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1

Enhanced antibacterial and anti-biofilm activities of silver nanoparticles against Gram-negative and Gram-positive bacteria  

NASA Astrophysics Data System (ADS)

Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results suggest that AgNPs could be used as an adjuvant for the treatment of infectious diseases.

Gurunathan, Sangiliyandi; Han, Jae Woong; Kwon, Deug-Nam; Kim, Jin-Hoi

2014-07-01

2

Enhanced antibacterial and anti-biofilm activities of silver nanoparticles against Gram-negative and Gram-positive bacteria  

PubMed Central

Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results suggest that AgNPs could be used as an adjuvant for the treatment of infectious diseases. PMID:25136281

2014-01-01

3

Enhanced antibacterial and anti-biofilm activities of silver nanoparticles against Gram-negative and Gram-positive bacteria.  

PubMed

Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results suggest that AgNPs could be used as an adjuvant for the treatment of infectious diseases. PMID:25136281

Gurunathan, Sangiliyandi; Han, Jae Woong; Kwon, Deug-Nam; Kim, Jin-Hoi

2014-01-01

4

Efficient enzymatic systems for synthesis of novel ?-mangostin glycosides exhibiting antibacterial activity against Gram-positive bacteria.  

PubMed

Two enzymatic systems were developed for the efficient synthesis of glycoside products of ?-mangostin, a natural xanthonoid exhibiting anti-oxidant, antibacterial, anti-inflammatory, and anticancer activities. In these systems, one-pot reactions for the synthesis of UDP-?-D-glucose and UDP-?-D-2-deoxyglucose were modified and combined with a glycosyltransferase (GT) from Bacillus licheniformis DSM-13 to afford C-3 and C-6 position modified glucose and 2-deoxyglucose conjugated novel ?-mangostin derivatives. ?-Mangostin 3-O-?-D-glucopyranoside, ?-mangostin 6-O-?-D-glucopyranoside, ?-mangostin 3,6-di-O-?-D-glucopyranoside, ?-mangostin 3-O-?-D-2-deoxyglucopyranoside, ?-mangostin 6-O-?-D-2-deoxyglucopyranoside, and ?-mangostin 3,6-di-O-?-D-2-deoxyglucopyranoside were successfully produced in practical quantities and characterized by high-resolution quadruple time-of-flight electrospray ionization-mass spectrometry (HR-QTOF ESI/MS), (1)H and (13)C NMR analyses. In excess of the substrate, the maximum productions of three ?-mangostin glucopyranosides (4.8 mg/mL, 86.5 % overall conversion of ?-mangostin) and three ?-mangostin 2-deoxyglucopyronosides (4.0 mg/mL, 79 % overall conversion of ?-mangostin) were achieved at 4-h incubation period. All the ?-mangostin glycosides exhibited improved water solubility, and their antibacterial activity against three Gram-positive bacteria Micrococcus luteus, Bacillus subtilis, and Staphylococcus aureus was drastically enhanced by the glucosylation at C-3 position. In this study, diverse glycosylated ?-mangostin were produced in significant quantities by using inexpensive starting materials and recycling co-factors within a reaction vessel without use of expensive NDP-sugars in the glycosylation reactions. PMID:25038930

Le, Tuoi Thi; Pandey, Ramesh Prasad; Gurung, Rit Bahadur; Dhakal, Dipesh; Sohng, Jae Kyung

2014-10-01

5

In vitro antibacterial activities of PD 138312 and PD 140248, new fluoronaphthyridines with outstanding gram-positive potency.  

PubMed Central

PD 138312 and PD 140248 are new quinolones with high in vitro activities against a wide spectrum of bacterial species, notably including gram-positive isolates. The respective MICs (in micrograms per milliliter) of PD 138312 and PD 140248 capable of inhibiting > or = 90% of the strains were < or = 0.06 and < or = 0.06 for oxacillin-susceptible and -resistant staphylococci, streptococci (including Streptococcus pyogenes, S. agalactiae, S. pneumoniae, and viridans group streptococci), Haemophilus influenzae, Moraxella catarrhalis, and Neisseria gonorrhoeae; 0.125 and 0.03 for Legionella pneumophila; 0.25 and 0.125 for Listeria monocytogenes; 0.25 and 0.25 for Enterococcus faecalis; 0.5 and 0.06 for anaerobic gram-positive cocci; 0.5 and 0.25 for Acinetobacter spp.; 0.5 and 0.5 for members of the family Enterobacteriaceae (excluding Serratia marcescens); 2 and 0.5 for Bacteroides fragilis; 2 and 2 for Serratia marcescens and ciprofloxacin-resistant staphylococci; and 8 and 4 for Pseudomonas aeruginosa. PMID:8109918

Huband, M D; Cohen, M A; Meservey, M A; Roland, G E; Yoder, S L; Dazer, M E; Domagala, J M

1993-01-01

6

Antibacterial activity of silver-doped hydroxyapatite nanoparticles against gram-positive and gram-negative bacteria  

NASA Astrophysics Data System (ADS)

Ag-doped nanocrystalline hydroxyapatite nanoparticles (Ag:HAp-NPs) (Ca10- x Ag x (PO4)6(OH)2, x Ag = 0.05, 0.2, and 0.3) with antibacterial properties are of great interest in the development of new products. Coprecipitation method is a promising route for obtaining nanocrystalline Ag:HAp with antibacterial properties. X-ray diffraction identified HAp as an unique crystalline phase in each sample. The calculated lattice constants of a = b = 9.435 Ĺ, c = 6.876 Ĺ for x Ag = 0.05, a = b = 9.443 Ĺ, c = 6.875 Ĺ for x Ag = 0.2, and a = b = 9.445 Ĺ, c = 6.877 Ĺ for x Ag = 0.3 are in good agreement with the standard of a = b = 9.418 Ĺ, c = 6.884 Ĺ (space group P63/m). The Fourier transform infrared and Raman spectra of the sintered HAp show the absorption bands characteristic to hydroxyapatite. The Ag:HAp nanoparticles are evaluated for their antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, Providencia stuartii, Citrobacter freundii and Serratia marcescens. The results showed that the antibacterial activity of these materials, regardless of the sample types, was greatest against S. aureus, K. pneumoniae, P. stuartii, and C. freundii. The results of qualitative antibacterial tests revealed that the tested Ag:HAp-NPs had an important inhibitory activity on P. stuartii and C. freundii. The absorbance values measured at 490 nm of the P. stuartii and C. freundii in the presence of Ag:HAp-NPs decreased compared with those of organic solvent used (DMSO) for all the samples ( x Ag = 0.05, 0.2, and 0.3). Antibacterial activity increased with the increase of x Ag in the samples. The Ag:HAp-NP concentration had little influence on the bacterial growth ( P. stuartii).

Ciobanu, Carmen Steluta; Iconaru, Simona Liliana; Le Coustumer, Phillippe; Constantin, Liliana Violeta; Predoi, Daniela

2012-06-01

7

Synthesis and structure–activity relationship studies of 4-arylthiosemicarbazides as topoisomerase IV inhibitors with Gram-positive antibacterial activity. Search for molecular basis of antibacterial activity of thiosemicarbazides  

Microsoft Academic Search

1-(indol-2-carbonyl)-4-(4-nitrophenyl)-thiosemicarbazide was synthesized and antibacterial and type IIA topoisomerases (DNA gyrase and topoisomerase IV) activity was evaluated. It was found that it shows activity against Gram-positive bacteria with MICs of 50 ?g\\/mL and inhibitory action against topoisomerase IV with an IC50 of 14 ?M. Although modification of its structure resulted in molecules with a lower biological profile, our observations strongly implicate that

Agata Siwek; Pawe? St?czek; Joanna Stefa?ska

8

Antibacterial activity of silver-doped hydroxyapatite nanoparticles against gram-positive and gram-negative bacteria.  

PubMed

Ag-doped nanocrystalline hydroxyapatite nanoparticles (Ag:HAp-NPs) (Ca10-xAgx(PO4)6(OH)2, xAg?=?0.05, 0.2, and 0.3) with antibacterial properties are of great interest in the development of new products. Coprecipitation method is a promising route for obtaining nanocrystalline Ag:HAp with antibacterial properties. X-ray diffraction identified HAp as an unique crystalline phase in each sample. The calculated lattice constants of a?=?b?=?9.435 Ĺ, c?=?6.876 Ĺ for xAg?=?0.05, a?=?b?=?9.443 Ĺ, c?=?6.875 Ĺ for xAg?=?0.2, and a?=?b?=?9.445 Ĺ, c?=?6.877 Ĺ for xAg?=?0.3 are in good agreement with the standard of a?=?b?=?9.418 Ĺ, c?=?6.884 Ĺ (space group P63/m). The Fourier transform infrared and Raman spectra of the sintered HAp show the absorption bands characteristic to hydroxyapatite. The Ag:HAp nanoparticles are evaluated for their antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, Providencia stuartii, Citrobacter freundii and Serratia marcescens. The results showed that the antibacterial activity of these materials, regardless of the sample types, was greatest against S. aureus, K. pneumoniae, P. stuartii, and C. freundii. The results of qualitative antibacterial tests revealed that the tested Ag:HAp-NPs had an important inhibitory activity on P. stuartii and C. freundii. The absorbance values measured at 490 nm of the P. stuartii and C. freundii in the presence of Ag:HAp-NPs decreased compared with those of organic solvent used (DMSO) for all the samples (xAg?=?0.05, 0.2, and 0.3). Antibacterial activity increased with the increase of xAg in the samples. The Ag:HAp-NP concentration had little influence on the bacterial growth (P. stuartii). PMID:22721352

Ciobanu, Carmen Steluta; Iconaru, Simona Liliana; Le Coustumer, Phillippe; Constantin, Liliana Violeta; Predoi, Daniela

2012-01-01

9

Antibacterial activity of silver-doped hydroxyapatite nanoparticles against gram-positive and gram-negative bacteria  

PubMed Central

Ag-doped nanocrystalline hydroxyapatite nanoparticles (Ag:HAp-NPs) (Ca10-xAgx(PO4)6(OH)2, xAg?=?0.05, 0.2, and 0.3) with antibacterial properties are of great interest in the development of new products. Coprecipitation method is a promising route for obtaining nanocrystalline Ag:HAp with antibacterial properties. X-ray diffraction identified HAp as an unique crystalline phase in each sample. The calculated lattice constants of a?=?b?=?9.435 Ĺ, c?=?6.876 Ĺ for xAg?=?0.05, a?=?b?=?9.443 Ĺ, c?=?6.875 Ĺ for xAg?=?0.2, and a?=?b?=?9.445 Ĺ, c?=?6.877 Ĺ for xAg?=?0.3 are in good agreement with the standard of a?=?b?=?9.418 Ĺ, c?=?6.884 Ĺ (space group P63/m). The Fourier transform infrared and Raman spectra of the sintered HAp show the absorption bands characteristic to hydroxyapatite. The Ag:HAp nanoparticles are evaluated for their antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, Providencia stuartii, Citrobacter freundii and Serratia marcescens. The results showed that the antibacterial activity of these materials, regardless of the sample types, was greatest against S. aureus, K. pneumoniae, P. stuartii, and C. freundii. The results of qualitative antibacterial tests revealed that the tested Ag:HAp-NPs had an important inhibitory activity on P. stuartii and C. freundii. The absorbance values measured at 490 nm of the P. stuartii and C. freundii in the presence of Ag:HAp-NPs decreased compared with those of organic solvent used (DMSO) for all the samples (xAg?=?0.05, 0.2, and 0.3). Antibacterial activity increased with the increase of xAg in the samples. The Ag:HAp-NP concentration had little influence on the bacterial growth (P. stuartii). PMID:22721352

2012-01-01

10

Synthesis and structure-activity relationship studies of 4-arylthiosemicarbazides as topoisomerase IV inhibitors with Gram-positive antibacterial activity. Search for molecular basis of antibacterial activity of thiosemicarbazides.  

PubMed

1-(indol-2-carbonyl)-4-(4-nitrophenyl)-thiosemicarbazide was synthesized and antibacterial and type IIA topoisomerases (DNA gyrase and topoisomerase IV) activity was evaluated. It was found that it shows activity against Gram-positive bacteria with MICs of 50 ?g/mL and inhibitory action against topoisomerase IV with an IC(50) of 14 ?M. Although modification of its structure resulted in molecules with a lower biological profile, our observations strongly implicate that thiosemicarbazide derivatives participate in at least two different mechanisms of antibacterial activity; one is connected with the inhibition of topoisomerase IV, while the nature of the other cannot be elucidated from the limited data collected thus far. The differences in bioactivity further investigated by the molecular modeling approach and docking studies suggest that inhibitory activity of 4-arylthiosemicarbazides is connected with electronic structure rather than the geometry of the molecule. PMID:21978836

Siwek, Agata; St?czek, Pawe?; Stefa?ska, Joanna

2011-11-01

11

In Vitro Antibacterial Activity of Modithromycin, a Novel 6,11-Bridged Bicyclolide, against Respiratory Pathogens, Including Macrolide-Resistant Gram-Positive Cocci?  

PubMed Central

The in vitro activities of modithromycin against Gram-positive and -negative respiratory pathogens, including macrolide-resistant cocci with different resistance mechanisms, were compared with those of other macrolide and ketolide agents. MICs were determined by the broth microdilution method. All 595 test strains used in this study were isolated from Japanese medical facilities. The erm (ribosome methylase) and/or mef (efflux pump) gene, which correlated with resistance to erythromycin as well as clarithromycin and azithromycin, was found in 81.8%, 21.3%, and 23.2% of Streptococcus pneumoniae, Streptococcus pyogenes, and methicillin-susceptible Staphylococcus aureus (MSSA) strains, respectively. Modithromycin showed MIC90s of 0.125 ?g/ml against these three cocci, including macrolide-resistant strains. In particular, the MIC of modithromycin against ermB-carrying S. pyogenes was ?32-fold lower than that of telithromycin. The activities of modithromycin as well as telithromycin were little affected by the presence of mefA or mefE in both streptococci. Against Gram-negative pathogens, modithromycin showed MIC90s of 0.5, 8, and 0.031 ?g/ml against Moraxella catarrhalis, Haemophilus influenzae, and Legionella spp., respectively. The MICs of modithromycin against M. catarrhalis and H. influenzae were higher than those of telithromycin and azithromycin. However, modithromycin showed the most potent anti-Legionella activity among the macrolide and ketolide agents tested. These results suggested that the bicyclolide agent modithromycin is a novel class of macrolides with improved antibacterial activity against Gram-positive cocci, including telithromycin-resistant streptococci and intracellular Gram-negative bacteria of the Legionella species. PMID:21220534

Sato, Takafumi; Tateda, Kazuhiro; Kimura, Soichiro; Iwata, Morihiro; Ishii, Yoshikazu; Yamaguchi, Keizo

2011-01-01

12

Enhancement of Antibacterial Activity of Capped Silver Nanoparticles in Combination with Antibiotics, on Model Gram-Negative and Gram-Positive Bacteria  

PubMed Central

The nanoparticles used in this study were prepared from AgNO3 using NaBH4 in the presence of capping agents such as citrate, sodium dodecyl sulfate, and polyvinylpyrrolidone. The formed nanoparticles were characterized with UV-Vis, TEM, and XRD. The generation of silver nanoparticles was confirmed from the appearance of yellow colour and an absorption maximum between 399 and 404?nm. The produced nanoparticles were found to be spherical in shape and polydisperse. For citrate, SDS, and PVP capped nanoparticles, the average particle sizes were 38.3 ± 13.5, 19.3 ± 6.0, and 16.0 ± 4.8?nm, respectively. The crystallinity of the nanoparticles in FCC structure is confirmed from the SAED and XRD patterns. Also, the combined antibacterial activity of these differently capped nanoparticles with selected antibiotics (streptomycin, ampicillin, and tetracycline) was evaluated on model Gram-negative and Gram-positive bacteria, employing disc diffusion assay. The activity of the tested antibiotics was enhanced in combination with all the stabilized nanoparticles, against both the Gram classes of bacteria. The combined effects of silver nanoparticles and antibiotics were more prominent with PVP capped nanoparticles as compared to citrate and SDS capped ones. The results of this study demonstrate potential therapeutic applications of silver nanoparticles in combination with antibiotics. PMID:23970844

Kora, Aruna Jyothi; Rastogi, Lori

2013-01-01

13

Antibacterial activity of Lactobacillus acidophilus strains isolated from honey marketed in Malaysia against selected multiple antibiotic resistant (MAR) Gram-positive bacteria.  

PubMed

A total of 32 lactic acid bacteria (LAB) were isolated from 13 honey samples commercially marketed in Malaysia, 6 strains identified as Lactobacillus acidophilus by API CHL50. The isolates had antibacterial activities against multiple antibiotic resistant's Staphylococcus aureus (25 to 32 mm), Staphylococcus epidermis (14 to 22 mm) and Bacillus subtilis (12 to 19 mm) in the agar overlay method after 24 h incubation at 30 °C. The crude supernatant was heat stable at 90 °C and 121 °C for 1 h. Treatment with proteinase K and RNase II maintained the antimicrobial activity of all the supernatants except sample H006-A and H010-G. All the supernatants showed antimicrobial activities against target bacteria at pH 3 and pH 5 but not at pH 6 within 72 h incubation at 30 °C. S. aureus was not inhibited by sample H006-A isolated from Libyan honey and sample H008-D isolated from Malaysian honey at pH 5, compared to supernatants from other L. acidophilus isolates. The presence of different strains of L. acidophilus in honey obtained from different sources may contribute to the differences in the antimicrobial properties of honey. PMID:22757710

Aween, Mohamed Mustafa; Hassan, Zaiton; Muhialdin, Belal J; Eljamel, Yossra A; Al-Mabrok, Asma Saleh W; Lani, Mohd Nizam

2012-07-01

14

Bioengineered Nisin A Derivatives with Enhanced Activity against Both Gram Positive and Gram Negative Pathogens  

PubMed Central

Nisin is a bacteriocin widely utilized in more than 50 countries as a safe and natural antibacterial food preservative. It is the most extensively studied bacteriocin, having undergone decades of bioengineering with a view to improving function and physicochemical properties. The discovery of novel nisin variants with enhanced activity against clinical and foodborne pathogens has recently been described. We screened a randomized bank of nisin A producers and identified a variant with a serine to glycine change at position 29 (S29G), with enhanced efficacy against S. aureus SA113. Using a site-saturation mutagenesis approach we generated three more derivatives (S29A, S29D and S29E) with enhanced activity against a range of Gram positive drug resistant clinical, veterinary and food pathogens. In addition, a number of the nisin S29 derivatives displayed superior antimicrobial activity to nisin A when assessed against a range of Gram negative food-associated pathogens, including E. coli, Salmonella enterica serovar Typhimurium and Cronobacter sakazakii. This is the first report of derivatives of nisin, or indeed any lantibiotic, with enhanced antimicrobial activity against both Gram positive and Gram negative bacteria. PMID:23056510

Field, Des; Begley, Maire; O'Connor, Paula M.; Daly, Karen M.; Hugenholtz, Floor; Cotter, Paul D.; Hill, Colin; Ross, R. Paul

2012-01-01

15

In Vitro Activities of Linezolid against Important Gram-Positive Bacterial Pathogens Including Vancomycin-Resistant Enterococci  

Microsoft Academic Search

The emergence of resistance in gram-positive bacteria has necessitated a search for new antimicrobial agents. Linezolid is an oxazolidinone, a new class of antibacterial agents with enhanced activity against pathogens. We compared the activity of linezolid to those of other antimicrobial agents against 3,945 clinical isolates. Linezolid demonstrated potent activity against all isolates tested. For all vancomycin-susceptible enterococci, staphylococci, and

GARY A. NOSKIN; FARIDA SIDDIQUI; VALENTINA STOSOR; DONNA HACEK; LANCE R. PETERSON

1999-01-01

16

In Vitro and In Vivo Activities of PD 0305970 and PD 0326448, New Bacterial Gyrase/Topoisomerase Inhibitors with Potent Antibacterial Activities versus Multidrug-Resistant Gram-Positive and Fastidious Organism Groups?  

PubMed Central

PD 0305970 and PD 0326448 are new bacterial gyrase and topoisomerase inhibitors (quinazoline-2,4-diones) that possess outstanding in vitro and in vivo activities against a wide spectrum of bacterial species including quinolone- and multidrug-resistant gram-positive and fastidious organism groups. The respective MICs (?g/ml) for PD 0305970 capable of inhibiting ?90% of bacterial strains tested ranged from 0.125 to 0.5 versus staphylococci, 0.03 to 0.06 versus streptococci, 0.25 to 2 versus enterococci, and 0.25 to 0.5 versus Moraxella catarrhalis, Haemophilus influenzae, Listeria monocytogenes, Legionella pneumophila, and Neisseria spp. PD 0326448 MIC90s were generally twofold higher versus these same organism groups. Comparative quinolone MIC90 values were 4- to 512-fold higher than those of PD 0305970. In testing for frequency of resistance, PD 0305970 and levofloxacin showed low levels of development of spontaneous resistant mutants versus both Staphylococcus aureus and Streptococcus pneumoniae. Unlike quinolones, which target primarily gyrA and parC, analysis of resistant mutants in S. pneumoniae indicates that the likely targets of PD 0305970 are gyrB and parE. PD 0305970 demonstrated rapid bactericidal activity by in vitro time-kill testing versus streptococci. This bactericidal activity carried over to in vivo testing, where PD 0305970 and PD 0326448 displayed outstanding Streptococcus pyogenes 50% protective doses (PD50s) (oral dosing) of 0.7 and 3.6 mg/kg, respectively (ciprofloxacin and levofloxacin PD50s were >100 and 17.7 mg/kg, respectively). PD 0305970 was also potent in a pneumococcal pneumonia mouse infection model (PD50 = 3.2 mg/kg) and was 22-fold more potent than levofloxacin. PMID:17261623

Huband, Michael D.; Cohen, Michael A.; Zurack, Margaret; Hanna, Debra L.; Skerlos, Laura A.; Sulavik, Mark C.; Gibson, Glenn W.; Gage, Jeffrey W.; Ellsworth, Edmund; Stier, Michael A.; Gracheck, Stephen J.

2007-01-01

17

In vitro antimicrobial activity of GAR936 tested against antibiotic-resistant gram-positive blood stream infection isolates and strains producing extended-spectrum ?-lactamases  

Microsoft Academic Search

GAR-936, a new, semisynthetic glycylcycline, has shown good antibacterial activity against a wide range of clinically important Gram-positive and –negative aerobic bacteria including Streptococcus pneumoniae,Hemophilus influenzae,Moraxella catarrhalis,Neisseria gonorrhoeae, most Enterobacteriaceae, Staphylococcus aureus and Enterococcus spp. The purpose of this study was to determine the activity of GAR-936 against a range of Gram-positive and –negative bloodstream isolates including many strains producing

Douglas J Biedenbach; Mondell L Beach; Ronald N Jones

2001-01-01

18

Antimicrobial activity of metal oxide nanoparticles against Gram-positive and Gram-negative bacteria: a comparative study  

PubMed Central

Background Nanomaterials have unique properties compared to their bulk counterparts. For this reason, nanotechnology has attracted a great deal of attention from the scientific community. Metal oxide nanomaterials like ZnO and CuO have been used industrially for several purposes, including cosmetics, paints, plastics, and textiles. A common feature that these nanoparticles exhibit is their antimicrobial behavior against pathogenic bacteria. In this report, we demonstrate the antimicrobial activity of ZnO, CuO, and Fe2O3 nanoparticles against Gram-positive and Gram-negative bacteria. Methods and results Nanosized particles of three metal oxides (ZnO, CuO, and Fe2O3) were synthesized by a sol–gel combustion route and characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy techniques. X-ray diffraction results confirmed the single-phase formation of all three nanomaterials. The particle sizes were observed to be 18, 22, and 28 nm for ZnO, CuO, and Fe2O3, respectively. We used these nanomaterials to evaluate their antibacterial activity against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. Conclusion Among the three metal oxide nanomaterials, ZnO showed greatest antimicrobial activity against both Gram-positive and Gram-negative bacteria used in this study. It was observed that ZnO nanoparticles have excellent bactericidal potential, while Fe2O3 nanoparticles exhibited the least bactericidal activity. The order of antibacterial activity was demonstrated to be the following: ZnO > CuO > Fe2O3. PMID:23233805

Azam, Ameer; Ahmed, Arham S; Oves, Mohammad; Khan, Mohammad S; Habib, Sami S; Memic, Adnan

2012-01-01

19

Pyrrolidine bis-cyclic guanidines with antimicrobial activity against drug-resistant Gram-positive pathogens  

E-print Network

and bactericidal activities against the important human pathogen methicillin-resis- tant Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis (VRE), and two Gram-negative bacterial species. At least 20 in the preeminent Gram-positive bacterial pathogen Staphylococcus aureus, which is increasingly unresponsive

Nizet, Victor

20

Antimicrobial Activities of Leaf Extracts of Guava (Psidium guajava L.) on Two Gram-Negative and Gram-Positive Bacteria  

PubMed Central

Aim. To determine the antimicrobial potential of guava (Psidium guajava) leaf extracts against two gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and two gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) which are some of foodborne and spoilage bacteria. The guava leaves were extracted in four different solvents of increasing polarities (hexane, methanol, ethanol, and water). The efficacy of these extracts was tested against those bacteria through a well-diffusion method employing 50??L leaf-extract solution per well. According to the findings of the antibacterial assay, the methanol and ethanol extracts of the guava leaves showed inhibitory activity against gram-positive bacteria, whereas the gram-negative bacteria were resistant to all the solvent extracts. The methanol extract had an antibacterial activity with mean zones of inhibition of 8.27 and 12.3?mm, and the ethanol extract had a mean zone of inhibition of 6.11 and 11.0?mm against B. cereus and S. aureus, respectively. On the basis of the present finding, guava leaf-extract might be a good candidate in the search for a natural antimicrobial agent. This study provides scientific understanding to further determine the antimicrobial values and investigate other pharmacological properties. PMID:24223039

Biswas, Bipul; Rogers, Kimberly; McLaughlin, Fredrick; Yadav, Anand

2013-01-01

21

In Vitro Activity of Telavancin against Resistant Gram-Positive Bacteria?  

