuentes, Narcis; Hilpert, Kai; Golyshin, Peter N.; Golyshina, Olga V.; Privé, Florence; Hess, Matthias; Mantovani, Hilario C.; Creevey, Christopher J.; Huws, Sharon A.

2017-07-01

Antimicrobial peptides (AMPs) are gaining popularity as alternatives for treatment of bacterial infections and recent advances in omics technologies provide new platforms for AMP discovery. We sought to determine the antibacterial activity of a novel antimicrobial peptide, buwchitin, against Enterococcus faecalis. Buwchitin was identified from a rumen bacterial metagenome library, cloned, expressed and purified. The antimicrobial activity of the recombinant peptide was assessed using a broth microdilution susceptibility assay to determine the peptide's killing kinetics against selected bacterial strains. The killing mechanism of buwchitin was investigated further by monitoring its ability to cause membrane depolarization (diSC3(5) method) and morphological changes in E. faecalis cells. Transmission electron micrographs of buwchitin treated E. faecalis cells showed intact outer membranes with blebbing, but no major damaging effects and cell morphology changes. Buwchitin had negligible cytotoxicity against defibrinated sheep erythrocytes. Although no significant membrane leakage and depolarization was observed, buwchitin at minimum inhibitory concentration (MIC) was bacteriostatic against E. faecalis cells and inhibited growth in vitro by 70% when compared to untreated cells. These findings suggest that buwchitin, a rumen derived peptide, has potential for antimicrobial activity against E. faecalis.

Antifungal activity of multifunctional Fe 3O 4-Ag nanocolloids

NASA Astrophysics Data System (ADS)

Chudasama, Bhupendra; Vala, Anjana K.; Andhariya, Nidhi; Upadhyay, R. V.; Mehta, R. V.

2011-05-01

In recent years, rapid increase has been observed in the population of microbes that are resistant to conventionally used antibiotics. Antifungal drug therapy is no exception and now resistance to many of the antifungal agents in use has emerged. Therefore, there is an inevitable and urgent medical need for antibiotics with novel antimicrobial mechanisms. Aspergillus glaucus is the potential cause of fatal brain infections and hypersensitivity pneumonitis in immunocompromised patients and leads to death despite aggressive multidrug antifungal therapy. In the present article, we describe the antifungal activity of multifunctional core-shell Fe 3O 4-Ag nanocolloids against A. glaucus isolates. Controlled experiments are also carried out with Ag nanocolloids in order to understand the role of core (Fe 3O 4) in the antifungal action. The minimum inhibitory concentration (MIC) of nanocolloids is determined by the micro-dilution method. MIC of A. glaucus is 2000 μg/mL. The result is quite promising and requires further investigations in order to develop a treatment methodology against this death causing fungus in immunocompromised patients.

Antileishmanial activity study and theoretical calculations for 4-amino-1,2,4-triazole derivatives

NASA Astrophysics Data System (ADS)

Süleymanoğlu, Nevin; Ünver, Yasemin; Ustabaş, Reşat; Direkel, Şahin; Alpaslan, Gökhan

2017-09-01

4-amino-1,2,4-triazole derivatives; 4-amino-1-((5-mercapto-1,3,4-oxadiazole-2-yl)methyl)-3-(thiophene-2-ylmethyl)-1H-1,2,4-triazole-5(4H)-one (1) and 4-amino-1-((4-amino-5 mercapto-4H-1,2,4-triazole-3-yl)methyl)-3-(thiophene-2-ylmethyl)-1H-1,2,4-triazole-5(4H)-one (2) were studied theoretically by Density Functional Theory (DFT) method with 6-311++G(d,p) basis set, structural and some spectroscopic parameters were determined. Significant differences between the experimental and calculated values of vibrational frequencies and chemical shifts were explained by the presence of intermolecular (Ssbnd H⋯O and Ssbnd H⋯N type) hydrogen bonds in structures. The Molecular Electrostatic Potential (MEP) maps obtained at B3LYP/6-311G++(d,p) support the existence of hydrogen bonds. Compounds were tested against to Leishmania infantum promastigots by microdilution broth assay with Alamar Blue Dye. Antileishmanial activity of 4-amino-1,2,4-triazole derivative (2) is remarkable.

Antibacterial efficacy of Mangifera indica L. kernel and Ocimum sanctum L. leaves against Enterococcus faecalis dentinal biofilm

PubMed Central

Subbiya, Arunajatesan; Mahalakshmi, Krishnan; Pushpangadan, Sivan; Padmavathy, Kesavaram; Vivekanandan, Paramasivam; Sukumaran, Vridhachalam Ganapathy

2013-01-01

Introduction: The Enterococcus faecalis biofilm in the root canal makes it difficult to be eradicated by the conventional irrigants with no toxicity to the tissues. Hence, plant products with least side effects are explored for their use as irrigants in the root canal therapy. Aim: To evaluate and compare the antibacterial efficacy of Mangifera indica L. kernel (mango kernel) and Ocimum sanctum L. leaves (tulsi) extracts with conventional irrigants (5% sodium hypochlorite (NaOCl) and 2% chlorhexidine) against E. faecalis dentinal biofilm. Materials and Methods: Agar diffusion and broth microdilution assay was performed with the herbal extracts and conventional irrigants (2% chlorhexidine and 5% NaOCl) against E. faecalis planktonic cells. The assay was extended onto 3 week E. faecalis dentinal biofilm. Results: Significant reduction of colony forming units (CFU)/mL was observed for the herbal groups and the antibacterial activity of the herbal groups was at par with 5% NaOCl. Conclusions: The antibacterial activity of these herbal extracts is found to be comparable with that of conventional irrigants both on the biofilm and planktonic counterparts. PMID:24082577

In vitro antifungal effect of black cumin seed quinones against dairy spoilage yeasts at different acidity levels.

PubMed

Halamova, Katerina; Kokoska, Ladislav; Flesar, Jaroslav; Sklenickova, Olga; Svobodova, Blanka; Marsik, Petr

2010-12-01

The antiyeast activity of the black cumin seed (Nigella sativa) quinones dithymoquinone, thymohydroquinone (THQ), and thymoquinone (TQ) were evaluated in vitro with a broth microdilution method against six dairy spoilage yeast species. Antifungal effects of the quinones were compared with those of preservatives commonly used in milk products (calcium propionate, natamycin, and potassium sorbate) at two pH levels (4.0 and 5.5). THQ and TQ possessed significant antiyeast activity and affected the growth of all strains tested at both pH levels, with MICs ranging from 8 to 128 μg/ml. With the exception of the antibiotic natamycin, the inhibitory effects of all food preservatives against the yeast strains tested in this study were strongly affected by differences in pH, with MICs of ≥16 and ≥512 μg/ml at pH 4.0 and 5.5, respectively. These findings suggest that HQ and TQ are effective antiyeast agents that could be used in the dairy industry as chemical preservatives of natural origin.

Evaluation of the antifungal activity and modulation between Cajanus cajan (L.) Millsp. leaves and roots ethanolic extracts and conventional antifungals.

PubMed

Brito, Samara A; Rodrigues, Fabíola F G; Campos, Adriana R; da Costa, José G M

2012-04-01

The use and investigation of natural products with antimicrobial activity from vegeral source have been reported by several researchers. Cajanus cajan (Fabaceae) is a multiple use specie mainly as human food. In popular medicine, diverse parts of the plant are used as sedative and to treat cough, hepatitis, and diabetes. This study shows the characterization of secondary metabolites present in ehtanolic extracts from leaves and roots of Cajanus cajan by phytochemical prospection. The evaluation of the antifungal activity was performed by the microdilution method, and from the subinhibitory concentrations (MIC 1/8) the modulatory activity of antifungical (fluconazole and ketoconazole) was analyzed by the direct contact assay against C. albicans ATCC40006, Candida krusei ATCC 6538 and Candida tropicalis ATCC 40042. The results showed the presence of tannins, flavonoids, and alkaloids in both extracts as the clinically relevant antifungal activity. The modulatory potential is presented by the antifungal tested against yeasts. The extracts studied here have demonstrated to be a new therapeutic source to treat these microorganism-associated diseases.

Acinetobacter baumannii producing OXA-23 detected in the Czech Republic.

PubMed

Senkyrikova, Marketa; Husickova, Vendula; Chroma, Magdalena; Sauer, Pavel; Bardon, Jan; Kolar, Milan

2013-12-01

Acinetobacter baumannii is an opportunistic pathogen posing an increased risk to hospitalized persons, causing nosocomial pneumonias, urinary tract infections and postoperative infections. Between 1 December 2011 and 30 September 2012, strains of Acinetobacter spp. were isolated from clinical samples obtained from hospitalized patients. Susceptibility to antibiotics was determined by the standard microdilution method and phenotypic testing was used to detect the presence of serine carbapenemases and metallo-beta-lactamases. The polymerase chain reaction was used to detect the genes encoding carbapenemases. Pulsed field gel electrophoresis was used to investigate the genetic relationship among the carbapenem resistant isolates of Acinetobacter baumannii. In three strains of Acinetobacter baumannii enzyme OXA-23 was detected. This positive result was confirmed by restriction analysis and sequencing. The study reported an OXA-23-producing strains of Acinetobacter baumannii in the Czech Republic. All three strains isolated from Military Hospital patients had a completely identical restriction profile, indicating clonal spread of a strain carrying serine carbapenemase OXA-23 in this health care facility. Moreover this was the first time the strain was detected in the country in patients who had not stayed abroad.

Daptomycin non-susceptibility in vancomycin-intermediate Staphylococcus aureus (VISA) and heterogeneous-VISA (hVISA): implications for therapy after vancomycin treatment failure.

PubMed

Kelley, Peter G; Gao, Wei; Ward, Peter B; Howden, Benjamin P

2011-05-01

The aim of this study was to establish the relationship between reduced vancomycin and daptomycin susceptibility among Australasian vancomycin-intermediate Staphylococcus aureus (VISA) and heterogeneous-VISA (hVISA) isolates from patients never exposed to daptomycin. Forty-seven stored clinical isolates of hVISA/VISA collected before November 2008 from around Australia and New Zealand were selected. Daptomycin and vancomycin MIC testing was performed using broth microdilution (BMD) and Etest methods. Daptomycin population analysis was performed on a subset of isolates. The percentage of daptomycin non-susceptible isolates was 0% for vancomycin-susceptible S. aureus (VSSA) (Etest and BMD), for hVISA it was 26% by Etest and 15% by BMD, and for VISA 62% by Etest and 38% by BMD. Population analysis profile testing demonstrated daptomycin heteroresistance among the hVISA and VISA strains tested. This is the highest rate of daptomycin non-susceptibility reported among hVISA isolates to date. Clinicians should exhibit caution when using daptomycin in situations where serious hVISA or VISA infection is a possibility.

An in vitro antibacterial study of savory essential oil and geraniol in combination with standard antimicrobials.

PubMed

Miladinović, Dragoljub L; Ilić, Budimir S; Kocić, Branislava D; Miladinović, Marija D

2014-11-01

The chemical composition and antibacterial activity of Satureja kitaibelii Wierzb. ex Heuff. (savory) essential oil were examined, as well as the association between it and standard antimicrobials: tetracycline and chloramphenicol. The antibacterial activities of geraniol, the main constituent of S. kitaibelii oil, individually and in combination with standard antimicrobials were also determined. The interactions of the essential oil and geraniol with antimicrobials toward five selected strains were evaluated using the microdilution checkerboard assay in combination with chemometric methods. Oxygenated monoterpenes were the most abundant compound class in the oil (59.7%), with geraniol (50.4%) as the major compound. The essential oil exhibited in vitro antibacterial activity against all tested bacterial strains, but the activities were lower than those of the standard antimicrobials. The combinations savory oil-chloramphenicol, savory oil-tetracycline and geraniol-chloramphenicol produced predominantly synergistic interactions (FIC indices in the range 0.21-0.87) and substantial reductions in the MIC values of antimicrobials against Gram-negative bacteria, the pharmacological treatment of which is very difficult nowadays. In the PCA and HCA analyses these combinations form a separate group.

Chemical composition and resistance-modifying effect of the essential oil of Lantana camara Linn

PubMed Central

Sousa, Erlânio O.; Silva, Natálya F.; Rodrigues, Fabiola F. G.; Campos, Adriana R.; Lima, Sidney G.; Costa, José Galberto M.

2010-01-01

In this work, the chemical constituents, antibacterial and modulatory activities of the essential oil of Lantana camara Linn were studied. The essential oil was extracted from the leaves of L. camara by hydrodistillation method using Clevenger's apparatus and its chemical constituents were separated and identified by GC-MS, and the relative content of each constituent was determined by area normalization. Among the 25 identified components, bicyclogermacrene (19.42%), isocaryophyllene (16.70%), valecene (12.94%) and germacrene D (12.34%) were the main constituents. The oil was examined to antibacterial and modulatory activities against the multiresistant strains of Escherichia coli and Staphylococcus aureus by microdilution test. The results show an inhibitory activity to E. coli (MIC 512 μg/ml) and S. aureus (MIC 256 μg/ml). The synergism of the essential oil and aminoglycosides was verified too, with significant reduction of MICs (7 ×, 1250-5 μg/ml) against E. coli. It is suggested that the essential oil of Lantana camara Linn could be used as a source of plant-derived natural products with resistance-modifying activity. PMID:20668570

Antimicrobial and Anti-Inflammatory Activities of Pterygota macrocarpa and Cola gigantea (Sterculiaceae)

PubMed Central

Agyare, Christian; Koffuor, George Asumeng; Boamah, Vivian Etsiapa; Adu, Francis; Mensah, Kwesi Boadu; Adu-Amoah, Louis

2012-01-01

Pterygota macrocarpa and Cola gigantea are African medicinal plants used in traditional medicine for the treatment of sores, skin infections, and other inflammatory conditions including pains. This study therefore aims at investigating the antimicrobial properties of ethanol leaf and stem bark extracts of P. macrocarpa and C. gigantea using the agar diffusion and the micro-dilution techniques and also determining the anti-inflammatory properties of the extracts of these plants in carrageenan-induced foot edema in seven-day old chicks. The minimum inhibitory concentration of both ethanol leaf and bark extracts of P. macrocarpa against the test organisms was from 0.125 to 2.55 mg/mL and that of C. gigantea extracts was 0.125 to 2.75 mg/mL. Extracts with concentration of 50 mg/mL were most active against the test organisms according to the agar diffusion method. All the extracts of P. macrocarpa and C. gigantea at 30, 100, and 300 mg/kg body weight except ethanol leaf extract of C. gigantea exhibited significant anti-inflammatory effects (P ≤ 0.001). PMID:22690251

The anthraquinones rubiadin and its 1-methyl ether isolated from Heterophyllaea pustulata reduces Candida tropicalis biofilms formation.

PubMed

Marioni, Juliana; da Silva, María Angel; Cabrera, José Luis; Montoya, Susana C Núñez; Paraje, María Gabriela

2016-11-15

Candida tropicalis is increasingly becoming among the most commonly isolated pathogens causing fungal infections with an important biofilm-forming capacity. This study addresses the antifungal effect of rubiadin (AQ1) and rubiadin 1-methyl ether (AQ2), two photosensitizing anthraquinones (AQs) isolated from Heterophyllaea pustulata, against C. tropicalis biofilms, by studying the cellular stress and antioxidant response in two experimental conditions: darkness and irradiation. The combination with Amphotericin B (AmB) was assayed to evaluate the synergic effect. Biofilms of clinical isolates and reference strain of Candida tropicalis were treated with AQs (AQ1 or AQ2) and/or AmB, and the biofilms depletion was studied by crystal violet and confocal scanning laser microscopy (CSLM). The oxidant metabolites production and the response of antioxidant defense system were also evaluated under dark and irradiation conditions, being the light a trigger for photo-activation of the AQs. The Reactive Oxygen Species (ROS) were detected by the reduction of Nitro Blue Tetrazolium test, and Reactive Nitrogen Intermediates (RNI) by the Griess assay. ROS accumulation was also detected inside biofilms by using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) probe, which was visualized by CSLM. Superoxide dismutase (SOD) activity and the total antioxidant capacity of biofilms were measured by spectrophotometric methods. The minimun inhibitory concentration for sessile cells (SMIC) was determined for each AQs and AmB. The fractional inhibitory concentration index (FICI) was calculated for the combinations of each AQ with AmB by the checkerboard microdilution method. Biofilm reduction of both strains was more effective with AQ1 than with AQ2. The antifungal effect was mediated by an oxidative and nitrosative stress under irradiation, with a significant accumulation of endogenous ROS detected by CSLM and an increase in the SOD activity. Thus, the prooxidant-antioxidant balance was altered especially by AQ1. The best synergic combination with AmB was also obtained with AQ1 (80.5%) (FICI=0.74). Under irradiation, the oxidative stress was the predominant effect, altering the prooxidant-antioxidant balance, which may be the cause of the irreversible cell injury in the biofilm. Our results showed synergism of these natural AQs with AmB. Therefore, the photosensitizing AQ1 could be an alternative for the Candida infections treatment, which deserves further investigation. Copyright © 2016 Elsevier GmbH. All rights reserved.

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

Synergism of coumarins from the Chinese drug Zanthoxylum nitidum with antibacterial agents against methicillin-resistant Staphylococcus aureus (MRSA).

PubMed

Zuo, Guo-Ying; Wang, Chun-Juan; Han, Jun; Li, Yu-Qing; Wang, Gen-Chun

2016-12-15

Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious therapeutic challenge in current clinic and new drug development. Natural coumarins have diverse bioactivities and the potential of resistance modifying effects. This study is to present in-depth evaluations of in vitro antimicrobial activities of four natural coumarins 5-geranyloxy-7-methoxycoumarin (Gm, 1), (5,7-dimethoxy-8-prenyloxycoumarin (artanin, Ar, 2)), isopimpinellin (Is, 3) and phellopterin (Ph, 4) from Zanthoxylum nitidum (Roxb.) DC. (Rutaceae) extracts, focusing on their potential restoration the activity of conventional antibacterial agents against clinical MRSA strains. Bioactivity-guided fractionation and spectral analyses were used to isolate the coumarins and identify the structures, respectively. The double broth microdilution method was used to assay the coumarins' alone activity. The classic checkerboard microdilution and dynamic time-killing methods were used to evaluate combinatory effects. The four plant coumarins Gm (1), Ar (2), Is (3) and Ph (4) were isolated and identified from Z. nitidum extracts. Coumarins 1-4 displayed promising inhibition against both MSSA and MRSA with minimal inhibitory concentrations (MICs) of 8-64µg/ml, but very weak against Gram-negative pathogen and yeast with MICs of 256 to ≥1024µg/ml. The geranyloxy and prenyloxy substitutions showed to be more active than the methoxy substitution on the coumarin skeletons. 1-4 also showing different extent of synergism with a total of eight conventional antibacterial agents, i.e. chloramphenicol (CL), gentamicin (CN), fosfomycin (FF), levofloxacin (LE), minocycline (MI), piperacillin/tazobactam (P/T), teicoplanin (TE) and vancomycin (VA) against ten clinical MRSA strains. Four to ten of the tested MRSA strains showed bacteriostatic synergy in the eleven combinations. The anti-MRSA modifying effects were related to different arrangement in the combinations with fractional inhibitory concentration indices (FICIs) from 0.187 to 1.125 and the three combinations CN (Is), CL (Ph) and MI (Gm) were the best ones. The enhancement of activity was also shown by 2-64 of dose reduction indices (DRIs) of the combined MICs, with VA (Ph) combination resulted the biggest DRI. The resistance of MRSA to antibacterial agents could be reversed in the combinations of CL (Gm or Ph), LE (Ph) and MI (Is) following the Clinical and Laboratory Standards Institute (CLSI) criteria. Six combinations P/T (Gm), TE (Ar), CN (Is), VA (Ph) and CL (Gm or Ph) also showed bactericidal synergy with Δlog 10 CFU/ml >2 at 24h incubation. The coumarins showed high potentiating effects of the antibacterial agents against multi-drug resistant SA. The resistance reversal effect of CL, LE and MI warrants further pharmacological investigation on combinatory therapy for the sake of fighting against MRSA infections. Copyright © 2016 Elsevier GmbH. All rights reserved.

In vitro antifungal activity of fatty acid methyl esters of the seeds of Annona cornifolia A.St.-Hil. (Annonaceae) against pathogenic fungus Paracoccidioides brasiliensis.

PubMed

Lima, Luciana Alves Rodrigues dos Santos; Johann, Susana; Cisalpino, Patrícia Silva; Pimenta, Lúcia Pinheiro Santos; Boaventura, Maria Amélia Diamantino

2011-01-01

Fatty acids are abundant in vegetable oils. They are known to have antibacterial and antifungal properties. Antifungal susceptibility was evaluated by broth microdilution assay following CLSI (formerly the NCCLS) guidelines against 16 fungal strains of clinical interest. In this work, fatty acid methyl esters (FAME) was able to inhibit 12 clinical strains of the pathogenic fungus Paracoccidioides brasiliensis and were also active in the bioautographic assay against Cladosporium sphaerospermum. FAME was a more potent antifungal than trimethoprim-sulfamethoxazole against P. brasiliensis under the experimental conditions tested.

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.

In vitro activity of RP 74501-RP 74502, a novel streptogramin antimicrobial mixture, against clinical isolates of Legionella species.

PubMed Central

Edelstein, P H; Edelstein, M A

1993-01-01

Agar and broth microdilution MICs of RP 74501-RP 74502, a mixture of streptogramin antimicrobial agents that inhibited 90% of 22 Legionella strains tested, were 0.64 and 0.08 microgram/ml, respectively; respective erythromycin values were 1.0 and 0.12 microgram/ml. RP 74501-RP 74502 at 1 microgram/ml was more active than the same erythromycin concentration in a macrophage system for both L. pneumophila strains studied but at a lower concentration (0.25 microgram/ml) was much less active than erythromycin. PMID:8494390

In Vitro Interactions between Tacrolimus and Azoles against Candida albicans Determined by Different Methods▿

PubMed Central

Sun, Shujuan; Li, Yan; Guo, Qiongjie; Shi, Changwen; Yu, Jinlong; Ma, Lin

2008-01-01

Combination therapy could be of use for the treatment of fungal infections, especially those caused by drug-resistant fungi. However, the methods and approaches used for data generation and result interpretation need further optimizing. The fractional inhibitory concentration index (FICI) is the most commonly used method, but it has several drawbacks in characterizing antifungal drug interaction. Alternatively, some new methods can be used such as the ΔE model (difference between the predicted and measured fungal growth percentages) and the response surface approach, which uses the concentration-effect relationship over the whole concentration range instead of just the MIC. In the present study, in vitro interactions between tacrolimus (FK506) and three azoles—fluconazole (FLC), itraconazole (ITR), and voriconazole (VRC)-against Candida albicans were evaluated by the checkerboard microdilution method and time-killing test. The intensity of the interactions was determined by visual reading and the spectrophotometric method in a checkerboard assay, and the nature of the interactions was assessed by nonparametric models of FICI and ΔE. Colony counting and colorimetric viable detection methods (2,3-bis {2-methoxy-4-nitro-5-[(sulfenylamino) carbonyl]-2H-tetrazolium hydroxide} [XTT] reduction test) were used for evaluating the combination antifungal effects over time. Synergistic and indifferent effects were found for the combination of FK506 and azoles against azole-sensitive strains, while strong synergy was found against azole-resistant strains analyzed by FICI. The ΔE model gave more consistent results with FICI. The positive interactions were also confirmed by the time-killing test. Our findings suggest a potential role for combination therapy with calcineurin pathway inhibitors and azoles to augment activity against resistant C. albicans. PMID:18056277

[Serotype distribution and antimicrobial resistance of Salmonella isolates from retail chicken carcasses in six provinces of China].

PubMed

Hu, Y J; He, Y Y; Wang, Y R; Liu, C; Wang, M M; Gan, X; Wang, W; Yan, S F; Bai, Y; Peng, Z X; Li, F Q; Xu, J

2018-04-06

Objective: To obtain the serotype diversity and antimicrobial resistance of Salmonella isolates recovered from retail chicken carcasses for sale in six regions of China. Methods: From August 2010 to March 2012, each month 20 retail chicken carcasses including freshly slaughtered, chilled and frozen samples were collected from supermarkets and farmer's markets in 7 monitoring sites in Beijing, Jilin province, Inner Mongolia Autonomous, Shanxi province, Jiangsu province and Guangdong province, respectively. Samples were routinely collected for 12 months for each site. 1 680 chicken carcasses were collected in total and 2 629 Salmonella strains were isolated by PCR and biochemical method. Luminex xMAP method and classical slide agglutination method were carried out to determine isolates' serotypes. Minimal inhibitory concentrations (MICs) of 10 classes of antimicrobials including 14 agents were determined using broth micro-dilution method. Mocular methods were used to determine antimicrobial resistance genes of CIP-CTX-CT co-resistant isolates. Results: In all, 2 629 Salmonella isolates, there were 17 seorgroups and 58 serotypes, B and D1 were the dominant serogroups with rates of 34.7% ( n= 913) and 31.0% ( n= 815), Enteritidis (30.8%, n= 810), Indiana (17.6%, n= 463), Infantis (10.6%, n= 278) were the top three serovars. We found 224 CIP-CTX co-resistant S . Indiana containing 3 colistin resistant strains, one of them carrying mcr -1 gene and being ESBLs positive, which demonstrated a nine multi drug resistance against 11 antimicrobials tested. Conclusion: These data began to describe the complicated serovar diversity and heavy antimicrobial resistance of Salmonella isolates recovered from retail chicken carcasses in six regions of China. The findings highlight the emergence of ciprofloxacin and cefotaxime co-resistant S . Indiana and also a mcr -1 positive S . Indiana with heavy multi drug resistance.