PubMed Central

The in vitro activity of telavancin was tested against 743 predominantly antimicrobial-resistant, gram-positive isolates. Telavancin was highly active against methicillin-resistant staphylococci (MIC90, 0.5 to 1 ?g/ml), streptococci (all MICs, ?0.12 ?g/ml), and VanB-type enterococci (all MICs, ?2 ?g/ml). Time-kill studies demonstrated the potent bactericidal activity of telavancin. PMID:18443122

Krause, Kevin M.; Renelli, Marika; Difuntorum, Stacey; Wu, Terry X.; Debabov, Dmitri V.; Benton, Bret M.

2008-01-01

22

Silver nanoparticles synthesized by pulsed laser ablation: as a potent antibacterial agent for human enteropathogenic gram-positive and gram-negative bacterial strains.  

PubMed

Present investigation deals with the study, to quantify the antibacterial property of silver nanoparticles (SNPs), synthesized by pulsed laser ablation (PLA) in aqueous media, on some human enteropathogenic gram-positive and gram-negative bacterial strains. Antibacterial property was studied by measuring the zone of inhibition using agar cup double-diffusion method, minimum inhibitory concentration by serial dilution method, and growth curve for 24 h. The results clearly show the potency of antibacterial property of PLA-synthesized SNPs and suggest that it can be used as an effective growth inhibitor against various pathogenic bacterial strains in various medical devices and antibacterial control systems. PMID:24801405

Pandey, Jitendra Kumar; Swarnkar, R K; Soumya, K K; Dwivedi, Priyanka; Singh, Manish Kumar; Sundaram, Shanthy; Gopal, R

2014-10-01

23

Structure-Activity Relationships of 3,3?-Phenylmethylene-bis-4-hydroxycoumarins: Selective and Potent Inhibitors of Gram-Positive Bacteria  

PubMed Central

Dicoumarols and coumarin derivatives have shown a variety of pharmaceutical activities and have been found to be potent inhibitor for the NAD(P)H-dependent flavoproteins. In this report, dicoumarol and its derivatives containing the substituted benzene ring at the methylenebis position were synthesized and evaluated for their antibacterial activity against gram-positive bacteria: Staphylococcus aureus and Bacillus subtilis, and gram-negative bacteria: Escherichia coli and Klebsiella sp. The results showed that the synthesized dicoumarols affect cell growth but are selective against gram-positive over gram-negative bacterial cells. However, for most derivatives, the substitution of steric bulky benzene group on the methylenebis position appears to decrease in the efficacy of antibacterial effect. This finding is roughly described by the predicted poorer docked structure of the derivatives to a homology model of S. aureus flavoprotein. 3D-QSAR study highlighted structural features around the substituted benzene ring of dicoumarols as the antibacterial activity. CoMFA and CoMSIA contour maps support the idea that steric repulsion at the para position could diminish the antibacterial activity. The results of this study provide a better understanding of the molecular basis for the antibacterial activity of dicoumarols. PMID:24459419

Chavasiri, Warinthorn

2013-01-01

24

In Vitro Activities of RWJ-54428 (MC-02,479) against Multiresistant Gram-Positive Bacteria  

PubMed Central

RWJ-54428 (MC-02,479) is a new cephalosporin with a high level of activity against gram-positive bacteria. In a broth microdilution susceptibility test against methicillin-resistant Staphylococcus aureus (MRSA), RWJ-54428 was as active as vancomycin, with an MIC at which 90% of isolates are inhibited (MIC90) of 2 ?g/ml. For coagulase-negative staphylococci, RWJ-54428 was 32 times more active than imipenem, with an MIC90 of 2 ?g/ml. RWJ-54428 was active against S. aureus, Staphylococcus epidermidis, and Staphylococcus haemolyticus isolates with reduced susceptibility to glycopeptides (RWJ-54428 MIC range, ?0.0625 to 1 ?g/ml). RWJ-54428 was eight times more potent than methicillin and cefotaxime against methicillin-susceptible S. aureus (MIC90, 0.5 ?g/ml). For ampicillin-susceptible Enterococcus faecalis (including vancomycin-resistant and high-level aminoglycoside-resistant strains), RWJ-54428 had an MIC90 of 0.125 ?g/ml. RWJ-54428 was also active against Enterococcus faecium, including vancomycin-, gentamicin-, and ciprofloxacin-resistant strains. The potency against enterococci correlated with ampicillin susceptibility; RWJ-54428 MICs ranged between ?0.0625 and 1 ?g/ml for ampicillin-susceptible strains and 0.125 and 8 ?g/ml for ampicillin-resistant strains. RWJ-54428 was more active than penicillin G and cefotaxime against penicillin-resistant, -intermediate, and -susceptible strains of Streptococcus pneumoniae (MIC90s, 0.25, 0.125, and ?0.0625 ?g/ml, respectively). RWJ-54428 was only marginally active against most gram-negative bacteria; however, significant activity was observed against Haemophilus influenzae and Moraxella catarrhalis (MIC90s, 0.25 and 0.5 ?g/ml, respectively). This survey of the susceptibilities of more than 1,000 multidrug-resistant gram-positive isolates to RWJ-54428 indicates that this new cephalosporin has the potential to be useful in the treatment of infections due to gram-positive bacteria, including strains resistant to currently available antimicrobials. PMID:11302805

Chamberland, Suzanne; Blais, Johanne; Hoang, Monica; Dinh, Cynthia; Cotter, Dylan; Bond, Emmett; Gannon, Carla; Park, Craig; Malouin, Francois; Dudley, Michael N.

2001-01-01

25

Mutactimycin E, a New Anthracycline Antibiotic with Gram-positive Activity  

Microsoft Academic Search

Resistance to currently available antibiotics has become a widely recognized crisis in the medical community. To address this, many companies and researchers are refocusing their attention towards natural products, which have an excellent track record of producing effective antibacterial drugs. The AMRI natural product library was screened for activity against multi-drug resistant Staphylococcus aureus (MDRSA). The active samples were counter

D Craig Hopp; John Rabenstein; Joshua Rhea; Chris Smith; Khadidja Romari; Midori Clarke; Linda Francis; Macarena Irigoyen; Dennis Milanowski; Michele Luche; Grant J Carr; Ulla Mocek

2008-01-01

26

Antioxidant activity via DPPH, gram-positive and gram-negative antimicrobial potential in edible mushrooms.  

PubMed

Edible mushrooms (EMs) are nutritionally rich source of proteins and essential amino acids. In the present study, the antioxidant activity via 1,1-diphenyl-2-picrylhydrazyl (DPPH) and antimicrobial potential in EMs (Pleurotus ostreatus, Morchella esculenta, P. ostreatus (Black), P. ostreatus (Yellow) and Pleurotus sajor-caju) were investigated. The DPPH radical scavenging activity revealed that the significantly higher activity (66.47%) was observed in Morchella esculenta at a maximum concentration. Similarly, the dose-dependent concentrations (200, 400, 600, 800 and 1000 µg) were also used for other four EMs. Pleurotus ostreatus exhibited 36.13% activity, P. ostreatus (Black (B)) exhibited 30.64%, P. ostreatus (Yellow (Y)) exhibited 40.75% and Pleurotus sajor-caju exhibited 47.39% activity at higher concentrations. Furthermore, the antimicrobial potential were investigated for its toxicity against gram-negative bacterial strains (Escherichia coli, Pseudomonas aeroginosa, Salmonella typhi, Klebsiella pneumonia, Erwinia carotovora and Agrobacterium tumifaciens), gram-positive bacterial strains (Bacillus subtilis, Bacillus atrophaeus and Staphylococcus aureus) and a fungal strain (Candida albicans) in comparison with standard antibiotics. Antimicrobial screening revealed that the ethanol extract of P. ostreatus was active against all microorganism tested except E. coli. Maximum zone of inhibition (13 mm) was observed against fungus and A. tumifaciens. P. sajor-caju showed best activities (12.5 mm) against B. subtilis, B. atrophaeus and K. pneumonia. P. ostreatus (Y) showed best activities against P. aeroginosa (21.83 mm), B. atrophaeus (20 mm) and C. albicans (21 mm). P. ostreatus (B) exhibited best activities against C. albicans (16 mm) and slightly lower activities against all other microbes except S. typhi. M. esculenta possess maximum activities in terms of inhibition zone against all microorganisms tested except S. typhi. PMID:23095488

Ahmad, Nisar; Mahmood, Fazal; Khalil, Shahid Akbar; Zamir, Roshan; Fazal, Hina; Abbasi, Bilal Haider

2014-10-01

27

Comparative in vitro activity of DU-6859a, a new fluoroquinolone agent, against gram-positive cocci.  

PubMed Central

The in vitro activity of DU-6859a (DU), a new fluoroquinolone agent, was evaluated against 233 gram-positive cocci and was compared with those of ciprofloxacin, vancomycin, nafcillin, and ampicillin. The MICs of DU for 90% of the staphylococci tested were < or = 0.06 microgram/ml. All of the groups A and B and viridans group streptococci were inhibited by < or = 0.125 microgram of DU per ml, which was 32-fold more active than ciprofloxacin. On the basis of MICs for 90% of the strains tested, DU was 32- and 16-fold more active than ciprofloxacin against Enterococcus faecalis and Enterococcus faecium, respectively. The bactericidal activity of DU was demonstrated by time-kill techniques against all ciprofloxacin-susceptible enterococci. DU shows promise for the treatment of infections with gram-positive cocci and warrants further evaluation by in vitro and in vivo studies. PMID:8203863

Korten, V; Tomayko, J F; Murray, B E

1994-01-01

28

Comparative in vitro activities of L-695,256, a novel carbapenem, against gram-positive bacteria.  

PubMed Central

The in vitro activity of a prototype 2-aryl carbapenem, L-695,256, against gram-positive bacteria was examined. All streptococci and oxacillin-susceptible and -resistant staphylococci were inhibited at concentrations of < or = 0.125, < or = 0.125, and 4 micrograms/ml, respectively. The activity of L-695,256 was superior to that of imipenem against other organisms intrinsically resistant to beta-lactams. PMID:7786011

Malanoski, G; Collins, L; Eliopoulos, C T; Moellering, R C; Eliopoulos, G M

1995-01-01

29

Assessing the interactions of a natural antibacterial clay with model Gram-positive and Gram-negative human pathogens  

NASA Astrophysics Data System (ADS)

The emergence of antibiotic resistant bacteria and increasing accumulations of antibiotics in reclaimed water, drive the quest for new natural antimicrobials. We are studying the antibacterial mechanism(s) of clays that have shown an ability to destroy bacteria or significantly inhibit their growth. One possible mode of action is from soluble transition metal species, particularly reduced Fe, capable of generating deleterious oxygen radical species. Yet another possibility is related to membrane damage as a consequence of physical or electrostatic interaction between clay and bacteria. Both mechanisms could combine to produce cell death. This study addresses a natural antibacterial clay from the NW Amazon basin, South America (AMZ clay). Clay mineralogy is composed of disordered kaolinite (28.9%), halloysite (17.8%) illite (12%) and smectite (16.7%). Mean particle size is 1.6?m and total and specific surface area 278.82 and 51.23 m2/g respectively. The pH of a suspension (200mg/ml) is 4.1 and its Eh is 361mV after 24h of equilibration. The ionic strength of the water in equilibrium with the clay after 24 h. is 6 x10-4M. These conditions, affect the element solubility, speciation, and interactions between clay and bacteria. Standard microbiological methods were used to assess the viability of two model bacteria (Escherichia coli and Bacillus subtilis) after incubation with clay at 37 degC for 24 hrs. A threefold reduction in bacterial viability was observed upon treatment with AMZ clay. We separated the cells from the clay using Nycodenz gradient media and observed the mounts under the TEM and SEM. Results showed several membrane anomalies and structural changes that were not observed in the control cells. Additionally, clay minerals appeared in some places attached to cell walls. Experiments showed that exchanging AMZ clay with KCl caused loss of antibacterial property. Among the exchangeable -and potentially toxic- ions we measured Al+3, Cu+2, Zn+2, Ba+2 and Co+2. Besides being toxic at high concentrations, these species affect the electrophoretic interactions between clay and bacteria surfaces. Additionally, the cation exchange neutralizes the clay surface charge thus modifying further the behavior of particles in suspension. Therefore, we evaluated the clay and bacteria zeta potential (?) as an index for possible electrostatic forces and modeled the total interactions using DLVO theory. We suspended the particles in water equilibrated with clay (leachate). Results show that at pH 4, the ? of clays is -14 mV while it is -3mV for bacteria. The divalent ions and trivalent Aluminum, present in the AMZ leachate, compress the thickness of the double layer (hydration shell) thus decreasing electrostatic repulsion and allowing particles to come closer. The proximity of particles increases the probability of attractive forces to bind clays and cells. In summary, results indicate that a process other than simple chemical transfer from clay to bacteria is operating. The electrostatic attraction and physical proximity may enhance the toxic action of metals and interfere with the membrane properties or processes.

Londono, S. C.; Williams, L. B.

2013-12-01

30

In vitro activity of biapenem against clinical isolates of gram-positive and gram-negative bacteria.  

PubMed Central

The in vitro activity of biapenem, a new carbapenem previously designated L-627, was compared with those of imipenem and several other antimicrobial agents against 771 clinical bacterial isolates. Against gram-positive organisms, biapenem was found to be approximately as active as imipenem, inhibiting 90% of isolates of most species at concentrations within one dilution of the MIC of imipenem for 90% of the isolates. Against gram-negative organisms and Bacteroides fragilis, biapenem was at least as active as and often more active than imipenem, with MICs for 90% of the isolates two- to eightfold lower than those of imipenem. PMID:8239623

Malanoski, G J; Collins, L; Wennersten, C; Moellering, R C; Eliopoulos, G M

1993-01-01

31

In vitro activities of ramoplanin, selected glycopeptides, fluoroquinolones, and other antibiotics against clinical bloodstream isolates of gram-positive cocci.  

PubMed Central

The susceptibilities of 316 gram-positive bacteremic isolates to ramoplanin, vancomycin, and teicoplanin and seven other antibiotics were tested. Ramoplanin demonstrated MICs of < or = 0.25 microgram/ml for at least 99% of Staphylococcus aureus isolates and 100% of coagulase-negative staphylococci tested. For both oxacillin-susceptible and oxacillin-resistant S. aureus and coagulase-negative staphylococci, the activity of ramoplanin surpassed those of both vancomycin and teicoplanin. Ramoplanin and teicoplanin had comparable activities against enterococci and Streptococcus pneumoniae and were superior to vancomycin. PMID:8494388

Lawrence, T; Rotstein, C; Beam, T R; Gorzynski, E A; Amsterdam, D

1993-01-01

32

A super-family of transcriptional activators regulates bacteriophage packaging and lysis in Gram-positive bacteria  

PubMed Central

The propagation of bacteriophages and other mobile genetic elements requires exploitation of the phage mechanisms involved in virion assembly and DNA packaging. Here, we identified and characterized four different families of phage-encoded proteins that function as activators required for transcription of the late operons (morphogenetic and lysis genes) in a large group of phages infecting Gram-positive bacteria. These regulators constitute a super-family of proteins, here named late transcriptional regulators (Ltr), which share common structural, biochemical and functional characteristics and are unique to this group of phages. They are all small basic proteins, encoded by genes present at the end of the early gene cluster in their respective phage genomes and expressed under cI repressor control. To control expression of the late operon, the Ltr proteins bind to a DNA repeat region situated upstream of the terS gene, activating its transcription. This involves the C-terminal part of the Ltr proteins, which control specificity for the DNA repeat region. Finally, we show that the Ltr proteins are the only phage-encoded proteins required for the activation of the packaging and lysis modules. In summary, we provide evidence that phage packaging and lysis is a conserved mechanism in Siphoviridae infecting a wide variety of Gram-positive bacteria. PMID:23771138

Quiles-Puchalt, Nuria; Tormo-Mas, Maria Angeles; Campoy, Susana; Toledo-Arana, Alejandro; Monedero, Vicente; Lasa, Inigo; Novick, Richard P.; Christie, Gail E.; Penades, Jose R.

2013-01-01

33

Zulu medicinal plants with antibacterial activity  

Microsoft Academic Search

Aqueous, methanolic and ethyl acetate extracts of 14 plants used in traditional Zulu medicine for treatment of ailments of an infectious nature were screened for antibacterial activity. Most of the activity detected was against Gram-positive bacteria. Tuber bark extracts of Dioscorea sylvatica had activity against Gram-negative Escherichia coli and extracts of Dioscorea dregeana, Cheilanthes viridis and Vernonia colorata were active

Jonathan E. Kelmanson; Anna K. Jäger; Johannes van Staden

2000-01-01

34

In vitro activity of telavancin compared with vancomycin and linezolid against Gram-positive organisms isolated from cancer patients.  

PubMed

Telavancin is a dual action, bactericidal lipoglycopeptide. Its in vitro activity was compared with vancomycin and linezolid against 392 Gram-positive isolates from cancer patients. MIC90 values (?g ml(-1)) for telavancin, vancomycin and linezolid were determined for methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), methicillin-susceptible (MS), methicillin-resistant (MR), coagulase-negative staphylococci (CoNS), viridans group streptococci (VGS), Streptococcus pneumoniae, Bacillus species, Corynebacterium species and Micrococcus species. Telavancin had potent activity against ?-hemolytic streptococci and Staphylococcus lugdunensis. Whereas 100% of MRSA and 98% of MSSA had vancomycin MICs ? 1.0 ?g ml(-1) (minimum inhibitory concentrations (MICs) at which poor clinical responses have been reported), the highest telavancin MIC was 0.38 ?g ml(-1). For CoNS, 95% of MS and 100% of MR isolates had vancomycin MICs ? 1.0 ?g ml(-1), whereas the highest telavancin MIC was 0.38 ?g ml(-1). Furthermore, 48% of VGS had vancomycin MICs ? 1.0 ?g ml(-1), whereas the highest telavancin MIC was 0.064 ?g ml(-1). A similar pattern was noticed for S. lugdunensis, Bacillus species, Corynebacterium species and ?-hemolytic streptococci. These data suggest that telavancin and linezolid have potent activity against most Gram-positive organisms that cause infections in cancer patients. Consequently, they may be considered as alternatives to vancomycin, especially in institutions wherein a substantial proportion of infections are caused by organisms with vancomycin MICs ? 1.0 ?g ml(-1). PMID:24824818

Rolston, Kenneth; Wang, Weiqun; Nesher, Lior; Coyle, Elizabeth; Shelburne, Samuel; Prince, Randall A

2014-07-01

35

In vitro activity of cephalosporin RWJ-54428 (MC-02479) against multidrug-resistant gram-positive cocci.  

PubMed

RWJ-54428 (MC-02479) is a novel cephalosporin that binds to penicillin-binding protein (PBP) PBP 2' (PBP 2a) of methicillin-resistant staphylococci. Its in vitro activity was assessed against 472 gram-positive cocci, largely selected as epidemiologically unrelated isolates with multidrug resistance. The MIC at which 50% of isolates are inhibited (MIC(50)) and MIC(90) of RWJ-54428 for methicillin-resistant Staphylococcus aureus (MRSA) were 1 and 2 microg/ml, respectively, whereas they were 0.5 and 0.5 microg/ml, respectively, for methicillin-susceptible S. aureus. The MIC(50) and MIC(90) were 1 and 4 microg/ml, respectively, for methicillin-resistant coagulase-negative staphylococci (MRCoNS), whereas they were 0.25 and 1 microg/ml, respectively, for methicillin-susceptible isolates. The highest MICs for MRSA and MRCoNS isolates were 2 and 4 microg/ml, respectively. The MIC(50) and MIC(90) of RWJ-54428 for Enterococcus faecalis were 0.5 and 1 microg/ml, respectively, but they were 4 and 8 microg/ml, respectively, for Enterococcus faecium. For penicillin-susceptible, -intermediate, and -resistant pneumococci, the MIC(90)s of RWJ-54428 were 0.03, 0.25, and 0.5 microg/ml, respectively, with the highest MIC for a pneumococcus being 1 microg/ml, recorded for a strain for which penicillin and cefotaxime MICs were 8 and 4 microg/ml. MICs for Lancefield group A, B, C, and G streptococci were < or =0.008 microg/ml; those for viridans group streptococci, including isolates not susceptible to penicillin, were from 0.015 to 0.5 microg/ml. RWJ-54428 did not select resistant mutants of MRSA or enterococci in challenge experiments and has the potential to be useful for the treatment of infections caused by gram-positive cocci. PMID:11796337

Johnson, Alan P; Warner, Marina; Carter, Michael; Livermore, David M

2002-02-01

36

In Vitro Activity of Cephalosporin RWJ-54428 (MC-02479) against Multidrug-Resistant Gram-Positive Cocci  

PubMed Central

RWJ-54428 (MC-02479) is a novel cephalosporin that binds to penicillin-binding protein (PBP) PBP 2? (PBP 2a) of methicillin-resistant staphylococci. Its in vitro activity was assessed against 472 gram-positive cocci, largely selected as epidemiologically unrelated isolates with multidrug resistance. The MIC at which 50% of isolates are inhibited (MIC50) and MIC90 of RWJ-54428 for methicillin-resistant Staphylococcus aureus (MRSA) were 1 and 2 ?g/ml, respectively, whereas they were 0.5 and 0.5 ?g/ml, respectively, for methicillin-susceptible S. aureus. The MIC50 and MIC90 were 1 and 4 ?g/ml, respectively, for methicillin-resistant coagulase-negative staphylococci (MRCoNS), whereas they were 0.25 and 1 ?g/ml, respectively, for methicillin-susceptible isolates. The highest MICs for MRSA and MRCoNS isolates were 2 and 4 ?g/ml, respectively. The MIC50 and MIC90 of RWJ-54428 for Enterococcus faecalis were 0.5 and 1 ?g/ml, respectively, but they were 4 and 8 ?g/ml, respectively, for Enterococcus faecium. For penicillin-susceptible, -intermediate, and -resistant pneumococci, the MIC90s of RWJ-54428 were 0.03, 0.25, and 0.5 ?g/ml, respectively, with the highest MIC for a pneumococcus being 1 ?g/ml, recorded for a strain for which penicillin and cefotaxime MICs were 8 and 4 ?g/ml. MICs for Lancefield group A, B, C, and G streptococci were ?0.008 ?g/ml; those for viridans group streptococci, including isolates not susceptible to penicillin, were from 0.015 to 0.5 ?g/ml. RWJ-54428 did not select resistant mutants of MRSA or enterococci in challenge experiments and has the potential to be useful for the treatment of infections caused by gram-positive cocci. PMID:11796337

Johnson, Alan P.; Warner, Marina; Carter, Michael; Livermore, David M.

2002-01-01

37

Screening of Yemeni medicinal plants for antibacterial and cytotoxic activities  

Microsoft Academic Search

Ethanolic extracts of 20 selected plant species used by Yemeni traditional healers to treat infectious diseases were screened for their antibacterial activity against both Gram-positive and Gram-negative bacteria, as well as for cytotoxic activity. Fourteen of the ethanolic extracts showed variable degrees of antibacterial activity. The active ethanolic extracts were partitioned between ethyl acetate and water for a first separation.

N. A. Awadh Ali; W.-D Jülich; C Kusnick; U Lindequist

2001-01-01

38

Discovery of Novel Cell Wall-Active Compounds Using PywaC, a Sensitive Reporter of Cell Wall Stress, in the Model Gram-Positive Bacterium Bacillus subtilis  

PubMed Central

The emergence of antibiotic resistance in recent years has radically reduced the clinical efficacy of many antibacterial treatments and now poses a significant threat to public health. One of the earliest studied well-validated targets for antimicrobial discovery is the bacterial cell wall. The essential nature of this pathway, its conservation among bacterial pathogens, and its absence in human biology have made cell wall synthesis an attractive pathway for new antibiotic drug discovery. Herein, we describe a highly sensitive screening methodology for identifying chemical agents that perturb cell wall synthesis, using the model of the Gram-positive bacterium Bacillus subtilis. We report on a cell-based pilot screen of 26,000 small molecules to look for cell wall-active chemicals in real time using an autonomous luminescence gene cluster driven by the promoter of ywaC, which encodes a guanosine tetra(penta)phosphate synthetase that is expressed under cell wall stress. The promoter-reporter system was generally much more sensitive than growth inhibition testing and responded almost exclusively to cell wall-active antibiotics. Follow-up testing of the compounds from the pilot screen with secondary assays to verify the mechanism of action led to the discovery of 9 novel cell wall-active compounds. PMID:24687489

Czarny, T. L.; Perri, A. L.; French, S.

2014-01-01

39

The PECACE domain: a new family of enzymes with potential peptidoglycan cleavage activity in Gram-positive bacteria  

PubMed Central

Background The metabolism of bacterial peptidoglycan is a dynamic process, synthases and cleavage enzymes are functionally coordinated. Lytic Transglycosylase enzymes (LT) are part of multienzyme complexes which regulate bacterial division and elongation. LTs are also involved in peptidoglycan turnover and in macromolecular transport systems. Despite their central importance, no LTs have been identified in the human pathogen Streptococcus pneumoniae. We report the identification of the first putative LT enzyme in S. pneumoniae and discuss its role in pneumococcal peptidoglycan metabolism. Results Homology searches of the pneumococcal genome allowed the identification of a new domain putatively involved in peptidoglycan cleavage (PECACE, PEptidoglycan CArbohydrate Cleavage Enzyme). This sequence has been found exclusively in Gram-positive bacteria and gene clusters containing pecace are conserved among Streptococcal species. The PECACE domain is, in some instances, found in association with other domains known to catalyze peptidoglycan hydrolysis. Conclusions A new domain, PECACE, putatively involved in peptidoglycan hydrolysis has been identified in S. pneumoniae. The probable enzymatic activity deduced from the detailed analysis of the amino acid sequence suggests that the PECACE domain may proceed through a LT-type or goose lyzosyme-type cleavage mechanism. The PECACE function may differ largely from the other hydrolases already identified in the pneumococcus: LytA, LytB, LytC, CBPD and PcsB. The multimodular architecture of proteins containing the PECACE domain is another example of the many activities harbored by peptidoglycan hydrolases, which is probably required for the regulation of peptidoglycan metabolism. The release of new bacterial genomes sequences will probably add new members to the five groups identified so far in this work, and new groups could also emerge. Conversely, the functional characterization of the unknown domains mentioned in this work can now become easier, since bacterial peptidoglycan is proposed to be the substrate. PMID:15717932

Pagliero, Estelle; Dideberg, Otto; Vernet, Thierry; Di Guilmi, Anne Marie

2005-01-01

40

Novel antibiotics targeting respiratory ATP synthesis in Gram-positive pathogenic bacteria.  

PubMed

Emergence of drug-resistant bacteria represents a high, unmet medical need, and discovery of new antibacterials acting on new bacterial targets is strongly needed. ATP synthase has been validated as an antibacterial target in Mycobacterium tuberculosis, where its activity can be specifically blocked by the diarylquinoline TMC207. However, potency of TMC207 is restricted to mycobacteria with little or no effect on the growth of other Gram-positive or Gram-negative bacteria. Here, we identify diarylquinolines with activity against key Gram-positive pathogens, significantly extending the antibacterial spectrum of the diarylquinoline class of drugs. These compounds inhibited growth of Staphylococcus aureus in planktonic state as well as in metabolically resting bacteria grown in a biofilm culture. Furthermore, time-kill experiments showed that the selected hits are rapidly bactericidal. Drug-resistant mutations were mapped to the ATP synthase enzyme, and biochemical analysis as well as drug-target interaction studies reveal ATP synthase as a target for these compounds. Moreover, knockdown of the ATP synthase expression strongly suppressed growth of S. aureus, revealing a crucial role of this target in bacterial growth and metabolism. Our data represent a proof of principle for using the diarylquinoline class of antibacterials in key Gram-positive pathogens. Our results suggest that broadening the antibacterial spectrum for this chemical class is possible without drifting off from the target. Development of the diarylquinolines class may represent a promising strategy for combating Gram-positive pathogens. PMID:22615276

Balemans, Wendy; Vranckx, Luc; Lounis, Nacer; Pop, Ovidiu; Guillemont, Jérôme; Vergauwen, Karen; Mol, Selena; Gilissen, Ron; Motte, Magali; Lançois, David; De Bolle, Miguel; Bonroy, Kristien; Lill, Holger; Andries, Koen; Bald, Dirk; Koul, Anil

2012-08-01

41

In vitro Activity of Cefdinir (FK482) and Ten Other Antibiotics against Gram-Positive and Gram-Negative Bacteria Isolated from Adult and Pediatric Patients  

Microsoft Academic Search

The in vitro activity of cefdinir, an oral aminothiazolyl hy-droxyimino cephalosporin was compared with that of cefixime, cefpodoxime, cefaclor, cephalexin, ciprofloxacin, ofloxacin, oxacillin, ampicillin, vancomycin and trimethoprim-sulfamethoxazole against 279 gram-positive and gram-negative recent clinical isolates from adult and pediatric patients. Cefdinir was the most active drug among the cephalosporins against oxacil-lin-sensitive Staphylococcus aureus and coagulase-negative staphylococci, Streptococcus pneumoniae, S. pyogenes,

Tanveer Sultan; Aldona L. Baltch; Raymond P. Smith; William Ritz

1994-01-01

42

Lysis of gram-positive and gram-negative bacteria by antibacterial porous polymeric monolith formed in microfluidic biochips for sample preparation.  

PubMed

Bacterial cell lysis is demonstrated using polymeric microfluidic biochips operating via a hybrid mechanical shearing/contact killing mechanism. These biochips are fabricated from a cross-linked poly(methyl methacrylate) (X-PMMA) substrate by well-controlled, high-throughput laser micromachining. The unreacted double bonds at the surface of X-PMMA provide covalent bonding for the formation of a porous polymeric monolith (PPM), thus contributing to the mechanical stability of the biochip and eliminating the need for surface treatment. The lysis efficiency of these biochips was tested for gram-positive (Enterococcus saccharolyticus and Bacillus subtilis) and gram-negative bacteria (Escherichia coli and Pseudomonas fluorescens) and confirmed by off-chip PCR without further purification. The influence of the flow rate when pumping the bacterial suspension through the PPM, and of the hydrophobic-hydrophilic balance on the cell lysis efficiency was investigated at a cell concentration of 10(5) CFU/mL. It was shown that the contribution of contact killing to cell lysis was more important than that of mechanical shearing in the PPM. The biochip showed better lysis efficiency than the off-chip chemical, mechanical, and thermal lysis techniques used in this work. The biochip also acts as a filter that isolates cell debris and allows PCR-amplifiable DNA to pass through. The system performs more efficient lysis for gram-negative than for gram-positive bacteria. The biochip does not require chemical/enzymatic reagents, power consumption, or complicated design and fabrication processes, which makes it an attractive on-chip lysis device that can be used in sample preparation for genetics and point-of-care diagnostics. The biochips were reused for 20 lysis cycles without any evidence of physical damage to the PPM, significant performance degradation, or DNA carryover when they were back-flushed between cycles. The biochips efficiently lysed both gram-positive and gram-negative bacteria in about 35 min per lysis and PPM regeneration cycle. PMID:25059724

Aly, Mohamed Aly Saad; Gauthier, Mario; Yeow, John

2014-09-01

43

Role for intracellular platelet-activating factor in the circulatory failure in a model of gram-positive shock.  

PubMed Central

1. This study investigates the effects of two structurally different antagonists of platelet-activating factor (PAF), BN52021 and WEB2086, on the circulatory and renal failure elicited by lipoteichoic acid (LTA) from Staphylococcus aureus (an organism without endotoxin) in anaesthetized rats. 2. Administration of LTA (10 mg kg-1, i.v.) caused hypotension and vascular hyporeactivity to noradrenaline (1 microgram kg-1, i.v.) WEB2086 (5 mg kg-1, i.v., 20 min before and 150 min after LTA) inhibited the delayed fall in mean arterial blood pressure (at 300 min: 99 +/- 6 mmHg vs. 75 +/- 6 mmHg, P < 0.01) and prevented the decrease in pressor response to noradrenaline (at 300 min: 36 +/- 5 mmHg min vs. 17 +/- 5 mmHg min, P < 0.01). Surprisingly, BN52021 (20 mg kg-1, i.v., 20 min before and 150 min after LTA) neither prevented the hypotension (74 +/- 6 mmHg) nor the vascular hyporeactivity (21 +/- 5 mmHg min). However, BN52021 inhibited the hypotension to injections of PAF as well as the circulatory failure elicited by lipopolysaccharides (10 mg kg-1, i.v.). 3. LTA caused an increase in plasma concentration of creatinine from 39 +/- 5 microM (sham-operated) to 70 +/- 8 microM and urea from 4.7 +/- 0.1 to 13.1 +/- 1.6 mM. The renal failure elicited by LTA was significantly inhibited by WEB2086 (creatinine: 45 +/- 4 microM and urea: 5.7 +/- 0.7 mM), but not by BN52021. 4. The induction of nitric oxide synthase activity in lungs by LTA was attenuated by WEB2086 from 98 +/- 17 to 40 +/- 15 pmol L-citrulline 30 min-1 mg-1 protein (P < 0.01), but not by BN52021 (148 +/- 21 pmol L-citrulline 30 min-1 mg-1 protein). Similarly, WEB2086, but not BN52021, inhibited the increase in plasma nitrite concentration associated with the delayed circulatory failure caused by LTA. The release of tumour necrosis factor-alpha (TNF-alpha) after injection of LTA was not attenuated by WEB2086. 5. The induction of nitrite release by cultured macrophages activated with LTA (10 micrograms ml-1 for 24 h) was inhibited by 74 +/- 4% by WEB2086 (3 x 10(-4) M), but not by BN52021, indicating that only WEB2086 acts on intracellular PAF receptors. 6. Thus, the intracellular release of PAF contributes to the circulatory and renal failure and induction of nitric oxide synthase elicited by LTA in anaesthetized rats. The difference between the two structurally different PAF antagonists in our septic shock models using either LTA or lipopolysaccharide (LPS), shows the importance of models for Gram-positive sepsis in the elucidation of the pathophysiology of septic shock and for the evaluation of potential drugs. PMID:8719795

De Kimpe, S. J.; Thiemermann, C.; Vane, J. R.

1995-01-01

44

Antibacterial Activity of Glutathione-Coated Silver Nanoparticles against Gram Positive and Gram Negative Bacteria  

E-print Network

systems (iii) causing damage in respiration, (iv) perturbation of cellular growth, and (v) interaction. Interference in bacterial cell replication is observed for both cellular strains when exposed to GSH stabilized and other cell constituents (ii) causing K+ loss from the membrane, with disruption of cellular transport

45

In Vitro Activities of Daptomycin, Vancomycin, Quinupristin- Dalfopristin, Linezolid, and Five Other Antimicrobials against 307 Gram-Positive Anaerobic and 31 Corynebacterium Clinical Isolates  

Microsoft Academic Search

The activities of daptomycin, a cyclic lipopeptide, and eight other agents were determined against 338 strains of gram-positive anaerobic bacteria and corynebacteria by the NCCLS reference agar dilution method with supplemented brucella agar for the anaerobes and Mueller-Hinton agar for the corynebacteria. The dapto- mycin MICs determined on Ca2-supplemented (50 mg\\/liter) brucella agar plates were one- to fourfold lower than

Ellie J. C. Goldstein; Diane M. Citron; C. Vreni Merriam; Yumi A. Warren; Kerrin L. Tyrrell; Helen T. Fernandez

2003-01-01

46

Activity of Linezolid against 3,251 Strains of Uncommonly Isolated Gram-Positive Organisms: Report from the SENTRY Antimicrobial Surveillance Program  

Microsoft Academic Search

Linezolid was tested against 32 species of uncommonly isolated gram-positive organisms (3,251 strains) by reference MIC methods and found to be highly active (MIC50 range, 0.25 to 2 g\\/ml; MIC90 range, 0.25 to 2 g\\/ml). Only one isolate (viridans group streptococcus; 0.03% of tested strains) was resistant to linezolid.

Ronald N. Jones; Matthew G. Stilwell; Patricia A. Hogan; Daniel J. Sheehan

2007-01-01

47

In vitro Activity of Monoclonal and Recombinant Yeast Killer Toxin-like Antibodies Against Antibiotic-resistant Gram-positive Cocci  

Microsoft Academic Search

Background: Monoclonal (mAbKT) and recom- binant single-chain (scFvKT) anti-idiotypic anti- bodies were produced to represent the internal image of a yeast killer toxin (KT) characterized by a wide spectrum of antimicrobial activity, including Gram-positive cocci. Pathogenic eukaryotic and prokaryotic microorganisms, such as Candida albi- cans, Pneumocystis carinii, and a multidrug-resistant strain of Mycobacterium tuberculosis, presenting spe- cific, although yet undefined,

S. Conti; W. Magliani; S. Arseni; E. Dieci; A. Salati; P. E. Varaldo; L. Polonelli

2000-01-01

48

Isolation and Characterization of Microsphaera multipartita gen. nov., sp. nov., a Polysaccharide-Accumulating Gram-Positive Bacterium from Activated Sludge  

Microsoft Academic Search

A new gram-positive bacterium was isolated from activated sludge acclimated with sugar-containing syn- thetic wastewater. This organism, designated strain Y-104T (T = type strain), was a coccus-shaped, aerobic chemoorganotroph that had a strictly respiratory type of metabolism with oxygen as the terminal electron acceptor. This strain accumulates large amounts of polysaccharide in its cells. Strain Y-104T has the following chemotaxonomic

YUKIHIKO YOSHIM; AURA HIRAISHI; KAZUNORI NAKAMUFU

49

Expanding the Use of a Fluorogenic Method to Determine Activity and Mode of Action of Bacillus thuringiensis Bacteriocins Against Gram-Positive and Gram-Negative Bacteria  

PubMed Central

Previously we described a rapid fluorogenic method to measure the activity of five bacteriocins produced by Mexican strains of Bacillus thuringiensis against B. cereus 183. Here we standardize this method to efficiently determine the activity of bacteriocins against both Gram-positive and Gram-negative bacteria. It was determined that the crucial parameter required to obtain reproducible results was the number of cells used in the assay, that is, ~4?×?108?cell/mL and ~7?×?108?cell/mL, respectively, for target Gram-positive and Gram-negative bacteria. Comparative analyses of the fluorogenic and traditional well-diffusion assays showed correlation coefficients of 0.88 to 0.99 and 0.83 to 0.99, respectively, for Gram-positive and Gram-negative bacteria. The fluorogenic method demonstrated that the five bacteriocins of B. thuringiensis have bacteriolytic and bacteriostatic activities against all microorganisms tested, including clinically significant bacteria such as Listeria monocytogenes, Proteus vulgaris, and Shigella flexneri reported previously to be resistant to the antimicrobials as determined using the well-diffusion protocol. These results demonstrate that the fluorogenic assay is a more sensitive, reliable, and rapid method when compared with the well-diffusion method and can easily be adapted in screening protocols for bacteriocin production by other microorganisms. PMID:22919330

de la Fuente-Salcido, Norma M.; Barboza-Corona, J. Eleazar; Espino Monzon, A. N.; Pacheco Cano, R. D.; Balagurusamy, N.; Bideshi, Dennis K.; Salcedo-Hernandez, Ruben

2012-01-01

50

Antibacterial activity of traditional Australian medicinal plants  

Microsoft Academic Search

Fifty-six ethanolic extracts of various parts of 39 plants used in traditional Australian Aboriginal medicine were investigated for their antibacterial activities against four Gram-positive (Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus and Streptococcus pyogenes) and four Gram-negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Salmonella typhimurium) bacterial species. In a plate-hole diffusion assay, 12 extracts inhibited the growth of one or

Enzo A Palombo; Susan J Semple

2001-01-01

51

Antibacterial activity of gemini quaternary ammonium salts.  

PubMed

A series of gemini quaternary ammonium salts (chlorides and bromides), with various hydrocarbon chain and spacer lengths, were tested. These compounds exhibited antibacterial activity against both Gram-positive and Gram-negative bacteria and were not mutagenic. The strongest antibacterial effect was observed for TMPG-10 Cl (against Pseudomonas aeruginosa ATCC 27853) and TMPG-12 Br (against Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 11229 and clinical ESBL(+) isolate 434) surfactants. These compounds inhibited the adhesion of Staphylococcus epidermidis ATCC 35984 to a polystyrene surface and eradicated biofilm formed by P. aeruginosa PAO1. The activity of studied compounds was dependent on hydrocarbon chain length. PMID:24236547

Ob??k, Ewa; Piecuch, Agata; Guz-Regner, Katarzyna; Dworniczek, Ewa

2014-01-01

52

Antibacterial activity of South African plants used for medicinal purposes  

Microsoft Academic Search

Crude extracts from 21 South African medicinal plants, traditionally used for ailments of an infectious or septic nature, were screened for in vitro antibacterial activity using the agar diffusion and dilution methods. Almost all the activity exhibited was against Gram-positive bacteria, with 12 of the 21 plant species tested showing some activity against Bacillus subtilis. Only the Warburgia salutaris methanol

Tonia Rabe; Johannes van Staden

1997-01-01

53

Antibacterial Effects of Low Power Laser Light and Volatile Oil of Fennel (Foeniculum vulgare var. dulce) on Gram-positive and Gram-negative Bacteria  

Microsoft Academic Search

In this study, the antibacterial effects of a toluidine blue O (TBO), light from a helium\\/neon (He - Ne) laser and essential oil extracted from seeds, leaves and stems of Sweet fennel plants (foliarly sprayed with nicotinamide by concentrations in a range of (zero, 20, 40, 80 & 100 mg\\/L) on Escherichia coli, Serratia marcesence, Klebsiella pneumoniae as a gram-negative

AMIRA A. EL-ADLY; EMAD A. ABADA; FATMA A. GHARIB

54

Antibacterial activities of fluorovinyl- and chlorovinylglycine and several derived dipeptides.  

PubMed Central

The in vitro antibacterial activities of several halovinylglycine compounds and their L-norvalyl peptide derivatives are presented. The most potent of them, L-norvalyl-L-chlorovinylglycine, displayed good activity against gram-positive organisms, including methicillin-resistant Staphylococcus species. Chlorovinylglycine is an efficient inhibitor of alanine racemase, but the antibacterial activity of L-norvalyl-L-chlorovinylglycine may involve other physiological targets as well. PMID:3284459

Patchett, A A; Taub, D; Weissberger, B; Valiant, M E; Gadebusch, H; Thornberry, N A; Bull, H G

1988-01-01

55

Composition and Antibacterial Activity of Achillea asplenifolia Essential Oil  

Microsoft Academic Search

The oil of a wild growing population of Achillea asplenifolia Vent, was studied for yield, composition and antibacterial activity. The major components in the oil were ?-caryophyllene (17.6%), germacrene D (15.6%) and chamazulene (13.3%). In an antibacterial diffusion assay, the oil showed activity against all tested Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) and Gram-positive Staphylococcus aureus.

Nebojsa Simic; Radosav Palic; Vlatka Vajs; Slobodan Milosavljevic; Dejan Djokovic

2002-01-01

56

Alternating electric fields combined with activated carbon for disinfection of Gram negative and Gram positive bacteria in fluidized bed electrode system.  

PubMed

Strong electric fields for disinfection of wastewaters have been employed already for several decades. An innovative approach combining low strength (7 V/cm) alternating electric fields with a granular activated carbon fluidized bed electrode (FBE) for disinfection was presented recently. For disinfection performance of FBE several pure microbial cultures were tested: Bacillus subtilis, Bacillus subtilis subsp. subtilis, Enterococcus faecalis as representatives from Gram positive bacteria and Erwinia carotovora, Pseudomonas luteola, Pseudomonas fluorescens and Escherichia coli YMc10 as representatives from Gram negative bacteria. The alternating electric field amplitude and shape were kept constant. Only the effect of alternating electric field frequency on disinfection performance was investigated. From the bacteria tested, the Gram negative strains were more susceptible and the Gram positive microorganisms were more resistant to FBE disinfection. The collected data indicate that the efficiency of disinfection is frequency and strain dependent. During 6 h of disinfection, the decrease above 2 Log units was achieved with P. luteola and E. coli at 10 kHz and at dual frequency shift keying (FSK) modulated signal with frequencies of 10 kHz and 140 kHz. FBE technology appears to offer a new way for selective bacterial disinfection, however further optimizations are needed on treatment duration, and energy input, to improve effectiveness. PMID:24012021

Racyte, Justina; Bernard, Séverine; Paulitsch-Fuchs, Astrid H; Yntema, Doekle R; Bruning, Harry; Rijnaarts, Huub H M

2013-10-15

57

Silver triflate catalyzed synthesis of 3-aminoalkylated indoles and evaluation of their antibacterial activities  

PubMed Central

An efficient, one-pot synthesis was developed for 3-aminoalkylated indoles by three-component coupling reaction of aldehydes, N-methylanilines, and indoles using AgOTf as a catalyst. A series of twenty 3-aminoalkylated indoles was evaluated for their antibacterial activities against both Gram negative and Gram positive bacteria. Compounds 4b and 4r showed good antibacterial activity against both Gram positive and Gram negative strains. However, inversing the property of substituent (from 4r to 4q) resulted in the significant fall in the magnitude of antibacterial activity against Escherichia coli. PMID:22373086

2011-01-01

58

A new hybrid bacteriocin, Ent35–MccV, displays antimicrobial activity against pathogenic Gram-positive and Gram-negative bacteria  

PubMed Central

Bacteriocins and microcins are ribosomally synthesized antimicrobial peptides that are usually active against phylogenetically related bacteria. Thus, bacteriocins are active against Gram-positive while microcins are active against Gram-negative bacteria. The narrow spectrum of action generally displayed by bacteriocins from lactic acid bacteria represents an important limitation for the application of these peptides as clinical drugs or as food biopreservatives. The present study describes the design and expression of a novel recombinant hybrid peptide combining enterocin CRL35 and microcin V named Ent35–MccV. The chimerical bacteriocin displayed antimicrobial activity against enterohemorrhagic Escherichia coli and Listeria monocytogenes clinical isolates, among other pathogenic bacteria. Therefore, Ent35–MccV may find important applications in food or pharmaceutical industries. PMID:23650575

Acuńa, Leonardo; Picariello, Gianluca; Sesma, Fernando; Morero, Roberto D.; Bellomio, Augusto

2012-01-01

59

In vitro activities of daptomycin, vancomycin, quinupristin- dalfopristin, linezolid, and five other antimicrobials against 307 gram-positive anaerobic and 31 Corynebacterium clinical isolates.  

PubMed

The activities of daptomycin, a cyclic lipopeptide, and eight other agents were determined against 338 strains of gram-positive anaerobic bacteria and corynebacteria by the NCCLS reference agar dilution method with supplemented brucella agar for the anaerobes and Mueller-Hinton agar for the corynebacteria. The daptomycin MICs determined on Ca(2+)-supplemented (50 mg/liter) brucella agar plates were one- to fourfold lower than those determined in unsupplemented media. Daptomycin was highly active (MICs, active than vancomycin against Clostridium innocuum and 16 of 34 strains of vancomycin-resistant lactobacilli. Three strains of C. difficile for which quinupristin-dalfopristin and linezolid MICs were >8 microg/ml were inhibited by <1 microg of daptomycin per ml. Daptomycin MICs were >or=4 microg/ml for most strains of Clostridium clostridioforme, Clostridium paraputrificum, Clostridium tertium, and Clostridium ramosum; the isolates were generally more resistant to other antimicrobials. Daptomycin was two- to fourfold less active against Actinomyces spp. than vancomycin, quinupristin-dalfopristin, or linezolid. Twenty-nine of 31 strains of Corynebacterium spp., including Corynebacterium jeikeium, Corynebacterium amycolatum, and Corynebacterium pseudodiphtheriticum, were inhibited by activities against a broad range of gram-positive organisms including vancomycin-resistant C. innocuum and lactobacillus strains and quinupristin-dalfopristin- and linezolid-resistant C. difficile strains. PMID:12499210

Goldstein, Ellie J C; Citron, Diane M; Merriam, C Vreni; Warren, Yumi A; Tyrrell, Kerrin L; Fernandez, Helen T

2003-01-01

60

In Vitro Activities of Daptomycin, Vancomycin, Quinupristin- Dalfopristin, Linezolid, and Five Other Antimicrobials against 307 Gram-Positive Anaerobic and 31 Corynebacterium Clinical Isolates  

PubMed Central

The activities of daptomycin, a cyclic lipopeptide, and eight other agents were determined against 338 strains of gram-positive anaerobic bacteria and corynebacteria by the NCCLS reference agar dilution method with supplemented brucella agar for the anaerobes and Mueller-Hinton agar for the corynebacteria. The daptomycin MICs determined on Ca2+-supplemented (50 mg/liter) brucella agar plates were one- to fourfold lower than those determined in unsupplemented media. Daptomycin was highly active (MICs, ?2 ?g/ml) against many strains including 36 of 37 peptostreptococci, 37 of 48 isolates of the Eubacterium group, and all strains of Propionibacterium spp., Clostridium perfringens, Clostridium difficile, and other Clostridium spp. It was fourfold or greater more active than vancomycin against Clostridium innocuum and 16 of 34 strains of vancomycin-resistant lactobacilli. Three strains of C. difficile for which quinupristin-dalfopristin and linezolid MICs were >8 ?g/ml were inhibited by <1 ?g of daptomycin per ml. Daptomycin MICs were ?4 ?g/ml for most strains of Clostridium clostridioforme, Clostridium paraputrificum, Clostridium tertium, and Clostridium ramosum; the isolates were generally more resistant to other antimicrobials. Daptomycin was two- to fourfold less active against Actinomyces spp. than vancomycin, quinupristin-dalfopristin, or linezolid. Twenty-nine of 31 strains of Corynebacterium spp., including Corynebacterium jeikeium, Corynebacterium amycolatum, and Corynebacterium pseudodiphtheriticum, were inhibited by ?0.25 ?g of daptomycin per ml. For two strains of “Corynebacterium aquaticum,” 8 ?g of daptomycin per ml was required for inhibition. Daptomycin demonstrated very good activities against a broad range of gram-positive organisms including vancomycin-resistant C. innocuum and lactobacillus strains and quinupristin-dalfopristin- and linezolid-resistant C. difficile strains. PMID:12499210

Goldstein, Ellie J. C.; Citron, Diane M.; Merriam, C. Vreni; Warren, Yumi A.; Tyrrell, Kerrin L.; Fernandez, Helen T.