In Vitro Activity of Plazomicin against Gram-Negative and Gram-Positive Isolates Collected from United States Hospitals and Comparative Activity of Aminoglycosides against Carbapenem-Resistant Enterobacteriaceae and Isolates Carrying Carbapenemase Genes.

PubMed

Castanheira, Mariana; Davis, Andrew P; Mendes, Rodrigo E; Serio, Alisa W; Krause, Kevin M; Flamm, Robert K

2018-06-04

Plazomicin and comparators agents were tested using the CLSI reference broth microdilution method against 4,825 clinical isolates collected during 2014 and 2015 in 70 United States hospitals as part of the ALERT (Antimicrobial Longitudinal Evaluation and Resistance Trends) program. Plazomicin (MIC 50/90 , 0.5/2 μg/ml) inhibited 99.2% of 4,362 Enterobacteriaceae at ≤4 μg/ml. Amikacin, gentamicin, and tobramycin inhibited 98.9%, 90.3%, and 90.3% of these isolates, respectively, applying CLSI breakpoints. The activity of plazomicin was similar among Enterobacteriaceae species with MIC 50 values ranging from 0.25 to 1 μg/ml, with exception of Proteus mirabilis and indole-positive Proteaee that displayed MIC 50 values of 2 μg/ml. Against 97 carbapenem-resistant Enterobacteriaceae (CRE) that included 87 isolates carrying bla KPC , plazomicin inhibited all but 1 isolate at ≤2 μg/ml (99.0% and 98.9%, respectively). Amikacin and gentamicin inhibited 64.9% and 56.7% of the CRE isolates at the respective CLSI breakpoints. Plazomicin inhibited 96.5/95.5% of the gentamicin-resistant, 96.9/96.5% of the tobramycin-resistant and 64.3/90.0% of the amikacin-resistant isolates using CLSI/EUCAST breakpoints. The activity of plazomicin against Pseudomonas aeruginosa (MIC 50/90 , 4/16 μg/ml) and Acinetobacter spp. (MIC 50/90 , 2/16 μg/ml) isolates was similar. Plazomicin was active against coagulase-negative staphylococci (MIC 50/90 , 0.12/0.5 μg/ml) and Staphylococcus aureus (MIC 50/90 , 0.5/0.5 μg/ml), but had limited activity against Enterococcus spp. (MIC 50/90 , 16/64 μg/ml) and Streptococcus pneumoniae (MIC 50/90 , 32/64 μg/ml). Plazomicin activity against the Enterobacteriaceae tested, including CRE and isolates carrying bla KPC from U.S. hospitals, support the development plan for plazomicin to treat serious infections caused by resistant Enterobacteriaceae in patients with limited treatment options. Copyright © 2018 American Society for Microbiology.

Assessment of carvacrol for control of avian aspergillosis in intratracheally challenged chickens in comparison to voriconazole with a reference on economic impact.

PubMed

Tartor, Y H; Hassan, F A M

2017-11-01

This study was designed to investigate the efficacy of essential oils as an alternative prophylaxis and treatment for avian aspergillosis. The in vitro susceptibility of Aspergillus fumigatus strains to antifungal drugs and carvacrol, thymol, eugenol, thymoquinone and cinnamon was determined using the macrodiffusion and microdilution methods. Carvacrol has antifungal activity in comparison to voriconazole (VCZ) (MIC 0·5, 0·25 μg ml -1 respectively). While cinnamon, euganol, thymol and thymoquinone displayed moderate to weak inhibitory activity. For the efficacy study, five groups of 10-day-old chicks (n = 48) were infected intratracheally either with A. fumigatus conidia or saline (negative control). Chicks in carvacrol prophylactic and treatment (CRPT) group were fed for 10 days beginning from hatch with carvacrol (200 mg kg -1 per diet) supplemented diets. VCZ (VCZT:20 mg kg -1 body weight (BW)), carvacrol treatment (CRT, CRPT) was started upon appearance of the first clinical signs and continued for 10 days. Birds were monitored for an additional 15 days following treatment. Fungal burden and therapeutic efficacy were assessed by survival, BW, quantitative (q) culture (CFU), quantitative real-time PCR (qPCR) and histopathological changes at several time points. Serum biochemical changes were also assessed. VCZT, CRPT, CRT in comparison to the sham-treated (SHAM) group have prolonged survival (87·5, 83·4, 79·2, 41·7% respectively). In VCZT and CRPT, a significant reduction in clinical signs, lesions, CFU and qPCR counts to the limit of detection were observed. CRPT has the lowest BW reduction, economic losses and significant low total cholesterol levels. Carvacrol has a promising potential to be used as a prophylactic and treatment against A. fumigatus. Prognosis of avian aspergillosis is often poor due to delayed diagnosis and treatment failure. However, the widespread uses of azole prophylaxis in birds are thought to be the major driver of azole resistance. These findings create a possibility to develop an effective drug-free alternative strategy for control of avian aspergillosis. © 2017 The Society for Applied Microbiology.

In Vitro Activity of the Novel Lactone Ketolide Nafithromycin (WCK 4873) against Contemporary Clinical Bacteria from a Global Surveillance Program.

PubMed

Flamm, R K; Rhomberg, P R; Sader, H S

2017-12-01

Nafithromycin (WCK 4873), a novel antimicrobial agent of the lactone ketolide class, is currently in phase 2 development for treatment of community-acquired bacterial pneumonia (CABP). A total of 4,739 nonduplicate isolates were selected from a 2014 global surveillance program at medical institutions located in 43 countries within the United States, Europe, Latin America, and the Asia-Pacific region. Nafithromycin and comparator agents were used for susceptibility testing by reference broth microdilution methods. Nafithromycin was active against Staphylococcus aureus (MIC 50/90 , 0.06/>2 μg/ml), including erythromycin-resistant strains exhibiting an inducible clindamycin resistance phenotype (MIC 50/90 , 0.06/0.06 μg/ml) and telithromycin-susceptible strains (MIC 50/90 , 0.06/0.06 μg/ml), but it exhibited limited activity against most telithromycin-resistant and clindamycin-resistant isolates that were constitutively resistant to macrolides (MIC 50/90 , >2/>2 μg/ml). Nafithromycin was very active (MIC 50/90 , 0.015/0.06 μg/ml) against 1,911 Streptococcus pneumoniae strains, inhibiting all strains, with MIC values of ≤0.25 μg/ml. Telithromycin susceptibility was 99.9% for Streptococcus pneumoniae strains, and nafithromycin was up to 8-fold more potent than telithromycin. Overall, 37.9% of S. pneumoniae strains were resistant to erythromycin, and 19.7% were resistant to clindamycin. Nafithromycin was highly active against 606 Streptococcus pyogenes strains (MIC 50/90 , 0.015/0.015 μg/ml), inhibiting 100.0% of isolates at ≤0.5 μg/ml, and MIC 50/90 values (0.015/0.015 to 0.03 μg/ml) were similar for the 4 geographic regions. Nafithromycin and telithromycin demonstrated comparable in vitro activities against 1,002 Haemophilus influenzae isolates and 504 Moraxella catarrhalis isolates. Overall, nafithromycin showed potent in vitro activity against a broad range of contemporary (2014) global pathogens. These results support the continued clinical development of nafithromycin for treatment of CABP. Copyright © 2017 American Society for Microbiology.

Meropenem-Vaborbactam Tested against Contemporary Gram-Negative Isolates Collected Worldwide during 2014, Including Carbapenem-Resistant, KPC-Producing, Multidrug-Resistant, and Extensively Drug-Resistant Enterobacteriaceae.

PubMed

Castanheira, Mariana; Huband, Michael D; Mendes, Rodrigo E; Flamm, Robert K

2017-09-01

We evaluated the activity of meropenem-vaborbactam against contemporary nonfastidious Gram-negative clinical isolates, including Enterobacteriaceae isolates with resistance phenotypes and carbapenemase genotypes. Meropenem-vaborbactam (inhibitor at 8 μg/ml) and comparators were susceptibility tested by reference broth microdilution methods against 14,304 Gram-negative clinical isolates collected worldwide during 2014. Carbapenemase-encoding genes were screened by PCR and sequencing. Meropenem-vaborbactam (MIC 50/90 , ≤0.015/0.06 μg/ml) inhibited 99.1 and 99.3% of the 10,426 Enterobacteriaceae isolates tested at ≤1 and ≤2 μg/ml, respectively. Meropenem inhibited 97.3 and 97.7% of these isolates at the same concentrations. Against Enterobacteriaceae isolates displaying carbapenem-resistant Enterobacteriaceae (CRE) ( n = 265), multidrug-resistant (MDR) ( n = 1,210), and extensively drug-resistant (XDR) ( n = 161) phenotypes, meropenem-vaborbactam displayed MIC 50/90 values of 0.5/32, 0.03/1, and 0.5/32 μg/ml, respectively, whereas meropenem activities were 16/>32, 0.06/32, and 0.5/32 μg/ml, respectively. Among all geographic regions, the highest meropenem-vaborbactam activities were observed for CRE and MDR isolates from the United States (MIC 50/90 , 0.03/1 and 0.03/0.12 μg/ml, respectively). Meropenem-vaborbactam was very active against 135 KPC producers, and all isolates were inhibited by concentrations of ≤8 μg/ml (133 isolates by concentrations of ≤2 μg/ml). This combination had limited activity against isolates producing metallo-β-lactamases (including 25 NDM-1 and 16 VIM producers) and/or oxacillinases (27 OXA-48/OXA-163 producers) that were detected mainly in Asia-Pacific and some European countries. The activity of meropenem-vaborbactam was similar to that of meropenem alone against Pseudomonas aeruginosa , Acinetobacter spp., and Stenotrophomonas maltophilia Meropenem-vaborbactam was active against contemporary Enterobacteriaceae isolates collected worldwide, and this combination demonstrated enhanced activity compared to those of meropenem and most comparator agents against CRE isolates and KPC producers, the latter of which are often MDR. Copyright © 2017 American Society for Microbiology.

Antimicrobial Activity of Ceftolozane-Tazobactam Tested against Enterobacteriaceae and Pseudomonas aeruginosa with Various Resistance Patterns Isolated in U.S. Hospitals (2011-2012)

PubMed Central

Flamm, Robert K.; Sader, Helio S.; Jones, Ronald N.

2013-01-01

Ceftolozane/tazobactam, a novel antimicrobial agent with activity against Pseudomonas aeruginosa (including drug-resistant strains) and other common Gram-negative pathogens (including most extended-spectrum-β-lactamase [ESBL]-producing Enterobacteriaceae strains), and comparator agents were susceptibility tested by a reference broth microdilution method against 7,071 Enterobacteriaceae and 1,971 P. aeruginosa isolates. Isolates were collected consecutively from patients in 32 medical centers across the United States during 2011 to 2012. Overall, 15.7% and 8.9% of P. aeruginosa isolates were classified as multidrug resistant (MDR) and extensively drug resistant (XDR), and 8.4% and 1.2% of Enterobacteriaceae were classified as MDR and XDR. No pandrug-resistant (PDR) Enterobacteriaceae isolates and only one PDR P. aeruginosa isolate were detected. Ceftolozane/tazobactam was the most potent (MIC50/90, 0.5/2 μg/ml) agent tested against P. aeruginosa and demonstrated good activity against 310 MDR strains (MIC50/90, 2/8 μg/ml) and 175 XDR strains (MIC50/90, 4/16 μg/ml). Ceftolozane/tazobactam exhibited high overall activity (MIC50/90, 0.25/1 μg/ml) against Enterobacteriaceae and retained activity (MIC50/90, 4/>32 μg/ml) against many 601 MDR strains but not against the 86 XDR strains (MIC50, >32 μg/ml). Ceftolozane/tazobactam was highly potent (MIC50/90, 0.25/0.5 μg/ml) against 2,691 Escherichia coli isolates and retained good activity against most ESBL-phenotype E. coli isolates (MIC50/90, 0.5/4 μg/ml), but activity was low against ESBL-phenotype Klebsiella pneumoniae isolates (MIC50/90, 32/>32 μg/ml), explained by the high rate (39.8%) of meropenem coresistance observed in this species phenotype. In summary, ceftolozane/tazobactam demonstrated high potency and broad-spectrum activity against many contemporary Enterobacteriaceae and P. aeruginosa isolates collected in U.S. medical centers. Importantly, ceftolozane/tazobactam retained potency against many MDR and XDR strains. PMID:24100499

Diagnostic microbiology in veterinary dermatology: present and future.

PubMed

Guardabassi, Luca; Damborg, Peter; Stamm, Ivonne; Kopp, Peter A; Broens, Els M; Toutain, Pierre-Louis

2017-02-01

The microbiology laboratory can be perceived as a service provider rather than an integral part of the healthcare team. The aim of this review is to discuss the current challenges of providing a state-of-the-art diagnostic veterinary microbiology service including the identification (ID) and antimicrobial susceptibility testing (AST) of key pathogens in veterinary dermatology. The Study Group for Veterinary Microbiology (ESGVM) of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) identified scientific, technological, educational and regulatory issues impacting the predictive value of AST and the quality of the service offered by microbiology laboratories. The advent of mass spectrometry has significantly reduced the time required for ID of key pathogens such as Staphylococcus pseudintermedius. However, the turnaround time for validated AST methods has remained unchanged for many years. Beyond scientific and technological constraints, AST methods are not harmonized and clinical breakpoints for some antimicrobial drugs are either missing or inadequate. Small laboratories, including in-clinic laboratories, are usually not adequately equipped to run up-to-date clinical microbiologic diagnostic tests. ESGVM recommends the use of laboratories employing mass spectrometry for ID and broth micro-dilution for AST, and offering assistance by expert microbiologists on pre- and post-analytical issues. Setting general standards for veterinary clinical microbiology, promoting antimicrobial stewardship, and the development of new, validated and rapid diagnostic methods, especially for AST, are among the missions of ESGVM. © 2017 The Authors. Veterinary Dermatology published by John Wiley & Sons Ltd on behalf of the ESVD and ACVD.

Synthesis, characterization, computational studies, antimicrobial activities and carbonic anhydrase inhibitor effects of 2-hydroxy acetophenone-N-methyl p-toluenesulfonylhydrazone and its Co(II), Pd(II), Pt(II) complexes

NASA Astrophysics Data System (ADS)

Özbek, Neslihan; Alyar, Saliha; Memmi, Burcu Koçak; Gündüzalp, Ayla Balaban; Bahçeci, Zafer; Alyar, Hamit

2017-01-01

2-Hydroxyacetophenone-N-methyl p-toluenesulfonylhydrazone (afptsmh) derived from p-toluenesulfonicacid-1-methylhydrazide (ptsmh) and its Co(II), Pd(II), Pt(II) complexes were synthesized for the first time. Synthesized compounds were characterized by spectroscopic methods (FT-IR, 1Hsbnd 13C NMR, LC-MS, UV-vis), magnetic susceptibility and conductivity measurements. 1H and 13C shielding tensors for crystal structure of ligand were calculated with GIAO/DFT/B3LYP/6-311++G(d,p) methods in CDCl3. The vibrational band assignments were performed at B3LYP/6-311++G(d,p) theory level combined with scaled quantum mechanics force field (SQMFF) methodology. The antibacterial activities of synthesized compounds were studied against some Gram positive and Gram negative bacteria by using microdilution and disc diffusion methods. In vitro enzyme inhibitory effects of the compounds were measured by UV-vis spectrophotometer. The enzyme activities against human carbonic anhydrase II (hCA II) were evaluated as IC50 (the half maximal inhibitory concentration) values. It was found that afptsmh and its metal complexes have inhibitory effects on hCA II isoenzyme. General esterase activities were determined using alpha and beta naphtyl acetate substrates (α- and β-NAs) of Drosophila melanogaster (D. melanogaster). Activity results show that afptsmh does not strongly affect the bacteria strains and also shows poor inhibitory activity against hCAII isoenzyme whereas all complexes posses higher biological activities.

In-vitro activity of essential oils, in particular Melaleuca alternifolia (tea tree) oil and tea tree oil products, against Candida spp.

PubMed

Hammer, K A; Carson, C F; Riley, T V

1998-11-01

The in-vitro activity of a range of essential oils, including tea tree oil, against the yeast candida was examined. Of the 24 essential oils tested by the agar dilution method against Candida albicans ATCC 10231, three did not inhibit C. albicans at the highest concentration tested, which was 2.0% (v/v) oil. Sandalwood oil had the lowest MIC, inhibiting C. albicans at 0.06%. Melaleuca alternifolia (tea tree) oil was investigated for activity against 81 C. albicans isolates and 33 non-albicans Candida isolates. By the broth microdilution method, the minimum concentration of oil inhibiting 90% of isolates for both C. albicans and non-albicans Candida species was 0.25% (v/v). The minimum concentration of oil killing 90% of isolates was 0.25% for C. albicans and 0.5% for non-albicans Candida species. Fifty-seven Candida isolates were tested for sensitivity to tea tree oil by the agar dilution method; the minimum concentration of oil inhibiting 90% of isolates was 0.5%. Tests on three intra-vaginal tea tree oil products showed these products to have MICs and minimum fungicidal concentrations comparable to those of non-formulated tea tree oil, indicating that the tea tree oil contained in these products has retained its anticandidal activity. These data indicate that some essential oils are active against Candida spp., suggesting that they may be useful in the topical treatment of superficial candida infections.

In vitro SCREENING ANTIBACTERIAL ACTIVITY OF Bidens pilosa LINNÉ AND Annona crassiflora MART. AGAINST OXACILLIN RESISTANT Staphylococcus aureus (ORSA) FROM THE AERIAL ENVIRONMENT AT THE DENTAL CLINIC

PubMed Central

da Silva, Jeferson; Cerdeira, Cláudio Daniel; Chavasco, Juliana Moscardini; Cintra, Ana Beatriz Pugina; da Silva, Carla Brigagão Pacheco; de Mendonça, Andreia Natan; Ishikawa, Tati; Boriollo, Marcelo Fabiano Gomes; Chavasco, Jorge Kleber

2014-01-01

Currently multiresistant Staphylococcus aureus is one common cause of infections with high rates of morbidity and mortality worldwide, which directs scientific endeavors in search for novel antimicrobials. In this study, nine extracts from Bidens pilosa (root, stem, flower and leaves) and Annona crassiflora (rind fruit, stem, leaves, seed and pulp) were obtained with ethanol: water (7:3, v/v) and their in vitro antibacterial activity evaluated through both the agar diffusion and broth microdilution methods against 60 Oxacillin Resistant S. aureus (ORSA) strains and against S. aureus ATCC6538. The extracts from B. pilosa and A. crassiflora inhibited the growth of the ORSA isolates in both methods. Leaves of B. pilosa presented mean of the inhibition zone diameters significantly higher than chlorexidine 0.12% against ORSA, and the extracts were more active against S. aureus ATCC (p < 0.05). Parallel, toxicity testing by using MTT method and phytochemical screening were assessed, and three extracts (B. pilosa, root and leaf, and A. crassiflora, seed) did not evidence toxicity. On the other hand, the cytotoxic concentrations (CC50 and CC90) for other extracts ranged from 2.06 to 10.77 mg/mL. The presence of variable alkaloids, flavonoids, tannins and saponins was observed, even though there was a total absence of anthraquinones. Thus, the extracts from the leaves of B. pilosa revealed good anti-ORSA activity and did not exhibit toxicity. PMID:25076435

In Vitro Control of Uropathogenic Microorganisms with the Ethanolic Extract from the Leaves of Cochlospermum regium (Schrank) Pilger.

PubMed

Leme, Danny Ellen Meireles; Rodrigues, Allan Belarmino; de Almeida-Apolonio, Adriana Araújo; Dantas, Fabiana Gomes da Silva; Negri, Melyssa Fernanda Norman; Svidzinski, Terezinha Inez Estivalet; Mota, Jonas da Silva; Cardoso, Claudia Andrea Lima; de Oliveira, Kelly Mari Pires

2017-01-01

The roots of Cochlospermum regium , popularly known as "algodãozinho-do-cerrado," are used for the treatment of genitourinary infections. However, the removal of their subterranean structures results in the death of the plant, and the use of the leaves becomes a viable alternative. Therefore, the antimicrobial activity of Cochlospermum regium leaf's ethanolic extract and its action on the biofilm formation of microorganisms associated with urinary infection were evaluated. The total phenolic compounds, flavoids, and tannins were quantified using the reagents Folin-Ciocalteu, aluminum chloride, and vanillin, respectively. The antimicrobial activity was evaluated by the broth microdilution method and the effect of the extract in the biofilm treatment was measured by the drop plate method. Cytotoxicity was evaluated by the method based on the reduction of MTS and the mutagenicity by the Ames test. The ethanolic extract of C. regium leaves presented 87.4 mg/EQ of flavonoids, 167.2 mg/EAG of total phenolic compounds, and 21.7 mg/ECA of condensed tannins. It presented reduction of the biofilm formation for E. coli and C. tropicalis and antimicrobial action of 1 mg/mL and 0.5 mg/mL, respectively. The extract showed no cytotoxicity and mutagenicity at the concentrations tested. This study demonstrated that C. regium leaves are a viable option for the treatment of genitourinary infections and for the species preservation.

In Vitro Control of Uropathogenic Microorganisms with the Ethanolic Extract from the Leaves of Cochlospermum regium (Schrank) Pilger

PubMed Central

Leme, Danny Ellen Meireles; Rodrigues, Allan Belarmino; de Almeida-Apolonio, Adriana Araújo; Dantas, Fabiana Gomes da Silva; Svidzinski, Terezinha Inez Estivalet; Mota, Jonas da Silva; Cardoso, Claudia Andrea Lima

2017-01-01

The roots of Cochlospermum regium, popularly known as “algodãozinho-do-cerrado,” are used for the treatment of genitourinary infections. However, the removal of their subterranean structures results in the death of the plant, and the use of the leaves becomes a viable alternative. Therefore, the antimicrobial activity of Cochlospermum regium leaf's ethanolic extract and its action on the biofilm formation of microorganisms associated with urinary infection were evaluated. The total phenolic compounds, flavoids, and tannins were quantified using the reagents Folin-Ciocalteu, aluminum chloride, and vanillin, respectively. The antimicrobial activity was evaluated by the broth microdilution method and the effect of the extract in the biofilm treatment was measured by the drop plate method. Cytotoxicity was evaluated by the method based on the reduction of MTS and the mutagenicity by the Ames test. The ethanolic extract of C. regium leaves presented 87.4 mg/EQ of flavonoids, 167.2 mg/EAG of total phenolic compounds, and 21.7 mg/ECA of condensed tannins. It presented reduction of the biofilm formation for E. coli and C. tropicalis and antimicrobial action of 1 mg/mL and 0.5 mg/mL, respectively. The extract showed no cytotoxicity and mutagenicity at the concentrations tested. This study demonstrated that C. regium leaves are a viable option for the treatment of genitourinary infections and for the species preservation. PMID:29375642

Biologically active Schiff bases containing thiophene/furan ring and their copper(II) complexes: Synthesis, spectral, nonlinear optical and density functional studies

NASA Astrophysics Data System (ADS)

Gündüzalp, Ayla Balaban; Özsen, İffet; Alyar, Hamit; Alyar, Saliha; Özbek, Neslihan

2016-09-01

Schiff bases; 1,8-bis(thiophene-2-carboxaldimine)-p-menthane (L1) and 1,8-bis(furan-2-carboxaldimine)-p-menthane (L2) have been synthesized and characterized by elemental analysis, 1Hsbnd 13C NMR, UV-vis, FT-IR and LC-MS methods. 1H and 13C shielding tensors for L1 and L2 were calculated with GIAO/DFT/B3LYP/6-311++G(d,p) methods in CDCl3. The vibrational band assignments, nonlinear optical (NLO) activities, frontier molecular orbitals (FMOs) and absorption spectrum have been investigated by the same basis set. Schiff base-copper(II) complexes have been synthesized and structurally characterized with spectroscopic methods, magnetic and conductivity measurements. The spectroscopic data suggest that Schiff base ligands coordinate through azomethine-N and thiophene-S/furan-O donors (as SNNS and ONNO chelating systems) to give a tetragonal geometry around the copper(II) ions. Schiff bases and Cu(II) complexes have been screened for their biological activities on different species of pathogenic bacteria, those are, Gram positive bacteria: Bacillus subtitilus, Yersinia enterotica, Bacillus cereus, Listeria monocytogenes, Micrococcus luteus and Gram negative bacteria: Escherichia coli, Pseudomonas aeroginosa, Shigella dysenteriae, Salmonella typhi, Klebsiella pseudomonas by using microdilution technique (MIC values in mM). Biological activity results show that Cu(II) complexes have higher activities than parent ligands and metal chelation may affect significantly the antibacterial behavior of the organic ligands.