2003-01-01

61

Activities of the Semisynthetic Glycopeptide LY191145 against Vancomycin-Resistant Enterococci and Other Gram-Positive Bacteria  

Microsoft Academic Search

LY191145 is the prototype of a series of compounds with activities against vancomycin-resistant enterococci derived by modification of the glycopeptide antibiotic LY264826. LY191145 had MICs for vancomycin- and teicoplanin-resistant enterococci of <4 mg\\/ml for 50% of isolates and <16 mg\\/ml for 90% of isolates. Its MICs for vancomycin-resistant, teicoplanin-susceptible enterococci were 1 to 8 mg\\/ml. LY191145 retains the potent activities

THALIA I. NICAS; DEBORAH L. MULLEN; JANE E. FLOKOWITSCH; DAVID A. PRESTON; NANCY J. SNYDER; ROBERT E. STRATFORD; ANDROBIN D. G. COOPER

1995-01-01

62

Activity of Bay y3118 against quinolone-susceptible and -resistant gram-negative and gram-positive bacteria.  

PubMed Central

The activity of Bay y3118 against laboratory strains of bacteria, including those with mutations in gyrA, with decreased expression of outer membrane proteins, and/or that are multiply resistant, and 121 selected clinical isolates, including highly fluoroquinolone-resistant bacteria from Spain and Argentina, was determined. Bay y3118 was extremely active (MICs, < or = 1 microgram/ml) against all bacteria, including quinolone-resistant laboratory strains. However, Bay y3118 was less active against 46 of 121 quinolone-resistant clinical isolates, such that > or = 16 micrograms of Bay y3118 per ml was required to inhibit 3 isolates. The concentration of Bay y3118 required to inhibit DNA synthesis by 50% correlated well with the MIC. Bay y3118 had accumulation kinetics similar to those of previously studied fluoroquinolones, e.g., ciprofloxacin, and there was a 50% decrease in the steady-state concentration in those members of the family Enterobacteriaceae that lacked porin proteins. Magnesium chloride at 20 mM apparently abolished the accumulation of Bay y3118 into Escherichia coli and reduced the level of accumulation into other gram-negative bacteria and Staphylococcus aureus. Carbonyl cyanide m-chlorophenylhydrazone at 100 microM enhanced the accumulation of Bay y3118 into E. coli, but it had a minimal effect on accumulation into S. aureus. PMID:8203834

Piddock, L J; Marshall, A J; Jin, Y F

1994-01-01

63

Characterisation and in vitro activities of surface attached dihydropyrrol-2-ones against Gram-negative and Gram-positive bacteria.  

PubMed

Bacterial infection of biomedical devices is still a major barrier to their use. This is compounded by increasing antibiotic resistance. Here, the specific covalent attachment of a series of dihydropyrrol-2-one (DHP), analogues of bacterial quorum sensing inhibitors, to surfaces via a Michael-type addition reaction is described. Differences in efficiency of attachment related to the substituent groups were found by X-ray photoelectron spectroscopy. The physical characteristics of the surfaces were further explored by atomic force microscopy and contact angle measurements. The ability of these coatings to prevent the formation of a biofilm by Pseudomonas aeruginosa and Staphylococcus aureus was examined using confocal laser scanning microscopy and image analysis. The DHP-treated surfaces showed significant reductions in bacterial adhesion without increased killing for both strains of bacteria (p < 0.001). 5-Methylene-1-(prop-2-enoyl)-4-phenyl-dihydropyrrol-2-one was identified as having broad spectrum activity and consequently represents an excellent candidate for the development of novel surfaces for the prevention of biomedical device infections. PMID:21038151

Ho, Kitty K K; Cole, Nerida; Chen, Renxun; Willcox, Mark D P; Rice, Scott A; Kumar, Naresh

2010-11-01

64

Antibacterial and antioxidant activities in Sideritis italica (Miller) Greuter et Burdet essential oils  

Microsoft Academic Search

Sideritis italica (Miller) Greuter et Burdet is a widespread Lamiacea in the Mediterranean region used in traditional medicine. Essential oils were antibacterial against nine ATCC and as many clinically isolated Gram-positive and Gram-negative bacterial strains. Antibacterial activity was also found against Helicobacter pylori: a dose-dependant inhibition was shown between 5 and 25?g\\/ml. The antibacterial activity of the oils was expressed

Adriana Basile; Felice Senatore; Rosalba Gargano; Sergio Sorbo; Marisa Del Pezzo; Alfredo Lavitola; Alberto Ritieni; Maurizio Bruno; Daniela Spatuzzi; Daniela Rigano; Maria Luisa Vuotto

2006-01-01

65

Antimicrobial activity of daptomycin tested against gram-positive strains collected in European hospitals: results from 7 years of resistance surveillance (2003-2009).  

PubMed

Daptomycin is a cyclic lipopeptide approved by the European medicines Agency (EMEA) for the treatment of complicated skin and soft tissue infections (cSSTI) and Staphylococcus aureus bacteremia and endocarditis. We evaluated the in vitro activity of daptomycin and comparators tested against clinical isolates from european hospitals over a 7-year period (2003-2009). A total of 36,769 consecutive isolates were collected in 34 medical centers located in 13 European countries, Turkey and Israel. the collection included S. aureus (18,352; 27.2% oxacillin-resistant [MRSA]); coagulase-negative staphylococci (CoNS; 6,874), Enterococcus spp. (7,241; 9.4% vancomycin-resistant), ?-hemolytic (3,009), viridans group streptococci (1,176), and Streptococcus bovis/gallolyticus (107). The organisms were isolated mainly from patients with bloodstream infection (56%) or cSSTI (23%). Daptomycin was very active against S. aureus and CoNS (MIC(50/90), 0.25/0.5 mg/l for both organisms), and its activity was not adversely influenced by oxacillin resistance. All Enterococcus faecalis strains were susceptible to daptomycin (MIC(50/90), 1/1 mg/l). Daptomycin (MIC(50/90), 2/2 mg/l; 100.0% susceptible) and linezolid (MIC(50/90), 1/2 mg/l; 99.7% susceptible) were the most active agents tested against vancomycin-resistant E. faecium. Vancomycin- resistant and -susceptible enterococcal strains were equally susceptible to daptomycin. Daptomycin was also active against ?-hemolytic streptococci (MIC(50/90), 0.06/0.25 mg/l; 100.0% susceptible), viridans group streptococci (MIC(50/90), 0.25/0.5 mg/l; 99.8% susceptible) and S. bovis (MIC(50/90), 0.06/0.12 mg/l; 100.0% susceptible).In summary, daptomycin was very potent against this large collection (36,769) of Gram-positive organisms isolated in european hospitals, and its activity remained stable across the 7-year period evaluated (2003-2009), using reference methods and interpretive criteria. Decreases in daptomycin potency were not observed since EMEA approval and widespread clinical use, and emerging resistance to other compounds did not adversely influence daptomycin activity against contemporary Gram-positive species. PMID:21803696

Sader, H S; Farrell, D J; Jones, R N

2011-08-01

66

Antibacterial activity of plants that are used in the treatment of heartwater in livestock and the isolation and identification of bioactive compounds from Petalidium Oblongifolium and Ipomoea adenioides.  

E-print Network

??The general antibacterial activity of Drimia delagoansis, Petalidium oblongifolium and Ipomoea adenioides was determined using selected Gram-positive and Gram-negative bacteria. Only extracts or compounds with… (more)

Mokwala, Phatlane William

2007-01-01

67

Synthesis and antibacterial activity of nitroaryl thiadiazole-gatifloxacin hybrids.  

PubMed

A number of gatifloxacin analogues containing a nitroaryl-1,3,4-thiadiazole moiety attached to the piperazine ring at C-7 position were prepared and evaluated as antibacterial agents against a panel of gram-positive and gram-negative bacteria. Among synthesized compounds, nitrofuran analog 6a exhibited more potent inhibitory activity against gram-positive bacteria including Staphylococcus epidermidis (MIC=0.0078 microg/mL), Bacillus subtilis (MIC=0.0039 microg/mL), Enterococcus faecalis (MIC=0.125 microg/mL) and Micrococcus luteus (MIC=0.125 microg/mL), with respect to other synthesized compounds and reference drug gatifloxacin. The target compounds were also assessed for their cytotoxic activity against normal mouse fibroblast (NIH/3T3) cells using MTT assay. The results indicated that these compounds exhibit antibacterial activity at non-cytotoxic concentrations. PMID:18950903

Jazayeri, Seyyedehsamira; Moshafi, Mohammad Hassan; Firoozpour, Loghman; Emami, Saeed; Rajabalian, Saeed; Haddad, Mitra; Pahlavanzadeh, Farahnaz; Esnaashari, Manzarbanoo; Shafiee, Abbas; Foroumadi, Alireza

2009-03-01

68

Antimicrobial Activity of the Investigational Pleuromutilin Compound BC-3781 Tested against Gram-Positive Organisms Commonly Associated with Acute Bacterial Skin and Skin Structure Infections  

PubMed Central

BC-3781 is a novel semisynthetic pleuromutilin antimicrobial agent developed as an intravenous and oral therapy for acute bacterial skin and skin structure infections (ABSSSI) and respiratory tract infections (RTI). BC-3781 and comparator agents were tested by the broth microdilution method against 1,893 clinical Gram-positive organisms predominantly causing ABSSSI. BC-3781 exhibited potent activity against methicillin-resistant Staphylococcus aureus (MIC50/90, 0.12/0.25 ?g/ml), coagulase-negative staphylococci (MIC50/90, 0.06/0.12 ?g/ml), ?-hemolytic streptococci (MIC50/90, 0.03/0.06 ?g/ml), viridans group streptococci (MIC50/90, 0.12/0.5 ?g/ml), and Enterococcus faecium (including vancomycin-nonsusceptible strains) (MIC50/90, 0.12/2 ?g/ml). Compared with other antibiotics in use for the treatment of ABSSSI, BC-3781 displayed the lowest MICs and only a minimal potential for cross-resistance with other antimicrobial classes. PMID:22232289

Biedenbach, Douglas J.; Paukner, Susanne; Ivezic-Schoenfeld, Zrinka; Jones, Ronald N.

2012-01-01

69

Antibacterial, antifungal and antiviral activity of propolis of different geographic origin  

Microsoft Academic Search

Propolis samples from different geographic origins were investigated for their antibacterial (against Staphylococcus aureus and Escherichia coli), antifungal (against Candida albicans) and antiviral (against Avian influenza virus) activities. All samples were active against the fungal and Gram-positive bacterial test strains, and most showed antiviral activity. The activities of all samples were similar in spite of the differences in their chemical

A Kujumgiev; I Tsvetkova; Yu Serkedjieva; V Bankova; R Christov; S Popov

1999-01-01

70

In vitro antibacterial activity of some plant essential oils  

Microsoft Academic Search

BACKGROUND:: To evaluate the antibacterial activity of 21 plant essential oils against six bacterial species. METHODS:: The selected essential oils were screened against four gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus vulgaris) and two gram-positive bacteria Bacillus subtilis and Staphylococcus aureus at four different concentrations (1:1, 1:5, 1:10 and 1:20) using disc diffusion method. The MIC of the

Seenivasan Prabuseenivasan; Manickkam Jayakumar; Savarimuthu Ignacimuthu

2006-01-01

71

Antibacterial screening of Citrullus colocynthis.  

PubMed

Crude ethanolic extracts of fruits, leaves, stems and roots of Citrullus colocynthis Schrad were examined for their antibacterial potentialities against Gram positive and Gram negative bacilli. Ethanolic extracts of fruits, leaves, stems and roots were found to be active against Gram positive bacilli, viz., Bacillus pumilus and Staphylococcus aureus, while fruit and root extracts in double strength gave positive results against Gram positive bacillus (Bacillus subtilis). The Gram negative bacilli viz., Escherichia coli and Pseudomonas aeruginosa showed no response. PMID:16414561

Memon, Usman; Brohi, Abdul Hakeem; Ahmed, Syed Waseemuddin; Azhar, Iqbal; Bano, Husan

2003-01-01

72

ANTIBACTERIAL SCREENING OF CITRULLUS COLOCYNTHIS  

Microsoft Academic Search

Crude ethanolic extracts of fruits, leaves, stems and roots of Citrulus colocynthis Schrad were examined for their antibacterial potentialities against Gram positive and Gram negative bacilli. Ethanolic extracts of fruits, leaves, stems and roots were found to be active against Gram positive bacilli, viz., Bacilus pumilus and Staphylococcus aureus, while fruit and root extracts in double strength gave positive results

USMAN MEMON; ABDUL HAKEEM BROHI; SYED WASEEMUDDIN AHMED; IQBAL AZHAR; HUSAN BANO

73

Optimizing the antibacterial activity of a lead structure discovered by "SAR by MS" technology.  

PubMed

We report on lead optimization of a compound that was originally discovered to bind bacterial 23S rRNA near the L11 binding site and inhibit translation in vitro, but lacked detectable antibacterial activity. In this study, we were able to generate compounds with antibacterial activity against Gram-negative and Gram-positive pathogens, including a methicillin-resistant S. aureus strain. PMID:15454207

Jefferson, Elizabeth A; Seth, Punit P; Robinson, Dale E; Winter, Dana K; Miyaji, Alycia; Risen, Lisa M; Osgood, Stephen A; Bertrand, Myra; Swayze, Eric E

2004-11-01

74

Correlation between Major Constituents and Antibacterial Activities of Some Plant Essential Oils against Some Pathogenic Bacteria  

Microsoft Academic Search

Five different plant essential oils (Satureja hortensis, Thymus sipyleus ssp. rosulans, Thymus haussknechtii, Origanum rotundifolium (cultured form) and Origanum acutidens (wild and cultured form)) and their two major constituents carvacarol and thymol were evaluated for antibacterial activity against food-borne Gram negative (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Salmonella enteritidis) and Gram positive bacteria (Bacillus subtilis, Streptococcus pyogenes and Enterococcus

Neslihan Dikbas; Recep Kotan; Fatih Dadasoglu; Kenan Karagöz; Ramazan Çakmakci

75

Screening of antibacterial activity of Amaicha del Valle (Tucumán, Argentina) propolis  

Microsoft Academic Search

Propolis is extensively used in Argentine folk medicine. Alcoholic extracts of propolis from four localities of Amaicha del Valle (El Paraiso, La Banda Este, La Banda Oeste and El Molino), Province of Tucumán and from Cerrillos, Province of Santiago del Estero, Argentina were prepared. All showed antibacterial activity against Gram positive bacteria, the propolis from La Banda Este being the

M. I. Nieva Moreno; M. I. Isla; N. G. Cudmani; M. A. Vattuone; A. R. Sampietro

1999-01-01

76

Antibacterial activities of some marine algae from the Aegean Sea (Turkey)  

Microsoft Academic Search

In this study, methanolic extracts of six marine algae belong to Rhodophyceae (Corallina officinalis), Phaeophyceae (Cystoseira barbata, Dictyota dichotoma, Halopteris filicina, Cladostephus spongiosus f. verticillatus) and Chlorophyceae (Ulva rigida) from the North Aegean Sea (Turkey) were studied for their antibacterial activity against pathogenic microbes, 3 gram positive (Staphylococcus aureus, Micrococcus luteus and Enterococcus faecalis) and 3 Gram negative (Escherichia coli,

E. Taskin; M. Ozturk; O. Kurt

77

Synergistic antibacterial activity between Thymus vulgaris and Pimpinella anisum essential oils and methanol extracts  

Microsoft Academic Search

Essential oils (EOs) and methanol extracts obtained from aerial parts of Thymus vulgaris and Pimpinella anisum seeds were evaluated for their single and combined antibacterial activities against nine Gram-positive and Gram-negative pathogenic bacteria: Staphylococcus aureus, Bacillus cereus, Escherichia coli, Proteus vulgaris, Proteus mirabilis, Salmonella typhi, Salmonella typhimurium, Klebsiella pneumoniae and Pseudomonas aeruginosa. The essential oils and methanol extracts revealed promising

Firas A. Al-Bayati

2008-01-01

78

Comparative In Vitro Activities of AC98-6446, a Novel Semisynthetic Glycopeptide Derivative of the Natural Product Mannopeptimycin  , and Other Antimicrobial Agents against Gram-Positive Clinical Isolates  

Microsoft Academic Search

AC98-6446 is a novel semisynthetic cyclic glycopeptide antibiotic related to the natural product mannopep- timycin (AC98-1). In the present study the activity of AC98-6446 was evaluated against a variety of recent clinical gram-positive pathogens including multiply resistant strains. AC98-6446 demonstrated similar potent activities against methicillin-susceptible and methicillin-resistant staphylococci and glycopeptide-intermediate staphylococcal isolates (MICs at which 90% of isolates are inhibited

Peter J. Petersen; T. Z. Wang; Russell G. Dushin; Patricia A. Bradford

2004-01-01

79

Antibacterial activities of erythromycins A, B, C, and D and some of their derivatives.  

PubMed Central

The MICs of erythromycins A, B, C, and D and some of their derivatives were determined against 21 gram-positive and 15 gram-negative microorganisms. Antibacterial activity was confined to gram-positive and very few gram-negative bacteria. Erythromycin B was somewhat less active than erythromycin A, and erythromycin C and D showed about half that activity or even less. Most other derivatives had negligible activity. Determination of potency by diffusion and turbidimetric assays were in line with MICs. The examination of the results of these assays, however, revealed that there are differences between the data of different laboratories, depending on the microorganisms and conditions used. PMID:4091529

Kibwage, I O; Hoogmartens, J; Roets, E; Vanderhaeghe, H; Verbist, L; Dubost, M; Pascal, C; Petitjean, P; Levol, G

1985-01-01

80

Synthesis and antibacterial activity of some novel N-substituted piperazinyl-quinolones.  

PubMed

A series of N-substituted-piperazinyl-quinolones were synthesized and evaluated for in vitro antibacterial activity. Compounds with a 2-(2,4-dichlorophenyl)-2-oxoethyl group attached to the piperazine ring (5a-c) had similar antibacterial activity to the reference drugs, ciprofloxacin, norfloxacin and enoxacin against both Gram-positive and Gram-negative bacteria. The oximes 6a-c and 6g-i were almost less active than corresponding ketones against the tested microorganisms, however the 2,4-difluorophenyl analogues (6g-i) were more active than 2,4-dichlorophenyl derivatives (6a-c). If the hydrogen of oxime is replaced with a benzyl group (6d-f & 6j-l), in-vitro antibacterial activity was decreased against both Gram-positive and Gram-negative bacteria. Generally ciprofloxacin derivatives were more active than norfloxacin and enoxacin derivatives. PMID:11822230

Foroumadi, A; Davood, A; Mirzaei, M; Emami, S; Moshafi, M H

2001-01-01

81

Comparative In Vitro Activities of SMT19969, a New Antimicrobial Agent, against Clostridium difficile and 350 Gram-Positive and Gram-Negative Aerobic and Anaerobic Intestinal Flora Isolates  

PubMed Central

The comparative in vitro activity of SMT19969, a novel, narrow-spectrum, nonabsorbable agent, was studied against 50 ribotype-defined Clostridium difficile strains, 174 Gram-positive and 136 Gram-negative intestinal anaerobes, and 40 Gram-positive aerobes. SMT19969 was one dilution more active against C. difficile isolates (MIC range, 0.125 to 0.5 ?g/ml; MIC90, 0.25 ?g/ml), including ribotype 027 strains, than fidaxomicin (range, 0.06 to 1 ?g/ml; MIC90, 0.5 ?g/ml) and two to six dilutions lower than either vancomycin or metronidazole. SMT19969 and fidaxomicin were generally less active against Gram-negative anaerobes, especially the Bacteroides fragilis group species, than vancomycin and metronidazole, suggesting that SMT19969 has a lesser impact on the normal intestinal microbiota that maintain colonization resistance. SMT19969 showed limited activity against other Gram-positive anaerobes, including Bifidobacteria species, Eggerthella lenta, Finegoldia magna, and Peptostreptococcus anaerobius, with MIC90s of >512, >512, 64, and 64 ?g/ml, respectively. Clostridium species showed various levels of susceptibility, with C. innocuum being susceptible (MIC90, 1 ?g/ml) and C. ramosum and C. perfringens being nonsusceptible (MIC90, >512 ?g/ml). Activity against Lactobacillus spp. (range, 0.06 to >512 ?g/ml; MIC90, >512 ?g/ml) was comparable to that of fidaxomicin and varied by species and strain. Gram-positive aerobic cocci (Staphylococcus aureus, Enterococcus faecalis, E. faecium, and streptococci) showed high SMT19969 MIC90 values (128 to >512 ?g/ml). PMID:23877700

Citron, Diane M.; Tyrrell, Kerin L.; Merriam, C. Vreni

2013-01-01

82

Crystallography of Gram-Positive Bacterial Adhesins  

Microsoft Academic Search

\\u000a Both Gram-negative and Gram-positive pathogens display a multitude of proteins and protein assemblies (pili or fimbriae) on\\u000a their cell surfaces, which are often used for adherence and initiate colonization and pathogenesis. Adhesive proteins known\\u000a as MSCRAMMs (microbial surface components recognizing adhesive matrix molecules), anchored by a specific enzyme called sortase\\u000a in Gram-positive bacteria, target the host’s extracellular matrix proteins (ECM)

Vengadesan Krishnan; Sthanam V. L. Narayana

83

Antimicrobial Resistance in Gram-Positive Bacteria  

Microsoft Academic Search

Gram-positive bacteria are common causes of bloodstream and other infections in hospitalized patients in the United States, and the percentage of nosocomial bloodstream infections caused by antibiotic-resistant gram-positive bacteria is increasing. Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are of particular concern. In the United States, approximately 60% of staphylococcal infections in the intensive care unit are now caused

Louis B. Rice

2006-01-01

84

Screening of Ethanol, Petroleum Ether and Chloroform Extracts of Medicinal Plants, Lawsonia inermis L. and Mimosa pudica L. for Antibacterial Activity  

PubMed Central

Organic extracts (ethanol, petroleum ether and chloroform) of two medicinal plants Lawsonia inermis L. and Mimosa pudica L. were proven for antibacterial properties against 15 Gram-positive and Gram-negative human pathogenic bacteria. Among the three types of extracts tested, ethanol extract was found to possess maximum antibacterial activity. The diameter of the zone of inhibition of bacterial growth showed that Gram-negative bacteria are more sensitive than Gram-positive bacteria to plant extracts. Between the two plants species studied, Lawsonia inermis extract showed more antibacterial activity compared to Mimosa pudica extract. PMID:21188055

Akter, A.; Neela, F. A.; Khan, M. S. I.; Islam, M. S.; Alam, M. F.

2010-01-01

85

[Antibacterial activity of water soluble fraction from Scolopendra subspinipes mutilans].  

PubMed

The water soluble fraction (SWSF) of centipede Scolopendra subspinipes mautilans, injected with Escherichia coli K12 D31 for 3-4 days showed broad-spectrum antimicrobial activity against Gram-positive, Gram-negative bacteria and fungi. It showed strong antibacterial activity against E. coli K12D31 at different temperatures, pH and ionic strengths. It did not show any hemolytic and agglutination activities at the concentration below 600 microg/ml. After E. coli K12 D31 treated with SWSF, the ultrastructure showed that its outer cell wall was broken, surface collapsed and intracellular substances leaked out. PMID:17539295

Ren, Wen-hua; Zhang, Shuang-quan; Song, Da-xiang; Zhou, Kai-ya

2007-01-01

86

Synthesis and antibacterial activity of quinolone-based compounds containing a coumarin moiety.  

PubMed

A new series of quinolone-based compounds containing a coumarin moiety have been synthesized and studied for their antibacterial activity against a panel of gram-positive and gram-negative bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). The results of the antibacterial evaluation of N-[2-(coumarin-3-yl)ethyl]piperazinyl quinolone derivatives in comparison with parent quinolones (norfloxacin, ciprofloxacin, and enoxacin) indicated that N-[2-(coumarin-3-yl)-2-oxoethyl]ciprofloxacin derivative (compound 8b) showed comparable or more potent antibacterial activity with respect to the reference drugs against the test strains. Generally, in both gram-positive and gram-negative bacteria, better results are obtained with cyclopropyl at the N-1 position of the quinolone ring and 2-oxo- on the ethyl spacer of coumarin and piperazine rings. PMID:18072241

Emami, Saeed; Foroumadi, Alireza; Faramarzi, Mohammad A; Samadi, Nasrin

2008-01-01

87

Antibacterial activity of essential oils from palmarosa, evening primrose, lavender and tuberose.  

PubMed

Essential oils extracted from flower petals of palmarosa (Cymbopogon martini), evening primrose (Primula rosea), lavender (Lavandula angustifolia) and tuberose (Polianthus tuberosa) were tested for their antibacterial activities against gram-positive and gram-negative bacteria. Different concentrations of each essential oil ranging from 10-100% were tested. Both gram-positive and gram-negative bacteria were found susceptible to the studied flower essential oils. With increase in concentration of essential oil, increase in zone of inhibition was observed thus dose-dependent response was clear for each essential oil. Essential oil extracted from Cymbopogon martini showed the highest activity against both gram positive and gram negative bacteria among the tested essential oils. PMID:20336210

Lodhia, M H; Bhatt, K R; Thaker, V S

2009-03-01

88

Antibacterially active substances  

Microsoft Academic Search

Synthesis of two hydroxy-derivatives of nalidixic acid as a result of microbial transformation was demonstrated in certain\\u000a species of the genusAspergillus. Aspergillus alliaceus produced 7-hydroxy-nalidixic acid andAspergillus niger 6-hydroxy-nalidixic acid. It was demonstrated that the antibacterial activity of both hydroxy-derivatives (tested inEscherichia coli) was lower than that of the initial nalidixis acid.