Antimicrobial, Anti-inflammatory and Antioxidant Activities of Jatropha multifida L. (Euphorbiaceae)

PubMed Central

Anani, Kokou; Adjrah, Yao; Améyapoh, Yaovi; Karou, Simplice Damintoti; Agbonon, Amegnona; de Souza, Comlan; Gbeassor, Messanvi

2016-01-01

Background: Jatropha multifida is used in Togolease folk medicine for the healing of chronic wounds. Objective: This study aims to investigate antibacterial, anti-inflammatory and antioxidant activities of the leaves ethanolic extract. Materials and Methods: The antimicrobial activity was assayed by National Committee for Clinical Laboratory Standards broth microdilution method on strains of Staphylococcus aureus and Pseudomoas aeruginosa isolated from wounds, whereas the anti-inflammatory activity was performed by carrageenan and histamine induced paw edema method in rat modele. The 2, 2-diphenyl-1picrylhydrazyl (DPPH) free radical scavenging and ferric reducing antioxidant power (FRAP) were used for the antioxidant activity. Results: The antibacterial assay showed an in vitro growth inhibition of P. aeruginosa and S. aureus in dose-dependent manner, with minimum inhibitory concentration values ranging from 2.5 to 3.12 mg/mL for S. aureus and from 6.25 to 12.5 mg/mL for P. aeruginosa. The maximum paw anti-inflammatory effect occurred after 3 and 5 h administration of histamine and carrageenan, respectively. The DPPH radical scavenging and the FRAP assays yielded weak antioxidant activity. Conclusion: J. multifida possesses antibacterial and anti-inflammatory activities that could justify the use of the plant for the treatment of wounds in the folk medicine. SUMMARY Antibacterial on germs isolated from wound, anti-inflammatory and antioxidant activities of Jatropha multifida were assayed by NCCLS broth method, carrageenan and histamine, DPPH and FRAP respectively. The results indicated that Jatropha multifida possesses antibacterial and anti-inflammatory and weak antioxidant activities that could justify its use for the treatment of wounds in the folk medicine. PMID:27034606

In vivo and in vitro control activity of plant essential oils against three strains of Aspergillus niger.

PubMed

Kumar, Peeyush; Mishra, Sapna; Kumar, Atul; Kumar, Sanjeev; Prasad, Chandra Shekhar

2017-09-01

Contamination of environment and food from the prevalent spores and mycotoxins of Aspergillus niger has led to several diseases in humans and other animals. The present study investigated the control activity of plant essential oils against three strains of A. niger. In the elaborate assays done through microdilution plate assay and agar disk diffusion assay in the lab condition and in vivo assay on the stored wheat grains, the essential oil of Thymus vulgaris depicted overall superior efficacy. In microdilution plate assay, the oil of Anethum graveolens showed best fungistatic activity, while best fungicidal activity was depicted by Syzygium aromaticum oil. The oil of T. vulgaris showed moderate control efficacy against A. niger strains with its antifungal activity resulting mainly due to killing of microorganism rather than growth inhibition. In agar disk diffusion assay, T. vulgaris oil with a zone of inhibition (ZOI) of 23.3-61.1% was the most effective fungicide. The in vivo assay to evaluate the protection efficacy of oils for stored wheat grains against A. niger (AN1) revealed T. vulgaris (90.5-100%) to be the best control agent, followed by the oil of S. aromaticum (61.9-100%). The GC-MS analysis of T. vulgaris oil indicated the presence of thymol (39.11%), γ-terpinene (19.73%), o-cymene (17.21%), and β-pinene (5.38%) as major oil components. Phytotoxic effects of the oils on wheat seeds showed no significant phytotoxic effect of oils in terms of seed germination or seedling growth. The results of the study demonstrated control potentiality of essential oils for the protection of stored wheat against A. niger with prospect for development of eco-friendly antifungal products.

Penicillin-Binding Protein Transpeptidase Signatures for Tracking and Predicting β-Lactam Resistance Levels in Streptococcus pneumoniae

PubMed Central

Metcalf, Benjamin J.; Chochua, Sopio; Li, Zhongya; Gertz, Robert E.; Walker, Hollis; Hawkins, Paulina A.; Tran, Theresa; Whitney, Cynthia G.; McGee, Lesley; Beall, Bernard W.

2016-01-01

ABSTRACT β-Lactam antibiotics are the drugs of choice to treat pneumococcal infections. The spread of β-lactam-resistant pneumococci is a major concern in choosing an effective therapy for patients. Systematically tracking β-lactam resistance could benefit disease surveillance. Here we developed a classification system in which a pneumococcal isolate is assigned to a “PBP type” based on sequence signatures in the transpeptidase domains (TPDs) of the three critical penicillin-binding proteins (PBPs), PBP1a, PBP2b, and PBP2x. We identified 307 unique PBP types from 2,528 invasive pneumococcal isolates, which had known MICs to six β-lactams based on broth microdilution. We found that increased β-lactam MICs strongly correlated with PBP types containing divergent TPD sequences. The PBP type explained 94 to 99% of variation in MICs both before and after accounting for genomic backgrounds defined by multilocus sequence typing, indicating that genomic backgrounds made little independent contribution to β-lactam MICs at the population level. We further developed and evaluated predictive models of MICs based on PBP type. Compared to microdilution MICs, MICs predicted by PBP type showed essential agreement (MICs agree within 1 dilution) of >98%, category agreement (interpretive results agree) of >94%, a major discrepancy (sensitive isolate predicted as resistant) rate of <3%, and a very major discrepancy (resistant isolate predicted as sensitive) rate of <2% for all six β-lactams. Thus, the PBP transpeptidase signatures are robust indicators of MICs to different β-lactam antibiotics in clinical pneumococcal isolates and serve as an accurate alternative to phenotypic susceptibility testing. PMID:27302760

Anti-inflammatory activity of Vismia guianensis (Aubl.) Pers. extracts and antifungal activity against Sporothrix schenckii.

PubMed

Oliveira, A H; de Oliveira, G G; Carnevale Neto, F; Portuondo, D F; Batista-Duharte, A; Carlos, I Z

2017-01-04

Vismia guianensis (Aubl.) Pers. is traditionally used in North and Northeast of Brazil for the treatment of dermatomycoses. Since the strategy associating immunomodulators with antifungal drugs seems to be promissory to improve the treatment efficacy in fungal infections, we aimed to investigate the antifungal activity of V. guianensis ethanolic extract of leaves (VGL) and bark (VGB) against Sporothrix schenckii ATCC 16345 and their antinflammatory activities. The extracts were analyzed by HPLC-DAD-IT MS/MS for in situ identification of major compounds. Antifungal activity was evaluated in vitro (microdilution test) and in vivo using a murine model of S. schenckii infection. The production of TNF-α, IFN-γ, IL-4, IL-10 and IL-12 by measured by ELISA, as well as measured the production and inhibition of the NO after treatment with the plant extracts or itraconazole (ITR). Two O-glucosyl-flavonoids and 16 prenylated benzophenone derivatives already described for Vismia were detected. Both VGL and VGB showed significant antifungal activity either in in vitro assay of microdilution (MIC=3.9µg/mL) and in vivo model of infection with reduction of S. schenckii load in spleen. It was also observed a predominance of reduction in the production of NO and the proinflammatory cytokines evaluated except TNFα, but with stimulation of IL-10, as evidence of a potential anti-inflammatory effect associated. The results showed that both VGL and VGB have a significant antifungal against S. schenckii and an anti-inflammatory activity. These results can support the use of these extracts for alternative treatment of sporotrichosis. Copyright © 2016 Elsevier B.V. All rights reserved.

Phytochemical Characterization of Terminalia catappa Linn. Extracts and Their antifungal Activities against Candida spp.

PubMed

Terças, Analucia G; Monteiro, Andrea de Souza; Moffa, Eduardo B; Dos Santos, Julliana R A; de Sousa, Eduardo M; Pinto, Anna R B; Costa, Paola C da Silva; Borges, Antonio C R; Torres, Luce M B; Barros Filho, Allan K D; Fernandes, Elizabeth S; Monteiro, Cristina de Andrade

2017-01-01

Terminalia catappa Linn bark is used to treat dysentery by various populations in Southeast Asian countries, and its leaves have also been used in traditional medicine to treat hepatitis in India and the Philippines. Here, the antifungal actions of crude hydro-alcoholic extract (TcHE) and fractions from T. catappa leaves were assessed via the agar diffusion and microdilution tests on Candida reference strains and clinical isolates from patients with acquired immunodeficiency syndrome (AIDS). Additionally, the potential cytotoxic effects of TcHE were assessed on cultured human peripheral blood mononuclear cells (PBMC). T. catappa fractions and sub-fractions were analyzed by gas chromatography coupled to mass spectrometry with electron impact (GC/MS/EI), high-performance liquid chromatography coupled to mass spectrometry "electrospray" ionization in positive mode (HPLC/MS/MS/ESI + ) and hydrogen nuclear magnetic resonance ( 1 HNMR). TcHE and its fractions were able to inhibit the growth of all tested Candida strains with the n -butanol (FBuOH) fraction presenting the best antifungal activity. Testing of different FBuOH sub-fractions (SF) showed that SF10 was the most active against Candida spp. Fractioning of SF10 demonstrated that 5 out of its 15 sub-fractions were active against Candida spp., with SF10.5 presenting the highest activity. Chemical analysis of SF10 detected hydrolysable tannins (punicalin, punicalagin), gallic acid and flavonoid C-glycosides. Overall, the results showed that T. catappa L. leaf extract, fractions and sub-fractions were antifungal against Candida spp. and may be useful to treat diseases caused by this fungus.

Phytochemical Characterization of Terminalia catappa Linn. Extracts and Their antifungal Activities against Candida spp.

PubMed Central

Terças, Analucia G.; Monteiro, Andrea de Souza; Moffa, Eduardo B.; dos Santos, Julliana R. A.; de Sousa, Eduardo M.; Pinto, Anna R. B.; Costa, Paola C. da Silva; Borges, Antonio C. R.; Torres, Luce M. B.; Barros Filho, Allan K. D.; Fernandes, Elizabeth S.; Monteiro, Cristina de Andrade

2017-01-01

Terminalia catappa Linn bark is used to treat dysentery by various populations in Southeast Asian countries, and its leaves have also been used in traditional medicine to treat hepatitis in India and the Philippines. Here, the antifungal actions of crude hydro-alcoholic extract (TcHE) and fractions from T. catappa leaves were assessed via the agar diffusion and microdilution tests on Candida reference strains and clinical isolates from patients with acquired immunodeficiency syndrome (AIDS). Additionally, the potential cytotoxic effects of TcHE were assessed on cultured human peripheral blood mononuclear cells (PBMC). T. catappa fractions and sub-fractions were analyzed by gas chromatography coupled to mass spectrometry with electron impact (GC/MS/EI), high-performance liquid chromatography coupled to mass spectrometry “electrospray” ionization in positive mode (HPLC/MS/MS/ESI+) and hydrogen nuclear magnetic resonance (1HNMR). TcHE and its fractions were able to inhibit the growth of all tested Candida strains with the n-butanol (FBuOH) fraction presenting the best antifungal activity. Testing of different FBuOH sub-fractions (SF) showed that SF10 was the most active against Candida spp. Fractioning of SF10 demonstrated that 5 out of its 15 sub-fractions were active against Candida spp., with SF10.5 presenting the highest activity. Chemical analysis of SF10 detected hydrolysable tannins (punicalin, punicalagin), gallic acid and flavonoid C-glycosides. Overall, the results showed that T. catappa L. leaf extract, fractions and sub-fractions were antifungal against Candida spp. and may be useful to treat diseases caused by this fungus. PMID:28443078

Cymbopogon citratus essential oil: effect on polymicrobial caries-related biofilm with low cytotoxicity.

PubMed

Oliveira, Maria Alcionéia Carvalho de; Borges, Aline Chiodi; Brighenti, Fernanda Lourenção; Salvador, Marcos José; Gontijo, Aline Vidal Lacerda; Koga-Ito, Cristiane Yumi

2017-11-06

The objective of this study was to evaluate the effects of Cymbopogon citratus essential oil and its main compound (citral) against primary dental colonizers and caries-related species. Chemical characterization of the essential oil was performed by gas chromatography/mass spectroscopy (GC/MS), and the main compound was determined. Antimicrobial activity was tested against Actinomyces naeslundii, Lactobacillus acidophilus, S. gordonii, S. mitis, S. mutans, S. sanguinis and S. sobrinus. Minimum inhibitory and bactericide concentrations were determined by broth microdilution assay for streptococci and lactobacilli reference, and for clinical strains. The effect of the essential oil on bacterial adhesion and biofilm formation/disruption was investigated. Negative (without treatment) and positive controls (chlorhexidine) were used. The effect of citral on preformed biofilm was also tested using the same methodology. Monospecies and microcosm biofilms were tested. ANOVA or Kruskal-Wallis tests were used (α=0.05). Cytotoxicity of the essential oil to human keratinocytes was performed by MTT assay. GC/MS demonstrated one major component (citral). The essential oil showed an inhibitory effect on all tested bacterial species, including S. mutans and L. acidophilus. Essential oil of C. citratus (10X MIC) reduced the number of viable cells of lactobacilli and streptococci biofilms (p < 0.05). The essential oil inhibited adhesion of caries-related polymicrobial biofilm to dental enamel (p < 0.01). Citral significantly reduced the number of viable cells of streptococci biofilm (p < 0.001). The essential oil showed low cytotoxicity to human keratinocytes. Based on these findings, this study can contribute to the development of new formulations for products like mouthwash, against dental biofilms.

The synergy of honokiol and fluconazole against clinical isolates of azole-resistant Candida albicans.

PubMed

Jin, J; Guo, N; Zhang, J; Ding, Y; Tang, X; Liang, J; Li, L; Deng, X; Yu, L

2010-09-01

To evaluate the interaction of fluconazole (FLC) and honokiol (HNK) in vitro and vivo against azole-resistant (azole-R) clinical isolates of Candida albicans. A checkerboard microdilution method was used to study the in vitro interaction of FLC and HNK in 24 azole-R clinical isolates of C. albicans. In vivo antifungal activity was performed to further analyse the interaction between FLC and HNK. In the in vitro study, synergism was observed in all 24 FLC-resistant strains tested as determined by fractional inhibitory concentration index (FICI), and in 22 strains by Delta E models. No antagonistic activity was observed in any of the strains tested. These positive interactions were also confirmed by using the time-killing test for the selected strain C. albicans YL371, which shows strong susceptible to the combination of HNK and FLC. In the in vivo study, the mice with candidiasis were treated successfully by a combination therapy of HNK with FLC, the results showed a decrease of the colony forming unit in infected and treated animals compared to the controls, at the conditions of the treatment used in this study. Synergistic activity of HNK and FLC against clinical isolates of FLC-resistant C. albicans was observed in vitro and in vivo. This report might provide a potential therapeutic method to overcome the problem of drug-resistance in C. albicans.

Strong and Nonspecific Synergistic Antibacterial Efficiency of Antibiotics Combined with Silver Nanoparticles at Very Low Concentrations Showing No Cytotoxic Effect.

PubMed

Panáček, Aleš; Smékalová, Monika; Kilianová, Martina; Prucek, Robert; Bogdanová, Kateřina; Večeřová, Renata; Kolář, Milan; Havrdová, Markéta; Płaza, Grażyna Anna; Chojniak, Joanna; Zbořil, Radek; Kvítek, Libor

2015-12-28

The resistance of bacteria towards traditional antibiotics currently constitutes one of the most important health care issues with serious negative impacts in practice. Overcoming this issue can be achieved by using antibacterial agents with multimode antibacterial action. Silver nano-particles (AgNPs) are one of the well-known antibacterial substances showing such multimode antibacterial action. Therefore, AgNPs are suitable candidates for use in combinations with traditional antibiotics in order to improve their antibacterial action. In this work, a systematic study quantifying the synergistic effects of antibiotics with different modes of action and different chemical structures in combination with AgNPs against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus was performed. Employing the microdilution method as more suitable and reliable than the disc diffusion method, strong synergistic effects were shown for all tested antibiotics combined with AgNPs at very low concentrations of both antibiotics and AgNPs. No trends were observed for synergistic effects of antibiotics with different modes of action and different chemical structures in combination with AgNPs, indicating non-specific synergistic effects. Moreover, a very low amount of silver is needed for effective antibacterial action of the antibiotics, which represents an important finding for potential medical applications due to the negligible cytotoxic effect of AgNPs towards human cells at these concentration levels.

Evaluation of anti-bacterial and anti-oxidant potential of andrographolide and echiodinin isolated from callus culture of Andrographis paniculata Nees

PubMed Central

Arifullah, Mohmmed; Namsa, Nima Dandu; Mandal, Manabendra; Chiruvella, Kishore Kumar; Vikrama, Paritala; Gopal, Ghanta Rama

2013-01-01

Objective To evaluate the anti-bacterial and anti-oxidant activity of andrographolide (AND) and echiodinin (ECH) of Andrographis paniculata. Methods In this study, an attempt has been made to demonstrate the anti-microbial and anti-oxidant activity of isolated AND and ECH by broth micro-dilution method and 2,2-diphenyl-2-picryl-hydrazyl (DPPH) assay, respectively. Structure elucidation was determined by electro-spray ionization-MSD, NMR (1H and 13C) and IR spectra. Results AND was effective against most of the strains tested including Mycobacterium smegmatis, showing broad spectrum of growth inhibition activity with Minimum inhibitory concentration values against Staphylococcus aureus (100 µg/mL), Streptococcus thermophilus (350 µg/mL) Bacillus subtilis (100 µg/mL), Escherichia coli (50 µg/mL), Mycobacterium smegmatis (200 µg/mL), Klebsiella pneumonia (100 µg/mL), and Pseudomonas aeruginosa (200 µg/mL). ECH showed specific anti-bacterial activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa at a concentration higher than 225 µg/mL. Both AND and ECH were not effective against the two yeast strains, Candida albicans and Saccharomyces cerevisiae tested in this study. Conclusion This preliminary study showed promising anti-bacterial activity and moderate free radical scavenging activity of AND and ECH, and it may provide the scientific rationale for its popular folklore medicines. PMID:23905016

Inhibition of crystallization caused by Proteus mirabilis during the development of infectious urolithiasis by various phenolic substances.

PubMed

Torzewska, Agnieszka; Rozalski, Antoni

2014-01-01

Infectious urolithiasis is a consequence of persistent urinary tract infections caused by urease producing bacteria e.g. Proteus mirabilis. These stones are composed of struvite and carbonate apatite. Their rapid growth and high recurrence indicate that so far appropriate methods of treatment have not been found. In the present study, the inhibitory effect of phenolic compounds was investigated in vitro against formation of struvite/apatite crystals. The impact of these substances with different chemical structures on crystallization caused by clinical isolates of P. mirabilis was tested spectrophotometrically using a microdilution method. Among the 11 tested compounds resveratrol, epigallocatechin gallate, peralgonidin, vanillic and coffee acids at the concentrations 250-1000 μg/ml inhibited P. mirabilis urease activity and crystallization. However, only vanillic acid had such an effect on all tested strains of P. mirabilis. Therefore, using an in vitro model, bacterial growth, crystallization, urease activity and pH were examined for 24h in synthetic urine with vanillic acid. Effect of vanillic acid was compared with that of other known struvite/apatite crystallization inhibitors (acetohydroxamic acid, pyrophosphate) and it was shown that vanillic acid strongly inhibited bacterial growth and the formation of crystals. It can be assumed that this compound, after further studies, can be used in the treatment or prophylaxis of infectious urolithiasis. Copyright © 2013 Elsevier GmbH. All rights reserved.

Chemical composition, antioxidant and antibacterial activities of essential oils from leaves and flowers of Eugenia klotzschiana Berg (Myrtaceae).

PubMed

Carneiro, Nárgella S; Alves, Cassia C F; Alves, José M; Egea, Mariana B; Martins, Carlos H G; Silva, Thayná S; Bretanha, Lizandra C; Balleste, Maira P; Micke, Gustavo A; Silveira, Eduardo V; Miranda, Mayker L D

2017-01-01

Many essential oils (EOs) of different plant species possess interesting antimicrobial effects on buccal bacteria and antioxidant properties. Eugenia klotzschiana Berg (pêra-do-cerrado, in Portuguese) is a species of Myrtaceae with restricted distribution in the Cerrado. The essential oils were extracted through the hydrodistillation technique using a modified Clevenger apparatus (2 hours) and chemically characterized by GC-MS. The major compounds were α-copaene (10.6 %) found in oil from leaves in natura, β-bisabolene (17.4 %) in the essential oil from dry leaves and α-(E)-bergamotene (29.9 %) in oil from flowers. The antioxidant activity of essential oils showed similarities in both methods under analysis (DPPH and ABTS˙+) and the results suggested moderate to high antioxidant activity. The antibacterial activity was evaluated by determining minimum inhibitory concentrations (MICs), using the microdilution method. MIC values below 400 µg/mL were obtained against Streptococcus salivarius (200 µg/mL), S. mutans (50 µg/mL), S. mitis (200 µg/mL) and Prevotella nigrescens (50 µg/mL). This is the first report of the chemical composition and antibacterial and antioxidant activities of the essential oils of E. klotzschiana. These results suggest that E. klotzschiana, a Brazilian plant, provide initial evidence of a new and alternative source of substances with medicinal interest.

Melipona mondury produces a geopropolis with antioxidant, antibacterial and antiproliferative activities.

PubMed

Santos, Tássia L A Dos; Queiroz, Raphael F; Sawaya, Alexandra C H F; Lopez, Begoña Gimenez-Cassina; Soares, Milena B P; Bezerra, Daniel P; Rodrigues, Ana Carolina B C; Paula, Vanderlúcia F DE; Waldschmidt, Ana Maria

2017-01-01

Geopropolis is a special type of propolis produced by stingless bees. Several pharmacological properties have been described for different types of geopropolis, but there have been no previous studies of the geopropolis from Melipona mondury. In this study, we investigated the antioxidant, antibacterial, and antiproliferative activities of M. mondury geopropolis, and determined its chemical profile. The antioxidant activity was determined using in vitro ABTS·+, ·DPPH, and β-carotene/linoleic acid co-oxidation methods. The antibacterial activity was determined using a microdilution method with Pseudomonas aeruginosa, Staphylococcus aureus, and methicillin-resistant S. aureus. The antiproliferative effect was determined in tumor cell lines using the Alamar Blue assay. The chemical profile was obtained using UHPLC-MS and UHPLC-MS/MS. The butanolic fraction had the highest concentration of phenolic compounds and more potent antioxidant properties in all assays. This fraction also had bacteriostatic and bactericidal effects against all bacterial strains at low concentrations, especially S. aureus. The hexane fraction had the highest antiproliferative potential, with IC50 values ranging from 24.2 to 46.6 µg/mL in HL-60 (human promyelocytic leukemia cell) and K562 (human chronic myelocytic leukemia cell), respectively. Preliminary chemical analysis indicates the presence of terpenes and gallic acid in the geopropolis. Our results indicate the therapeutic potential of geopropolis from M. mondury against inflammatory, oxidative, infectious, and neoplastic diseases.

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®

Chemical Composition, Antimicrobial and Antioxidant Activities of Essential Oils from Two Avicennia schaueriana Stapf & Leechm. Ex Moldenke (Acanthaceae) Populations.

PubMed

Machado, Kamilla N; Kaneko, Telma M; Young, Maria Cláudia M; Murakami, Cynthia; Cordeiro, Inês; Moreno, Paulo Roberto H

2017-05-01

Avicennia schaueriana Stapf & Leechm. ex Moldenke (Acanthaceae) is a native species from the Brazilian mangroves presenting ecological and economic significance. This study compared the composition and the biological activities from the essential oils obtained from two A. schaueriana populations collected at Jureia-Itatins and Ilha do Cardoso. Essential oils were obtained by conventional means, and their compositions were analyzed by GC-MS. Screening assays for antimicrobial activity were carried out by the microdilution method and the antioxidant potential was assessed by the DPPH scavenging method. The GC-MS analysis indicated that the Jureia oil (1) was composed mostly of the fatty acids palmitic (46.5%) and myristic (11.6%) acids, while the main components for the Ilha do Cardoso oil (2) were eugenol (19.7%), eugenol acetate (12.9%) and palmitic acid (15.1%). The oils showed an IC50 of 0.9 ± 0.011 mg/mL for 1 and 1.13 ± 0.028 mg/mL for 2 in the DPPH assay. The antimicrobial assay indicated MIC > 217 µg/mL for all tested microorganisms. The different essential oil composition may indicate the presence of chemotypes for A. schaueriana. The antioxidant activity of the oils was weak if compared with flavonoids. Despite the high MIC values, these oils presented some antibacterial potential against Pseudomonas aeruginosa.

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.

Essential Oil from Origanum vulgare Completely Inhibits the Growth of Multidrug-Resistant Cystic Fibrosis Pathogens.

PubMed

Pesavento, Giovanna; Maggini, Valentina; Maida, Isabel; Lo Nostro, Antonella; Calonico, Carmela; Sassoli, Chiara; Perrin, Elena; Fondi, Marco; Mengoni, Alessio; Chiellini, Carolina; Vannacci, Alfredo; Gallo, Eugenia; Gori, Luigi; Bogani, Patrizia; Bilia, Anna Rita; Campana, Silvia; Ravenni, Novella; Dolce, Daniela; Firenzuoli, Fabio; Fani, Renato

2016-06-01

Essential oils (EOs) are known to inhibit the growth of a wide range of microorganisms. Particularly interesting is the possible use of EOs to treat multidrug-resistant cystic fibrosis (CF) pathogens. We tested the essential oil (EO) from Origanum vulgare for in vitro antimicrobial activity, against three of the major human opportunistic pathogens responsible for respiratory infections in CF patients; these are methicillin-resistant Staphylococcus aureus, Stenotrophomonas maltophilia and Achromobacter xylosoxidans. Antibiotic susceptibility of each strain was previously tested by the standard disk diffusion method. Most strains were resistant to multiple antibiotics and could be defined as multi-drug-resistant (MDR). The antibacterial activity of O. vulgare EO (OEO) against a panel of 59 bacterial strains was evaluated, with MIC and MBC determined at 24, 48 and 72 hours by a microdilution method. The OEO was effective against all tested strains, although to a different extent. The MBC and MIC of OEO for S. aureus strains were either lower or equal to 0.50%, v/v, for A. xylosoxidans strains were lower or equal to 1% and 0.50%, v/v, respectively; and for S. maltophilia strains were lower or equal to 0.25%, v/v. The results from this study suggest that OEO might exert a role as an antimicrobial in the treatment of CF infections.

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).

In vitro antibiotic susceptibility of Dutch Mycoplasma synoviae field isolates originating from joint lesions and the respiratory tract of commercial poultry.

PubMed

Landman, W J M; Mevius, D J; Veldman, K T; Feberwee, A

2008-08-01

The in vitro susceptibility of 17 Dutch Mycoplasma synoviae isolates from commercial poultry to enrofloxacin, difloxacin, doxycycline, tylosin and tilmicosin was examined. Three isolates originated from joint lesions and 14 were from the respiratory tract. The type strain M. synoviae WVU 1853 was included as a control strain. Antibiotic susceptibility was tested quantitatively using the broth microdilution test. Based on initial and final minimum inhibitory concentration values, all tested isolates were susceptible to doxycycline, tylosin and tilmicosin. Two isolates from the respiratory tract were resistant to enrofloxacin and showed intermediate resistance to difloxacin.

Failure of Quality Control Measures To Prevent Reporting of False Resistance to Imipenem, Resulting in a Pseudo-Outbreak of Imipenem-Resistant Pseudomonas aeruginosa

PubMed Central

Carmeli, Yehuda; Eichelberger, Karen; Soja, Don; Dakos, Joanna; Venkataraman, Lata; DeGirolami, Paola; Samore, Matthew

1998-01-01

False results showing an outbreak of Pseudomonas aeruginosa with resistance to imipenem were traced to a defective lot of microdilution MIC testing panels. These panels contained two- to threefold lower concentrations of imipenem than expected and resulted in artifactual two- to fourfold increases in MICs of imipenem. The quality-control MIC results for Pseudomonas aeruginosa ATCC 27853 were 4 μg/ml, the highest value within the range recommended by the National Committee for Clinical Laboratory Standards. We recommend that this value be considered out of the quality-control range. PMID:9466787

In vitro inhibitory activities of magnolol against Candida spp.

PubMed

Zhou, Peiru; Fu, Jingya; Hua, Hong; Liu, Xiaosong

2017-01-01

Candida spp. cause various infections involving the skin, mucosa, deep tissues, and even life-threatening candidemia. They are regarded as an important pathogen of nosocomial bloodstream infection, with a high mortality rate. As a result of prolonged exposure to azoles, the therapeutic failure associated with azoles resistance has become a serious challenge in clinical situations. Therefore, novel, alternative antifungals are required urgently. In the present study, the CLSI M-27A broth microdilution method and the 2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction assay were used to evaluate the antifungal effects of magnolol against various standard Candida strains in planktonic mode and biofilm formation, respectively. The antifungal activity of magnolol was demonstrated in planktonic C. albicans and non-albicans Candida species, especially fluconazole-resistant Candida krusei , with the minimum inhibitory concentrations ranging from 10 to 40 μg/mL. The BMIC 90 (minimum concentration with 90% Candida biofilm inhibited) values of magnolol ranged from 20 to 160 μg/mL, whereas the BMIC 90 values of fluconazole were more than 128 μg/mL. As an alternative and broad-spectrum antifungal agent, magnolol might be of benefit to the treatment of refractory Candida infection.

Antimicrobial resistance and molecular characterization of Staphylococcus haemolyticus in a Chinese hospital.

PubMed

Yu, M-H; Chen, Y-G; Yu, Y-S; Chen, C-L; Li, L-J

2010-05-01

The aim of this study was to perform the molecular characterization of methicillin-resistant Staphylococcus haemolyticus (MRSH) from clinical specimens of patients in a Chinese hospital. One hundred and thirty-three strains of S. haemolyticus collected from April 2002 to April 2003 were analyzed. Antimicrobial susceptibility to 15 antimicrobial agents was determined by the broth microdilution method. The resistant rates to penicillin G and oxacillin were higher than 90%. There were no isolates resistant to linezolid or vancomycin, and only 6.0% of the strains were resistant to teicoplanin. The positivity rate for mecA genes was 90.2% by polymerase chain reaction (PCR). Ninety MRSH (isolated from inpatients and mecA-gene-positive) were genotyped by pulsed-field gel electrophoresis (PFGE) after SmaI digestion. Twenty-five different PFGE patterns (A approximately Y) were found and a major clone (type A; n = 36) with five subtypes was identified. Clone A was detected during a 1-year period. Identical PFGE types were found in different wards and patients. The results of this study suggest the clonal spread of MRSH within our hospital. This emphasizes the need for control and prevention measures.

Molecular identification and antifungal susceptibility profile of Candida species isolated from patients with vulvovaginitis in Tehran, Iran.

PubMed

Sharifynia, Somayeh; Falahati, Mehraban; Akhlaghi, Lame; Foroumadi, Alireza; Fateh, Roohollah

2017-01-01

Rapid and accurate identification and evaluation of antifungal susceptibility pattern of Candida isolates are crucial to determine suitable antifungal drugs for the treatment of patients with vulvovaginitis candidiasis. Vaginal samples were collected from 150 women with suspicious vaginal candidiasis, and then cultured on Sabouraoud's Dextrose Agar with chloramphenicol to isolate Candida species. After identification of Candida isolates using polymerase chain reaction-restriction fragment length polymorphism technique, antifungal susceptibility testing of four azolic antifungal drugs was carried out using broth microdilution method according to the CLSI M27-A3. Candida species were isolated from eighty suspected patients (61.79%). The most common pathogen was Candida albicans (63.75%). Resistance to fluconazole and ketoconazole was observed in 27.5% and 23.75% of Candida isolates, respectively, and only 2% of Candida isolates were resistant to miconazole. Interestingly, resistance to fluconazole in C. albicans was more than other Candida species. The results indicated that therapy should be selected according to the antifungal susceptibility tests for the prevention of treatment failure and miconazole therapy can be considered as the best therapeutic choice in the management of vulvovaginitis.

Ibuprofen-Mediated Reversal of Fluconazole Resistance in Clinical Isolates of Candida

PubMed Central

Sharma, Monika; Kotwal, Aarti; Thakuria, Bhaskar; Kakati, Barnali; Chauhan, Bhupendra Singh; Patras, Abhishek

2015-01-01

Introduction: In view of the increasing prevalence of invasive Candidiasis in today’s health-care scenario and the emergence of fluconazole resistance among clinical isolates of Candida, we sought to determine if Ibuprofen could elicit a reversal of fluconazole resistance and thereby offer a potential therapeutic breakthrough in fluconazole-resistant Candidiasis. Materials and Methods: We selected 69 clinical isolates of Candida, which demonstrated an MIC of >32 μg/ml for fluconazole, and subjected them to broth microdilution in presence and absence of Ibuprofen. Results: Forty two of the 69 isolates (60.9%) demonstrated reversal of Fluconazole resistance with concomitant use of Ibuprofen. This was characterized by significant species-wise variation (p=0.00008), with all the C. albicans isolates and none of the C. glabrata isolates demonstrating such reversal. Only 22.2% and 37.7% of C. krusei and C. tropicalis isolates respectively showed Ibuprofen-mediated reversal of Fluconazole resistance. Conclusion: Since Ibuprofen is a known efflux pump inhibitor, our findings hint at the possible mechanism of Fluconazole resistance in most of our Candida isolates and suggest a potential therapeutic alternative that could be useful in the majority of Fluconazole-resistant clinical isolates of Candida. PMID:25737988

Antibacterial, modulatory activity of antibiotics and toxicity from Rhinella jimi (Stevaux, 2002) (Anura: Bufonidae) glandular secretions.

PubMed

Sales, Débora Lima; Morais-Braga, Maria Flaviana Bezerra; Santos, Antonia Thassya Lucas Dos; Machado, Antonio Judson Targino; Araujo Filho, João Antonio de; Dias, Diógenes de Queiroz; Cunha, Francisco Assis Bezerra da; Saraiva, Rogério de Aquino; Menezes, Irwin Rose Alencar de; Coutinho, Henrique Douglas Melo; Costa, José Galberto Martins; Ferreira, Felipe Silva; Alves, Rômulo Romeu da Nóbrega; Almeida, Waltécio de Oliveira

2017-08-01

The increase in microorganisms with resistance to medications has caused a strong preoccupation within the medical and scientific community. Animal toxins studies, such as parotoid glandular secretions from amphibians, possesses a great potential in the development of drugs, such as antimicrobials, as these possess bioactive compounds. It was evaluated Rhinella jimi (Stevaux, 2002) glandular secretions against standard and multi-resistant bacterial strains; the effect of secretions combined with drugs; and determined the toxicity using two biologic in vivo models, and a in vitro model with mice livers. Standard strains were used for the determination of the Minimum Inhibitory Concentration (MIC), while for the modulatory activity of antibiotics, the clinical isolates Escherichia coli 06, Pseudomonas aeruginosa 03 and Staphylococcus aureus 10 were used. Modulatory activity was evaluated by the broth microdilution method with aminoglycosides and β-lactams as target antibiotics. The secretions in association with the antibiotics have a significant reduction in MIC, both the aminoglycosides and β-lactams. The toxicity and cytotoxicity results were lower than the values used in the modulation. R. jimi glandular secretions demonstrated clinically relevant results regarding the modulation of the tested antimicrobials. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Antimicrobial activity of natural products against Clostridium difficile in vitro.

PubMed

Roshan, N; Riley, T V; Hammer, K A

2017-05-10

To investigate the antimicrobial activity of various natural products against Clostridium difficile in vitro. The antibacterial activity of 20 natural products was determined by the agar well diffusion and broth microdilution assays against four C. difficile strains, three comparator organisms and four gastrointestinal commensal organisms. Of the raw natural products, garlic juice had the highest activity. The most active processed products were peppermint oil and the four pure compounds trans-cinnamaldehyde, allicin, menthol and zingerone. Furthermore, Bacteroides species had similar susceptibility to C. difficile to most natural products; however, Lactobacillus casei was less susceptible. The combined effect of natural products with vancomycin or metronidazole was determined using the conventional checkerboard titration method and the fractional inhibitory concentration index was calculated. The results showed a possible synergism between trans-cinnamaldehyde and vancomycin and partial synergy between trans-cinnamaldehyde and metronidazole. The study indicates a range of antimicrobial activity of natural products against C. difficile and suggests that they may be useful as alternative or complementary treatments for C. difficile infection (CDI), particularly as most are able to be given orally. This study encourages further investigation of natural products for treatment of CDI. © 2017 The Society for Applied Microbiology.

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.

The iron chelator deferasirox enhances liposomal amphotericin B efficacy in treating murine invasive pulmonary aspergillosis

PubMed Central

Ibrahim, Ashraf S.; Gebremariam, Teclegiorgis; French, Samuel W.; Edwards, John E.; Spellberg, Brad

2010-01-01

Objectives Increased bone marrow iron levels in patients with haematological malignancies is an independent risk factor for developing invasive pulmonary aspergillosis (IPA), suggesting an important role for iron uptake in the pathogenesis of IPA. We sought to determine the potential for combination therapy with the iron chelator deferasirox + liposomal amphotericin B (LAmB) to improve the outcome of murine IPA compared with LAmB monotherapy. Methods In vitro MIC and minimum fungicidal concentration (MFC) values of the iron chelator, deferasirox, for Aspergillus fumigatus were determined by microdilution assay. In addition, we studied the efficacy of deferasirox alone or combined with LAmB in treating immunocompromised mice infected with A. fumigatus via inhalation. Results Deferasirox was cidal in vitro against A. fumigatus, with an MIC and MFC of 25 and 50 mg/L, respectively. Deferasirox monotherapy modestly prolonged survival of mice with IPA. Combination deferasirox + LAmB therapy synergistically improved survival and reduced lung fungal burden compared with either monotherapy alone. Conclusions Iron chelation therapy with deferasirox alone or in combination with LAmB is effective in treating experimental IPA. Further study of deferasirox is warranted as adjunctive therapy for IPA infections. PMID:19942619

In vitro susceptibility and multilocus sequence typing of Fusarium isolates causing keratitis.

PubMed

Dallé da Rosa, P; Nunes, A; Borges, R; Batista, B; Meneghello Fuentefria, A; Goldani, L Z

2018-05-17

Fungal keratitis is recognized as a significant cause of ocular morbidity and blindness especially in developing countries. In this study, we aimed to present the molecular identification and susceptibility of Fusarium isolates causing fungal keratitis in a university hospital in southern Brazil. The samples were identified using the second largest subunit of the RNA polymerase gene (RPB2) and the translation elongation factor 1-alpha (TEF1), while the antifungal susceptibility was tested by the broth microdilution method according to the Clinical and Laboratory Standards Institute (CLSI) methodology. The majority of the isolates belonged to the Fusarium solani species complex (F. solani, F. keratoplasticum and F. falciforme) and Fusarium oxysporum species complex. Antifungal susceptibility has shown that amphotericin B and natamycin were the most effective antifungals across all isolates, followed by voriconazole. Variation among Fusarium complexes in their antifungal sensitivities was observed in our study. The identification of Fusarium species from human samples is important not only from an epidemiological viewpoint, but also for choosing the appropriate antifungal agent for difficult-to-treat Fusarium infections such as keratitis. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Antifungal activities of cytochalasins produced by Diaporthe miriciae, an endophytic fungus associated with tropical medicinal plants.

PubMed

Carvalho, Camila Rodrigues de; Ferreira-D'Silva, Alice; Wedge, David E; Cantrell, Charles L; Rosa, Luiz H

2018-06-06

In the present study, we evaluated the antifungal potential of cytochalasins produced by Diaporthe taxa against phytopathogenic fungi. Using molecular methods, seven endophytic fungal strains from the medicinal plants Copaifera pubiflora and Melocactus ernestii were identified as D. miriciae, while two isolates were identified to the genus level (Diaporthe sp.). All crude extracts of Diaporthe species produced via solid-state fermentation were evaluated by 1H NMR analyses. Crude extracts of the isolates D. miriciae UFMGCB 6350, 7719, 7646, 7653, 7701, 7772, and 7770 and Diaporthe sp. UFMGCB 7696 and 7720 were demonstrated to produce highly functionalized compounds. The extracts of D. miriciae UFMGCB 7719 and 6350 were selected as representative Diaporthe samples and subjected to bioassay-directed fractionation to isolate cytochalasins H and J. Cytochalasins H and J were evaluated for activities against the fungal plant pathogens Colletotrichum fragariae, C. gloeosporioides, C. acutatum, Botrytis cinerea, Fusarium oxysporum, Phomopsis obscurans, and P. viticola using microdilution broth assays. Cytochalasin H and J exhibited the most potent activities against the Phomopsis species tested. Our results showed that Diaporthe species were potential producers of different cytochalasins, which exhibit potential for controlling fungal diseases in planta and/or maintaining antagonism.

Anti-aging activities of extracts from Tunisian medicinal halophytes and their aromatic constituents

PubMed Central

Jdey, A.; Falleh, H.; Ben Jannet, S.; Mkadmini Hammi, K.; Dauvergne, X.; Magné, C.; Ksouri, R.

2017-01-01

Six medicinal halophytes widely represented in North Africa and commonly used in traditional medicine were screened for pharmacological properties to set out new promising sources of natural ingredients for cosmetic or nutraceutical applications. Thus, Citrullus colocynthis, Cleome arabica, Daemia cordata, Haloxylon articulatum, Pituranthos scoparius and Scorzonera undulata were examined for their in vitro antioxidant (DPPH scavenging and superoxide anion-scavenging, β-carotene bleaching inhibition and iron-reducing tests), antibacterial (microdilution method, against four human pathogenic bacteria) and anti-tyrosinase activities. Besides, their aromatic composition was determined by RP-HPLC. H. articulatum shoot extracts exhibited the strongest antioxidant activity and inhibited efficiently the growth of Salmonella enterica and Escherichia coli. P. scoparius and C. arabica inhibited slightly monophenolase, whereas H. articulatum was the most efficient inhibitor of diphenolase activity. Furthermore, H. articulatum exhibited the highest aromatic content (3.4 % DW), with dopamine as the major compound. These observations suggest that shoot extract of H. articulatum, and to a lesser extent of C. arabica, could be used as antioxidant, antibiotic as well as new natural skin lightening agents. Also, possible implication of aromatic compounds in anti-tyrosinase activity is discussed. PMID:28827992

Anti-aging activities of extracts from Tunisian medicinal halophytes and their aromatic constituents.

PubMed

Jdey, A; Falleh, H; Ben Jannet, S; Mkadmini Hammi, K; Dauvergne, X; Magné, C; Ksouri, R

2017-01-01

Six medicinal halophytes widely represented in North Africa and commonly used in traditional medicine were screened for pharmacological properties to set out new promising sources of natural ingredients for cosmetic or nutraceutical applications. Thus, Citrullus colocynthis , Cleome arabica , Daemia cordata , Haloxylon articulatum , Pituranthos scoparius and Scorzonera undulata were examined for their in vitro antioxidant (DPPH scavenging and superoxide anion-scavenging, β -carotene bleaching inhibition and iron-reducing tests), antibacterial (microdilution method, against four human pathogenic bacteria) and anti-tyrosinase activities. Besides, their aromatic composition was determined by RP-HPLC. H. articulatum shoot extracts exhibited the strongest antioxidant activity and inhibited efficiently the growth of Salmonella enterica and Escherichia coli . P. scoparius and C. arabica inhibited slightly monophenolase, whereas H. articulatum was the most efficient inhibitor of diphenolase activity. Furthermore, H. articulatum exhibited the highest aromatic content (3.4 % DW), with dopamine as the major compound. These observations suggest that shoot extract of H. articulatum , and to a lesser extent of C. arabica , could be used as antioxidant, antibiotic as well as new natural skin lightening agents. Also, possible implication of aromatic compounds in anti-tyrosinase activity is discussed.

Synergy of a combination of nisin and citric acid against Staphylococcus aureus and Listeria monocytogenes.

PubMed

Zhao, Xingchen; Zhen, Zhen; Wang, Xinyang; Guo, Na

2017-12-01

Food-borne diseases caused by pathogens, such as Staphylococcus aureus and Listeria monocytogenes, have long attracted attention globally from researchers, food industries, and food safety authorities. Nisin (NS) is the only bacteriocin used worldwide as a generally recognised as safe (GRAS) food preservative, while citric acid (CA) has an unrestricted use in foods since it has GRAS status. In this study, synergistic interactions of NS combined with CA against S. aureus and L. monocytogenes were studied by the chequerboard microdilution method, with fractional inhibitory concentration index values ranging from 0.25 to 0.375 and 0.19 to 0.375, respectively. The positive interactions were verified by time-kill studies in pasteurised milk and disk diffusion assays. The mechanism of the synergistic antibacterial of NS and CA is proposed following SEM analysis and the determination of release of cell constituents. These results suggest that the cell walls and membrane are the probable main targets of this antimicrobial combination. These findings indicated that the combination of NS and CA not only could be used as a new promising naturally sourced food preservative, but may also reduce the problem of bacterial resistance.

Antifungal activity of the pygidial gland secretion of Laemostenus punctatus (Coleoptera: Carabidae) against cave-dwelling micromycetes

NASA Astrophysics Data System (ADS)

Nenadić, Marija; Ljaljević-Grbić, Milica; Stupar, Miloš; Vukojević, Jelena; Ćirić, Ana; Tešević, Vele; Vujisić, Ljubodrag; Todosijević, Marina; Vesović, Nikola; Živković, Nemanja; Ćurčić, Srećko

2017-06-01

The antifungal potential of the pygidial gland secretion of the troglophilic ground beetle Laemostenus punctatus from a cave in Southeastern Serbia against cave-dwelling micromycetes, isolated from the same habitat, has been investigated. Eleven collected samples were analyzed and 32 isolates of cave-dwelling fungi were documented. A total of 14 fungal species were identified as members of the genera Aspergillus, Penicillium, Alternaria, Cladosporium, Rhizopus, Trichoderma, Arthrinium, Aureobasidium, Epicoccum, Talaromyces, and Fusarium. Five isolates were selected for testing the antifungal activity of the pygidial gland secretion: Talaromyces duclauxi, Aspergillus brunneouniseriatus, Penicillium sp., Rhizopus stolonifer, and Trichoderma viride. The microdilution method has been applied to detect minimal inhibitory concentrations (MICs) and minimal fungicidal concentrations (MFCs). The most sensitive isolate was Penicillium sp., while the other isolates demonstrated a high level of resistance to the tested agent. L. punctatus has developed a special mechanism of producing specific compounds that act synergistically within the secretion mixture, which are responsible for the antifungal action against pathogens from the cave. The results open opportunities for further research in the field of ground beetle defense against pathogens, which could have an important application in human medicine, in addition to the environmental impact, primarily.

Investigation of Total Phenolic and Flavonoid Contents, and Evaluation of Antimicrobial and Antioxidant Activities from Baeckea frutescens Extracts

NASA Astrophysics Data System (ADS)

Nisa, K.; Nurhayati, S.; Apriyana, W.; Indrianingsih, A. W.

2017-12-01

Baeckea frutescens L. is a medicinal plant endemic to the tropical area and it has been used by locals for topical and oral ailments. This study investigated total phenolic and flavonoid contents and also evaluated in vitro antimicrobial and antioxidant activities of of Baeckea frutescens crude extracts. These extracts were assessed for their antibacterial activities against strains of Escherichia coli, Staphylococcus aureus, Salmonella thypii, and Pseudomonas aureginosa by the broth micro-dilution methods using a modified tetrazolium-based colorimetric assay (3-(4, 5-dimethylthiazol)-2, 5-diphenyl tetrazolium bromide (MTT) assay). Baeckea frutescens crude extracts were also tested against the stable DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) free-radical. The results indicated that Baeckea frutescens water and ethanol extracts possesed remarkable antibacterial activity with the minimum inhibitory concentration less than 100 μg/ml against Escherichia coli and Salmonella thypi. On the evaluation of the antioxidant activity via DPPH assay, Baeckea frutescens ethanol extracts exhibited a good antioxidant activity with IC50 less than 50 μg/ml and Baeckea frutescens water extracts showed a moderate antioxidant activity with IC50 less than 100 μg/ml.

Activity of Kaempferia pandurata (Roxb.) rhizome ethanol extract against MRSA, MRCNS, MSSA, Bacillus subtilis and Salmonella typhi.

PubMed

Sukandar, Elin Yulinah; Sunderam, Nethiyakalyani; Fidrianny, Irda

2014-01-01

Temu kunci (Kaempferia pandurata (Roxb.)) has a number of benefits and one of these is antibacterial. The rhizome is said to have antibacterial activity against Streptococcus mutans, Lactocillus sp. and Candida albicans. The aim of the study is to test the antibacterial activity of Kaempferia pandurata (Roxb.) rhizome ethanol extract on methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant coagulase negative Staphylococci (MRCNS), methicillin-sensitive Staphylococcus aureus (MSSA), Bacillus subtilis and Salmonella typhi. Antimicrobial activity of the extract was assayed by the microdilution method using Mueller Hinton Broth with sterilized 96 round-bottomed microwells to determine the Minimum Inhibitory Concentration (MIC) as well as to determine the time-kill activity. The MIC of the extract was 16 ppm for both Bacillus subtilis and MRSA; 8 ppm for both MSSA and Salmonella typhi and 4 ppm for MRCNS. Ethanol extract of Kaempferia pandurata (Roxb.) showed antibacterial activity against all the tested bacteria and was the most potent against MRCNS, with MIC 4 ppm. The killing profile test of the extract displayed bactericidal activity at 8-16 ppm against MRSA, MSSA, Bacillus subtilis and Salmonella typhi and bacteriostatic activity at 4 ppm towards MRCNS.

Antibacterial activity of Zuccagnia punctata Cav. ethanolic extracts.