A. ?apek; A. Šimek; E. Svátek; M. Bud?šínský

1969-01-01

89

Antibacterial activity of Ulva lactuca against methicillin-resistant Staphylococcus aureus (MRSA)  

Microsoft Academic Search

Thein vitro antimicrobial activity of the marine green algaeUlva lactuca was examined against gram-positive bacteria, gram-negative bacteria, and a fungus. The ethyl-ether extract of algae exhibited\\u000a a broad-spectrum of antibacterial activity. but not antifungal activity againstCandida albicans. In particular, theU. lactuca extract showed strong activity aganst the bacterium methicillin-resistantStaphylococcus aureus (MRSA). This result confirms the potential use of seaweed extracts

Dong-Gun Lee; Sang Hyun Lee; Jong-Myung Ha; Bae-Jin Ha; Sung-Koo Kim; Jae-Hwa Lee

2007-01-01

90

Mechanism of Action of Recombinant Acc-Royalisin from Royal Jelly of Asian Honeybee against Gram-Positive Bacteria  

PubMed Central

The antibacterial activity of royalisin, an antimicrobial peptide from the royal jelly produced by honeybees, has been addressed extensively. However, its mechanism of action remains unclear. In this study, a recombinant royalisin, RAcc-royalisin from the royal jelly of Asian honeybee Apis cerana cerana, was expressed by fusing with glutathione S-transferase (GST) in Escherichia coli BL21, isolated and purified. The agar dilution assays with inhibition zone showed that RAcc-royalisin, similar to nisin, inhibits the growth of Gram-positive bacteria. The antibacterial activity of RAcc-royalisin was associated with its concentration, and was weakened by heat treatment ranging from 55°C to 85°C for 15 min. Both RAcc-royalisin and nisin exhibited the minimum inhibitory concentrations (MIC) of 62.5 µg/ml, 125 µg/ml, and 250 µg/ml against Gram-positive bacterial strains, Bacillus subtilis and Micrococcus flavus and Staphyloccocus aureus in the microplate assay, respectively. However, RAcc-royalisin did not show antimicrobial activity against tested Gram-negative bacterial and fungal strains. The antibacterial activity of RAcc-royalisin agrees well with the decrease in bacterial cell hydrophobicity, the leakage of 260-nm absorbing materials, and the observation by transmission electron microscopy, all indicating that RAcc-royalisin induced the disruption and dysfunction of cell walls and membranes. This is the first report detailing the antibacterial mechanism of royalisin against Gram-positive bacteria, and provides insight into the application of recombinant royalisin in food and pharmaceutical industries as an antimicrobial agent. PMID:23056609

Shen, Lirong; Liu, Dandan; Li, Meilu; Jin, Feng; Din, Meihui; Parnell, Laurence D.; Lai, Chao-Qiang

2012-01-01

91

Accentuate the (Gram) positive Victor Nizet  

E-print Network

, resisting local mucosal immune responses, or allowing SPN to outcom- pete other members of the local flora of the leading Gram-positive bacterial pathogens and their interactions with the human immune system. Many new colonizes the human host without causing symptoms (carrier state) or generates milder, self- limited mucosal

Nizet, Victor

92

Ethanol production in Gram-positive microbes  

DOEpatents

The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase. 2 figs.

Ingram, L.O.; Barbosa-Alleyne, M.D.F.

1996-01-09

93

Ethanol production in Gram-positive microbes  

DOEpatents

The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase.

Ingram, Lonnie O'Neal (Gainesville, FL); Barbosa-Alleyne, Maria D. F. (Gainesville, FL)

1996-01-01

94

Ethanol production in Gram-positive microbes  

DOEpatents

The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase. 2 figs.

Ingram, L.O.; Barbosa-Alleyne, M.D.F.

1999-06-29

95

Ethanol production in gram-positive microbes  

DOEpatents

The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase.

Ingram, Lonnie O'Neal (Gainesville, FL); Barbosa-Alleyne, Maria D. F. (Gainesville, FL)

1999-01-01

96

Acyl-sulfamates target the essential glycerol-phosphate acyltransferase (PlsY) in Gram-positive bacteria.  

PubMed

PlsY is the essential first step in membrane phospholipid synthesis of Gram-positive pathogens. PlsY catalyzes the transfer of the fatty acid from acyl-phosphate to the 1-position of glycerol-3-phosphate to form the first intermediate in membrane biogenesis. A series of non-metabolizable, acyl-sulfamate analogs of the acyl-phosphate PlsY substrate were prepared and evaluated as inhibitors of Staphylococcus aureus PlsY and for their Gram-positive antibacterial activities. From this series phenyl (8-phenyloctanoyl) sulfamate had the best overall profile, selectively inhibiting S. aureus phospholipid biosynthesis and causing the accumulation of both long-chain fatty acids and acyl-acyl carrier protein intermediates demonstrating that PlsY was the primary cellular target. Bacillus anthracis was unique in being more potently inhibited by long chain acyl-sulfamates than other bacterial species. However, it is shown that Bacillus anthracis PlsY is not more sensitive to the acyl-sulfamates than S. aureus PlsY. Metabolic profiling showed that B. anthracis growth inhibition by the acyl-sulfamates was not specific for lipid synthesis illustrating that the amphipathic acyl-sulfamates can also have off-target effects in Gram-positive bacteria. Nonetheless, this study further advances PlsY as a druggable target for the development of novel antibacterial therapeutics, through the discovery and validation of the probe compound phenyl (8-phenyloctanoyl) sulfamate as a S. aureus PlsY inhibitor. PMID:22795901

Cherian, Philip T; Yao, Jiangwei; Leonardi, Roberta; Maddox, Marcus M; Luna, Vicki A; Rock, Charles O; Lee, Richard E

2012-08-15

97

Acyl-sulfamates Target the Essential Glycerol-Phosphate Acyltransferase (PlsY) in Gram-Positive Bacteria  

PubMed Central

PlsY is the essential first step in membrane phospholipid synthesis of Gram-positive pathogens. PlsY catalyzes the transfer of the fatty acid from acyl-phosphate to the 1-position of glycerol-3-phosphate to form the first intermediate in membrane biogenesis. A series of non-metabolizable, acyl-sulfamate analogs of the acyl-phosphate PlsY substrate were prepared and evaluated as inhibitors of Staphylococcus aureus PlsY and for their Gram-positive antibacterial activities. From this series phenyl (8-phenyloctanoyl) sulfamate had the best overall profile, selectively inhibiting S. aureus phospholipid biosynthesis and causing the accumulation of both long-chain fatty acids and acyl-acyl carrier protein intermediates demonstrating that PlsY was the primary cellular target. Bacillus anthracis was unique in being more potently inhibited by long chain acyl-sulfamates than other bacterial species. However, it is shown that Bacillus anthracis PlsY is not more sensitive to the acyl-sulfamates than S. aureus PlsY. Metabolic profiling showed that B. anthracis growth inhibition by the acyl-sulfamates was not specific for lipid synthesis illustrating that the amphipathic acyl-sulfamates can also have off-target effects in Gram-positive bacteria. Nonetheless, this study further advances PlsY as a druggable target for the development of novel antibacterial therapeutics, through the discovery and validation of the probe compound phenyl (8-phenyloctanoyl) sulfamate as a S. aureus PlsY inhibitor. PMID:22795901

Cherian, Philip; Yao, Jiangwei; Leonardi, Roberta; Maddox, Marcus M.; Luna, Vicki A.; Rock, Charles O.; Lee, Richard E.

2012-01-01

98

Non-oxidative antibacterial activity of bovine neutrophil granule proteins towards mastitis pathogens.  

PubMed

Acid extracts of bovine neutrophil granules displayed potent antibacterial activity towards a number of mastitis pathogens in vitro. Killing of pathogens by acid extractable granule protein was dependent on incubation time, protein concentration, bacterial cell load, pH and ionic strength. Gram-negative and Gram-positive organisms showed variable sensitivity to granule extract. Strains of Staphylococcus aureus were the most resistant of tested organisms to granule extract. Gram-negative organisms were neither consistently more nor less sensitive than Gram-positive organisms. Maximal killing of Gram-positive pathogens, after 30 minutes exposure to granule extract at 37 degrees C, occurred between pH 7.0 and 8.0. The Gram-negative organism Escherichia coli B117 was more sensitive to neutrophil granule extract at pH 5.0. PMID:2816175

Grieve, P A; Mattila, T

1989-09-01

99

Synthesis of isoindole and benzoisoindole derivatives of teicoplanin pseudoaglycon with remarkable antibacterial and antiviral activities.  

PubMed

The primary amino function of teicoplanin pseudoaglycon has been transformed into arylthioisoindole or benzoisoindole and glycosylthioisoindole derivatives, in a reaction with o-phthalaldehyde or naphtalene-2,3-dicarbaldehyde and various thiols. All of the obtained semisynthetic antibiotics exhibited potent antibacterial activities against Gram-positive bacteria in the ng per ml concentration range. A few of them showed antiviral activity, in particular against influenza virus. PMID:23099097

Sipos, Attila; Török, Zsolt; R?th, Erzsébet; Kiss-Szikszai, Attila; Batta, Gyula; Bereczki, Ilona; Fejes, Zsolt; Borbás, Anikó; Ostorházi, Eszter; Rozgonyi, Ferenc; Naesens, Lieve; Herczegh, Pál

2012-12-01

100

Assessment of antibacterial activity of smaller chain tripeptides and tetrapeptides.  

PubMed

Our objective is to investigate the smaller chain tripeptides and tetrapeptides with the efforts mainly directed towards the identification of compounds presenting a high bactericidal activity. In this connection, 5 peptides, Met-Arg-Tyr (MRY), Met-Val-Tyr (MVY), Met-Ile-Cys-Tyr (MICY), Phe-Trp-Lys-Tyr (FWKY) and Met-Trp-Lys-Tyr (MWKY) were synthesized by solid phase peptide synthesis. The column eluted pure synthesized compounds were tested for in-vitro antibacterial disc diffusion assay using 2?g positive S. aureus, B.subtilis and 1?g negative E.coli bacterial strains at different concentrations predicted by pH and inhibitory concentration findings. 2 of the tetrapeptides, Phe-Trp-Lys-Tyr (FWKY) and Met-Trp-Lys-Tyr (MWKY) were found to be highly efficient against all the gram positive and microbial strains tested. Maximum activity was observed at a concentration of 300?µg/ml (499.17?µM) for the tetrapeptide Phe-Trp-Lys-Tyr (FWKY) against B. subtilis and at a concentration of 450?µg/ml (748.75?µM) against E. coli with the corresponding zonal inhibition diameter readings (17?mm; 16?mm). The tetrapeptide Met-Trp-Lys-Tyr (MWKY) was found to have high potency against S. aureus at a concentration of 450?µg/ml (769.23?µM) with the corresponding zonal inhibition diameter as 13?mm. The experimental results are analysed statistically by t-test at 5% and 1% level of significance. Our tetrapeptides have shown antibacterial action against both gram positive and gram negative strains and are considered safer as par with commercial antibiotics available today. Further clinical studies will make sure to position our potent small chain tetrapeptides in the arsenal of new broad spectrum anti-gram positive and anti-gram negative agent. PMID:24573977

Nagarajan, K; Kumar, V; Rai, P K; Singh, J; Panda, B P; Ghosh, L K

2014-11-01

101

Synthesis and Antibacterial Activity of Pentacyclines: A Novel Class of Tetracycline Analogs  

PubMed Central

Employing a highly efficient total synthesis approach, we synthesized and evaluated for antibacterial activity diverse and novel pentacycline analogs with systematic variations at C7, C8, C9, and C10. Certain substitution groups, as well as substitution patterns at various positions, were found to be preferred for increased antibacterial activity. A number of pentacycline analogs displayed potent activity in vitro and in vivo, especially against Gram-positive organisms. Several analogs have also shown promising oral bioavailability in rats and cynomolgus monkey. PMID:21500832

2011-01-01

102

Antibacterial and cytotoxic activities of the sesquiterpene lactones cnicin and onopordopicrin.  

PubMed

The antimicrobial and cytotoxic activities of chloroform extracts from the weeds Centaurea tweediei and C. diffusa, and the main sesquiterpene lactones isolated from these species, onopordopicrin and cnicin, respectively, were assayed. Results show that the chloroform extracts from both Centaurea species possess antibacterial activities against a panel of Gram-positive and Gram-negative bacteria. Remarkable antibacterial activity against methicillin-resistant Staphylococcus aureus was also measured. Both the extracts and the purified sesquiterpene lactones show high cytotoxicity against human-derived macrophages. Despite this cytotoxicity, C. diffusa chloroform extract and cnicin are attractive candidates for evaluation as antibiotics in topical preparations against skin-associated pathogens. PMID:21425665

Bach, Sandra M; Fortuna, Mario A; Attarian, Rodgoun; de Trimarco, Juliana T; Catalán, César A N; Av-Gay, Yossef; Bach, Horacio

2011-02-01

103

The antibacterial and antifungal activity of a soda-lime glass containing silver nanoparticles.  

PubMed

The antibacterial and antifungal activity of a low melting point soda-lime glass powder containing silver nanoparticles has been studied. Nano-Ag sepiolite fibres containing monodispersed silver nanoparticles (d(50) approximately 11 +/- 9 nm) were used as the source of silver. This powder presents a high antibacterial (against gram-positive and gram-negative bacteria) as well as antifungal (against I. orientalis) activity. The observed high activity against yeast has been explained by considering the inhibitory effect of the Ca(2+) lixiviated from the glass on the growth of the yeast colonies. PMID:19417439

Esteban-Tejeda, L; Malpartida, F; Esteban-Cubillo, A; Pecharromán, C; Moya, J S

2009-02-25

104

Antibacterial activity of selected fatty acids and essential oils against six meat spoilage organisms  

Microsoft Academic Search

The antibacterial activity of selected fatty acids and essential oils was examined against two gram-negative (Pseudomonas fluorescens and Serratia liquefaciens), and four gram-positive (Brochothrix thermosphacta, Carnobacterium piscicola, Lactobacillus curvatus, and Lactobacillus sake) bacteria involved in meat spoilage. Various amounts of each preservative were added to brain heart infusion or MRS (deMan, Rogosa and Sharpe) agars, and the minimum inhibitory concentration

Blaise Ouattara; Ronald E Simard; Richard A Holley; Gabriel J.-P Piette; André Bégin

1997-01-01

105

Antibacterial activity of the essential oil of Picea excelsa on Listeria, Staphylococcus aureus and coliform bacteria  

Microsoft Academic Search

Antibacterial activity of essential oil of Picea excelsa was tested with the dilution method against one strain of Listeria ivanovii, six of L. monocytogenes, three of Staphylococcus aureus, three of Escherichia coli, one of Klebsiella oxytoca, one of K. pneumoniae subsp. pneumoniae and one of Enterobacter cloacae. For Gram-positive bacteria in stationary phase, 0·07% of essential oil inhibited about 105colony

N. Canillac; A. Mourey

2001-01-01

106

Fighting infections due to multidrug-resistant Gram-positive pathogens.  

PubMed

Growing bacterial resistance in Gram-positive pathogens means that what were once effective and inexpensive treatments for infections caused by these bacteria are now being seriously questioned, including penicillin and macrolides for use against pneumococcal infections and-in hospitals-oxacillin for use against staphylococcal infections. As a whole, multidrug-resistant (MDR) Gram-positive pathogens are rapidly becoming an urgent and sometimes unmanageable clinical problem. Nevertheless, and despite decades of research into the effects of antibiotics, the actual risk posed to human health by antibiotic resistance has been poorly defined; the lack of reliable data concerning the outcomes resulting from antimicrobial resistance stems, in part, from problems with study designs and the methods used in resistence determination. Surprisingly little is known, too, about the actual effectiveness of the many types of intervention aimed at controlling antibiotic resistance. New antibiotics active against MDR Gram-positive pathogens have been recently introduced into clinical practice, and the antibiotic pipeline contains additional compounds at an advanced stage of development, including new glycopeptides, new anti-methicillin-resistant Staphylococcus aureus (MRSA) beta-lactams, and new diaminopyrimidines. Many novel antimicrobial agents are likely to be niche products, endowed with narrow antibacterial spectra and/or targeted at specific clinical problems. Therefore, an important educational goal will be to change the current, long-lasting attitudes of both physicians and customers towards broad-spectrum and multipurpose compounds. Scientific societies, such as the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), must play a leading role in this process. PMID:19335367

Cornaglia, G

2009-03-01

107

Biological counterstrike: antibiotic resistance mechanisms of Gram-positive cocci.  

PubMed

The development of antibiotic resistance by bacteria is an evolutionary inevitability, a convincing demonstration of their ability to adapt to adverse environmental conditions. Since the emergence of penicillinase-producing Staphylococcus aureus in the 1940s, staphylococci, enterococci and streptococci have proved themselves adept at developing or acquiring mechanisms that confer resistance to all clinically available antibacterial classes. The increasing problems of methicillin-resistant S. aureus and coagulase-negative staphylococci (MRSA and MRCoNS), glycopeptide-resistant enterococci and penicillin-resistant pneumococci in the 1980s, and recognition of glycopeptide-intermediate S. aureus in the 1990s and, most recently, of fully vancomycin-resistant isolates of S. aureus have emphasised our need for new anti-Gram-positive agents. Antibiotic resistance is one of the major public health concerns for the beginning of the 21st century. The pharmaceutical industry has responded with the development of oxazolidinones, lipopeptides, injectable streptogramins, ketolides, glycylcyclines, second-generation glycopeptides and novel fluoroquinolones. However, clinical use of these novel agents will cause new selective pressures and will continue to drive the development of resistance. This review describes the various antibiotic resistance mechanisms identified in isolates of staphylococci, enterococci and streptococci, including mechanisms of resistance to recently introduced anti-Gram-positive agents. PMID:15811020

Woodford, N

2005-05-01

108

Activity of ceftaroline and comparator agents tested against contemporary Gram-positive and -negative (2011) isolates collected in Europe, Turkey, and Israel  

PubMed Central

The activity of ceftaroline was tested against 8233 isolates mainly collected from bloodstream, urinary, respiratory and skin and soft tissue specimens in European medical centers during 2011. This cephalosporin displayed activity against Staphylococcus aureus (MIC50, 0·25 mg/l), with greater activity against MRSA (MIC50, 1 mg/l) than other ?-lactams tested. Against Streptococcus pneumoniae, including penicillin-resistant strains, other streptococcal groups and Haemophilus spp., ceftaroline was highly active and MIC90 values ranged from ?0·015 to 0·12 mg/l. Ceftaroline, like other cephalosporins, had limited activity against ESBL-phenotype Enterobacteriaceae, but showed good activity against isolates not displaying an ESBL-phenotype. Ceftaroline remains very active against MRSA and other organisms than could be associated with its approved indications in the EU (complicated skin and soft tissue infections and community-acquired pneumonia). PMID:24070006

Castanheira, Mariana; Jones, Ronald N; Sader, Helio S

2014-01-01

109

Size-dependent antimicrobial properties of CuO nanoparticles against Gram-positive and -negative bacterial strains  

PubMed Central

Background CuO is one of the most important transition metal oxides due to its captivating properties. It is used in various technological applications such as high critical temperature superconductors, gas sensors, in photoconductive applications, and so on. Recently, it has been used as an antimicrobial agent against various bacterial species. Here we synthesized different sized CuO nanoparticles and explored the size-dependent antibacterial activity of each CuO nanoparticles preparation. Methods CuO nanoparticles were synthesized using a gel combustion method. In this approach, cupric nitrate trihydrate and citric acid were dissolved in distilled water with a molar ratio of 1:1. The resulting solution was stirred at 100°C, until gel was formed. The gel was allowed to burn at 200°C to obtain amorphous powder, which was further annealed at different temperatures to obtain different size CuO nanoparticles. We then tested the antibacterial properties using well diffusion, minimum inhibitory concentration, and minimum bactericidal concentration methods. Results XRD spectra confirmed the formation of single phase CuO nanoparticles. Crystallite size was found to increase with an increase in annealing temperature due to atomic diffusion. A minimum crystallite size of 20 nm was observed in the case of CuO nanoparticles annealed at 400°C. Transmission electron microscopy results corroborate well with XRD results. All CuO nanoparticles exhibited inhibitory effects against both Gram-positive and -negative bacteria. The size of the particles was correlated with its antibacterial activity. Conclusion The antibacterial activity of CuO nanoparticles was found to be size-dependent. In addition, the highly stable minimum-sized monodispersed copper oxide nanoparticles synthesized during this study demonstrated a significant increase in antibacterial activities against both Gram-positive and -negative bacterial strains. PMID:22848176

Azam, Ameer; Ahmed, Arham S; Oves, M; Khan, MS; Memic, Adnan

2012-01-01

110

Comparative in vitro activities of teicoplanin, daptomycin, ramoplanin, vancomycin, and PD127,391 against blood isolates of gram-positive cocci.  

PubMed Central

The in vitro activities of teicoplanin, daptomycin, ramoplanin, and PD127,391, a new quinolone, were compared with that of vancomycin. Teicoplanin showed the lowest MICs against Enterococcus faecalis. Ramoplanin was slightly more active than the other peptide antibiotics against oxacillin-resistant Staphylococcus aureus. The MICs of the four peptide antibiotics were similar for the oxacillin-susceptible S. aureus. Daptomycin had good activity against staphylococci but was the least active agent against E. faecalis. The MICs of vancomycin against all isolates were in general higher than those of the new antibiotics, with the exceptions of the MICs of daptomycin against E. faecalis and teicoplanin against oxacillin-resistant Staphylococcus epidermidis. PD127,391 was the most active agent against all staphylococcal isolates. PMID:1324649

Shonekan, D; Mildvan, D; Handwerger, S

1992-01-01

111

Synthesis and in vitro antibacterial activity of some N-(5-aryl-1,3,4-thiadiazole-2-yl)piperazinyl quinolone derivatives.  

PubMed

A series of N-[5-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazole-2-yl] and N-[5-(nitrophenyl)-1,3,4-thiadiazole-2-yl] piperazinyl quinolone derivatives (5a-c and 5d-l) were synthesized and evaluated for in vitro antibacterial activity against some Gram-positive and Gram-negative bacteria. The antibacterial data revealed that all nitroimidazole derivatives (5a-c) showed interesting activity against tested Gram-positive bacteria (minimum inhibitory concentration, MIC=0.008-0.03 microg/ml) while they did not show good activity against Gram-negative organisms. Despite the significant activity of nitroimidazole series, all nitrophenyl analogues (5d-l) were inactive against both Gram-positive and Gram-negative bacteria. Among all of the tested compounds, 5a (ciprofloxacin derivative in nitroimidazole series) exhibited excellent activity against Staphylococcus aureus and Staphylococcus epidermidis (MIC=0.008 microg/ml). PMID:14505733

Foroumadi, Alireza; Soltani, Fatemeh; Moshafi, Mohammad Hasan; Ashraf-Askari, Rogheeyeh

2003-10-01

112

Macrophage Migration Inhibitory Factor is a Critical Mediator of the Activation of Immune Cells by Exotoxins of Gram-Positive Bacteria  

Microsoft Academic Search

Discovered in the early 1960s as a T cell cytokine, the protein mediator known as macrophage migration inhibitory factor (MIF) has been found recently to be a pituitary peptide released during the physiological stress response, a proinflammatory macrophage cytokine secreted after LPS stimulation, and a T cell product expressed as part of the antigen-dependent activation response. We report herein that

Thierry Calandra; Lori A. Spiegel; Christine N. Metz; Richard Bucala

1998-01-01

113

Draft Genome Sequence Analysis of a Pseudomonas putida W15Oct28 Strain with Antagonistic Activity to Gram-Positive and Pseudomonas sp. Pathogens  

PubMed Central

Pseudomonas putida is a member of the fluorescent pseudomonads known to produce the yellow-green fluorescent pyoverdine siderophore. P. putida W15Oct28, isolated from a stream in Brussels, was found to produce compound(s) with antimicrobial activity against the opportunistic pathogens Staphylococcus aureus, Pseudomonas aeruginosa, and the plant pathogen Pseudomonas syringae, an unusual characteristic for P. putida. The active compound production only occurred in media with low iron content and without organic nitrogen sources. Transposon mutants which lost their antimicrobial activity had the majority of insertions in genes involved in the biosynthesis of pyoverdine, although purified pyoverdine was not responsible for the antagonism. Separation of compounds present in culture supernatants revealed the presence of two fractions containing highly hydrophobic molecules active against P. aeruginosa. Analysis of the draft genome confirmed the presence of putisolvin biosynthesis genes and the corresponding lipopeptides were found to contribute to the antimicrobial activity. One cluster of ten genes was detected, comprising a NAD-dependent epimerase, an acetylornithine aminotransferase, an acyl CoA dehydrogenase, a short chain dehydrogenase, a fatty acid desaturase and three genes for a RND efflux pump. P. putida W15Oct28 genome also contains 56 genes encoding TonB-dependent receptors, conferring a high capacity to utilize pyoverdines from other pseudomonads. One unique feature of W15Oct28 is also the presence of different secretion systems including a full set of genes for type IV secretion, and several genes for type VI secretion and their VgrG effectors. PMID:25369289

Ye, Lumeng; Hildebrand, Falk; Dingemans, Jozef; Ballet, Steven; Laus, George; Matthijs, Sandra; Berendsen, Roeland; Cornelis, Pierre

2014-01-01

114

Comparative In Vitro Activities of AC98-6446, a Novel Semisynthetic Glycopeptide Derivative of the Natural Product Mannopeptimycin ?, and Other Antimicrobial Agents against Gram-Positive Clinical Isolates  

PubMed Central

AC98-6446 is a novel semisynthetic cyclic glycopeptide antibiotic related to the natural product mannopeptimycin ? (AC98-1). In the present study the activity of AC98-6446 was evaluated against a variety of recent clinical gram-positive pathogens including multiply resistant strains. AC98-6446 demonstrated similar potent activities against methicillin-susceptible and methicillin-resistant staphylococci and glycopeptide-intermediate staphylococcal isolates (MICs at which 90% of isolates are inhibited [MIC90s], 0.03 to 0.06 ?g/ml). AC98-6446 also demonstrated good activities against both vancomycin-resistant and -susceptible strains of enterococci (MIC90s, 0.12 and 0.25 ?g/ml, respectively) as well as against streptococcal strains (MIC90s, ? 0.008 to 0.03 ?g/ml). AC98-6446 demonstrated bactericidal activity in terms of the reduction in the viable counts (>3 log10 CFU/ml) of staphylococcal and streptococcal isolates and a marked decrease in the viable counts of most enterococcal strains (from 0.2 to 2.5 log10 CFU/ml). Unlike vancomycin, which demonstrates time-dependent killing, AC98-6446 demonstrated concentration-dependent killing. The potent activity, novel structure, and bactericidal activity demonstrated by AC98-6446 make it an attractive candidate for further development. PMID:14982758

Petersen, Peter J.; Wang, T. Z.; Dushin, Russell G.; Bradford, Patricia A.