PubMed

Zampini, Iris C; Vattuone, Marta A; Isla, Maria I

2005-12-01

The present study was conducted to investigate antibacterial activity of Zuccagnia punctata ethanolic extract against 47 strains of antibiotic-resistant Gram-negative bacteria and to identify bioactive compounds. Inhibition of bacterial growth was investigated using agar diffusion, agar macrodilution, broth microdilution and bioautographic methods. Zuccagnia punctata extract was active against all assayed bacteria (Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterobacter cloacae, Serratia marcescens, Morganella morganii, Acinetobacter baumannii, Pseudomonas aeruginosa, Stenotrophomonas maltophilia) with minimal inhibitory concentration (MIC) values ranging from 25 to 200 microg/mL. Minimal bactericidal concentration (MBC) values were identical or two-fold higher than the corresponding MIC values. Contact bioautography, indicated that Zuccagnia punctata extracts possess one major antibacterial component against Pseudomonas aeruginosa and at least three components against. Klebsiella pneumoniae and Escherichia coli. Activity-guided fractionation of 1he ethanol extract on a silica gel column yielded a compound (2',4'-dihydroxychalcone), which exhibited strong antibacterial activity with MIC values between 0.10 and 1.00 microg/mL for Proteus mirabilis, Enterobacter cloacae, Serratia marcescens, Morganella morganii, Acinetobacter baumannii, Pseudomonas aeruginosa, Stenotrophomonas maltophilia. These values are lower than imipenem (0.25-16 microg/mL). Zuccagnia punctata might provide promising therapeutic agents against infections with multi-resistant Gram-negative bacteria.

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.

Impact of Vancomycin MIC on Treatment Outcomes in Invasive Staphylococcus aureus Infections

PubMed Central

Song, Kyoung-Ho; Kim, Moonsuk; Kim, Chung Jong; Cho, Jeong Eun; Choi, Yun Jung; Park, Jeong Su; Ahn, Soyeon; Jang, Hee-Chang; Park, Kyung-Hwa; Jung, Sook-In; Yoon, Nara; Kim, Dong-Min; Hwang, Jeong-Hwan; Lee, Chang Seop; Lee, Jae Hoon; Kwak, Yee Gyung; Kim, Eu Suk; Park, Seong Yeon; Park, Yoonseon; Lee, Kkot Sil; Lee, Yeong-Seon

2016-01-01

ABSTRACT There are conflicting data on the association of vancomycin MIC (VAN-MIC) with treatment outcomes in Staphylococcus aureus infections. We investigated the relationship between high VAN-MIC and 30-day mortality and identified the risk factors for mortality in a large cohort of patients with invasive S. aureus (ISA) infections, defined as the isolation of S. aureus from a normally sterile site. Over a 2-year period, 1,027 adult patients with ISA infections were enrolled in 10 hospitals, including 673 (66%) patients with methicillin-resistant S. aureus (MRSA) infections. There were 200 (19.5%) isolates with high VAN-MIC (≥1.5 mg/liter) by Etest and 87 (8.5%) by broth microdilution (BMD). The all-cause 30-day mortality rate was 27.4%. High VAN-MIC by either method was not associated with all-cause 30-day mortality, and this finding was consistent across MIC methodologies and methicillin susceptibilities. We conclude that high VAN-MIC is not associated with increased risk of all-cause 30-day mortality in ISA infections. Our data support the view that VAN-MIC alone is not sufficient evidence to change current clinical practice. PMID:27956430

Antimicrobial activity of Northwestern Mexican plants against Helicobacter pylori.

PubMed

Robles-Zepeda, Ramón E; Velázquez-Contreras, Carlos A; Garibay-Escobar, Adriana; Gálvez-Ruiz, Juan C; Ruiz-Bustos, Eduardo

2011-10-01

Helicobacter pylori is the major etiologic agent of such gastric disorders as chronic active gastritis and gastric carcinoma. Over the past few years, the appearance of antibiotic-resistant bacteria has led to the development of better treatments, such as the use of natural products. This study evaluated the anti-H. pylori activity of 17 Mexican plants used mainly in the northwestern part of Mexico (Sonora) for the empirical treatment of gastrointestinal disorders. The anti-H. pylori activity of methanolic extracts of the plants was determined by using the broth microdilution method. The 50% minimum inhibitory concentrations ranged from less than 200 to 400 μg/mL for Castella tortuosa, Amphipterygium adstringens, Ibervillea sonorae, Pscalium decompositum, Krameria erecta, Selaginella lepidophylla, Pimpinella anisum, Marrubium vulgare, Ambrosia confertiflora, and Couterea latiflora and were greater than 800 μg/mL for Byophyllum pinnatum, Tecoma stans linnaeus, Kohleria deppena, Jatropha cuneata, Chenopodium ambrosoides, and Taxodium macronatum. Only Equisetum gigantum showed no activity against H. pylori. This study suggests the important role that these plants may have in the treatment of gastrointestinal disorders caused by H. pylori. The findings set the groundwork for further characterization and elucidation of the active compounds responsible for such activity.

Antibacterial and antifungal activities of some Mexican medicinal plants.

PubMed

Ruiz-Bustos, E; Velazquez, C; Garibay-Escobar, A; García, Z; Plascencia-Jatomea, M; Cortez-Rocha, M O; Hernandez-Martínez, J; Robles-Zepeda, R E

2009-12-01

In Mexico about 4,000 plant species have some medicinal use. The aim of this work was to evaluate the antimicrobial activity of six Mexican medicinal plants against fungi and Gram-positive and Gram-negative bacteria. Methanolic extracts were prepared from the Mexican medicinal plants Amphypteringium adstrigens, Castella tortuosa, Coutarea latiflora, Ibervillea sonorae, Jatropha cuneata, and Selaginella lepidophylla. The antibacterial and antifungal activities of the plants were determined by the broth microdilution method and the radial growth inhibition assay, respectively. All Mexican plants tested showed antimicrobial activity. Among the six plant extracts analyzed, J. cuneata showed the highest growth-inhibitory activity against fungi, Gram-positive and Gram-negative bacteria (J. cuneata > A. adstrigens > C. latiflora > C. tortuosa > I. sonorae approximately S. lepidophylla). Shigella flexneri and Staphylococcus aureus were the most susceptible bacteria to plant extracts. Complete inhibition of S. flexneri growth was observed with J. cuneata methanolic extract at 90 microg/mL. This plant extract also showed the strongest antifungal activity against Fusarium verticillioides and Aspergillus niger. Our data suggest that the medicinal plants tested have important antimicrobial properties. This is the first report describing the antimicrobial activities of several of the Mexican medicinal plants used in this study.

[Susceptibility to azithromycin and other antibiotics in recent isolates of Salmonella, Shigella and Yersinia].

PubMed

Martín-Pozo, Angeles; Arana, David M; Fuentes, Miriam; Alós, Juan-Ignacio

2014-01-01

Azithromycin represents an alternative option to treat bacterial diarrhea when the antibiotic therapy is indicated. Little is known regarding the susceptibility to azithromycin in enteropathogens in Spain. The MICs of azithromycin were determined by E-test against Salmonella non-typhi (SNT), Shigella and Yersinia isolates collected over the last three years (2010-2012). In addition, the susceptibility to other antibiotics usually used to treat gastrointestinal diseases was determined in these isolates by using a microdilution method. A total of 139 strains of SNT, Shigella and Yersinia were studied. All of them, except one strain, had a MIC≤16mg/L of azithromycin. In the adult population, 14.7% and 40.6% of SNT and Shigella isolates, respectively, were resistant to at least 2 of following antibiotics: amoxicillin, trimethoprim-sulfamethoxazole and ciprofloxacin. In the pediatric population, 10% of SNT clinical isolates and 28.6% (2/7) of Shigella isolates were resistant to amoxicillin and trimethoprim-sulfamethoxazole. In our experience, azithromycin would be a useful antibiotic alternative to treat bacterial diarrhea. Copyright © 2013 Elsevier España, S.L. y Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Imipenem-resistant Gram-negative bacterial isolates carried by persons upon medical examination in Korea.

PubMed

Kim, So Yeon; Shin, Sang Yop; Rhee, Ji-Young; Ko, Kwan Soo

2017-08-01

Carbapenem-resistant Gram-negative bacteria (CR-GNB) have emerged and disseminated worldwide, become a great concern worldwide including Korea. The prevalence of fecal carriage of imipenem-resistant Gram-negative bacteria (IR-GNB) in persons in Korea was investigated. Stool samples were collected from 300 persons upon medical examination. Samples were screened for IR-GNB by using MacConkey agar with 2 μl/ml imipenem. Species were identified by 16S rRNA gene sequence analysis, and antimicrobial susceptibility was determined by the broth microdilution method. In total, 82 IR-GNB bacterial isolates were obtained from 79 (26.3%) out of 300 healthy persons. Multilocus sequence typing analysis showed very high diversity among IR P. aeruginosa, S. maltophilia, and E. cloacae isolates, and pulsed-field gel electrophoresis revealed five main pulsotypes of IR P. mirabilis. As for the presence of metallo-β-lactamases (MBLs), only one IMP-25-producing S. marcescens isolate was identified. Although only one carbapenemase-producing isolate was identified, the high colonization rates with IR-GNB isolates in this study is notable because carriers may be a reservoir for the dissemination of resistant pathogens within the community as well as in health care institutions.

Anti-inflammatory activity of animal oils from the Peruvian Amazon.

PubMed

Schmeda-Hirschmann, Guillermo; Delporte, Carla; Valenzuela-Barra, Gabriela; Silva, Ximena; Vargas-Arana, Gabriel; Lima, Beatriz; Feresin, Gabriela E

2014-10-28

Animal oils and fats from the fishes Electrophorus electricus and Potamotrygon motoro, the reptiles Boa constrictor, Chelonoidis denticulata (Geochelone denticulata) and Melanosuchus niger and the riverine dolphin Inia geoffrensis are used as anti-inflammatory agents in the Peruvian Amazon. The aim of the study was to assess the topic anti-inflammatory effect of the oils/fats as well as to evaluate its antimicrobial activity and fatty acid composition. The oils/fats were purchased from a traditional store at the Iquitos market of Belen, Peru. The topic anti-inflammatory effect was evaluated by the mice ear edema induced by arachidonic acid (AA) and 12-O-tetradecanoylphorbol-13-acetate (TPA) at the dose of 3mg oil/ear. Indomethacine and nimesulide were used as reference anti-inflammatory drugs. The application resembles the traditional topical use of the oils. The antimicrobial effect of the oils/fats was assessed by the microdilution test against reference strains of Escherichia coli, Staphylococcus aureus and Salmonella enteritidis. The fatty acid composition of the oils/fats (as methyl esters) was determined by GC and GC-MS analysis after saponification. All oils/fats showed topic anti-inflammatory activity, with better effect in the TPA-induced mice ear edema assay. The most active drugs were Potamotrygon motoro, Melanosuchus niger and Geochelone denticulata. In the AA-induced assay, the best activity was found for Potamotrygon motoro and Electrophorus electricus oil. The oil of Electrophorus electricus also showed a weak antimicrobial effect with MIC values of 250 µg/mL against Escherichia coli ATCC 25922 and Salmonella enteritidis-MI. The main fatty acids in the oils were oleic, palmitic and linoleic acids. Topical application of all the oils/fats investigated showed anti-inflammatory activity in the mice ear edema assay. The effect can be related with the identity and composition of the fatty acids in the samples. This study gives support to the traditional use of animal oils/fats as ant-inflammatory agents in the Peruvian Amazon. However, new alternative should be encouraged due to the conservation status of several of the animal sources of the crude drugs. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

40 CFR 53.16 - Supersession of reference methods.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Supersession of reference methods. 53... (CONTINUED) AMBIENT AIR MONITORING REFERENCE AND EQUIVALENT METHODS General Provisions § 53.16 Supersession of reference methods. (a) This section prescribes procedures and criteria applicable to requests that...

In vitro synergism of magnolol and honokiol in combination with antibacterial agents against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA).

PubMed

Zuo, Guo-Ying; Zhang, Xin-Juan; Han, Jun; Li, Yu-Qing; Wang, Gen-Chun

2015-12-01

Methicillin-resistant Staphylococcus aureus (MRSA) is a problematic pathogen posing a serious therapeutic challenge in the clinic. It is often multidrug-resistant (MDR) to conventional classes of antibacterial agents and there is an urgent need to develop new agents or strategies for treatment. Magnolol (ML) and honokiol (HL) are two naturally occurring diallylbiphenols which have been reported to show inhibition of MRSA. In this study their synergistic effects with antibacterial agents were further evaluated via checkerboard and time-kill assays. The susceptibility spectrum of clinical MRSA strains was tested by the disk diffusion method. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of ML and HL were assayed by broth microdilution. The synergy was evaluated through checkerboard microdilution and time-killing experiments. ML and HL showed similar activity against both MSSA and MRSA with MIC/MBC at 16 ~ 64 mg/L, with potency similar to amikacin (AMK) and gentamicin (GEN). When they were used in combination with conventional antibacterial agents, they showed bacteriostatic synergy with FICIs between 0.25 ~ 0.5, leading to the combined MICs decreasing to as low as 1 ~ 2 and 1 ~ 16 mg/L for ML (HL) and the agents, respectively. MIC50 of the combinations decreased from 16 mg/L to 1 ~ 4 mg/L for ML (HL) and 8 ~ 128 mg/L to 2 ~ 64 mg/L for the antibacterial agents, which exhibited a broad spectrum of synergistic action with aminoglycosides (AMK, etilmicin (ETM) and GEN), floroquinolones (levofloxacin (LEV), ciprofloxacin and norfloxacin), fosfomycin (FOS) and piperacillin. The times of dilution (TOD, the extent of decreasing in MIC value) were determined up to 16 for the combined MIC. A more significant synergy after combining was determined as ML (HL) with AMK, ETM, GEN and FOS. ML (HL) combined with antibacterial agents did not show antagonistic effects on any of the ten MRSA strains. Reversal effects of MRSA resistance to AMK and GEN by ML and HL were also observed, respectively. All the combinations also showed better dynamic bactericidal activity against MRSA than any of single ML (HL) or the agents at 24 h incubation. The more significant synergy of combinations were determined as HL (ML) + ETM, HL + LEV and HL + AMK (GEN or FOS), with △LC24 of 2.02 ~ 2.25. ML and HL showed synergistic potentiation of antibacterial agents against clinical isolates of MRSA and warrant further pharmacological investigation.

In Vitro Interactions between Aspirin and Amphotericin B against Planktonic Cells and Biofilm Cells of Candida albicans and C. parapsilosis

PubMed Central

Zhou, Yabin; Wang, Ganggang; Li, Yutang; Liu, Yang; Song, Yu; Zheng, Wenshuai; Zhang, Ning; Hu, Xiaoyan; Yan, Shikun

2012-01-01

The increase in drug resistance and invasion caused by biofilm formation brings enormous challenges to the management of Candida infection. Aspirin's antibiofilm activity in vitro was discovered recently. The spectrophotometric method and the XTT {2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide} reduction assay used for data generation make it possible to evaluate fungal biofilm growth accurately. The combined use of the most commonly used methods, the fractional inhibitory concentration index (FICI) and a newly developed method, the ΔE model, which uses the concentration-effect relationship over the whole concentration range instead of using the MIC index alone, makes the interpretation of results more reliable. As an attractive tool for studying the pharmacodynamics of antimicrobial agents, time-kill curves can provide detailed information about antimicrobial efficacy as a function of both time and concentration. In the present study, in vitro interactions between aspirin (acetylsalicylic acid [ASA]) and amphotericin B (AMB) against planktonic cells and biofilm cells of Candida albicans and C. parapsilosis were evaluated by the checkerboard microdilution method and the time-kill test. Synergistic and indifferent effects were found for the combination of ASA and AMB against planktonic cells, while strong synergy was found against biofilm cells analyzed by FICI. The ΔE model gave more consistent results with FICI. The positive interactions in concentration were also confirmed by the time-kill test. Moreover, this approach also revealed the pharmacodynamics changes of ASA and synergistic action on time. Our findings suggest a potential clinical use for combination therapy with ASA and AMB to augment activity against biofilm-associated infections. PMID:22391539

Triterpenoids from Acacia ataxacantha DC: antimicrobial and antioxidant activities.

PubMed

Amoussa, Abdou Madjid O; Lagnika, Latifou; Bourjot, Mélanie; Vonthron-Senecheau, Cathérine; Sanni, Ambaliou

2016-08-12

Acacia ataxacantha is a medicinal specie used extensively in traditional medicine of Benin republic to treat infectious diseases. Our previous study showed interesting antibacterial and antifungal activities against six strains of bacteria and six strains of fungi. The aim of this study was to investigate the antimicrobial and antioxidant activities of compounds isolated from A. ataxacantha. Chromatographic and spectroscopic methods were used to isolate and identify three compounds (1-3) from the bark of A. ataxacantha. Phytochemical investigation of A. ataxacantha (Fabaceae) led to the isolation of three triterpenoids (1-3). The structure of isolated compounds was established by differents spectroscopic methods such as UV, (1)H NMR, (13)C NMR, 2D NMR and Mass. All isolated compounds were tested for antimicrobial activity using agar disc-diffusion and microdilution methods. The radical scavenging activity of isolated compounds was assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Phytochemical investigation led to the isolation and identification of lupeol (1), betulinic acid (2) and betulinic acid-3-trans-caffeate (3). Moderate antimicrobial activity was obtained with compound 3 against methicillin-resitant Staphylococcus aureus, Enterococcus feacalis and Pseudomonas aeruginosa with MIC value of 25 μg/ml and Staphylococcus aureus (MIC of 50 μg/ml). Compounds 3 was more active against Staphylococcus epidermidis and Candida albicans with a MIC value of 12.5 μg/ml in boths cases. Compounds 3 had also interesting antioxidant activity with an IC50 of 3.57 μg/ml compared to quercetin (1.04 μg/ml). The overall results of this study provide evidence that the compound 3, isolated from A. ataxacantha, exhibit antimicrobial activity against Gram-positive and Gram-negative bacteria and yeast, especially against C. albicans.

Molecular identification and amphotericin B susceptibility testing of clinical isolates of Aspergillus from 11 hospitals in Korea.

PubMed

Heo, Min Seok; Shin, Jong Hee; Choi, Min Ji; Park, Yeon Joon; Lee, Hye Soo; Koo, Sun Hoe; Lee, Won Gil; Kim, Soo Hyun; Shin, Myung Geun; Suh, Soon Pal; Ryang, Dong Wook

2015-11-01

We investigated the species distribution and amphotericin B (AMB) susceptibility of Korean clinical Aspergillus isolates by using two Etests and the CLSI broth microdilution method. A total of 136 Aspergillus isolates obtained from 11 university hospitals were identified by sequencing the internal transcribed spacer (ITS) and β-tubulin genomic regions. Minimal inhibitory concentrations (MICs) of AMB were determined in Etests using Mueller-Hinton agar (Etest-MH) and RPMI agar (Etest-RPG), and categorical agreement with the CLSI method was assessed by using epidemiological cutoff values. ITS sequencing identified the following six Aspergillus species complexes: Aspergillus fumigatus (42.6% of the isolates), A. niger (23.5%), A. flavus (17.6%), A. terreus (11.0%), A. versicolor (4.4%), and A. ustus (0.7%). Cryptic species identifiable by β-tubulin sequencing accounted for 25.7% (35/136) of the isolates. Of all 136 isolates, 36 (26.5%) had AMB MICs of ≥2 μg/mL by the CLSI method. The categorical agreement of Etest-RPG with the CLSI method was 98% for the A. fumigatus, A. niger, and A. versicolor complexes, 87% for the A. terreus complex, and 37.5% for the A. flavus complex. That of Etest-MH was ≤75% for the A. niger, A. flavus, A. terreus, and A. versicolor complexes but was higher for the A. fumigatus complex (98.3%). Aspergillus species other than A. fumigatus constitute about 60% of clinical Aspergillus isolates, and reduced AMB susceptibility is common among clinical isolates of Aspergillus in Korea. Molecular identification and AMB susceptibility testing by Etest-RPG may be useful for characterizing Aspergillus isolates of clinical relevance.

ANTI-ADHESIVE AND ANTI-BIOFILM ACTIVITIES IN VITRO OF LINEZOLID, VANCOMYCIN, TIGECYCLINE AND DAPTOMYCIN AGAINST STAPHYLOCOCCUS HAEMOLYTICUS.

PubMed

Juda, Marek; Helon, Pawel; Malm, Anna

2016-11-01

Biofilm may be formed on wide variety of surfaces, including indwelling medical devices, leading to several infectious diseases, e.g., bacteremia and sepsis. The most,important pathogens related with infections associated with medical devices are coagulase-negative staphylococci, including Staphylococcus haeinolyticus - bacterial species which express quite often the multidrug resistance. The four clinical multiresistant and methicillin-resistant S. haenzolyticus were included in the present study. The evaluation of drug susceptibility was performed by using disc-diffusion method and broth microdilution method according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. The biofilm formation on the Nelaton catheter and the effect of linezolid, vancomycin, tigecycline and daptomycin on the biofilm formation and disruption of mature structure was based on the method with TTC (2,3,5-triphenyltetrazolium chloride). The adhesion process of S. haenzolyticus to the Nelaton catheter was inhibited by antibiotics, as follows: line-zolid at concentration 0.25-0.5 x MIC, vancomycin - concentration 0.5 x MIC, tigecycline - concentration 0.25-4 x MIC and daptomycin - concentration 0.06-1 x MIC, depending on the isolate. Linezolid inhibited the biofilm formation at concentration between 0.5-1 x MIC, vancomycin - 1-2 x MIC, tigecycline - 0.5-4 x MIC and daptomycin - 0.06-2 x MIC. The concentration of linezolid eradicating the mature biofilm was found to be 1-2 x MIC, vancomycin - 2-8 x MIC, tigecycline - 2-4 x MIC and daptomycin - 0.06-2 x MIC. The most active antibiotic against S. haentolyticus biofilm formation and disruption of mature structure seems to be daptomycin.

[Prevalence of Candida albican serotypes in blood isolates in Chile, and first report of Candida dubliniensis candidemia].

PubMed

Silva, Víctor; Cabrera, Macarena; Díaz, María Cristina; Abarca, Claudia; Hermosilla, Germán

2003-06-01

Our main goal was to determine the prevalence of C. albicans serotypes isolates from blood cultures and identify the presence of C. dubliniensis. We studied 47 strains identified as C. albicans by conventional methods, 28 were isolated from children and 19 from adult patients. The strains were re-identified by standard methods and phenotypic screening as xylose assimilation and growth at 42 degrees C. API ID 32C (bioMérieux) was employed with the C. dubliniensis suspected strains and confirmation was made by molecular fingerprinting using random amplified polymorphic DNA (RAPD). The C. albicans serotype was determined by agglutination with antiserum anti-antigen 6 from cell wall (Candida Check, Iatron Inc., Japan) and the in vitro susceptibilities were evaluated by a microdilution method. From 47 strains, 46 were confirmed as C. albicans, 31 of them (67%) were serotype A. Adult patients presented a high prevalence of serotype A (95%) and children presented a frequency of 52% of the serotype B (p<0.05). We confirmed the identification of C. dubliniensis in one strain isolated from an infant. All serotype B strains were susceptible to fluconazole, itraconazole and amphotericin B. On the other hand, 3% and 6% of serotype A strains were "susceptible dose dependent" to fluconazole and itraconazole, respectively. C. albicans serotype A was predominant in adult candidemia and its distribution was homogenous in children patients. All strains were highly susceptible to antifungals. We report here the first case of C. dubliniensis candidemia in South America.

A simple screening test for the detection of metallo-β-lactamase-producing Pseudomonas aeruginosa and Acinetobacter in a tertiary care hospital.

PubMed

Wan Nor Amilah, W A W; Noor Izani, N J; Ng, W K; Ashraful Haq, J

2012-12-01

Clinical utilization of carbapenems remains under threat with the emergence of acquired carbapenemase-producing bacteria, particularly metallo-β-lactamases (MBL). Rapid detection of MBL-producing Gram-negative bacilli is essential to prevent their widespread dissemination. However, no standardized detection method is available for routine laboratory use. The purpose of the study was to evaluate a chelating-agent based double disk synergic test and disk potentiation test for MBL-producing strain detection and to determine the isolation rate of MBL-producing Pseudomonas aeruginosa and Acinetobacter from clinical samples in our tertiary teaching hospital. A total of 22 and 66 imipenem-resistant P. aeruginosa and Acinetobacter isolates respectively were tested with ceftazidime (CAZ) disk by modified double disk synergic test and disk potentiation test using ethylenediaminetetraacetic acid (EDTA) and 2-mercaptopropionic acid (as chelating agents) to detect MBL production. The tests were compared with EDTA-phenanthroline-imipenem (EPI) microdilution MIC test as gold standard. MBL positive strains were detected in 17 (77.3%) P. aeruginosa and 2 (3.5%) Acinetobacter isolates. The disk potentiation test with 2-mercaptopropionic acid (2-MPA) dilution of 1:12 provided the most acceptable sensitivities and specificities (88.2% sensitivity and 100% specificity in P. aeruginosa; 100% sensitivity and specificity in Acinetobacter) compared to other screening methods used in this study. This study provided useful information on the local prevalence of MBL-producing P. aeruginosa and Acinetobacter in our hospital. Disc potentiation test with CAZ/2-MPA disc appears to be reliable and convenient MBL detection method in the routine clinical laboratory.

Phytomedical investigation of Najas minor All. in the view of the chemical constituents

PubMed Central

Topuzovic, Marina D.; Radojevic, Ivana D.; Dekic, Milan S.; Radulovic, Niko S.; Vasic, Sava M.; Comic, Ljiljana R.; Licina, Braho Z.