2004-01-01

115

Influence of pH, Heat and Enzymatic Treatments on the Activity of Antibacterial Substance in MRS and Milk Media Produced by Lactobacillus fermentum F6  

Microsoft Academic Search

This study aimed to investigate the influence of pH, heat and enzymatic treatments on the activity of antibacterial substance in MRS, skim soy milk and bovine milk media fermented by a potential probiotic Lactobacillus fermentum F6. The antibacterial activity of the culture supernatant of L. fermentum F6 was tested against a wide range of Gram-positive and Gram-negative pathogenic bacteria including

Yong ZHANG; Yong LIU; Yan BAO; He-ping ZHANG

2010-01-01

116

Antioxidative, antibrowning and antibacterial activities of sixteen floral honeys.  

PubMed

Commonly consumed honeys from sixteen different single floral sources were analyzed for their in vitro antioxidant capacities by several methods including DPPH, ABTS, FRAP, SASR and MDA assays. The total polyphenol contents varied among the tested honeys and were highly correlated to their antioxidant capacity values. The antioxidant capacity of Chinese milk vetch flower honeys was significantly higher than those of other flower honeys. All honeys tested were active in inhibiting the browning of apple homogenate and linden honey displayed the highest inhibition rate as 85%. When the antimicrobial activity of the investigated honeys was screened using Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli), clover honey exhibited the strongest antibacterial activity as 2.2 mg mL(-1) kanamycin equivalent inhibition. PMID:21860856

Chang, Xin; Wang, Jiehua; Yang, Shaohui; Chen, Shan; Song, Yingjin

2011-09-01

117

Biotransformation of clerodane diterpenoids by Rhizopus stolonifer and antibacterial activity of resulting metabolites.  

PubMed

Microbial transformation of clerodane lactone (1) by a plant pathogen fungus, Rhizopus stolonifer, resulted in the production of metabolites 3 and 4. While incubation of clerodane methyl ester (2) by R. stolonifer yielded metabolites 5-8. The structures of the transformed products were determined by the spectroscopic techniques and compounds 4, 7 and 8 were found. The antibacterial activity of clerodane diterpenoids 1 and 2 and their metabolites 3-8 were also studied. The metabolites 3-7 showed moderate activities against both Gram-positive and Gram-negative organisms. While metabolite 8 showed a moderate activity against Gram-positive organisms and a good activity against Gram-negative organisms. PMID:23535269

Iqbal Choudhary, M; Mohammad, Mohammad Yasin; Musharraf, Syed Ghulam; Onajobi, Ismail; Mohammad, Akhtar; Anis, Itrat; Shah, Muhammad Raza; Atta-Ur-Rahman

2013-06-01

118

Rose Bengal-decorated silica nanoparticles as photosensitizers for inactivation of gram-positive bacteria  

NASA Astrophysics Data System (ADS)

A new type of photosensitizer, made from Rose Bengal (RB)-decorated silica (SiO2-NH2-RB) nanoparticles, was developed to inactivate gram-positive bacteria, including Methicillin-resistant Staphylococcus aureus (MRSA), with high efficiency through photodynamic action. The nanoparticles were characterized microscopically and spectroscopically to confirm their structures. The characterization of singlet oxygen generated by RB, both free and immobilized on a nanoparticle surface, was performed in the presence of anthracene-9,10-dipropionic acid. The capability of SiO2-NH2-RB nanoparticles to inactivate bacteria was tested in vitro on both gram-positive and gram-negative bacteria. The results showed that RB-decorated silica nanoparticles can inactivate MRSA and Staphylococcus epidermidis (both gram-positive) very effectively (up to eight-orders-of-magnitude reduction). Photosensitizers of such design should have good potential as antibacterial agents through a photodynamic mechanism.

Guo, Yanyan; Rogelj, Snezna; Zhang, Peng

2010-02-01

119

Synthesis and antibacterial activity of of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Silver nanoparticles have been known to have inhibitory and bactericidal effects but the antimicrobial mechanism have not been clearly revealed. Here, we report on the synthesis of metallic nanoparticles of silver using wild strains of Penicillium isolated from environment. Kinetics of the formation of nanosilver was monitored using the UV-Vis. TEM micrographs showed the formation of silver nanoparticles in the range 10-100 nm. Obtained Ag nanoparticles were evaluated for their antimicrobial activity against the gram-positive and gram-negative bacteria. As results, Bacillus cereus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were effectively inhibited. Nanosilver is a promising candidate for development of future antibacterial therapies because of its wide spectrum of activity.

Maliszewska, I.; Sadowski, Z.

2009-01-01

120

Screening for fractions of Oxytropis falcata Bunge with antibacterial activity.  

PubMed

Preliminary studies with the four extracts of Oxytropis falcate Bunge exhibited that the chloroform and ethyl acetate extracts showed stronger antibacterial activities against the nine tested Gram-positive and Gram-negative bacteria. The HPLC-scanned and bioassay-guided fractionation led to the isolation and identification of the main flavonoid compounds, i.e. rhamnocitrin, kaempferol, rhamnetin, 2',4'-dihydroxychalcone and 2',4',beta-trihydroxy-dihydrochalcon. Except 2',4',beta-trihydroxy-dihydrochalcon, four other compounds had good antibacterial activities. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of the four compounds ranged between 125 and 515 microg mL(-1). Staphylococcus aureus was the most susceptible to these compounds, with MIC and MBC values from 125 to 130 microg mL(-1). This is the first report of antibacterial activity in O. falcate Bunge. In this study, evidence to evaluate the biological functions of O. falcate Bunge is provided, which promote the rational use of this herb. PMID:19521909

Jiang, H; Hu, J R; Zhan, W Q; Liu, X

2009-01-01

121

Sortase enzymes in Gram-positive bacteria  

PubMed Central

Summary In Gram-positive bacteria proteins are displayed on the cell surface using sortase enzymes. These cysteine transpeptidases join proteins bearing an appropriate sorting signal to strategically positioned amino groups on the cell surface. Working alone, or in concert with other enzymes, sortases either attach proteins to the cross-bridge peptide of the cell wall or they link proteins together to form pili. Because surface proteins play a fundamental role in microbial physiology and are frequently virulence factors, sortase enzymes have been intensely studied since their discovery a little more than a decade ago. Based on their primary sequences and functions sortases can be partitioned into distinct families called class A to F enzymes. Most bacteria elaborate their surfaces using more than one type of sortase that function non-redundantly by recognizing unique sorting signals within their protein substrates. Here we review what is known about the functions of these enzymes and the molecular basis of catalysis. Particular emphasis is placed on ‘pilin’ specific class C sortases that construct structurally complex pili. Exciting new data have revealed that these enzymes are amazingly promiscuous in the substrates that they can employ and that there is a startling degree of diversity in their mechanism of action. We also review recent data that suggest that sortases are targeted to specific sites on the cell surface where they work with other sortases and accessory factors to properly function. PMID:22026821

Spirig, Thomas; Weiner, Ethan M.; Clubb, Robert T.

2013-01-01

122

Synthesis of novel benzimidazole functionalized chiral thioureas and evaluation of their antibacterial and anticancer activities.  

PubMed

A small library of benzimidazole functionalized chiral thioureas was prepared starting from natural amino acids (S)-alanine, (S)-phenylalanine, (S)-valine and (S)-leucine and also their (R)-isomers and studied their antimicrobial activity against a various Gram-positive and Gram-negative bacterial strains. In this study, compounds 5g and 5j were found to exhibit good antibacterial activity against both Gram-positive and Gram-negative bacterial strains such as Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus, Klebsiella planticola, Escherichia coli and Pseudomonas aeruginosa. In the cytotoxicity study, thioureas derived from non-natural amino acids 5a-l showed good activity against human cancer cell lines A549, MCF7, DU145, HeLa, and no cytotoxicity was observed with their antipodes 6a-l. PMID:25241926

Madabhushi, Sridhar; Mallu, Kishore Kumar Reddy; Vangipuram, Venkata Sairam; Kurva, Srinivas; Poornachandra, Y; Ganesh Kumar, C

2014-10-15

123

Synthesis and antibacterial activity of N-(5-benzylthio-1,3,4-thiadiazol-2-yl) and N-(5-benzylsulfonyl-1,3,4-thiadiazol-2-yl)piperazinyl quinolone derivatives.  

PubMed

A series of N-(5-benzylthio-1,3,4-thiadiazol-2-yl) and N-(5-benzylsulfonyl-1,3,4-thiadiazol-2-yl) derivatives of piperazinyl quinolones was synthesized and evaluated for antibacterial activity against Gram-positive and Gram-negative microorganisms. Some of these derivatives exhibit high activity against Gram-positive bacteria; Staphylococcus aureus and Staphylococcus epidermidis, comparable or more potent than their parent N-piperazinyl quinolones norfloxacin and ciprofloxacin as reference drugs. The SAR of this series indicates that both the structure of the benzyl unit and the S or SO(2) linker dramatically impact antibacterial activity. PMID:16105736

Foroumadi, Alireza; Emami, Saeed; Hassanzadeh, Abdolreza; Rajaee, Majid; Sokhanvar, Kazem; Moshafi, Mohammad Hassan; Shafiee, Abbas

2005-10-15

124

Synthesis of novel bisindolylmethane Schiff bases and their antibacterial activity.  

PubMed

In an effort to develop new antibacterial drugs, some novel bisindolylmethane derivatives containing Schiff base moieties were prepared and screened for their antibacterial activity. The synthesis of the bisindolylmethane Schiff base derivatives 3-26 was carried out in three steps. First, the nitro group of 3,3'-((4-nitrophenyl)-methylene)bis(1H-indole) (1) was reduced to give the amino substituted bisindolylmethane 2 without affecting the unsaturation of the bisindolylmethane moiety using nickel boride in situ generated. Reduction of compound 1 using various catalysts showed that combination of sodium borohydride and nickel acetate provides the highest yield for compound 2. Bisindolylmethane Schiff base derivatives were synthesized by coupling various benzaldehydes with amino substituted bisindolylmethane 2. All synthesized compounds were characterized by various spectroscopic methods. The bisindolylmethane Schiff base derivatives were evaluated against selected Gram-positive and Gram-negative bacterial strains. Derivatives having halogen and nitro substituent display weak to moderate antibacterial activity against Salmonella typhi, S. paratyphi A and S. paratyphi B. PMID:25102118

Imran, Syahrul; Taha, Muhammad; Ismail, Nor Hadiani; Khan, Khalid Mohammed; Naz, Farzana; Hussain, Memona; Tauseef, Saima

2014-01-01

125

Antibacterial Activity of Rhizome of Curcuma aromatica and Partial Purification of Active Compounds  

PubMed Central

The hexane extract of Curcuma aromatica, a plant belonging to the family Zingiberaceae was tested on 10 bacterial strains (clinical isolates and standard strains). Agar diffusion method was adopted for determining the antibacterial activity of the extract. The hexane extract was found to be active against all Gram-positive strains tested, but inactive against Gram-negative strains. The minimum inhibitory concentration and minimum bactericidal concentration were determined and found to be 539 ?g/ml. The phytochemical analysis of hexane extract by gas chromatography mass spectrometry revealed the presence of 13 compounds. The crude hexane extract was partially purified by thin layer chromatography. The zone showing good antibacterial activity was analysed further by gas chromatography mass spectrometry, UV/Vis spectrophotometry and Fourier transform infrared spectroscopy, which indicated the probable presence of germacrone. PMID:24591751

Revathi, S.; Malathy, N. S.

2013-01-01

126

In Vitro Activity of Plazomicin against 5,015 Gram-Negative and Gram-Positive Clinical Isolates Obtained from Patients in Canadian Hospitals as Part of the CANWARD Study, 2011-2012  

PubMed Central

Plazomicin is a next-generation aminoglycoside that is not affected by most clinically relevant aminoglycoside-modifying enzymes. The in vitro activities of plazomicin and comparator antimicrobials were evaluated against a collection of 5,015 bacterial isolates obtained from patients in Canadian hospitals between January 2011 and October 2012. Susceptibility testing was performed using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method, with MICs interpreted according to CLSI breakpoints, when available. Plazomicin demonstrated potent in vitro activity against members of the family Enterobacteriaceae, with all species except Proteus mirabilis having an MIC90 of ?1 ?g/ml. Plazomicin was active against aminoglycoside-nonsusceptible Escherichia coli, with MIC50 and MIC90 values identical to those for aminoglycoside-susceptible isolates. Furthermore, plazomicin demonstrated equivalent activities versus extended-spectrum ?-lactamase (ESBL)-producing and non-ESBL-producing E. coli and Klebsiella pneumoniae, with 90% of the isolates inhibited by an MIC of ?1 ?g/ml. The MIC50 and MIC90 values for plazomicin against Pseudomonas aeruginosa were 4 ?g/ml and 16 ?g/ml, respectively, compared with 4 ?g/ml and 8 ?g/ml, respectively, for amikacin. Plazomicin had an MIC50 of 8 ?g/ml and an MIC90 of 32 ?g/ml versus 64 multidrug-resistant P. aeruginosa isolates. Plazomicin was active against methicillin-susceptible and methicillin-resistant Staphylococcus aureus, with both having MIC50 and MIC90 values of 0.5 ?g/ml and 1 ?g/ml, respectively. In summary, plazomicin demonstrated potent in vitro activity against a diverse collection of Gram-negative bacilli and Gram-positive cocci obtained over a large geographic area. These data support further evaluation of plazomicin in the clinical setting. PMID:24550325

Adam, H.; Baxter, M.; Denisuik, A.; Lagace-Wiens, P.; Karlowsky, J. A.; Hoban, D. J.; Zhanel, G. G.

2014-01-01

127

Eco-friendly synthesis and in vitro antibacterial activities of some novel chalcones.  

PubMed

Chalcone derivatives have been synthesized by reaction of 1-(2,5-dimethyl-furan-3-yl)-ethanone with corresponding active aldehyde in ethanolic NaOH in microwave oven. The structure of these compounds was established by elemental analysis, IR, 1H-NMR, 13C-NMR, and EI-MS spectral analysis. The anti-bacterial activity of these compounds was first tested in vitro by the disc diffusion assay against two Gram-positive and two Gram-negative bacteria, and then the minimum inhibitory concentration (MIC) was determined with the reference of standard drug Chloramphenicol. The results showed that pyrazol containing chalcone (compound 8) inhibited both types of bacteria (Gram-positive and Gram-negative) better than chloramphenicol. PMID:24397034

Khan, Salman A; Asiri, Abdullah M; Alamry, Khalid A; El-Daly, Samy A; Zayed, Mohie A M

2013-01-01

128

Synthesis and Antibacterial Activity of Novel Curcumin Derivatives Containing Heterocyclic Moiety  

PubMed Central

A series of curcumin derivatives containing heterocyclic moiety have been synthesized and evaluated for their antibacterial activities. The chemical structures of the synthesized compounds were verified on the basis of spectral data and elemental analyses. Investigation of antimicrobial activity of the derivatives demonstrated the ability to inhibit Gram-positive microorganisms with zone of inhibition ranging from 14-18 mm, MIC ranging between 0.0625 and 0.25 mg/mL. Among all tested derivatives, diazepine 4 exhibited remarkable potency against Gram-positive bacteria S. aureus. An extensive study is underway to optimize the effectiveness of diazepine type of compounds and to determine their mode of action. PMID:24250571

A. Hamed, Othman; Mehdawi, Noha; Abu Taha, Adham; M. Hamed, Emad; A. Al-Nuri, Mohammed; S. Hussein, Ayman

2013-01-01

129

Composition and Antibacterial Activity of Heracleum Transcaucasicum and Heracleum Anisactis Aerial Parts Essential Oil  

PubMed Central

Purpose: Two plant essential oils (EOs), including those from Heracleum transcaucasicum and Heracleum anisactiss (Umbeliferae) were studied to detect the chemical constituents and evaluated for their antibacterial activities against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa. Methods: The EOs of H. transcaucasicum and H.anisactis (Apiacae) were obtained by hydrodistillation from aerial parts of the plants. The chemical analyses of the EOs were performed by GC/Mass spectrometry (GC/MS). Myristicin was found to be the principal constituent in both EOs. The susceptibility tests of EOs were performed by agar disc diffusion technique against Gram-positive and Gram-negative bacterial strains. Results: Eight components comprising 99.97% of the total essential oil of H. transcaucasicum and a total of three compounds accounting for 98.5% of the total oil composition of aerial parts of H. anisactis were identified, of which myristicin was the main compound in both EOs. The EOs of H. transcaucasicum and H. anisactis showed weak antibacterial property against Gram-positive strains of Staphylococcus aureus and Staphylococcus epidermidis with no measurable effect on Escherichia coli and Pseudomonas aeruginosa. Conclusion: Our GC-MS study revealed myristicin to be the major constituent of H. transcaucasicum and H.anisactis aerial parts. In spite of all the information available on the antibacterial properties of plants essential oils, we were not able to find significant antibacterial activity for both EOs. PMID:24312869

Torbati, Mohammadali; Nazemiyeh, Hossein; Lotfipour, Farzaneh; Asnaashari, Solmaz; Nemati, Mahboob; Fathiazad, Fatemeh

2013-01-01

130

Antibacterial Activity of Sirodesmin PL Phytotoxin: Application to the Selection of Phytotoxin-Deficient Mutants  

PubMed Central

Sirodesmin PL, a phytotoxin and mycotoxin produced by Leptosphaeria maculans, the causal agent of stem-canker disease of crucifers, exhibited antibacterial activity against gram-positive bacteria and particularly Bacillus subtilis. The importance of the disulfide bridge of the molecule in antibacterial activity was demonstrated. A simple and reliable bioassay based on the antibacterial activity of the toxin was performed for screening sirodesmin PL-deficient mutants when grown on solid culture medium. A mutant was selected and found to produce 3,700-fold less toxin than did the wild-type strain. A sensitive procedure for quantification of the toxin by high-pressure liquid chromatography was developed. Levels of product as low as 100 ng could be detected by this procedure. Images PMID:16347949

Boudart, Georges

1989-01-01

131

Antifungal and antibacterial activity of Haliclona sp. from the Persian Gulf, Iran.  

PubMed

In this study, antifungal and antibacterial activities of diethyl ether, methanol and aqueous extracts of Haliclona sp. were assessed (in vitro). The antibacterial activity of the extracts was determined by broth dilution methods against clinical Gram-negative bacteria: Escherichia coli, Pseudomonas aeruginosa and Gram-positive bacteria: Staphylococcus aureus aureus, Bacillus subtilis spizizenii. The antifungal activity of the extracts was determined by using a broth microdilution test against clinical fungi Candida albicans and Aspergillus fumigatus. Our results showed diethyl ether extract of Haliclona sp. was active on Gram-positive bacteria. In addition, methanol extract in comparison with diethyl ether extract had better activity against C. albicans (MIC: 0.75 mg/mL, MFC: 1.5mg/mL) and A. fumigatus (MIC: 2mg/mL, MFC: 3mg/mL). Aqueous extract had neither antifungal nor antibacterial activities. Based our results, Haliclona sp. can be considered as a source of novel antibiotic and antifungal. PMID:24934592

Nazemi, M; Alidoust Salimi, M; Alidoust Salimi, P; Motallebi, A; Tamadoni Jahromi, S; Ahmadzadeh, O

2014-09-01

132

Acquired inducible antimicrobial resistance in Gram-positive bacteria  

PubMed Central

A major contributor to the emergence of antibiotic resistance in Gram-positive bacterial pathogens is the expansion of acquired, inducible genetic elements. Although acquired, inducible antibiotic resistance is not new, the interest in its molecular basis has been accelerated by the widening distribution and often ‘silent’ spread of the elements responsible, the diagnostic challenges of such resistance and the mounting limitations of available agents to treat Gram-positive infections. Acquired, inducible antibiotic resistance elements belong to the accessory genome of a species and are horizontally acquired by transformation/recombination or through the transfer of mobile DNA elements. The two key, but mechanistically very different, induction mechanisms are: ribosome-sensed induction, characteristic of the macrolide–lincosamide–streptogramin B antibiotics and tetracycline resistance, leading to ribosomal modifications or efflux pump activation; and resistance by cell surface-associated sensing of ?-lactams (e.g., oxacillin), glycopeptides (e.g., vancomycin) and the polypeptide bacitracin, leading to drug inactivation or resistance due to cell wall alterations. PMID:22913355

Chancey, Scott T; Zahner, Dorothea; Stephens, David S

2012-01-01

133

Efficacy of telavancin, a lipoglycopeptide antibiotic, in experimental models of Gram-positive infection.  

PubMed

Telavancin is a parenteral lipoglycopeptide antibiotic with a dual mechanism of action contributing to bactericidal activity against multidrug-resistant Gram-positive pathogens. It has been approved for the treatment of complicated skin and skin structure infections due to susceptible Gram-positive bacteria and hospital-acquired/ventilator-associated bacterial pneumonia due to Staphylococcus aureus when other alternatives are unsuitable. Telavancin has been demonstrated to be efficacious in multiple animal models of soft tissue, cardiac, systemic, lung, bone, brain and device-associated infections involving clinically relevant Gram-positive pathogens, including methicillin-resistant S. aureus, glycopeptide-intermediate S. aureus, heterogeneous vancomycin-intermediate S. aureus and daptomycin non-susceptible methicillin-resistant S. aureus. The AUC0-24h/MIC ratio is the primary pharmacodynamically-linked pharmacokinetic parameter. The preclinical data for telavancin supports further investigative clinical evaluation of its efficacy in additional serious infections caused by susceptible Gram-positive pathogens. PMID:25382700

Hegde, Sharath S; Janc, James W

2014-12-01

134

Study of antibacterial activity by capillary electrophoresis using multiple UV detection points.  

PubMed

A new methodology for an antibacterial assay based on capillary electrophoresis with multiple UV detection points has been proposed. The possible antibacterial activity of cationic molecules on bacteria (Gram-positive and Gram-negative) is studied by detecting the bacteria before, during, and after their meeting with the cationic antibacterial compound. For that, a UV area imaging detector having two loops and three detection windows was used with a 95 cm ×100 ?m i.d. capillary. In the antibacterial assay, the bacteria (negatively charged) and the cationic molecules were injected separately from each end of the capillary. The bacteria were mobilized by anionic ITP mode while cationic molecules migrate in the opposite direction under conditions close to CZE. The cationic molecules were injected into the capillary as a broad band (injected volume about 16% of the volume of the capillary) to prevent dilution of the sample during the electrophoretic process. Bacteriolytic activity, as well as strong interactions between the small antibacterial molecules and the bacteria, can be investigated within a few minutes. The assay was used to study the antibacterial activity of dendrigraft poly-L-lysines on Micrococcus luteus and Erwinia carotovora. Because dendrigraft poly-L-lysines are nonimmunogenic and have low toxicity, this new class of dendritic biomacromolecules is very promising for antibacterial applications. PMID:22448657

Oukacine, Farid; Romestand, Bernard; Goodall, David M; Massiera, Gladys; Garrelly, Laurent; Cottet, Hervé

2012-04-01

135

Synthesis and structure-activity relationships of novel amino/nitro substituted 3-arylcoumarins as antibacterial agents.  

PubMed

A new series of amino/nitro-substituted 3-arylcoumarins were synthesized and their antibacterial activity against clinical isolates of Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) was evaluated. Some of these molecules exhibited antibacterial activity against S. aureus comparable to the standards used (oxolinic acid and ampicillin). The preliminary structure-activity relationship (SAR) study showed that the antibacterial activity against S. aureus depends on the position of the 3-arylcoumarin substitution pattern. With the aim of finding the structural features for the antibacterial activity and selectivity, in the present manuscript different positions of nitro, methyl, methoxy, amino and bromo substituents on the 3-arylcoumarin scaffold were reported. PMID:23348993

Matos, Maria J; Vazquez-Rodriguez, Saleta; Santana, Lourdes; Uriarte, Eugenio; Fuentes-Edfuf, Cristina; Santos, Ysabel; Muńoz-Crego, Angeles

2013-01-01

136

Anti-bacterial activity of Euphorbia fusiformis--a rare medicinal herb.  

PubMed

Euphorbia fusiformis Buch.-Ham. ex. D.Don (Euphorbiaceae) is a rare medicinal herb. Aqueous and organic solvent extracts of the leaves and rootstocks were investigated for anti-bacterial properties by using disc diffusion and well-in agar methods, against pathogenic strains of Gram positive (Bacillus subtilis and Staphylococcus aureus) and Gram negative bacteria (Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella typhii A and Salmonella typhii B). The different extracts differed significantly in their anti-bacterial properties with the methanolic extract being very effective followed by acetone and chloroform extracts. Aqueous and ethanolic extract showed very least activity. The result highlights that rootstock extracts had good anti-bacterial properties than leaf extracts. The results of this study support the use of this plant in traditional medicine to treat fever, wound infections and intestinal disorders. PMID:16159702

Natarajan, D; Britto, S John; Srinivasan, K; Nagamurugan, N; Mohanasundari, C; Perumal, G

2005-10-31

137

Conformationally constrained analogs of N-substituted piperazinylquinolones: synthesis and antibacterial activity of N-(2,3-dihydro-4-hydroxyimino-4H-1-benzopyran-3-yl)-piperazinylquinolones.  

PubMed

A series of novel quinolone agents bearing a particular bulky and conformationally constrained bicyclic substituent (2,3-dihydro-4-hydroxyimino-4H-1-benzopyran-3-yl- moiety) on the piperazine ring of 7-piperazinyl quinolones (norfloxacin, enoxacin, ciprofloxacin, and levofloxacin) were synthesized and evaluated against a panel of Gram-positive and Gram-negative bacteria. Among these derivatives, ciprofloxacin counterpart 9c, highly inhibited the tested Gram-positive bacteria, superior to that of the reference drugs, and displayed antibacterial activity at non-cytotoxic concentrations. PMID:19544301

Emami, Saeed; Foroumadi, Alireza; Samadi, Nasrin; Faramarzi, Mohammad A; Rajabalian, Saeed

2009-07-01

138

Antibacterial Activity of New Dibenzoxepinone Oximes with Fluorine and Trifluoromethyl Group Substituents  

PubMed Central

In this paper we present the antimicrobial activity of some newly synthesized dibenz[b,e]oxepin derivatives bearing the oximino moiety, and fluorine (F) and trifluoromethyl (CF3) group substituents. The chemical structure and purity of the new compounds were assessed by using elemental analysis, NMR and FTIR spectroscopy. The new compounds were screened for their antibacterial activity towards Gram-positive and Gram-negative strains, by qualitative and quantitative assays. Our results demonstrated that the CF3 and F disubstituted compounds could be considered for the further development of novel antimicrobial drugs. PMID:22072897

Limban, Carmen; Chifiriuc, Mariana Carmen

2011-01-01

139

Synthesis and antibacterial activities of acylide derivatives bearing an aryl-tetrazolyl chain  

PubMed Central

Seventeen acylides bearing an aryl-tetrazolyl alkyl-substituted side chain were synthesized, starting from clarithromycin, via several reactions including hydrolysis, acetylating, esterification, carbamylation, and Michael addition. The structures of all new compounds were confirmed by 1H nuclear magnetic resonance spectroscopy, 13C nuclear magnetic resonance spectroscopy, and mass spectrometry. All these synthesized acylides were evaluated for in vitro antimicrobial activities against gram-positive pathogens (Staphylococcus aureus, Staphylococcus epidermidis) and gram-negative pathogens (Pseudomonas aeruginosa, Escherichia coli), using the broth microdilution method. Results showed that compounds 10e, 10f, 10g, 10 h, 10o have good antibacterial activities. PMID:25284984

Shan, Ling-Xing; Sun, Ping-Hua; Guo, Bao-Qin; Xu, Xing-Jun; Li, Zhi-Qiang; Sun, Jia-Zhi; Zhou, Shu-Feng; Chen, Wei-Min

2014-01-01

140

Antibacterial and antifungal activity of a soda-lime glass containing copper nanoparticles.  

PubMed

A low melting point soda-lime glass powder containing copper nanoparticles with high antibacterial (against gram-positive and gram-negative bacteria) and antifungal activity has been obtained. Sepiolite fibres containing monodispersed copper nanoparticles (d(50) approximately 30 +/- 5 nm) were used as the source of the copper nanoparticles. The observed high activity of the obtained glass powder, particularly against yeast, has been explained by considering the inhibitory synergistic effect of the Ca(2+) lixiviated from the glass on the growth of the colonies. PMID:19907067

Esteban-Tejeda, L; Malpartida, F; Esteban-Cubillo, A; Pecharromán, C; Moya, J S

2009-12-16

141

In vitro antibacterial activity of water-soluble extract of aghalokpe.  

PubMed

Water-soluble extracts of the bark of aghalokpe, a big tropical tree which grows in the rainforest of Bendel State of Nigeria, showed in vitro antibacterial activity against several of the Enterobacteriaceae. The activity was more pronounced with gram-positive than the gram-negative species. The minimum inhibitory concentration (MIC) which is in the range of 3.125-50 micrograms/ml, compares well with some broad-spectrum antibiotics on the market. The extract was remarkably effective against Neisseria gonorrhoea. PMID:6322551

Williams, B; Popoola, B

1983-06-01

142

Antibacterial activity of cyclodextrins against Bacillus strains  

Microsoft Academic Search

Growth of alkaliphilic Bacillus halodurans C-125 both on agar plates and in liquid culture was inhibited by methyl-?-cyclodextrin (CD). Furthermore, resting cells of\\u000a the strain were lysed by contact with methyl-?-CD higher than 10 mM. ?-CD also showed lysis activity against Bacillus and related strains. The activity was not observed with Gram-negative and Gram-positive bacteria except for Bacillus strains. Fluorescence staining

Hui-Min Zhang; Zhijun Li; Katsuyuki Uematsu; Tohru Kobayashi; Koki Horikoshi

2008-01-01

143

Mode of antibacterial activity of Eclalbasaponin isolated from Eclipta alba.  

PubMed

The present study was undertaken to evaluate the mode of antibacterial activity of Eclalbasaponin isolated from Eclipta alba, against selected Gram-positive and Gram-negative bacteria. The probable chemical structure was determined by using various spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR) and mass spectroscopy. The antibacterial activity was evaluated by well diffusion technique, pH sensitivity, chemotaxis, and crystal violet assays. Eclalbasaponin showed clear zone of inhibition against both Bacillus subtilis and Pseudomonas aeruginosa and exhibited growth inhibition at the pH range of 5.5-9.0. The isolated saponin exhibited its positive chemoattractant property for both bacterial strains. Results of crystal violet assay and the presence of UV-sensitive materials in the cell-free supernatant confirmed the cellular damages caused by the treatment of Eclalbasaponin. The release of intracellular proteins due to the membrane damage was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Changes in the cell surface structure and membrane disruption were further revealed by FTIR and scanning electron microscopy analysis. The present study suggests that the isolated saponin from E. alba causes the disruption of the bacterial cell membrane which leads to the loss of bacterial cell viability. PMID:24013881

Ray, A; Bharali, P; Konwar, B K

2013-12-01

144

Evaluation of antioxidant and antibacterial activity of methanolic extracts of Gentiana kurroo royle  

PubMed Central

In this study our objective was to evaluate the antioxidant and antimicrobial activity of methanolic extracts of leaves and roots of Gentiana kurroo. The antioxidant activities of the extracts were examined using different biochemical assays namely diphenylpicrylhydrazyl (DPPH), nitroblue tetrazolium (NBT) and ferric reducing power (FRAP). In all the assays, root extract exhibited stronger antioxidant activity than that of leaves. The antibacterial activity of the extracts was also evaluated and MIC values were calculated by broth dilution method. Although, the extracts prevented the growth of both Gram positive and Gram negative bacteria, the MIC values of methanolic extract of the leaves were higher than those of the root extract. The antibacterial and antioxidant activity of the extracts was found to be positively associated with the total phenolic and flavonoid content of the extracts.

Baba, Shoib A.; Malik, Shahid A.

2014-01-01

145

Evaluation of antioxidant and antibacterial activity of methanolic extracts of Gentiana kurroo royle.  

PubMed

In this study our objective was to evaluate the antioxidant and antimicrobial activity of methanolic extracts of leaves and roots of Gentiana kurroo. The antioxidant activities of the extracts were examined using different biochemical assays namely diphenylpicrylhydrazyl (DPPH), nitroblue tetrazolium (NBT) and ferric reducing power (FRAP). In all the assays, root extract exhibited stronger antioxidant activity than that of leaves. The antibacterial activity of the extracts was also evaluated and MIC values were calculated by broth dilution method. Although, the extracts prevented the growth of both Gram positive and Gram negative bacteria, the MIC values of methanolic extract of the leaves were higher than those of the root extract. The antibacterial and antioxidant activity of the extracts was found to be positively associated with the total phenolic and flavonoid content of the extracts. PMID:25313286

Baba, Shoib A; Malik, Shahid A

2014-11-01

146

Genetic features of circular bacteriocins produced by Gram-positive bacteria.  

PubMed

This review highlights the main genetic features of circular bacteriocins, which require the co-ordinated expression of several genetic determinants. In general terms, it has been demonstrated that the expression of such structural genes must be combined with the activity of proteins involved in maturation (cleavage/circularization) and secretion outside the cell via different transporter systems, as well as multifaceted immunity mechanisms essential to ensuring the bacteria's self-protection against such strong inhibitors. Several circular antibacterial peptides produced by Gram-positive bacteria have been described to date, including enterocin AS-48, from Enterococcus faecalis S-48 (the first one characterized), gassericin A, from Lactobacillus gasseri LA39, and a similar one, reutericin 6, from Lactobacillus reuteri LA6, butyrivibriocin AR10, from the ruminal anaerobe Butyrivibrio fibrisolvens AR10, uberolysin, from Streptococcus uberis, circularin A, from Clostridium beijerinckii ATCC 25752, and subtilosin A, from Bacillus subtilis. We summarize here the progress made in the understanding of their principal genetic features over the last few years, during which the functional roles of circular proteins with wide biological activity have become clearer. PMID:18034824

Maqueda, Mercedes; Sánchez-Hidalgo, Marina; Fernández, Matilde; Montalbán-López, Manuel; Valdivia, Eva; Martínez-Bueno, Manuel

2008-01-01

147

Mycosynthesis: antibacterial, antioxidant and antiproliferative activities of silver nanoparticles synthesized from Inonotus obliquus (Chaga mushroom) extract.  

PubMed

In the present study, silver nanoparticles (AgNPs) were rapidly synthesized from silver nitrate solution at room temperature using Inonotus obliquus extract. The mycogenic synthesized AgNPs were characterized by UV-Visible absorption spectroscopy, Fourier transform infrared (FTIR), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). SEM revealed mostly spherical nanoparticles ranging from 14.7 to 35.2nm in size. All AgNPs concentrations showed good ABT radical scavenging activity. Further, AgNPs showed effective antibacterial activity against both gram negative and gram positive bacteria and antiproliferative activity toward A549 human lung cancer (CCL-185) and MCF-7 human breast cancer (HTB-22) cell lines. The samples demonstrated considerably high antibacterial, and antiproliferative activities against bacterial strains and cell lines. PMID:24380885

Nagajyothi, P C; Sreekanth, T V M; Lee, Jae-il; Lee, Kap Duk

2014-01-01

148

Synthesis, antibacterial activities and molecular docking studies of peptide and Schiff bases as targeted antibiotics.  

PubMed

A series of peptide and Schiff bases (PSB) were synthesized by reacting salicylic acid, primary diamines with salicylaldehyde or its derivatives, and 40 of which were newly reported. The inhibitory activities against Escherichia coli beta-ketoacyl-acyl carrier protein synthase III (ecKAS III) were investigated in vitro and molecular docking simulation also surveyed. Top 10 PSB compounds which possess both good inhibitory activity and well binding affinities were picked out, and their antibacterial activities against Gram-negative and Gram-positive bacterial strains were tested, expecting to exploit potent antibacterial agent with broad-spectrum antibiotics activity. The results demonstrate compound N-(3-(5-bromo-2-hydroxybenzylideneamino)propyl)-2-hydroxybenzamide (2d) can be as a potential antibiotics agent, displaying minimal inhibitory concentration values in the range of 0.39-3.13 microg/mL against various bacteria. PMID:19884012

Cheng, Kui; Zheng, Qing-Zhong; Qian, Yong; Shi, Lei; Zhao, Jing; Zhu, Hai-Liang

2009-12-01

149

Synthesis and antibacterial activity of nitroaryl thiadiazole-levofloxacin hybrids.  

PubMed

Novel levofloxacin-containing hybrids carrying a 5-(nitroaryl)-1,3,4-thiadiazol-2-yl group were synthesized and evaluated in vitro against Gram-positive and Gram-negative bacteria. Preliminary data indicated that levofloxacin-nitrofuran and levofloxacin-nitroimidazole hybrids have a potent activity against Gram-positive organisms with enhanced anti-staphylococcal activity compared with the parent quinolone (N-desmethyl levofloxacin). PMID:17036368

Foroumadi, Alireza; Mansouri, Shahla; Emami, Saeed; Mirzaei, Javad; Sorkhi, Maedeh; Saeid-Adeli, Nosratollah; Shafiee, Abbas

2006-11-01

150

Effects of Lactobacillus plantarum immobilization in alginate coated with chitosan and gelatin on antibacterial activity.  

PubMed

The present study aimed to investigate and evaluate the efficiency of immobilizing the Lactobacillus plantarum TN9 strain in alginate using chitosan and gelatin as coating materials, in terms of viability and antibacterial activity. The results indicate that maximum concentrations of L. plantarum TN9 strain were produced with 2% sodium alginate, 10(8)UFC/ml, and 1M calcium chloride. The viability and antibacterial activity of the L. plantarum TN9 cultures before and after immobilization in alginate, chitosan-coated alginate, and gelatin-coated alginate, were studied. The findings revealed that the viability of encapsulated L. plantarum could be preserved more than 5.8 log CFU/ml after 35 day of incubation at 4 °C, and no effects were observed when gelatin was used. The antibacterial activity of encapsulated L. plantarum TN9 against Gram-positive and Gram-negative pathogenic bacteria was enhanced in the presence of chitosan coating materials, and no activity was observed in the presence of gelatin. The effects of catalase and proteolytic enzymes on the culture supernatant of L. plantarum TN9 were also investigated, and the results suggested that the antibacterial activity observed was due to the production of organic acids. Taken together, the findings indicated that immobilization in chitosan enhanced the antibacterial activity of L. plantarum TN9 against several pathogenic bacteria. This encapsulated strain could be considered as a potential strong candidate for future application as an additive in the food and animal feed industries. PMID:24315948

Trabelsi, Imen; Ayadi, Dorra; Bejar, Wacim; Bejar, Samir; Chouayekh, Hichem; Ben Salah, Riadh

2014-03-01

151

Antibacterial activity and cytotoxicity of PEGylated poly(amidoamine) dendrimers†  

PubMed Central

We have investigated the antibacterial activity and cytotoxicity of a series of amino-terminated poly(amidoamine) (PAMAM) dendrimers modified with poly(ethylene glycol) (PEG) groups. The antibacterial activity of the PAMAM dendrimers and their derivatives against the common ocular pathogens, Pseudomonas aeruginosa and Staphylococcus aureus, was evaluated by their minimum inhibitory concentrations (MICs). For the unmodified third and fifth generation (G3 and G5) amino-terminated dendrimers, the MICs against both P. aeruginosa and S. aureus were in the range of 6.3–12.5 ?g mL?1, comparable to that of the antimicrobial peptide LL-37 (1.3–12.5 ?g mL?1) and within the wide range of 0.047–128 ?g mL?1 for the fluoroquinolone antibiotics. PEGylation of the dendrimers decreased their antibacterial activities, especially for the Gram-positive bacteria (S. aureus). The reduction in potency is likely due to the decrease in the number of protonated amino groups and shielding of the positive charges by the PEG chains, thus decreasing the electrostatic interactions of the dendrimers with the negatively-charged bacterial surface. Interestingly, localization of a greater number of amino groups on G5 vs. G3 dendrimers did not improve the potency. Significantly, even a low degree of PEGylation, e.g. 6% with EG11 on G3 dendrimer, greatly reduced the cytotoxicity towards human corneal epithelial cells while maintaining a high potency against P. aeruginosa. The cytotoxicity of the PEGylated dendrimers to host cells is much lower than that reported for antimicrobial peptides. Furthermore, the MICs of these dendrimers against P. aeruginosa are more than two orders of magnitude lower than other antimicrobial polymers reported to date. These results motivate further exploration of the potential of cationic dendrimers as a new class of antimicrobial agents that may be less likely to induce bacterial resistance than standard antibiotics. PMID:19756304

Lopez, Analette I.; Reins, Rose Y.; McDermott, Alison M.; Trautner, Barbara W.

2010-01-01

152

Antibacterial activity on Citrullus colocynthis Leaf extract.  

PubMed

Studies on the antibacterial activities of the leaf extract of Citrullus colocynthis (Cucurbitaceae), a medicinal plant used for the treatment of various ailments was carried out using agar disc diffusion technique. The results revealed that the crude acetone extract exhibited antibacterial activities against Pseudomonas aeruginosa with zones of inhibition measuring 14.0mm. The chloroform leaf extract exhibited no antibacterial activity against Staphylococcus aureus. The minimum inhibitory concentration for the chloroform extract was 4.0mm for Escherichia coli. PMID:22557336

Gowri, S Shyamala; Priyavardhini, S; Vasantha, K; Umadevi, M

2009-07-01

153

Chocolate agar, a differential medium for gram-positive cocci.  

PubMed Central

Reactions incurred on chocolate agar by gram-positive cocci were correlated with species identity. Darkening and clearing of the medium was usually associated with the species Staphylococcus epidermidis, Staphylococcus aureus, Staphylococcus simulans, and Streptococcus faecalis. Yellowing of chocolate agar was associated with alpha-hemolytic species of Streptococcus. The study demonstrated that reactions occurring on chocolate agar are useful in identifying gram-positive cocci. PMID:6490866

Gunn, B A

1984-01-01

154

Antibacterial activity of baking soda.  

PubMed

The antibacterial activity of baking soda (sodium bicarbonate) was assessed using three different experimental approaches. Standard minimum inhibitory concentration analyses revealed substantial inhibitory activity against Streptococcus mutans that was not due to ionic strength or high osmolarity. Short-term exposure assays showed significant killing of bacterial suspensions when baking soda was combined with the detergent sodium dodecylsulfate. Multiple, brief exposures of sucrose-colonized S mutans to baking soda and sodium dodecylsulfate caused statistically significant decreases in numbers of viable cells. Use of oral health care products with high concentrations of baking soda could conceivably result in decreased levels of cariogenic S mutans in saliva and plaque. PMID:12017929

Drake, D

1997-01-01

155

Antibacterial activity of baking soda.  

PubMed

The antibacterial activity of baking soda (sodium bicarbonate) was assessed using three different experimental approaches. Standard minimum inhibitory concentration analyses revealed substantial inhibitory activity against Streptococcus mutans that was not due to ionic strength or high osmolarity. Short-term exposure assays showed significant killing of bacterial suspensions when baking soda was combined with the detergent sodium dodecylsulfate. Multiple, brief exposures of sucrose-colonized S mutans to baking soda and sodium dodecylsulfate caused statistically significant decreases in numbers of viable cells. Use of oral health care products with high concentrations of baking soda could conceivably result in decreased levels of cariogenic S mutans in saliva and plaque. PMID:11524862

Drake, D

1996-01-01

156

Antibacterial activity of chitosan-based matrices on oral pathogens  

Microsoft Academic Search

Chitosan is a well sought-after polysaccharide in biomedical applications due to its biocompatibility, biodegradability to\\u000a non-toxic substances, and ease of fabrication into various configurations. However, alterations in the anti-bacterial properties\\u000a of chitosan in various forms is not completely understood. The objective of this study was to evaluate the anti-bacterial\\u000a properties of chitosan matrices in different configurations against two pathogens—Gram-positive Streptococcus

Aparna R. Sarasam; Phoebe Brown; Sharukh S. Khajotia; John J. Dmytryk; Sundararajan V. Madihally

2008-01-01

157

Chemical composition and antibacterial activity of propolis collected by three different races of honeybees in the same region.  

PubMed

The chemical analysis and antibacterial activity of three types of propolis collected three different races of Apis mellifera bee in the same apiary were investigated. Propolis samples were investigated by GC/MS, 48 compounds were identified 32 being new for propolis. The compounds identified indicated that the main plant sources of propolis were Populus alba, Populus tremuloides and Salix alba. The antimicrobial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans was evaluated. Ethanolic extracts of propolis samples showed high antibacterial activity against Gram-positive cocci (Staphylococcus aureus), but had a weak activity against Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and yeast (Candida albicans). Propolis sample collected by Apis mellifera caucasica showed a higher antibacterial activity than collected by Apis mellifera anatolica and Apis mellifera carnica. PMID:15848022

Silici, Sibel; Kutluca, Semiramis

2005-05-13

158

2,2'-Dithienyl diselenide pro-oxidant activity accounts for antibacterial and antifungal activities.  

PubMed

The aim of this study was to explore if 2,2'-dithienyl diselenide (DTDS) pro-oxidant activity is related to its antibacterial and antifungal actions. The antimicrobial activity of DTDS against bacterial and fungal was investigated in the broth microdilution assay (3.02-387 ?g/ml). Additionally, the survival curve of microorganisms in the presence of DTDS (12.09-193.5 ?g/ml) was performed. The involvement of pro-oxidant activity in the DTDS antimicrobial action was investigated by supplementing the growth medium with 10 mM glutathione or ascorbic acid in the disk diffusion technique (0.64-640 ?gDTDS/discs). The levels of reactive species (RS) induced by 25 mM DTDS were also determined. The results demonstrated that DTDS was effective in preventing the Gram-positive bacteria and Candida albicans growth. The minimum inhibitory concentration, twice and half concentrations of DTDS confirmed that the activity of compound was bactericidal for some microorganisms (Enterococcus faecalis, and Staphylococcus saprophyticus), bacteriostatic for Bacillus cereus and fungistatic for C. albicans. Antibacterial and antifungal actions of DTDS are related to the increase of reactive species levels. The presence of antioxidants in the growth medium avoided the DTDS antimicrobial action. In conclusion, DTDS showed promising antibacterial and antifungal actions, possibly related to its pro-oxidant activity. PMID:23683588

Pesarico, Ana Paula; Sartori, Gláubia; dos Santos, Camilla F A; Neto, José S S; Bortolotto, Vandreza; Santos, Roberto Christ Vianna; Nogueira, Cristina W; Prigol, Marina

2013-11-01

159

The antibacterial activity of Magainin I immobilized onto mixed thiols Self-Assembled Monolayers.  

PubMed

An antibacterial peptide, Magainin I, was covalently bound to a mixed 11-mercaptoundecanoďc acid (MUA) and 6-mercaptohexanol (C6OH) (ratio 1:3) Self-Assembled Monolayer (SAM) on gold surfaces. Each step of the surface functionalization was characterized by Polarization Modulation Reflection Absorption InfraRed Spectroscopy (PM-RAIRS) and X-ray Photoelectron Spectroscopy (XPS). The antibacterial activity of the anchored Magainin was tested against three Gram-positive bacteria (Listeria ivanovii, Enterococcus faecalis and Staphylococcus aureus), and the results revealed that the adsorbed Magainin I reduced by more than 50% the adhesion of bacteria at the surface, together with the killing of the bacteria that nonetheless adhered to the surface. No release of the peptide was observed upon contact with the bacterial suspension; the activity has proven to be persistent overtime, up to six months after the first use. PMID:19345992

Humblot, Vincent; Yala, Jean-Fabrice; Thebault, Pascal; Boukerma, Kada; Héquet, Arnaud; Berjeaud, Jean-Marc; Pradier, Claire-Marie

2009-07-01

160

Fabrication of pDMAEMA-coated silica nanoparticles and their enhanced antibacterial activity.  

PubMed

Thin pDMAEMA shells were formed on the surface of silica nanoparticles via vapor deposition polymerization. Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and elemental analysis have been used to characterize the resulting pDMAEMA-coated silica nanoparticles. Electron microscopy studies reveal that the thin polymer shell is formed on the silica surface. In this work, the particle diameter can be controlled (from ~19 to ~69 nm) by varying the size of silica core. The antibacterial performance of the core-shell nanoparticles was investigated against both Gram-positive (Escherichia coli) and Gram-negative (Staphylococcus aureus) bacteria. Importantly, the nano-sized pDMAEMA particles presented antibacterial activity against both bacteria without additional quaternization due to its enlarged surface area. Additionally, the bactericidal efficiency was enhanced by reducing the particle size, because the expanded surface area of the cationic polymer nanoparticles provides more active sites that can kill the bacteria. PMID:23838333

Song, Jooyoung; Jung, Yujung; Lee, Inkyu; Jang, Jyongsik

2013-10-01

161

Antibacterial properties of propolis (bee glue).  