2015-01-01

Plants are an abundant natural source of effective antibiotic compounds. Phytomedical investigations of certain plants haven't still been conducted. One of them is Najas minor (N. minor), an aquatic plant with confirmed allelopathy. Research conducted in this study showed the influence of water and ethyl acetate extracts of N. minor on microorganisms, in the view of chemical profiling of volatile constituents and the concentrations of total phenols, flavonoids and tannins. Antimicrobial activity was defined by determining minimum inhibitory and minimum microbicidal concentrations using microdilution method. Influence on bacterial biofilm formation was performed by tissue culture plate method. The total phenolics, flavonoids and condensed tannins were determined by Folin-Ciocalteu, aluminum chloride and butanol-HCl colorimetric methods. Chemical profiling of volatile constituents was investigated by GC and GC-MS. Water extract didn't have antimicrobial activity below 5000 µg/mL. Ethyl acetate extract has shown strong antimicrobial activity on G+ bacteria - Staphylococcus aureus PMFKGB12 and Bacillus subtilis (MIC < 78.13 µg/mL). The best antibiofilm activity was obtained on Escherichia coli ATCC25922 (BIC50 at 719 µg/mL). Water extract had higher yield. Ethyl acetate extract had a significantly greater amount of total phenolics, flavonoids and tannins. As major constituent hexahydrofarnesyl acetone was identified. The ethyl acetate extract effected only G+ bacteria, but the biofilm formation of G-bacteria was suppressed. There was a connection between those in vivo and in vitro effects against pathogenic bacterial biofilm formation. All of this points to a so far unexplored potential of N. minor. PMID:26535038

Two cases of sporotrichosis of the right upper extremity in right-handed patients with diabetes mellitus.

PubMed

Zhang, Yu; Hagen, Ferry; Wan, Zhe; Liu, Yufu; Liu, Yahong; Wang, Qingwen; de Hoog, Gert Sybren; Li, Ruoyu; Zhang, Junling

2016-01-01

Sporothrix species have proved to show high degrees of endemicity. Sporothrix globosa is the only pathogenic Sporothrix species that has till date been reported from China, where it is endemic in the northeastern provinces. We report two cases of lymphocutaneous sporotrichosis with diabetes mellitus as underlying disease in patients from the non-endemic area of China. A 59-year-old farmer and a 60-year-old gardener were admitted in February and June 2014, respectively. Both patients were right-handed men and presented with progressive plaques and nodules, which they had for several years, involving the right upper extremity. Skin biopsy from the granuloma was taken and cultured on Sabouraud medium, and molecular identification based on the calmodulin region was performed. Antifungal susceptibility testing was also performed with the microdilution method. Biopsy of the lesions showed the presence of infectious granuloma. The fungal cultures were identified as Sporothrix globosa by conventional methods, and confirmed by molecular identification. A subsequent course of oral antifungal therapy with low dosage of itraconazole was well tolerated and resolved the infection. Identification of fungal species and antifungal susceptibility testing are mandatory for epidemiological and therapeutic reasons. Early diagnosis of sporotrichosis is essential to prevent those sequelae when the disease progresses and provides highly effective methods for treating this emerging disease. Avoiding the exposure to plant material potentially contaminated with fungal spores should be recommended, especially in immunocompromised patients. Copyright © 2015 Revista Iberoamericana de Micología. Published by Elsevier Espana. All rights reserved.

A synergistic effect of artocarpanone from Artocarpus heterophyllus L. (Moraceae) on the antibacterial activity of selected antibiotics and cell membrane permeability

PubMed Central

Septama, Abdi Wira; Xiao, Jianbo; Panichayupakaranant, Pharkphoom

2017-01-01

Aim/Backgrounds: Artocarpanone isolated from Artocarpus heterophyllus L. (Moraceae) exhibits antibacterial activity. The present study investigated synergistic activity between artocarpanone and tetracycline, ampicillin, and norfloxacin, respectively, against methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Escherichia coli. Materials and Methods: A broth microdilution method was used for evaluating antibacterial susceptibility. Synergistic effects were identified using a checkerboard method, and a bacterial cell membrane disruption was investigated by assay of released 260 nm absorbing materials following bacteriolysis. Results and Discussion: Artocarpanone exhibited weak antibacterial activity against MRSA and P. aeruginosa with minimum inhibitory concentrations values of 125 and 500 μg/mL, respectively. However, the compound showed strong antibacterial activity against E. coli (7.8 μg/mL). The interaction between artocarpanone and all tested antibiotics revealed indifference and additive effects against P. aeruginosa and E. coli (fractional inhibitory concentration index [FICI] values of 0.75-1.25). The combination of artocarpanone (31.2 μg/mL) and norfloxacin (3.9 μg/mL) resulted in synergistic antibacterial activity against MRSA, with an FICI of 0.28, while the interaction between artocarpanone and tetracycline, and ampicillin showed an additive effect, with an FICI value of 0.5. A time-kill assay also indicated that artocarpanone had a synergistic effect on the antibacterial activity of norfloxacin. In addition, the combination of artocarpanone and norfloxacin altered the membrane permeability of MRSA. Conclusion: These findings suggest that artocarpanone may be used to enhance the antibacterial activity of norfloxacin against MRSA. PMID:28512600

ANTIBACTERIAL ACTIVITY OF DRACONTOMELON DAO EXTRACTS ON METHICILLIN-RESISTANT S. AUREUS (MRSA) AND E. COLI MULTIPLE DRUG RESISTANCE (MDR).

PubMed

Yuniati, Yuniati; Hasanah, Nurul; Ismail, Sjarif; Anitasari, Silvia; Paramita, Swandari

2018-01-01

Staphylococcus aureus , methicillin-resistant and Escherichia coli , multidrug-resistant included in the list of antibiotic-resistant priority pathogens from WHO. As multidrug-resistant bacteria problem is increasing, it is necessary to probe new sources for identifying antimicrobial compounds. Medicinal plants represent a rich source of antimicrobial agents. One of the potential plants for further examined as antibacterial is Dracontomelon dao (Blanco) Merr. & Rolfe. The present study designed to find the antibacterial activity of D. dao stem bark extracts on Methicillin-resistant S. aureus (MRSA) and E. coli Multiple Drug Resistance (MDR), followed by determined secondary metabolites with antibacterial activity and determined the value of MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration). D. dao stem bark extracted using 60% ethanol. Disc diffusion test methods used to find the antibacterial activity, following by microdilution methods to find the value of MIC and MBC. Secondary metabolites with antibacterial activity determined by bioautography using TLC (thin layer chromatography) methods. D. dao stem bark extracts are sensitive to MSSA, MRSA and E.coli MDR bacteria. The inhibition zone is 16.0 mm in MSSA, 11.7 mm in MRSA and 10.7 mm in E. coli MDR. The entire MBC/MIC ratios for MSSA, MRSA and E.coli MDR is lower than 4. The ratio showed bactericidal effects of D. dao stem bark extracts. In TLC results, colorless bands found to be secondary metabolites with antibacterial activity. D. dao stem bark extracts are potential to develop as antibacterial agent especially against MRSA and E. coli MDR strain.

Antimicrobial, Anti-inflammatory and Antioxidant Activities of Jatropha multifida L. (Euphorbiaceae).

PubMed

Anani, Kokou; Adjrah, Yao; Améyapoh, Yaovi; Karou, Simplice Damintoti; Agbonon, Amegnona; de Souza, Comlan; Gbeassor, Messanvi

2016-01-01

Jatropha multifida is used in Togolease folk medicine for the healing of chronic wounds. This study aims to investigate antibacterial, anti-inflammatory and antioxidant activities of the leaves ethanolic extract. The antimicrobial activity was assayed by National Committee for Clinical Laboratory Standards broth microdilution method on strains of Staphylococcus aureus and Pseudomoas aeruginosa isolated from wounds, whereas the anti-inflammatory activity was performed by carrageenan and histamine induced paw edema method in rat modele. The 2, 2-diphenyl-1picrylhydrazyl (DPPH) free radical scavenging and ferric reducing antioxidant power (FRAP) were used for the antioxidant activity. The antibacterial assay showed an in vitro growth inhibition of P. aeruginosa and S. aureus in dose-dependent manner, with minimum inhibitory concentration values ranging from 2.5 to 3.12 mg/mL for S. aureus and from 6.25 to 12.5 mg/mL for P. aeruginosa. The maximum paw anti-inflammatory effect occurred after 3 and 5 h administration of histamine and carrageenan, respectively. The DPPH radical scavenging and the FRAP assays yielded weak antioxidant activity. J. multifida possesses antibacterial and anti-inflammatory activities that could justify the use of the plant for the treatment of wounds in the folk medicine. Antibacterial on germs isolated from wound, anti-inflammatory and antioxidant activities of Jatropha multifida were assayed by NCCLS broth method, carrageenan and histamine, DPPH and FRAP respectively. The results indicated that Jatropha multifida possesses antibacterial and anti-inflammatory and weak antioxidant activities that could justify its use for the treatment of wounds in the folk medicine.

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.

Deviation of landmarks in accordance with methods of establishing reference planes in three-dimensional facial CT evaluation.

PubMed

Yoon, Kaeng Won; Yoon, Suk-Ja; Kang, Byung-Cheol; Kim, Young-Hee; Kook, Min Suk; Lee, Jae-Seo; Palomo, Juan Martin

2014-09-01

This study aimed to investigate the deviation of landmarks from horizontal or midsagittal reference planes according to the methods of establishing reference planes. Computed tomography (CT) scans of 18 patients who received orthodontic and orthognathic surgical treatment were reviewed. Each CT scan was reconstructed by three methods for establishing three orthogonal reference planes (namely, the horizontal, midsagittal, and coronal reference planes). The horizontal (bilateral porions and bilateral orbitales) and midsagittal (crista galli, nasion, prechiasmatic point, opisthion, and anterior nasal spine) landmarks were identified on each CT scan. Vertical deviation of the horizontal landmarks and horizontal deviation of the midsagittal landmarks were measured. The porion and orbitale, which were not involved in establishing the horizontal reference plane, were found to deviate vertically from the horizontal reference plane in the three methods. The midsagittal landmarks, which were not used for the midsagittal reference plane, deviated horizontally from the midsagittal reference plane in the three methods. In a three-dimensional facial analysis, the vertical and horizontal deviations of the landmarks from the horizontal and midsagittal reference planes could vary depending on the methods of establishing reference planes.

A reference estimator based on composite sensor pattern noise for source device identification

NASA Astrophysics Data System (ADS)

Li, Ruizhe; Li, Chang-Tsun; Guan, Yu

2014-02-01

It has been proved that Sensor Pattern Noise (SPN) can serve as an imaging device fingerprint for source camera identification. Reference SPN estimation is a very important procedure within the framework of this application. Most previous works built reference SPN by averaging the SPNs extracted from 50 images of blue sky. However, this method can be problematic. Firstly, in practice we may face the problem of source camera identification in the absence of the imaging cameras and reference SPNs, which means only natural images with scene details are available for reference SPN estimation rather than blue sky images. It is challenging because the reference SPN can be severely contaminated by image content. Secondly, the number of available reference images sometimes is too few for existing methods to estimate a reliable reference SPN. In fact, existing methods lack consideration of the number of available reference images as they were designed for the datasets with abundant images to estimate the reference SPN. In order to deal with the aforementioned problem, in this work, a novel reference estimator is proposed. Experimental results show that our proposed method achieves better performance than the methods based on the averaged reference SPN, especially when few reference images used.

Reference Value Advisor: a new freeware set of macroinstructions to calculate reference intervals with Microsoft Excel.

PubMed

Geffré, Anne; Concordet, Didier; Braun, Jean-Pierre; Trumel, Catherine

2011-03-01

International recommendations for determination of reference intervals have been recently updated, especially for small reference sample groups, and use of the robust method and Box-Cox transformation is now recommended. Unfortunately, these methods are not included in most software programs used for data analysis by clinical laboratories. We have created a set of macroinstructions, named Reference Value Advisor, for use in Microsoft Excel to calculate reference limits applying different methods. For any series of data, Reference Value Advisor calculates reference limits (with 90% confidence intervals [CI]) using a nonparametric method when n≥40 and by parametric and robust methods from native and Box-Cox transformed values; tests normality of distributions using the Anderson-Darling test and outliers using Tukey and Dixon-Reed tests; displays the distribution of values in dot plots and histograms and constructs Q-Q plots for visual inspection of normality; and provides minimal guidelines in the form of comments based on international recommendations. The critical steps in determination of reference intervals are correct selection of as many reference individuals as possible and analysis of specimens in controlled preanalytical and analytical conditions. Computing tools cannot compensate for flaws in selection and size of the reference sample group and handling and analysis of samples. However, if those steps are performed properly, Reference Value Advisor, available as freeware at http://www.biostat.envt.fr/spip/spip.php?article63, permits rapid assessment and comparison of results calculated using different methods, including currently unavailable methods. This allows for selection of the most appropriate method, especially as the program provides the CI of limits. It should be useful in veterinary clinical pathology when only small reference sample groups are available. ©2011 American Society for Veterinary Clinical Pathology.

Variability in the clinical distributions of Candida species and the emergence of azole-resistant non-Candida albicans species in public hospitals in the Midwest region of Brazil.

PubMed

Mattos, Karine; Rodrigues, Luana Carbonera; Oliveira, Kelly Mari Pires de; Diniz, Pedro Fernando; Marques, Luiza Inahê; Araujo, Adriana Almeida; Chang, Marilene Rodrigues

2017-01-01

Incidence and antifungal susceptibility of Candida spp. from two teaching public hospitals are described. The minimum inhibitory concentrations of fluconazole, voriconazole, itraconazole, and amphotericin B were determined using Clinical Laboratory Standard Institute broth microdilution and genomic differentiation using PCR. Of 221 Candida isolates, 50.2% were obtained from intensive care unit patients; 71.5% were recovered from urine and 9.1% from bloodstream samples. Candida parapsilosis sensu stricto was the most common candidemia agent. We observed variations in Candida species distribution in hospitals in the same geographic region and documented the emergence of non-C. albicans species resistant to azoles.

In Vitro Activity of Ceftaroline against Staphylococcus aureus Isolates Collected in 2012 from Latin American Countries as Part of the AWARE Surveillance Program.

PubMed

Biedenbach, Douglas J; Hoban, Daryl J; Reiszner, Edina; Lahiri, Sushmita D; Alm, Richard A; Sahm, Daniel F; Bouchillon, Samuel K; Ambler, Jane E

2015-12-01

The in vitro activities of ceftaroline and comparators, using broth microdilution, were determined against 1,066 Staphylococcus aureus isolates from hospitalized patients. Seventeen medical centers from Latin American countries contributed isolates. Methicillin-resistant S. aureus (MRSA) percentages ranged from 46% (Brazil) to 62% (Argentina). All methicillin-susceptible S. aureus (MSSA) isolates were susceptible to ceftaroline. Ceftaroline activity against MRSA varied with MIC90s of 0.5 (Venezuela) to 2 (Brazil, Chile, and Colombia) μg/ml, which was the highest MIC value. ST-5 was the most common sequence type. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Inhibitory effect of sodium hypochlorite and chlorhexidine digluconate in clinical isolates of Sporothrix schenckii.

PubMed

Madrid, Isabel Martins; Mattei, Antonella Souza; Santin, Rosema; dos Reis Gomes, Angelita; Cleff, Marlete Brum; Meireles, Mário Carlos Araújo

2012-05-01

The susceptibility of Sporothrix schenckii isolates from clinical cases of canine, feline and human sporotrichosis, and from the environment, was evaluated with 4% sodium hypochlorite and 6.6% chlorhexidine digluconate using the broth microdilution, agar diffusion and direct exposure techniques. The minimal inhibitory concentration was smaller than 0.8% for chlorhexidine digluconate and between 8% and 4% for sodium hypochlorite. Inhibition zones were not found in agar diffusion for sodium hypochlorite, and zones averaging 1.9 mm were found for chlorhexidine digluconate. In the direct exposure test, sodium hypochlorite demonstrated best performance at 20 min of contact, as chlorhexidine digluconate presented little antimicrobial activity. © 2011 Blackwell Verlag GmbH.

Synthesis, spectroscopic characterization and antimicrobial studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes with Schiff bases derived from 5-bromo-salicylaldehyde

NASA Astrophysics Data System (ADS)

Kursunlu, Ahmed Nuri; Guler, Ersin; Sevgi, Fatih; Ozkalp, Birol

2013-09-01

In this study, the new Schiff base ligands derived from condensation of amine and 5-bromo-salicylaldehyde were characterized. All compounds, the Schiff bases and the metal complexes, were characterized by elemental analyzes, FT-IR, 1H NMR, 13C NMR and magnetic susceptibility measurements. The synthesized ligands, along with their metal (II) complexes, were screened for their in vitro antibacterial activity against four Gram-negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Salmonella enteritidis) and four Gram-positive (Streptococcus pyogones, Bacillus cereus, Staphylococcus aureus and Methicillin-resistant S. aureus) bacterial strains by using disc diffusion and broth microdilution techniques.

Chemical composition and antifungal activity of the essential oils of Schinus weinmannifolius collected in the spring and winter.

PubMed

Hernandes, Camila; Taleb-Contini, Silvia H; Bartolomeu, Ana Carolina D; Bertoni, Bianca W; França, Suzelei C; Pereira, Ana Maria S

2014-09-01

Reports on the chemical and pharmacological profile of the essential oil of Schinus weinmannifolius do not exist, although other Schinus species have been widely investigated for their biological activities. This work aimed to evaluate the chemical composition and antimicrobial activity of the essential oil of S. weinmannifolius collected in the spring and winter. The essential oils were extracted by hydrodistillation, analyzed by GC/MS and submitted to microdilution tests, to determine the minimum inhibitory concentration. The oils displayed different chemical composition and antimicrobial action. Bicyclogermacrene and limonene predominated in the oils extracted in the winter and spring, respectively, whereas only the latter oil exhibited antifungal activity.

Defining the Reference Condition for Wadeable Streams in the Sand Hills Subdivision of the Southeastern Plains Ecoregion, USA

NASA Astrophysics Data System (ADS)

Kosnicki, Ely; Sefick, Stephen A.; Paller, Michael H.; Jarrell, Miller S.; Prusha, Blair A.; Sterrett, Sean C.; Tuberville, Tracey D.; Feminella, Jack W.

2014-09-01

The Sand Hills subdivision of the Southeastern Plains ecoregion has been impacted by historical land uses over the past two centuries and, with the additive effects of contemporary land use, determining reference condition for streams in this region is a challenge. We identified reference condition based on the combined use of 3 independent selection methods. Method 1 involved use of a multivariate disturbance gradient derived from several stressors, method 2 was based on variation in channel morphology, and method 3 was based on passing 6 of 7 environmental criteria. Sites selected as reference from all 3 methods were considered primary reference, whereas those selected by 2 or 1 methods were considered secondary or tertiary reference, respectively. Sites not selected by any of the methods were considered non-reference. In addition, best professional judgment (BPJ) was used to exclude some sites from any reference class, and comparisons were made to examine the utility of BPJ. Non-metric multidimensional scaling indicated that use of BPJ may help designate non-reference sites when unidentified stressors are present. The macroinvertebrate community measures Ephemeroptera, Plecoptera, Trichoptera richness and North Carolina Biotic Index showed no differences between primary and secondary reference sites when BPJ was ignored. However, there was no significant difference among primary, secondary, and tertiary reference sites when BPJ was used. We underscore the importance of classifying reference conditions, especially in regions that have endured significant anthropogenic activity. We suggest that the use of secondary reference sites may enable construction of models that target a broader set of management interests.

Resampling methods in Microsoft Excel® for estimating reference intervals

PubMed Central

Theodorsson, Elvar

2015-01-01

Computer- intensive resampling/bootstrap methods are feasible when calculating reference intervals from non-Gaussian or small reference samples. Microsoft Excel® in version 2010 or later includes natural functions, which lend themselves well to this purpose including recommended interpolation procedures for estimating 2.5 and 97.5 percentiles.
The purpose of this paper is to introduce the reader to resampling estimation techniques in general and in using Microsoft Excel® 2010 for the purpose of estimating reference intervals in particular.
Parametric methods are preferable to resampling methods when the distributions of observations in the reference samples is Gaussian or can transformed to that distribution even when the number of reference samples is less than 120. Resampling methods are appropriate when the distribution of data from the reference samples is non-Gaussian and in case the number of reference individuals and corresponding samples are in the order of 40. At least 500-1000 random samples with replacement should be taken from the results of measurement of the reference samples. PMID:26527366

Resampling methods in Microsoft Excel® for estimating reference intervals.

PubMed

Theodorsson, Elvar

2015-01-01

Computer-intensive resampling/bootstrap methods are feasible when calculating reference intervals from non-Gaussian or small reference samples. Microsoft Excel® in version 2010 or later includes natural functions, which lend themselves well to this purpose including recommended interpolation procedures for estimating 2.5 and 97.5 percentiles. 
The purpose of this paper is to introduce the reader to resampling estimation techniques in general and in using Microsoft Excel® 2010 for the purpose of estimating reference intervals in particular.
 Parametric methods are preferable to resampling methods when the distributions of observations in the reference samples is Gaussian or can transformed to that distribution even when the number of reference samples is less than 120. Resampling methods are appropriate when the distribution of data from the reference samples is non-Gaussian and in case the number of reference individuals and corresponding samples are in the order of 40. At least 500-1000 random samples with replacement should be taken from the results of measurement of the reference samples.

46 CFR 160.176-4 - Incorporation by reference.

Code of Federal Regulations, 2014 CFR

2014-10-01

... and Elongation, Breaking of Woven Cloth; Grab Method, incorporation by reference approved for § 160.176-13. (ii) Method 5132, Strength of Cloth, Tearing; Falling-Pendulum Method, incorporation by reference approved for § 160.176-13. (iii) Method 5134, Strength of Cloth, Tearing; Tongue Method...

46 CFR 160.176-4 - Incorporation by reference.

Code of Federal Regulations, 2013 CFR

2013-10-01

... and Elongation, Breaking of Woven Cloth; Grab Method, incorporation by reference approved for § 160.176-13. (ii) Method 5132, Strength of Cloth, Tearing; Falling-Pendulum Method, incorporation by reference approved for § 160.176-13. (iii) Method 5134, Strength of Cloth, Tearing; Tongue Method...

US Fish and Wildlife Service biomonitoring operations manual, Appendices A--K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gianotto, D.F.; Rope, R.C.; Mondecar, M.

1993-04-01

Volume 2 contains Appendices and Summary Sheets for the following areas: A-Legislative Background and Key to Relevant Legislation, B- Biomonitoring Operations Workbook, C-Air Monitoring, D-Introduction to the Flora and Fauna for Biomonitoring, E-Decontamination Guidance Reference Field Methods, F-Documentation Guidance, Sample Handling, and Quality Assurance/Quality Control Standard Operating Procedures, G-Field Instrument Measurements Reference Field Methods, H-Ground Water Sampling Reference Field Methods, I-Sediment Sampling Reference Field Methods, J-Soil Sampling Reference Field Methods, K-Surface Water Reference Field Methods. Appendix B explains how to set up strategy to enter information on the ``disk workbook``. Appendix B is enhanced by DE97006389, an on-line workbook formore » users to be able to make revisions to their own biomonitoring data.« less

[Synthesis of antibiotic loaded polylactic acid nanoparticles and their antibacterial activity against Escherichia coli O157:H7 and methicillin-resistant Staphylococcus aureus].

PubMed

Herrera, Mónica Tatiana; Artunduaga, Jhon Jhamilton; Ortiz, Claudia Cristina; Torres, Rodrigo Gonzalo

2017-01-24

Polymeric nanoparticles are promising nanotechnology tools to fight pathogenic bacteria resistant to conventional antibiotics. To synthesize polylactic acid nanoparticles loaded with ofloxacin and vancomycin, and to determine their antibacterial activity against Escherichia coli O157:H7 and methicillin-resistant Staphylococcus aureus (MRSA). We synthesized ofloxacin or vancomycin loaded polylactic acid nanoparticles by the emulsification-solvent evaporation method, and characterized them by dynamic light scattering, laser Doppler electrophoresis and scanning electron microscopy. We evaluated in vitro antibacterial activity of ofloxacin- and vancomycin-loaded polylactic acid nanoparticles against E. coli O157:H7 and MRSA using the broth microdilution method. Ofloxacin- and vancomycin-loaded polylactic acid nanoparticles registered a positive surface charge density of 21 mV and an average size lower than 379 nm. In vitro minimum inhibitory concentration (MIC50) of ofloxacin-polylactic acid nanoparticles was 0,001 μg/ml against E. coli O157:H7, i.e., 40 times lower than the free ofloxacin (MIC50: 0.04 μg/ml), indicating enhanced antibacterial activity while the in vitro MIC50 of vancomycin-polylactic acid nanoparticles was 0,005 μg/ml against MRSA, i.e., 100 times lower than that of free vancomycin (MIC50: 0.5 μg/ml). Polylactic acid nanoparticles loaded with ofloxacin and vancomycin showed a higher antibacterial activity. Polymeric nanoparticles are a possible alternative for drug design against pathogenic bacterial strains of public health interest.

Sensitivity of Candida albicans to essential oils: are they an alternative to antifungal agents?

PubMed

Bona, E; Cantamessa, S; Pavan, M; Novello, G; Massa, N; Rocchetti, A; Berta, G; Gamalero, E

2016-12-01

Candida albicans is an important opportunistic pathogen, responsible for the majority of yeast infections in humans. Essential oils, extracted from aromatic plants, are well-known antimicrobial agents, characterized by a broad spectrum of activities, including antifungal properties. The aim of this work was to assess the sensitivity of 30 different vaginal isolated strains of C. albicans to 12 essential oils, compared to the three main used drugs (clotrimazole, fluconazole and itraconazole). Thirty strains of C. albicans were isolated from vaginal swab on CHROMagar ™ Candida. The agar disc diffusion method was employed to determine the sensitivity to the essential oils. The antifungal activity of the essential oils and antifungal drugs (clotrimazole, itraconazole and fluconazole) were investigated using a microdilution method. Transmission and scanning electron microscopy analyses were performed to get a deep inside on cellular damages. Mint, basil, lavender, tea tree oil, winter savory and oregano essential oils inhibited both the growth and the activity of C. albicans more efficiently than clotrimazole. Damages induced by essential oils at the cellular level were stronger than those caused by clotrimazole. Candida albicans is more sensitive to different essential oils compared to the main used drugs. Moreover, the essential oil affected mainly the cell wall and the membranes of the yeast. The results of this work support the research for new alternatives or complementary therapies against vaginal candidiasis. © 2016 The Society for Applied Microbiology.

Antibacterial and antioxidant activities in extracts of fully grown cladodes of 8 cultivars of cactus pear.

PubMed

Sánchez, E; Dávila-Aviña, J; Castillo, S L; Heredia, N; Vázquez-Alvarado, R; García, S

2014-04-01

The antimicrobial and antioxidant activities of some cultivars of the nopal cactus have not been determined. In this study, 8 cultivars of nopal cacti from Mexico were assayed for phenolic content, antioxidant activities, and antimicrobial activities against Campylobacter Jejuni, Vibrio cholera, and Clostridium Perfringens. Plant material was washed, dried, and macerated in methanol. Minimum bactericidal concentrations (MBCs) were determined using the broth microdilution method. Antioxidant activities were quantitatively determined using spectrophotometric methods. The MCBs of the nopal cacti ranged from 1.1 to 12.5 mg/mL for c. jejuni, 4.4 to 30 mg/mL for V. cholera, and 0.8 to 16 mg/mL for C. perfringens in the cultivars Cardon Blanco, Real de Catorce, and Jalpa, respectively. High quantities of total phenols and total flavonoids were found in the Jalpa cacti (3.80 mg of gallic acid equivalent GAE/g dry weight [DW] and 36.64 mg of quercetin equivalents [QE]/g DW, respectively). 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities (RSA) were correlated to bioactive compound contents. The Villanueva cacti had the highest %RSA at 42.31%, and the lowest activity was recorded in Copena V1 at 19.98%. In conclusion, we found that some of the 8 cactus pear cultivars studied may be used for their antioxidant compounds or antimicrobials to control or prevent the contamination of foods. © 2014 Institute of Food Technologists®

Antimicrobial synergism and cytotoxic properties of Citrus limon L., Piper nigrum L. and Melaleuca alternifolia (Maiden and Betche) Cheel essential oils.

PubMed

Nikolić, Miloš M; Jovanović, Katarina K; Marković, Tatjana Lj; Marković, Dejan Lj; Gligorijević, Nevenka N; Radulović, Siniša S; Kostić, Marina; Glamočlija, Jasmina M; Soković, Marina D

2017-11-01

The chemical composition, antimicrobial and synergistic effect, and cytotoxic activity of Citrus limon (lemon), Piper nigrum (green pepper) and Melaleuca alternifoila (tea tree) essential oils (EOs) were investigated. Chemical analyses of essential oils were tested by GC-FID and GC-MS spectroscopy. The antimicrobial activity assay was conducted using microdilution method against several oral bacteria and Candida spp. originating from the humans with oral disorders. The synergistic antimicrobial activity was evaluated using checkerboard method. The cytotoxicity evaluation of EOs was assessed using MTT test. Limonene (37.5%) and β-pinene (17.9%) were the major compounds in C. limon oil, β-pinene (34.4%), δ-3-carene (19.7%), limonene (18.7%) and α-pinene (10.4%) in P. nigrum oil and terpinen-4-ol (38.6%) and γ-terpinene (21.7%) in M. alternifolia oil. The broad-spectrum antimicrobial activity was achieved by tested three EOs, with C. limon oil being the strongest against bacteria and M. alternifolia oil strongest against fungi. The EOs demonstrated synergism; their combined application revealed an increase in antimicrobial activity. All tested essential oils showed lower cytotoxic activity in comparison with the positive control, and the obtained results confirmed a dose-dependent activity. The results of this study encourage use of tested EOs in development of a novel agent intended for prevention or therapy of corresponding oral disorders. © 2017 Royal Pharmaceutical Society.

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

Evaluation of metal concentration and antioxidant, antimicrobial, and anticancer potentials of two edible mushrooms Lactarius deliciosus and Macrolepiota procera.

PubMed

Kosanić, Marijana; Ranković, Branislav; Rančić, Aleksandar; Stanojković, Tatjana

2016-07-01

This study is designed for the determination of metal concentrations, antioxidant, antimicrobial, and anticancer potential of two edible mushrooms Lactarius deliciosus and Macrolepiota procera. Concentrations of nine metals are determined and all metals are present in the allowable concentrations in the tested mushrooms except Cd in M. procera. Antioxidant activity was evaluated by free radical scavenging and reducing power. M. procera extract had more potent free radical scavenging activity (IC 50 =311.40 μg/mL) than L. deliciosus extract. Moreover, the tested extracts had effective reducing power. The total content of phenol in the extracts was examined using Folin-Ciocalteu reagent and obtained values expressed as pyrocatechol equivalents. Further, the antimicrobial potential was determined with a microdilution method on 15 microorganisms. Among the tested species, extract of L. deliciosus showed a better antimicrobial activity with minimum inhibitory concentration values ranging from 2.5 mg/mL to 20 mg/mL. Finally, the cytotoxic activity was tested using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method on human epithelial carcinoma HeLa cells, human lung carcinoma A549 cells, and human colon carcinoma LS174 cells. Extract of both mushrooms expressed similar cytotoxic activity with IC 50 values ranging from 19.01 μg/mL to 80.27 μg/mL. Copyright © 2016. Published by Elsevier B.V.

Erythromycin and penicillin resistance mechanisms among viridans group streptococci isolated from blood cultures of adult patients with underlying diseases.

PubMed

Ergin, Alper; Eser, Özgen Köseoğlu; Hasçelik, Gülşen

2011-04-01

The aim of the study was to evaluate the species distribution, antimicrobial susceptibility and erythromycin-penicillin resistance mechanisms of viridans streptococci (VGS) isolates from blood cultures of adult patients with underlying diseases. Fifty VGS blood culture isolates were screened for their antibiotic susceptibilities against penicillin G, erythromycin and tetracycline by E-test. Clindamycin, cefotaxime, chloramphenicol, levofloxacin, linezolid and vancomycin susceptibility were performed by broth microdilution method. Erythromycin and penicillin resistance genotypes, ermB and mefA/E, pbp1a, pbp2b and pbp2x are amplified using PCR method. The clinical isolates included Streptococcus mitis (n. 19), S.oralis (n. 13), S.sanguinis, S.parasanguinis (n. 6, each), S.salivarius, S.vestibularis (n. 2, each), S.constellatus, S.sobrinus (n. 1, each). The percentage resistance against erythromycin and penicillin was 36% and 30%, respectively. The genotypic carriage rate of erythromycin resistance genes were: 56% ermB, 28% mefE, 8% ermB+mefE. Penicillin-resistant isolates carried pbp2b (33.3%) and pbp2x (20%) genes. Twenty-four VGS isolates were recovered from patients with cancer. S.mitis and S.oralis predominated among patients with cancer who had erythromycin and penicillin resistance isolates. The importance of classical antimicrobial agents like penicillin and erythromycin warrants the continuous surveillance of invasive VGS isolates and can guide better treatment options especially in patients with underlying diseases.

Photochemically synthesized heparin-based silver nanoparticles: an antimicrobial activity study

NASA Astrophysics Data System (ADS)

Rodriguez-Torres, Maria del Pilar; Acosta-Torres, Laura Susana; Díaz-Torres, Luis Armando

2017-08-01

The antimicrobial activity of silver nanoparticles has been extensively studied in the last years. Such nanoparticles constitute a potential and promising approach for the development of new antimicrobial systems especially due to the fact that several microorganisms are developing resistance to some already existing antimicrobial agents, therefore making antibacterial and antimicrobial studies on alternative materials necessary to overcome this issue. Silver nanoparticle concentration and size are determining factors on the antimicrobial activity of these nano systems. Heparin is a polysaccharide that belongs to the glycosaminoglycans (GAGs) family, molecules formed by a base disaccharide whose components are joined by a glycosidic linkage that is a repeating unit along their structure. It is highly sulfated making it a negatively charged material that is also widely used as an anticoagulant in Medicine because its biocompatibility besides it is also produced within the human body, specifically in the mast cells. Heparin alone possesses antimicrobial activity although it has not been studied very much in detail, it only has been demonstrated that it inhibits E. coli, P. aeruginosa, S. aureus and S. epidermidis, so taking this into account, this study is dedicated to assess UV photochemically-synthesized (λ=254 nm) heparin-based silver nanoparticles antimicrobial activity using the agar disk diffusion method complemented by the broth microdilution method to estimate de minimum inhibitory concentration (MIC), that is the lowest concentration at which an antimicrobial will inhibit visible growth of a microorganism. The strains used were the ones aforementioned to assess the antimicrobial activity degree these heparinbased nanoparticles exhibit.

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.

Significant antibacterial activity and synergistic effects of camel lactoferrin with antibiotics against methicillin-resistant Staphylococcus aureus (MRSA).

PubMed

Redwan, Elrashdy M; El-Baky, Nawal Abd; Al-Hejin, Ahmed M; Baeshen, Mohammed N; Almehdar, Hussein A; Elsaway, Abdulrahman; Gomaa, Abu-Bakr M; Al-Masaudi, Saad Berki; Al-Fassi, Fahad A; AbuZeid, Isam Eldin; Uversky, Vladimir N

2016-01-01

Methicillin-resistant Staphylococcus aureus (MRSA) causes major healthcare problems in many countries, as it is present as several hospital- and community-associated strains. Hospital-associated MRSA is one of the most prevalent nosocomial pathogens throughout the world and infections caused by community-acquired MRSA are rising. This emphasizes the need for new and efficient anti-MRSA agents. We evaluated the antibacterial effects of camel lactoferrin (cLf) and human lactoferrin (hLf) alone and in combination with several antibiotics against MRSA. Antimicrobials were tested against MRSA and an S. aureus control strain by the agar disc diffusion method. The minimum inhibitory concentration (MIC) was determined for antimicrobials by the broth microdilution method. Synergy between cLf or hLf and antibiotics was examined by checkerboard and time-kill assays. The agar disc diffusion assay showed that MRSA growth was inhibited by cLf at 0.25-3 mg/ml and hLf at 1-3 mg/ml. cLf demonstrated 3 times higher inhibitory activity against MRSA than hLf in terms of MIC values (250 vs. 750 μg/ml, respectively). Biotinylated cLf was recognized by two membrane proteins of MRSA, 66-67 KDa. Combinations of cLf or hLf and oxacillin or vancomycin at sub-MIC levels enhanced in vitro antibacterial activity against MRSA compared with each agent alone. Copyright © 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Immortelle (Xeranthemum annuum L.) as a natural source of biologically active substances

PubMed Central

Stankovic, Milan S.; Radojevic, Ivana D.; Stefanovic, Olgica D.; Topuzovic, Marina D.; Comic, Ljiljana R.; Brankovic, Snežana R.

2011-01-01

Antioxidant and antimicrobial effects, total phenolic content and flavonoid concentrations of methanolic, acetone and ethyl acetate extracts from Xeranthemum annuum L. were investigated in this study. The total phenolic content was determined using Folin-Ciocalteu reagent and ranged between 101.33 to 159.48 mg GA/g. The concentration of flavonoids in various X. annuum extracts was determined using spectrophotometric method with aluminum chloride and the results varied from 22.25 to 62.42 mg RU/g. Antioxidant activity was monitored spectrophotometrically using DPPH reagent and expressed in terms of IC50 (µg/ml), and it ranged from 59.25 to 956.81 µg/ml. The highest phenolic content and capacity to neutralize DPPH radicals were found in the acetone extract. In vitro antimicrobial activity was determined by microdilution method. Minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) have been determined. Testing was conducted against 24 microorganisms, including 15 strains of bacteria (standard and clinical strains) and 9 species of fungi. Statistically significant difference in activity between the extracts of X. annuum L. was observed and the acetone extract was found most active. The activity of acetone extract was in accordance with total phenol content and flavonoid concentration measured in this extract. The tested extracts showed significant antibacterial activity against G+ bacteria and weak to moderate activity against other microorganisms. Based on the obtained results, X. annuum can be considered as a rich natural source of polyphenolic compounds with very good antioxidant and antimicrobial activity. PMID:27857677

Anti-Propionibacterium acnes assay-guided purification of brazilin and preparation of brazilin rich extract from Caesalpinia sappan heartwood.

PubMed

Nirmal, Nilesh Prakash; Panichayupakaranant, Pharkphoom

2014-09-01

Caesalpinia sappan L. (Leguminosae or Fabaceae) heartwood has been used as a coloring agent, with antibacterial activity in food, beverages, cosmetics, and garments. To purify brazilin from C. sappan heartwood and use it as a standard marker for the preparation and standardization of an active constituent-rich extract. Crude ethanol extracts of C. sappan heartwood (CSE) were fractionated to isolate brazilin by an anti-P. acnes assay-guided isolation. Quantitative analysis was performed by HPLC. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined by the broth microdilution method. Brazilin isolated from CSE possessed antibacterial activity against P. acnes with MIC and MBC values of 15.6 and 31.2 µg/mL, respectively. Brazilin was, therefore, used as a standard marker for standardization and preparation of a brazilin rich extract (BRE). BRE was prepared from CSE using a simple one-step purification using a macroporous resin column eluted with 35% v/v ethanol. This method increased the brazilin content in the BRE up to 39.9% w/w. The antibacterial activity of the standardized BRE against acne involved bacteria was higher than for the CSE but lower than brazilin. However, for industrial applications, a large-scale one-step preparation of BRE has more advantages than the use of pure brazilin in terms of convenience and a low-cost production process. Therefore, BRE is considered as a potential coloring agent with antibacterial activity which is used for pharmaceutical, cosmetic, and nutraceutical applications.

Antimicrobial susceptibility of Brachyspira hyodysenteriae isolated from 21 Polish farms.

PubMed

Zmudzki, J; Szczotka, A; Nowak, A; Strzelecka, H; Grzesiak, A; Pejsak, Z

2012-01-01

Swine dysentery (SD) is a common disease among pigs worldwide, which contributes to major production losses. Antimicrobial susceptibility testing of B. hyodysenteriae, the etiological agent of SD, is mainly performed by the agar dilution method. This method has certain limitations due to difficulties in interpretation of results. The aim of this study was the analysis of antimicrobial susceptibility of Brachyspira hyodysenteriae (B. hyodysenteriae) Polish field isolates by broth microdilution procedure. The study was performed on 21 isolates of B. hyodysenteriae, collected between January 2006 to December 2010 from cases of swine dysentery. VetMIC Brachyspira panels with antimicrobial agents (tiamulin, valnemulin, doxycycline, lincomycin, tylosin and ampicillin) were used for susceptibility testing of B. hyodysenteriae. The minimal inhibitory concentration (MIC) was determined by the broth dilution procedure. The lowest antimicrobial activity was demonstrated for tylosin and lincomycin, with inhibition of bacterial growth using concentrations > 128 microg/ml and 32 microg/ml, respectively. In the case of doxycycline, the MIC values were < or = 2.0 microg/ml. No decreased susceptibility to tiamulin was found among the Polish isolates and MIC values for this antibiotic did not exceed 1.0 microg/ml. The results of the present study confirmed that Polish B. hyodysenteriae isolates were susceptible to the main antibiotics (tiamulin and valnemulin) used in treatment of swine dysentery. Further studies are necessary to evaluate a possible slow decrease in susceptibility to tiamulin and valnemulin of B. hyodysenteriae strains in Poland.

Antifungal and antioxidant activities of Coleonema album and C. pulchellum against skin diseases.

PubMed

Fajinmi, Olufunke O; Grúz, Jiří; Tarkowski, Petr; Kulkarni, Manoj G; Finnie, Jeffrey F; Van Staden, Johannes

2017-12-01

Coleonema album (Thunb) Bart. & H. L. Wendl (Rutaceae) has been used in the formulation of skincare products, and the Khoisan people rub it on their skin to add luster. Coleonema pulchellum I. Williams has received less attention in the South African traditional medicine. This study investigates the antifungal and antioxidant activities of C. album and C. pulchellum essential oil (EO) and leaf extracts; and analyzes the chemical components of their EOs. Antifungal activity of leaf extracts was determined using the microdilution method with griseofulvin and ketoconazole as controls. Antifungal capacity of EO was investigated using the 'Volatile release plate method'. Trichophyton rubrum (ATCC 28188) and T. mentagrophytes (ATCC 9533) mycelia (0.3 cm diameter) were placed on fresh yeast malt agar in Petri dishes with filter paper (impregnated with 20 μL of EO) on the lid for direct exposure to EO volatiles while plates without EO were used as controls. The incubation time was seven days. Antioxidant activities of the leaf extracts were determined. Methanol leaf extract of C. pulchellum inhibited the growth of three fungi tested with MIC values of 195, 391 and 49 μg/mL for Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum gypseum, respectively. Terpenes formed the major components of the EO. The EO from both plants inhibited the growth of T. rubrum in vitro. This study revealed the therapeutic value of C. pulchellum. Coleonema album and C. pulchellum should be considered as potential plants for skin ointment from natural origin.

Phytocompounds and modulatory effects of Anacardium microcarpum (cajui) on antibiotic drugs used in clinical infections

PubMed Central

Barbosa-Filho, Valter M; Waczuk, Emily P; Leite, Nadghia F; Menezes, Irwin RA; da Costa, José GM; Lacerda, Sírleis R; Adedara, Isaac A; Coutinho, Henrique Douglas Melo; Posser, Thais; Kamdem, Jean P

2015-01-01

Background The challenge of antibiotic resistance and the emergence of new infections have generated considerable interest in the exploration of natural products from plant origins as combination therapy. In this context, crude ethanolic extract (CEE), ethyl acetate fraction (EAF), and methanolic fraction (MF) from Anacardium microcarpum were tested alone or in combination with antibiotics (amikacin, gentamicin, ciprofloxacin, and imipenem) against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Methods Antibiotic resistance-modifying activity was performed using the microdilution method by determining the minimal inhibitory concentration (MIC). In addition, phytochemical prospecting analyses of tested samples were carried out. Results Our results indicated that all the extracts showed low antibacterial activity against multidrug-resistant strains (MIC =512 μg/mL). However, addition of CEE, EAF, and MF to the growth medium at the subinhibitory concentration (MIC/8=64 μg/mL) significantly modulated amikacin- and gentamicin-resistant E. coli 06. CEE and EAF also demonstrated a significant (P<0.001) synergism with imipenem against S. aureus. In contrast, MF antagonized the antibacterial effect of ciprofloxacin and gentamicin against P. aeruginosa 03 and S. aureus 10, respectively. Qualitative phytochemical analysis of the extracts revealed the presence of secondary metabolites including phenols, flavonoids, xanthones, chalcones, and tannin pyrogallates. Conclusion Taken together, our results suggest that A. microcarpum is a natural resource with resistance-modifying antibacterial activity that needs to be further investigated to overcome the present resistant-infection problem. PMID:26604695

Identification of Group G Streptococcal Isolates from Companion Animals in Japan and Their Antimicrobial Resistance Patterns.

PubMed

Tsuyuki, Yuzo; Kurita, Goro; Murata, Yoshiteru; Goto, Mieko; Takahashi, Takashi

2017-07-24

In this study, we conducted a species-level identification of group G streptococcal (GGS) isolates from companion animals in Japan and analyzed antimicrobial resistance (AMR) patterns. Strains were isolated from sterile and non-sterile specimens collected from 72 animals with clinical signs or symptoms in April-May, 2015. We identified the strain by 16S rRNA sequencing, mass spectrometry (MS), and an automated method based on their biochemical properties. Antimicrobial susceptibility was determined using the broth microdilution method and E-test. AMR determinants (erm(A), erm(B), mef(A), tet(M), tet(O), tet(K), tet(L), and tet(S)) in corresponding resistant isolates were amplified by PCR. The 16S rRNA sequencing identified the GGS species as Streptococcus canis (n = 68), Streptococcus dysgalactiae subsp. equisimilis (n = 3), and S. dysgalactiae subsp. dysgalactiae (n = 1). However, there were discrepancies between the sequencing data and both the MS and automated identification data. MS and the automated biochemical technique identified 18 and 37 of the 68 sequencing-identified S. canis strains, respectively. The AMR rates were 20.8% for tetracycline and 5.6% for clarithromycin, with minimum inhibitory concentrations (MIC) 50 -MIC 90 of 2-64 and ≤ 0.12-0.25μg/mL, respectively. AMR genotyping showed single or combined genotypes: erm(B) or tet(M)-tet(O)-tet(S). Our findings show the unique characteristics of GGS isolates from companion animals in Japan in terms of species-level identification and AMR patterns.

Some Nigerian Anti-Tuberculosis Ethnomedicines: A Preliminary Efficacy Assessment

PubMed Central

Ibekwe, Nneka N.; Nvau, John B.; Oladosu, Peters O.; Usman, Auwal M.; Ibrahim, Kolo; Boshoff, Helena I.; Dowd, Cynthia S.; Orisadipe, Abayomi T.; Aiyelaagbe, Olapeju; Adesomoju, Akinbo A.; Barry, Clifton E.; Okogun, Joseph I.

2014-01-01

Ethnopharmacological significance Nigerian herbalists possess indigenous ethnomedicinal recipes for the management of tuberculosis and related ailments. Aim of the study To carry out a collaborative preliminary modern scientific evaluation of the efficacy of some Nigerian ethnomedicines used by traditional medicine practitioners (TMPs) in the management of tuberculosis and related ailments Materials and methods Ethnomedicinal recipes (ETMs) were collected from TMPs from locations in various ecological zones of Nigeria under a collaborative understanding. The aqueous methanolic extracts of the ETMs were screened against Mycobacterium bovis, BCG and Mycobacterium tuberculosis (M. tb.) strain H37Rv using the broth microdilution method. Results Extracts of ETMs screened against BCG showed 69% activity against the organism. The activities varied from weak, ≤ 2500μg /mL to highly active, 33μg /mL 64% of the extracts were active against M. tb. The activities of the extracts against M.tb. varied from weak, ≤ 2500μg /mL to highly active, 128μg/mL. There was 77% agreement in results obtained using BCG or M. tb. as test organisms Conclusion The results show clear evidence for the efficacy of the majority of indigenous Nigerian herbal recipes in the ethnomedicinal management of tuberculosis and related ailments. BCG may be effectively used, to a great extent, as the organism for screening for potential anti-M. tb. agents. A set of prioritization criteria for the selection of plants for initial further studies for the purpose of antituberculsis drug discovery research is proposed. PMID:24911338

A synergistic effect of artocarpanone from Artocarpus heterophyllus L. (Moraceae) on the antibacterial activity of selected antibiotics and cell membrane permeability.

PubMed

Septama, Abdi Wira; Xiao, Jianbo; Panichayupakaranant, Pharkphoom

2017-01-01

Artocarpanone isolated from Artocarpus heterophyllus L. (Moraceae) exhibits antibacterial activity. The present study investigated synergistic activity between artocarpanone and tetracycline, ampicillin, and norfloxacin, respectively, against methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa , and Escherichia coli . A broth microdilution method was used for evaluating antibacterial susceptibility. Synergistic effects were identified using a checkerboard method, and a bacterial cell membrane disruption was investigated by assay of released 260 nm absorbing materials following bacteriolysis. Artocarpanone exhibited weak antibacterial activity against MRSA and P. aeruginosa with minimum inhibitory concentrations values of 125 and 500 μg/mL, respectively. However, the compound showed strong antibacterial activity against E. coli (7.8 μg/mL). The interaction between artocarpanone and all tested antibiotics revealed indifference and additive effects against P. aeruginosa and E. coli (fractional inhibitory concentration index [FICI] values of 0.75-1.25). The combination of artocarpanone (31.2 μg/mL) and norfloxacin (3.9 μg/mL) resulted in synergistic antibacterial activity against MRSA, with an FICI of 0.28, while the interaction between artocarpanone and tetracycline, and ampicillin showed an additive effect, with an FICI value of 0.5. A time-kill assay also indicated that artocarpanone had a synergistic effect on the antibacterial activity of norfloxacin. In addition, the combination of artocarpanone and norfloxacin altered the membrane permeability of MRSA. These findings suggest that artocarpanone may be used to enhance the antibacterial activity of norfloxacin against MRSA.

Anti-Streptococcal activity of Brazilian Amazon Rain Forest plant extracts presents potential for preventive strategies against dental caries

PubMed Central

da SILVA, Juliana Paola Corrêa; de CASTILHO, Adriana Lígia; SARACENI, Cíntia Helena Couri; DÍAZ, Ingrit Elida Collantes; PACIÊNCIA, Mateus Luís Barradas; SUFFREDINI, Ivana Barbosa

2014-01-01

Caries is a global public health problem, whose control requires the introduction of low-cost treatments, such as strong prevention strategies, minimally invasive techniques and chemical prevention agents. Nature plays an important role as a source of new antibacterial substances that can be used in the prevention of caries, and Brazil is the richest country in terms of biodiversity. Objective In this study, the disk diffusion method (DDM) was used to screen over 2,000 Brazilian Amazon plant extracts against Streptococcus mutans. Material and Methods Seventeen active plant extracts were identified and fractionated. Extracts and their fractions, obtained by liquid-liquid partition, were tested in the DDM assay and in the microdilution broth assay (MBA) to determine their minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs). The extracts were also subjected to antioxidant analysis by thin layer chromatography. Results EB271, obtained from Casearia spruceana, showed significant activity against the bacterium in the DDM assay (20.67±0.52 mm), as did EB1129, obtained from Psychotria sp. (Rubiaceae) (15.04±2.29 mm). EB1493, obtained from Ipomoea alba, was the only extract to show strong activity against Streptococcus mutans (0.08 mg/mL

Biological Activities and Composition of Ferulago carduchorum Essential Oil

PubMed Central

Golfakhrabadi, Fereshteh; Khanavi, Mahnaz; Ostad, Seyed Nasser; Saeidnia, Soodabeh; Vatandoost, Hassan; Abai, Mohammad Reza; Hafizi, Mitra; Yousefbeyk, Fatemeh; Rad, Yaghoob Razzaghi; Baghenegadian, Ameneh; Ardekani, Mohammad Reza Shams

2015-01-01

Background: Ferulago carduchorum Boiss and Hausskn belongs to the Apiaceae family. This plant grows in west part of Iran that local people added it to dairy and oil ghee to delay expiration date and give them a pleasant taste. The aim of this study was to investigate the antioxidant, antimicrobial, acetyl cholinesterase inhibition, cytotoxic, larvicidal activities and composition of essential oil of F. carduchorum. Methods: Acetyl cholinesterase (AChE) inhibitory, larvicidal activities and chemical composition of essential oil of F. carduchorum were investigated. Besides, antioxidant, antimicrobial and cytotoxic activities of essential oil were tested using DPPH, microdilution method and MTT assay, respectively. Results: The major components of essential oil were (z)-β-ocimene (43.3%), α-pinene (18.23%) and bornyl acetate (3.98%). Among 43 identified components, monoterpenes were the most compounds (84.63%). The essential oil had noticeable efficiency against Candida albicans (MIC= 2340 μg ml−1) and it was effective against Anopheles stephensi with LC50 and LC90 values of 12.78 and 47.43 ppm, respectively. The essential oil could inhibit AChE (IC50= 23.6 μl ml−1). The essential oil showed high cytotoxicity on T47D, HEP-G2 and HT-29 cell lines (IC50< 2 μg ml−1). Conclusion: The essential oil of F. carduchorum collected from west of Iran had anti-Candida, larvicidal and cytotoxicity effects and should be further investigated in others in vitro and in vivo experimental models. PMID:26114148

Relevance of various animal models of human infections to establish therapeutic equivalence of a generic product of piperacillin/tazobactam.

PubMed

Agudelo, Maria; Rodriguez, Carlos A; Zuluaga, Andres F; Vesga, Omar

2015-02-01

After demonstrating with diverse intravenous antibacterials that pharmaceutical equivalence (PE) does not predict therapeutic equivalence, we tested a single generic product of piperacillin/tazobactam (TZP) in terms of PE, pharmacokinetics and in vitro/vivo pharmacodynamics against several pathogens in neutropenic mouse thigh, lung and brain infection models. A generic product was compared head-to-head against the innovator. PE was evaluated by microbiological assay. Single-dose serum pharmacokinetics were determined in infected mice, and the MIC/MBC were determined by broth microdilution. In vivo experiments were done in a blind fashion. Reproducibility was tested on different days using different infecting organisms and animal models. Neutropenic MPF mice were infected in the thighs with Staphylococcus aureus GRP-0057 or Pseudomonas aeruginosa PA01 and in the lungs or brain with Klebsiella pneumoniae ATCC 10031. Treatment started 2h (thigh and brain) or 14 h (lung) after infection and was administered every 3h over 24h (thigh and lung) or 48 h (brain). Both products exhibited the same MIC/MBC against each strain, yielded overlaid curves in the microbiological assay (P>0.21) and were bioequivalent (IC90 83-117% for AUC test/reference ratio). In vivo, the generic product and innovator were again undistinguishable in all models and against the different bacterial pathogens involved. The relevance of these neutropenic murine models of infection was established by demonstrating their accuracy to predict the biological response following simultaneous treatment with a generic product or the innovator of TZP. Therapeutic equivalence of the generic product was proved in every model and against different pathogens. Copyright © 2014 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

In vitro activity of Aloe vera inner gel against Helicobacter pylori strains.

PubMed

Cellini, L; Di Bartolomeo, S; Di Campli, E; Genovese, S; Locatelli, M; Di Giulio, M

2014-07-01

Aloe barbadensis Miller (Aloe vera) is a herbal remedy widely used for a variety of illnesses; A. vera leaf extracts have been promoted for detoxification, cure constipation, help flush out toxins and wastes from the body, promote digestion and are used in the treatment of peptic ulcer for cytoprotective action. The aim of this study was to evaluate the antibacterial activity of A. vera inner gel against both susceptible and resistant Helicobacter pylori strains isolated in Abruzzo region, Italy. The inner gel of leaves of a 5-year-old plant of A. vera was extracted, homogenized and tested from 800 to 1.56 mg ml(-1) against 14 clinical strains and one reference strain of H. pylori using the broth microdilution methodology. Furthermore, the sample of A. vera was investigated for the chemical fingerprint of anthraquinones. The inhibitory concentrations of A. vera inner gel were similar to the bactericidal ones, with values ranging from 6.25 to 800 mg ml(-1) . Fifty per cent of the detected strains, independently of their susceptibility profile, were inhibited in their growth at 100 mg ml(-1) . Aloe vera inner gel expresses antibacterial properties against H. pylori and, therefore, in combination with antibiotics, could represent a novel strategy for the treatment of the infection of H. pylori, especially in cases of multiresistance. The study demonstrates that the Aloe vera inner gel expresses antibacterial properties against both susceptible and resistant Helicobacter pylori strains. These findings may impact on the antimicrobial resistance phenomenon of H. pylori, proposing the A. vera inner gel as a novel effective natural agent for combination with antibiotics for the treatment of H. pylori gastric infection. © 2014 The Society for Applied Microbiology.

In vitro susceptibility of Sporothrix brasiliensis: Comparison of yeast and mycelial phases.

PubMed

Sanchotene, Karine Ortiz; Brandolt, Tchana Martinez; Klafke, Gabriel Baracy; Poester, Vanice Rodrigues; Xavier, Melissa Orzechowski

2017-11-01

Sporothrix brasiliensis has emerged as an important cause of sporotrichosis, particularly associated with feline and zoonotic cases. Owing to the paucity of data on antifungal activity against this species, the present study aimed to evaluate the in vitro susceptibility of clinical isolates of S. brasiliensis in the mycelial and yeast phases to itraconazole (ITZ), terbinafine (TRB), and amphotericin B (AMB). Thirty-five isolates from an outbreak of feline sporotrichosis in Southern Brazil were used. All of them were assessed in the yeast and filamentous phases using the broth microdilution technique in accordance with the respective reference protocols M27-A3 and M38-A2 of the Clinical and Laboratory Standards Institute (CLSI). In our study, TRB was the most active antifungal against both the filamentous and yeast phases, showing GM of the MIC of 0.343 μg/ml and 0.127 μg/ml, respectively. In the yeast phase, the GM of the MIC for TRB was significantly lower than that for both ITZ (P = .009) and AMB (P < .001). However, in the filamentous phase, the GM of the MIC for TRB was significantly lower than that of AMB (P < .001), but not different from that of ITZ (P = .091). AMB was the antifungal with the highest GM of the MIC for both phases (1.486 μg/ml for the filamentous phase and 0.660 μg/ml for the yeast). Our results may contribute to a better understanding of antifungal susceptibility profiles of clinical isolates of S. brasiliensis in the mycelial and yeast phases in further studies. © The Author 2017. 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.

Biosynthesis of Ag nanoparticles using Salicornia bigelovii and its antibacterial activity.

PubMed

Khatami, Mehrdad; Noor, Fatemeh Golshan; Ahmadi, Saeed; Aflatoonian, Mohammadreza

2018-04-01

In recent years, the field of nanotechnology has become the most active area of research in modern material science. While many chemical- as well as physical methods are also used, green synthesis of nanoparticles is becoming the most evolved method of synthesis. In this study, we synthesized silver nanoparticles from the seed extract of Salicornia bigelovii. This experimental study was conducted from December 2017 to January 2018 in Kerman University of Medical Sciences, Kerman, Iran. The effects of two concentrations (1m M and 4mM) on the synthesis of nanoparticles were studied. Characterizations were done using different methods including ultraviolet (UV) visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Antibacterial activity of Ag nanoparticles against Staphylococcus aureus and Escherichia coli was studied using microdilution method. The data were analyzed using Probit test in SPSS (Version 20, USA). Formation of the AgNPs was confirmed by surface plasmon spectra using UV-Vis spectrophotometer and absorbance peaks at 434 nm. The FTIR spectra showed the possible role of the functional group like carbonyl groups in reduction of silver ions to silver nanoparticles. The XRD analysis showed that the synthesized silver nanoparticles are of face-centered cubic structure. The TEM showed the formation of silver nanoparticles ranging in diameter from 1 to 50 nm. The minimal inhibitory concentration and minimal bactericidal concentration of AgNPs were determined for both S. aureus and E. coli 6.25 and 12.5 μg/mL, respectively. An environmentally friendly approach is more affordable than chemical methods. Physicochemical approaches can be harmful to the environment and to human health. Thus, the green synthesis methods are simple, less expensive, and can cut consumption of energy; they can be used for synthesis of fixed nanoparticles with preferred shape and size, without the use of toxic chemical agents.

Chemical composition and antibacterial activity of oils from Chrysicthys nigrodigitatus and Hepsetus odoe, two freshwater fishes from Yabassi, Cameroon.

PubMed

Simplice, Mouokeu Raymond; Macaire, Womeni Hilaire; Hervé, Njike Ngamga Fabrice; Fabrice, Tonfack Djikeng; Justin, Djopnang DJimbie; François, Tchoumbougnang; Jules-Roger, Kuiate

2018-03-12

Oils of fish origin are a very rich source of Omega - 3 and Omega - 6 fatty acids. They have been suggested to provide numerous health benefits for humans involving antimicrobial properties. Chrysichthys nigrodigitatus and Hepsetus odoe are two fishes well known in Cameroon. The chemical composition and the antibacterial activity of these fishes derived oils are unknown. The study was designed to valorise C. nigrodigitatus and H.s odoe oils activity against food poisoning bacteria. Oils were extracted by pressing and maceration methods. Their quality was assessed by analysing quality indexes including peroxides, acid, iodine, anisidine and thiobarbituric acid values. Chemical analysis was established by gas chromatography coupled to flame ionization detector. Antibacterial activity was evaluated by broth microdilution method. C. nigrodigitatus oil obtained by maceration exhibited highest acid (7.33 ± 0.00 mg KOH/g), anisidine (34.5 ± 1.84) and thiobarbituric acid (7.50 ± 0.30 μmol MDA/Kg) values compared to that obtained by pressing method (9.13 ± 0.64 and 6.72 ± 0.34 μmol MDA/Kg) respectively. H. odoe oil obtained by pressing method showed highest peroxide value (6.22 ± 1.31 meq O 2 /kg). Oil chemical analysis revealed long chain polyunsaturated fatty acids of the ω-3 family: linolenic acid (C18:3); eicosapentaenoic acid (C20:5) and docosahexaenoic acid (C22:6) and ω-6 family; arachidonic acid (C20:4). In addition, C. nigrodigitatus oil obtained by pressing and maceration methods showed Minimum Inhibitory Concentrations (MIC) values ranging from 32 to 64 mg/ml. H. odoe oil obtained by pressing method revealed MIC values ranging between 8 and 64 mg/ml. C. nigrodigitatus and H. odoe oils have activity against food poisoning bacteria, due to their chemical composition.

[Study on the experimental application of floating-reference method to noninvasive blood glucose sensing].

PubMed

Yu, Hui; Qi, Dan; Li, Heng-da; Xu, Ke-xin; Yuan, Wei-jie

2012-03-01

Weak signal, low instrument signal-to-noise ratio, continuous variation of human physiological environment and the interferences from other components in blood make it difficult to extract the blood glucose information from near infrared spectrum in noninvasive blood glucose measurement. The floating-reference method, which analyses the effect of glucose concentration variation on absorption coefficient and scattering coefficient, gets spectrum at the reference point and the measurement point where the light intensity variations from absorption and scattering are counteractive and biggest respectively. By using the spectrum from reference point as reference, floating-reference method can reduce the interferences from variation of physiological environment and experiment circumstance. In the present paper, the effectiveness of floating-reference method working on improving prediction precision and stability was assessed through application experiments. The comparison was made between models whose data were processed with and without floating-reference method. The results showed that the root mean square error of prediction (RMSEP) decreased by 34.7% maximally. The floating-reference method could reduce the influences of changes of samples' state, instrument noises and drift, and improve the models' prediction precision and stability effectively.

Impact of Homologous Resistance Mutations from Pathogenic Yeast on Saccharomyces cerevisiae Lanosterol 14α-Demethylase.

PubMed

Sagatova, Alia A; Keniya, Mikhail V; Tyndall, Joel D A; Monk, Brian C

2018-03-01

Fungal infections frequently affect immunodeficient individuals and are estimated to kill 1.35 million people per annum. Azole antifungals target the membrane-bound cytochrome P450 monooxygenase lanosterol 14α-demethylase (CYP51; Erg11p). Mutations in CYP51 can render the widely used triazole drugs less effective. The Candida albicans CYP51 mutation G464S and the double mutation Y132F G464S (Y140F and G464S by Saccharomyces cerevisiae numbering) as well as the CYP51A G54E/R/W mutations of Aspergillus fumigatus (G73E/R/W by S. cerevisiae numbering) have been reproduced in a recombinant C-terminal hexahistidine-tagged version of S. cerevisiae CYP51 (ScErg11p6×His). Phenotypes and X-ray crystal structures were determined for the mutant enzymes. Liquid microdilution assays showed that the G464S mutation in ScErg11p6×His conferred no difference in the susceptibility of yeast to triazole drugs but in combination with the Y140F mutation gave a 4-fold reduction in susceptibility to the short-tailed triazole fluconazole. The ScErg11p6×His Y140F G464S mutant was unstable during purification and was not crystallized. The ScErg11p6×His G73E/R/W mutations conferred increased susceptibly to all triazoles tested in liquid microdilution assays. High-resolution X-ray crystal structures reveal two different conformations of the ligand itraconazole, including a previously unseen conformation, as well as interactions between the tail of this triazole and the E/W73 residue. This study shows that S. cerevisiae CYP51 adequately represents some but not all mutations in CYP51s of pathogenic fungi. Insight into the molecular mechanisms of resistance mutations in CYP51 will assist the development of inhibitors that will overcome antifungal resistance. Copyright © 2018 American Society for Microbiology.

40 CFR Table E-1 to Subpart E of... - Summary of Test Requirements for Reference and Class I Equivalent Methods for PM2.5 and PM10-2.5

Code of Federal Regulations, 2010 CFR

2010-07-01

... Reference and Class I Equivalent Methods for PM2.5 and PM10-2.5 E Table E-1 to Subpart E of Part 53... MONITORING REFERENCE AND EQUIVALENT METHODS Procedures for Testing Physical (Design) and Performance Characteristics of Reference Methods and Class I and Class II Equivalent Methods for PM2.5 or PM10â2.5 Pt. 53...

Direct-to-digital holography reduction of reference hologram noise and fourier space smearing

DOEpatents

Voelkl, Edgar

2006-06-27

Systems and methods are described for reduction of reference hologram noise and reduction of Fourier space smearing, especially in the context of direct-to-digital holography (off-axis interferometry). A method of reducing reference hologram noise includes: recording a plurality of reference holograms; processing the plurality of reference holograms into a corresponding plurality of reference image waves; and transforming the corresponding plurality of reference image waves into a reduced noise reference image wave. A method of reducing smearing in Fourier space includes: recording a plurality of reference holograms; processing the plurality of reference holograms into a corresponding plurality of reference complex image waves; transforming the corresponding plurality of reference image waves into a reduced noise reference complex image wave; recording a hologram of an object; processing the hologram of the object into an object complex image wave; and dividing the complex image wave of the object by the reduced noise reference complex image wave to obtain a reduced smearing object complex image wave.

[The validation of the effect of correcting spectral background changes based on floating reference method by simulation].

PubMed

Wang, Zhu-lou; Zhang, Wan-jie; Li, Chen-xi; Chen, Wen-liang; Xu, Ke-xin

2015-02-01

There are some challenges in near-infrared non-invasive blood glucose measurement, such as the low signal to noise ratio of instrument, the unstable measurement conditions, the unpredictable and irregular changes of the measured object, and etc. Therefore, it is difficult to extract the information of blood glucose concentrations from the complicated signals accurately. Reference measurement method is usually considered to be used to eliminate the effect of background changes. But there is no reference substance which changes synchronously with the anylate. After many years of research, our research group has proposed the floating reference method, which is succeeded in eliminating the spectral effects induced by the instrument drifts and the measured object's background variations. But our studies indicate that the reference-point will changes following the changing of measurement location and wavelength. Therefore, the effects of floating reference method should be verified comprehensively. In this paper, keeping things simple, the Monte Carlo simulation employing Intralipid solution with the concentrations of 5% and 10% is performed to verify the effect of floating reference method used into eliminating the consequences of the light source drift. And the light source drift is introduced through varying the incident photon number. The effectiveness of the floating reference method with corresponding reference-points at different wavelengths in eliminating the variations of the light source drift is estimated. The comparison of the prediction abilities of the calibration models with and without using this method shows that the RMSEPs of the method are decreased by about 98.57% (5%Intralipid)and 99.36% (10% Intralipid)for different Intralipid. The results indicate that the floating reference method has obvious effect in eliminating the background changes.

Intra prediction using face continuity in 360-degree video coding

NASA Astrophysics Data System (ADS)

Hanhart, Philippe; He, Yuwen; Ye, Yan

2017-09-01

This paper presents a new reference sample derivation method for intra prediction in 360-degree video coding. Unlike the conventional reference sample derivation method for 2D video coding, which uses the samples located directly above and on the left of the current block, the proposed method considers the spherical nature of 360-degree video when deriving reference samples located outside the current face to which the block belongs, and derives reference samples that are geometric neighbors on the sphere. The proposed reference sample derivation method was implemented in the Joint Exploration Model 3.0 (JEM-3.0) for the cubemap projection format. Simulation results for the all intra configuration show that, when compared with the conventional reference sample derivation method, the proposed method gives, on average, luma BD-rate reduction of 0.3% in terms of the weighted spherical PSNR (WS-PSNR) and spherical PSNR (SPSNR) metrics.

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.

Significance of methicillin-teicoplanin resistant Staphylococcus haemolyticus in bloodstream infections in patients of the Semmelweis University hospitals in Hungary.

PubMed

Kristóf, K; Kocsis, E; Szabó, D; Kardos, S; Cser, V; Nagy, K; Hermann, P; Rozgonyi, F

2011-05-01

The purpose of this study was to quantify the impact of Staphylococcus haemolyticus in the epidemiology of the blood stream infection (BSI) and to characterize the rates and quantitative levels of resistance to antistaphylococcal drugs. During an eight-year period, 2967 BSIs of the patients hospitalized in different clinical departments of the Semmelweis University, Budapest, Hungary were analyzed. One hundred eighty-four were caused by S. haemolyticus, amounting to 6% of all infections. The antibacterial resistance of S. haemolyticus isolates was investigated by the broth microdilution method, vancomycin agar screen, population analysis profile and PCR for mecA, vanA and vanB genes detection. Epidemiological investigation was processed by determining phenotypic antibiotic resistance patterns and PFGE profiles. Extremely high MIC levels of resistance were obtained to oxacillin, erythromycin, clindamycin, gentamicin and ciprofloxacin. The incidence of teicoplanin reduced susceptibility revealed 32% without possessing either the vanA or vanB gene by the strains. PFGE revealed 56 well-defined genotypes indicating no clonal relationship of the strains. The propensity of S. haemolyticus to acquire resistance and its pathogenic potential in immunocompromised patients, especially among preterm neonates, emphasise the importance of species level identification of coagulase-negative staphylococci and routinely determine the MIC of proper antibacterial agents for these isolates.

The assessment of the antibacterial and antifungal activities of aspirin, EDTA and aspirin-EDTA combination and their effectiveness as antibiofilm agents.

PubMed

Al-Bakri, A G; Othman, G; Bustanji, Y

2009-07-01

To evaluate the antimicrobial activities of aspirin, EDTA and an aspirin-EDTA (A-EDTA) combination against Pseudomonas aeruginosa, Escherichia coli and Candida albicans in planktonic and biofilm cultures. Minimal inhibitory concentrations (MIC) and minimal biocidal concentrations (MBC) were determined using twofold broth microdilution and viable counting methods, respectively. Aspirin's recorded MIC values ranged from 1.2 to 2.7 mg ml(-1). Checkerboard assay demonstrated a synergism in antimicrobial activity upon combination. Aspirin's minimal biofilm eradication concentration values (MBEC) against the established biofilms ranged between 1.35 and 3.83 mg ml(-1). A complete eradication of bacterial biofilms was achieved after a 4-h treatment with the A-EDTA combination. Both aspirin and EDTA possess broad-spectrum antimicrobial activity for both planktonic and biofilm cultures. Aspirin used at the MBEC for 24 h was successful in eradicating P. aeruginosa, E. coli and C. albicans biofilms established on abiotic surfaces. Moreover, the exposure to the A-EDTA combination (4 h) effected complete bacterial biofilm eradication. There is a continuous need for the discovery of new antimicrobial agents. Aspirin and EDTA are 'nonantibiotic drugs', the combination of which can be used successfully to treat and eradicate biofilms established on abiotic surfaces.

In Vitro Antimicrobial and Antiproliferative Activity of Amphipterygium adstringens

PubMed Central

Rodriguez-Garcia, A.; Peixoto, I. T. A.; Verde-Star, M. J.; De la Torre-Zavala, S.; Aviles-Arnaut, H.; Ruiz, A. L. T. G.

2015-01-01

Amphipterygium adstringens is a plant widely used in Mexican traditional medicine for its known anti-inflammatory and antiulcer properties. In this work, we evaluated the in vitro antimicrobial and antiproliferative activities of the methanolic extract of A. adstringens against oral pathogens such as Streptococcus mutans, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Candida albicans, and Candida dubliniensis, using microdilution (MIC) and agar diffusion methods (MBC), and the antiproliferative activity evaluating total growth inhibition (TGI) by staining the protein content with sulforhodamine B (SRB), using nine human cancer cell lines. Crude extract (CE) of A. adstringens showed some degree of activity against one or more of the strains with a MIC from 0.125 mg/mL to 63 mg/mL and MBC from 1.6 to 6.3 mg/mL and cytotoxic activity, particularly against NCI-ADR/RES, an ovarian cell line expressing multiple resistance drugs phenotype. The CE is a complex mixture of possible multitarget metabolites that could be responsible for both antimicrobial and antiproliferative activities, and further investigation is required to elucidate the identity of active compounds. Nevertheless the CE itself is useful in the development of new antimicrobial treatment based on natural products to prevent oral diseases and as alternative natural source for cancer treatment and prevention. PMID:26451151

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.

Comparative analysis of the susceptibility to biocides and heavy metals of extended-spectrum β-lactamase-producing Escherichia coli isolates of human and avian origin, Germany.

PubMed

Deus, Daniela; Krischek, Carsten; Pfeifer, Yvonne; Sharifi, Ahmad Reza; Fiegen, Ulrike; Reich, Felix; Klein, Guenter; Kehrenberg, Corinna

2017-05-01

A total of 174 extended-spectrum β-lactamase (ESBL)-producing Escherichia coli isolates collected from humans (n=140) and healthy broiler chickens (n = 34) was included in the study. The MIC values of alkyl diaminoethyl glycin hydrochloride, benzethonium chloride, benzalkonium chloride, chlorhexidine, acriflavine, copper sulfate, silver nitrate and zinc chloride were determined by the broth microdilution method. Significant differences in MIC distributions were found between human and avian isolates and between CTX-M-, SHV- and TEM-type ESBL E. coli for chlorhexidine, silver nitrate, zinc chloride and copper sulfate by statistical analysis. Isolates with reduced susceptibility were investigated for the presence and localization of tolerance-mediating genes by PCR analysis and Southern blotting. The genes emrE, mdfA, sugE(c), cueO, copA, zntA and zitB were commonly present in isolates with elevated MICs, while the genes qacE∆1, qacF, qacH, sugE(p), cusC and pcoA, were less prevalent. In several isolates, a plasmid localization of the genes qacE∆1, qacF, qacH and sugE(p) on large plasmids >20 kb was detected. Copyright © 2017 Elsevier Inc. All rights reserved.