PubMed Central

Propolis (bee glue) was found to have antibacterial activity against a range of commonly encountered cocci and Gram-positive rods, including the human tubercle bacillus, but only limited activity against Gram-negative bacilli. These findings confirm previous reports of antimicrobial properties of this material, possibly attributable to its high flavonoid content. PMID:2182860

Grange, J M; Davey, R W

1990-01-01

162

Silver/poly (lactic acid) nanocomposites: preparation, characterization, and antibacterial activity  

PubMed Central

In this study, antibacterial characteristic of silver/poly (lactic acid) nanocomposite (Ag/PLA-NC) films was investigated, while silver nanoparticles (Ag-NPs) were synthesized into biodegradable PLA via chemical reduction method in diphase solvent. Silver nitrate and sodium borohydride were respectively used as a silver precursor and reducing agent in the PLA, which acted as a polymeric matrix and stabilizer. Meanwhile, the properties of Ag/PLA-NCs were studied as a function of the Ag-NP weight percentages (8, 16, and 32 wt% respectively), in relation to the use of PLA. The morphology of the Ag/PLA-NC films and the distribution of the Ag-NPs were also characterized. The silver ions released from the Ag/PLA-NC films and their antibacterial activities were scrutinized. The antibacterial activities of the Ag/PLA-NC films were examined against Gram-negative bacteria (Escherichia coli and Vibrio parahaemolyticus) and Gram-positive bacteria (Staphylococcus aureus) by diffusion method using Muller–Hinton agar. The results indicated that Ag/PLA-NC films possessed a strong antibacterial activity with the increase in the percentage of Ag-NPs in the PLA. Thus, Ag/PLA-NC films can be used as an antibacterial scaffold for tissue engineering and medical application. PMID:20856832

Shameli, Kamyar; Ahmad, Mansor Bin; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa; Rahman, Russly Abdul; Jokar, Maryam; Darroudi, Majid

2010-01-01

163

Optical control of antibacterial activity  

NASA Astrophysics Data System (ADS)

Bacterial resistance is a major problem in the modern world, stemming in part from the build-up of antibiotics in the environment. Novel molecular approaches that enable an externally triggered increase in antibiotic activity with high spatiotemporal resolution and auto-inactivation are highly desirable. Here we report a responsive, broad-spectrum, antibacterial agent that can be temporally activated with light, whereupon it auto-inactivates on the scale of hours. The use of such a ‘smart’ antibiotic might prevent the build-up of active antimicrobial material in the environment. Reversible optical control over active drug concentration enables us to obtain pharmacodynamic information. Precisely localized control of activity is achieved, allowing the growth of bacteria to be confined to defined patterns, which has potential for the development of treatments that avoid interference with the endogenous microbial population in other parts of the organism.

Velema, Willem A.; van der Berg, Jan Pieter; Hansen, Mickel J.; Szymanski, Wiktor; Driessen, Arnold J. M.; Feringa, Ben L.

2013-11-01

164

Investigation of structural, dielectric, magnetic and antibacterial activity of Cu-Cd-Ni-FeO4 nanoparticles  

NASA Astrophysics Data System (ADS)

Nanoparticles of Cu-Cd-Ni-FeO4 were synthesized by the auto-combustion process using a modified citric acid method. Antibacterial activity, structural, dielectric and magnetic properties were investigated. An assay showed the broad spectrum antibacterial activity of Cu-Cd-Ni-FeO4 against Gram positive and Gram negative pathogenic bacterial strains. The existence of single phase cubic spinel structure of ferrites was confirmed by X-ray diffraction measurement. Fourier transform infrared spectroscopy shows the two main absorption bands at lower frequency region. Surface morphology and compositional features were studied by scanning electron microscopy and energy dispersive X-ray spectroscopy analysis, respectively. Results indicated that the nanosize particles greatly influenced the antibacterial activity, as well as structural, dielectric and magnetic properties of the samples. Magnetic measurements of the samples were carried out by means of vibrating sample magnetometry and Mössbauer spectroscopy. Magnetic properties are strongly affected by Ni2+ substitution.

Hashim, Mohd.; Alimuddin; Shirsath, Sagar E.; Meena, S. S.; Kotnala, R. K.; Parveen, Ameena; Roy, Aashis S.; Kumar, Shalendra; Bhatt, Pramod; Kumar, Ravi

2013-09-01

165

Antibacterial activity of some Artemisia species extract.  

PubMed

The antimicrobial activities of ethanol, methanol and hexane extracts from Artemisia absinthium, Artemisia annua and Artemisia vulgaris were studied. Plant extracts were tested against five Gram-positive bacteria, two Gram-negative bacteria and one fungal strain. The results indicated that Artemisia annua alcoholic extracts are more effective against tested microorganisms. However, all plants extracts have moderate or no activity against Gram-negative bacteria. The obtained results confirm the justification of extracts of Artemisia species use in traditional medicine as treatment for microbial infections. PMID:20191854

Poiat?, Antonia; Tuchilu?, Cristina; Iv?nescu, Bianca; Ionescu, A; Laz?r, M I

2009-01-01

166

Synthesis, antibacterial activity, and quantitative structure-activity relationships of new (Z)-2-(nitroimidazolylmethylene)-3(2H)-benzofuranone derivatives.  

PubMed

A new series of (Z)-2-(1-methyl-5-nitroimidazole-2-ylmethylene)-3(2H)-benzofuranones (11a-p) and (Z)-2-(1-methyl-4-nitroimidazole-5-ylmethylene)-3(2H)-benzofuranones (12a-m) were synthesized and assayed for their antibacterial activity against Gram-positive and Gram-negative bacteria. Most of the 5-nitroimidazole analogues (11a-p) showed a remarkable inhibition of a wide spectrum of Gram-positive bacteria (Staphylococcus aureus, Streptococcus epidermidis, MRSA, and Bacillus subtilis) and Gram-negative Klebsiella pneumoniae, whereas 4-nitroimidazole analogues (12a-m) were not effective against selected bacteria. The quantitative structure-activity relationship investigations were applied to find out the correlation between the experimentally evaluated activities with various parameters of the compounds studied. The QSAR models built in this work had reasonable predictive power and could be explained by the observed trends in activities. PMID:17919903

Hadj-esfandiari, Narges; Navidpour, Latifeh; Shadnia, Hooman; Amini, Mohsen; Samadi, Nasrin; Faramarzi, Mohammad Ali; Shafiee, Abbas

2007-11-15

167

Synthesis of N-halamine-functionalized silica-polymer core-shell nanoparticles and their enhanced antibacterial activity  

NASA Astrophysics Data System (ADS)

N-halamine-functionalized silica-polymer core-shell nanoparticles with enhanced antibacterial activity were synthesized through the encapsulation of silica nanoparticles as support with polymeric N-halamine. The as-synthesized nanoparticles were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive x-ray spectrometry (EDX), dynamic light scattering (DLS), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR). These N-halamine-functionalized silica-polymer core-shell nanoparticles displayed powerful antibacterial performance against both Gram-positive bacteria and Gram-negative bacteria, and their antibacterial activities have been greatly improved compared with their bulk counterparts. Therefore, these N-halamine-functionalized silica-polymer core-shell nanoparticles have the potential for various significant applications such as in medical devices, healthcare products, water purification systems, hospitals, dental office equipment, food packaging, food storage, household sanitation, etc.

Dong, Alideertu; Huang, Jinfeng; Lan, Shi; Wang, Tao; Xiao, Linghan; Wang, Weiwei; Zhao, Tianyi; Zheng, Xin; Liu, Fengqi; Gao, Ge; Chen, Yuxin

2011-07-01

168

Aerobic Respiration in the Gram-Positive Bacteria  

Microsoft Academic Search

The group of Gram-positive bacteria is a major phylum of prokaryotes, including several typical saprophytic aerobes. Their\\u000a respiratory chains are apparently similar to those of eukaryotic mitochondria, but in several points are different from them.\\u000a The respiratory chain of Gram-positives, like many bacteria, contains branched electron transfer pathways, usually 1-3 heme-Cu\\u000a oxidases, but SoxB-type cytochrome c oxidases (cytochrome b(a\\/o)3) are

Nobhuito Sone; Cecilia Hagerhall; Junshi Sakamoto

169

Wall Teichoic Acids of Gram-Positive Bacteria  

PubMed Central

The peptidoglycan layers of many gram-positive bacteria are densely functionalized with anionic glycopolymers called wall teichoic acids (WTAs). These polymers play crucial roles in cell shape determination, regulation of cell division, and other fundamental aspects of gram-positive bacterial physiology. Additionally, WTAs are important in pathogenesis and play key roles in antibiotic resistance. We provide an overview of WTA structure and biosynthesis, review recent studies on the biological roles of these polymers, and highlight remaining questions. We also discuss prospects for exploiting WTA biosynthesis as a target for new therapies to overcome resistant infections. PMID:24024634

Brown, Stephanie; Santa Maria, John P.; Walker, Suzanne

2013-01-01

170

Antimicrobial glycopeptides: synthesis and antibacterial activity of N-linked and O-linked smaller chain glycopeptides.  

PubMed

Our objective is to synthesize the smaller chain N-linked and O-linked glycopeptides using sugars belong to mono, di and polysaccharides, with the efforts mainly directed towards the identification of antibacterial compounds. 7 glycopeptides, viz., Arg-Asn-Mannose, Arg-Asn-Lactose, His-Asn-Mannose, His-Asn-Lactose (N-glycopeptides), Arg-Ser-Lactose, Arg-Thr-Lactose, Arg-Thr-Starch (O-glycopeptides) were prepared by dicyclohexyl carbodimide (DCC) coupling for amino acids using microwave oven (50W power; 15?min) and activated and coupled with respective sugar moieties using microwave oven at 120?W for 20-25?min. The column eluted compounds were tested for disc diffusion assay using 3 gram positive S. aureus, B. subtilis, S. caprae and 3 gram negative E. coli, P. aeruginosa and S. sonnei strains at different concentrations predicted by pH and inhibitory concentrations. One of the test glycopeptide, His-Asn-Lactose was found to be very effective against all the microbial strains tested and 3 other Test Compounds, viz., His-Asn-Mannose, Arg-Thr-Lactose and Arg-Thr-Starch are also proved to be effective against 2?gram positive and 2?gram negative strains tested. Maximum activity was observed at a concentration of 450??g/ml (747.51?µM) for the N-glycopeptide His-Asn-Lactose with the corresponding zonal inhibition diameters (15?mm; 19?mm; 14?mm; 18?mm; 16?mm; 17?mm) against S. aureus, B. subtilis, S. caprae, E. coli, P. aeruginosa, S. sonnei. This is the first evidence based report that our N-glycopeptide, His-Asn-Lactose tested, has shown antibacterial action against both gram positive and gram negative strains. Further in vivo testing and clinical studies will make sure to position our potent small chain N-glycopeptide in the arsenal of new broad spectrum anti-gram positive and negative agent. PMID:24026960

Nagarajan, K; Taleuzzamman, M; Kumar, V; Singh, S; Singh, J; Panda, B P; Ghosh, L K

2014-04-01

171

Artemisia capillaris extracts as a green factory for the synthesis of silver nanoparticles with antibacterial activities.  

PubMed

We report a green synthesis of silver nanoparticles that uses extracts from the aerial part of Artemisia capillaris. Both water and 70% ethanol extracts successfully generated silver nanoparticles. The formation of silver nanoparticles was confirmed by surface plasmon resonance bands, Fourier transform-infrared spectra, high resolution-transmission electron and atomic force microscopic images. Various shapes of silver nanoparticles were generated with an average diameter of 29.71 nm with water extract and 29.62 nm with 70% ethanol extract. An improvement in antibacterial activity (MIC 8.35-16.7 microg/mL) was observed against a total of twenty different strains of Gram-negative and Gram-positive bacteria. A remarkable enhancement (approximately 12-fold) was observed against Pseudomonas aeruginosa, Escherichia coli, Enterobacter cloacae, Klebsiella oxytoca, and Klebsiella areogenes when compared with the extract alone. Silver nanoparticles produced by the 70% ethanol extract showed slightly higher antibacterial activity than those generated with the water extract. The correlation between total flavonoid content of each extract and the antibacterial activity did not exert any significant relationships. This report suggests that plant extracts have the potential to be used as powerful reducing agents for the production of biocompatible silver nanoparticles possessing enhanced antibacterial activities. PMID:23035437

Park, Youmie; Noh, Hwa Jung; Han, Lina; Kim, Hyun-Seok; Kim, Yong-Jae; Choi, Jae Sue; Kim, Chong-Kook; Kim, Yeong Shik; Cho, Seonho

2012-09-01

172

Activity of nine oral agents against gram-positive and gram-negative bacteria encountered in community-acquired infections: Use of pharmacokinetic\\/pharmacodynamic breakpoints in the comparative assessment of beta-lactam and macrolide antimicrobial agents  

Microsoft Academic Search

Background: The application of pharmacokinetic (PK) and pharmacodynamic (PD) data in conjunction with minimum inhibitory concentrations (MICs) of antibacterial agents has been shown to allow for improved selection and appropriate dosing of antimicrobial agents for specific infections, increasing the likelihood of bacteriologic cure and, through this, reducing the risk for the development of resistant organisms.Objectives: This study was undertaken to

Mihaela Peric; Frederick A Browne; Michael R Jacobs; Peter C Appelbaum

2003-01-01

173

Silver-doped manganese dioxide and trioxide nanoparticles inhibit both gram positive and gram negative pathogenic bacteria.  

PubMed

Palladium, ruthenium and silver-doped MnO2 and silver doped Mn2O3 nanoparticles were synthesized by simple co-precipitation technique. SEM-TEM analysis revealed the nano-size of these synthesized samples. XPS data illustrates that Mn is present in 4+ and 3+ oxidation states in MnO2 and Mn2O3 respectively. Thermal analysis gave significant evidence for the phase changes with increasing temperature. Antibacterial activity of these synthesized nanoparticles on three Gram positive bacterial cultures (Staphylococcus aureus ATCC 6538, Streptococcus epidermis ATCC 12228, Bacillus subtilis ATCC 6633) and three Gram negative cultures (Escherichia coli ATCC 8739, Salmonella abony NCTC 6017 and Klebsiella pneumoniae ATCC 1003) was investigated using a disc diffusion method and live/dead assay. Only Ag-doped MnO2 and Ag-doped Mn2O3 nanoparticles showed antibacterial property against all six-test bacteria but Ag-doped MnO2 was found to be more effective than Ag-doped Mn2O3. PMID:24140741

Kunkalekar, R K; Prabhu, M S; Naik, M M; Salker, A V

2014-01-01

174

Antimicrobial Peptide Resistance Mechanisms of Gram-Positive Bacteria  

PubMed Central

Antimicrobial peptides, or AMPs, play a significant role in many environments as a tool to remove competing organisms. In response, many bacteria have evolved mechanisms to resist these peptides and prevent AMP-mediated killing. The development of AMP resistance mechanisms is driven by direct competition between bacterial species, as well as host and pathogen interactions. Akin to the number of different AMPs found in nature, resistance mechanisms that have evolved are just as varied and may confer broad-range resistance or specific resistance to AMPs. Specific mechanisms of AMP resistance prevent AMP-mediated killing against a single type of AMP, while broad resistance mechanisms often lead to a global change in the bacterial cell surface and protect the bacterium from a large group of AMPs that have similar characteristics. AMP resistance mechanisms can be found in many species of bacteria and can provide a competitive edge against other bacterial species or a host immune response. Gram-positive bacteria are one of the largest AMP producing groups, but characterization of Gram-positive AMP resistance mechanisms lags behind that of Gram-negative species. In this review we present a summary of the AMP resistance mechanisms that have been identified and characterized in Gram-positive bacteria. Understanding the mechanisms of AMP resistance in Gram-positive species can provide guidelines in developing and applying AMPs as therapeutics, and offer insight into the role of resistance in bacterial pathogenesis.

McBride, Shonna M.

2014-01-01

175

Screening genomes of Gram-positive bacteria for  

E-print Network

Screening genomes of Gram-positive bacteria for double-glycine-motif- containing peptides Secreted-positive bacteria, the double-glycine (GG) motif plays a key role in many peptide secretion systems involved Microbiology Comment #12;peptides and class II bacteriocins, produced by streptococci and lactic acid bacteria

176

Protein secretion and surface display in Gram-positive bacteria  

PubMed Central

The cell wall peptidoglycan of Gram-positive bacteria functions as a surface organelle for the transport and assembly of proteins that interact with the environment, in particular, the tissues of an infected host. Signal peptide-bearing precursor proteins are secreted across the plasma membrane of Gram-positive bacteria. Some precursors carry C-terminal sorting signals with unique sequence motifs that are cleaved by sortase enzymes and linked to the cell wall peptidoglycan of vegetative forms or spores. The sorting signals of pilin precursors are cleaved by pilus-specific sortases, which generate covalent bonds between proteins leading to the assembly of fimbrial structures. Other precursors harbour surface (S)-layer homology domains (SLH), which fold into a three-pronged spindle structure and bind secondary cell wall polysaccharides, thereby associating with the surface of specific Gram-positive microbes. Type VII secretion is a non-canonical secretion pathway for WXG100 family proteins in mycobacteria. Gram-positive bacteria also secrete WXG100 proteins and carry unique genes that either contribute to discrete steps in secretion or represent distinctive substrates for protein transport reactions. PMID:22411983

Schneewind, Olaf; Missiakas, Dominique M.

2012-01-01

177

Purification, characterization and antibacterial activity of L-amino acid oxidase from Cerastes cerastes.  

PubMed

Antibiotic resistance presents a real problem in which new antibacterial molecules from natural secretions could be beneficial in the development of new drugs. In this study, Cerastes cerastes venom was investigated for its antibacterial activity against Gram-positive and Gram-negative bacteria. The antibacterial activity was evaluated by measuring the halo inhibition and minimum inhibitory concentration (MIC). An L-amino acid oxidase (CcLAAO) was purified from this venom using three chromatographic steps; its homogeneity (60 kDa) was confirmed by SDS-PAGE. LC-MS/MS analysis of CcLAAO showed similarities with other LAAO enzymes from Echis ocellatus and Viridovipera stejnegeri venoms. CcLAAO presents an antibacterial activity against three bacterial strains (Staphylococcus aureus, Methicillin-resistant S. aureus, and Pseudomonas aeruginosa) with MIC values of 10, 10, and 20 ?g/mL, respectively. However, no effect was observed against Escherichia coli and yeast strains. Kinetic parameters of CcLAAO evaluated on L-leucine at pH 8.0 and 20°C were Km = 0.06 mmol and Vmax = 164 mmol/min. PMID:24817275

Hanane-Fadila, Ziad-Meziane; Fatima, Laraba-Djebari

2014-08-01

178

Essential oil composition and antibacterial activity of Monticalia greenmaniana (Asteraceae).  

PubMed

The essential oils from fresh aerial parts of Monticalia greenmaniana (Hieron) C. Jeffrey (Asteraceae) collected in March, were analyzed by GC/MS. Oil yields (w/v) of 0.1% (flowers), 0.07%, (stems) and 0.1% (leaves) were obtained by hydrodistillation. Thirteen, sixteen and eighteen components, respectively, were identified by comparison of their mass spectra with those in the Wiley GC-MS Library data base. The major components of the flower and stem oils were 1-nonane (38.8% flowers; 33.5% stems), alpha-pinene (29.0% flowers; 14.8% stems) and germacrene D (15.6% flowers; 18.6% stems). However, in the leaf oil, germacrene D was observed at 50.7%, followed by beta-cedrene at 8.4%. The leaf essential oil showed a broad spectrum of antibacterial activity against the important human pathogenic Gram-positive and Gram-negative bacteria Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 19433), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853) and Klebsiella pneumoniae (ATCC 25955) with MIC values ranging from 75 to 6000 ppm. PMID:22474970

Cárdenas, José; Rojas, Janne; Rojas-Fermin, Luís; Lucena, María; Buitrago, Alexis

2012-02-01

179

Antibacterial activity of a novel series of 3-bromo-4-(1 H-3-indolyl)-2,5-dihydro-1 H-2,5-pyrroledione derivatives – An extended structure–activity relationship study  

Microsoft Academic Search

Compounds containing 3-bromo-2,5-dihydro-1H-2,5-pyrroledione and indole substructures were found to have antibacterial activity against resistant strains of Staphylococcus aureus and some other Gram positive bacteria. The investigated compounds exhibit minimal inhibition concentrations (MICs) lower than those of common antibiotics like vancomycin or ciprofloxacin. Activity against multiresistant strains suggests a mechanism of action different from common antibiotics. This might be important in

Siavosh Mahboobi; Emerich Eichhorn; Matthias Winkler; Andreas Sellmer; Ute Möllmann

2008-01-01

180

The Antibacterial Activity of Cassia fistula Organic Extracts  

PubMed Central

Background: Cassia fistula, is a flowering plant and a member of Fabaceae family. Its leaves are compound of 4 - 8 pairs of opposite leaflets. There are many Cassia species around the world which are used in herbal medicine. Objectives: This study was designed to examine in vitro anti-bacterial activity of methanolic and ethanolic extracts of C. fistula native to Khuzestan, Iran. Materials and Methods: The microbial inhibitory effect of methanolic and ethanolic extracts of C. fistula was tested on 3 Gram positive: Bacillus cereus, Staphylococcus aureus and S. epidermidis and 5 Gram negative: Salmonella Typhi, Kelebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis bacterial species using disc diffusion method at various concentrations. The minimum inhibitory and bactericidal concentrations (MIC and MBC) were measured by the tube dilution assay. Results: The extract of C. fistula was effective against B. cereus, S. aureus, S. epidermidis, E. coli and K. pneumoniae. The most susceptible microorganisms to ethanolic and methanolic extracts were E. coli and K. pneumoniae, respectively. Also B. cereus and S. aureus showed the least sensitivity to ethanolic and methanolic extracts, respectively. The MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) of ethanolic extracts against S. aureus, E. coli, S. epidermidis and K. pneumoniae were also determined. Conclusions: With respect to the obtained results and regarding to the daily increase of the resistant microbial strains to the commercial antibiotics, it can be concluded that these extracts can be proper candidates of antibacterial substance against pathogenic bacterial species especially S. aureus, E. coli, K. pneumoniae and S. epidermidis. PMID:25147664

Seyyednejad, Seyyed Mansour; Motamedi, Hossein; Vafei, Mouzhan; Bakhtiari, Ameneh

2014-01-01

181

Antibacterial activity of silver: The role of hydrodynamic particle size at nanoscale.  

PubMed

Silver shows the highest antimicrobial activities amongst all metals. It is better than many first line antibiotics. The antimicrobial properties of silver can be tuned by altering its physical and surface properties. Researchers have demonstrated enhancement in the antibacterial properties of silver with decreasing particle size from bulk to nano. In the present article, we study the effect of particle size of silver at nanoscale on their antimicrobial properties. Two samples of silver nanoparticles (SNPs) of same physical size (?8 nm) but different hydrodynamic size (59 and 83 nm) are prepared by chemical reduction of AgNO3 with oleylamine followed by phase transfer with triblock copolymer Pluronic F-127. Their antimicrobial properties are investigated by microdilution method against clinically important strains of gram positive (S. aureus and B. megaterium) and gram negative (P. vulgaris and S. sonnei) bacteria. Nearly 38-50% enhancement in the antibacterial action of SNPs was observed when their hydrodynamic size was reduced to 59 nm from 83 nm. It has been observed that the antibacterial action of SNPs was governed by their hydrodynamic size and not by their crystallite and physical size. The phenomenological model was also proposed which makes an attempt to explain the microscopic mechanism responsible for the size dependent antibacterial activities of silver. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 3361-3368, 2014. PMID:24166739

Khurana, Chandni; Vala, Anjana K; Andhariya, Nidhi; Pandey, O P; Chudasama, Bhupendra

2014-10-01

182

In Vitro and In Vivo Antibacterial Activities of S-4661, a New Carbapenem  

PubMed Central

The in vitro and in vivo antibacterial activities of S-4661, a new 1?-methylcarbapenem, were compared with those of imipenem, meropenem, biapenem, cefpirome, and ceftazidime. The activity of S-4661 against methicillin-susceptible staphylococci and streptococci was comparable to that of imipenem, with an MIC at which 90% of the strains tested were inhibited (MIC90) equal to 0.5 ?g/ml or less. S-4661 was highly active against members of the family Enterobacteriaceae, Haemophilus influenzae, and Moraxella catarrhalis, with MIC90s ranging from 0.032 to 0.5 ?g/ml. Against imipenem-resistant Pseudomonas aeruginosa, S-4661 was the most active among test agents (MIC90, 8 ?g/ml). Furthermore, S-4661 displayed a high degree of activity against many ceftazidime-, ciprofloxacin-, and gentamicin-resistant isolates of P. aeruginosa. The in vivo efficacy of S-4661 against experimentally induced infections in mice caused by gram-positive and gram-negative bacteria, including penicillin-resistant Streptococcus pneumoniae and drug-resistant P. aeruginosa, reflected its potent in vitro activity and high levels in plasma in mice. We conclude that S-4661 is a promising new carbapenem for the treatment of infections caused by gram-positive and -negative bacteria, including penicillin-resistant S. pneumoniae and drug-resistant P. aeruginosa. PMID:9449267

Tsuji, Masakatsu; Ishii, Yoshikazu; Ohno, Akira; Miyazaki, Shuichi; Yamaguchi, Keizo

1998-01-01

183

Evaluation of antibacterial and anthelmintic activities with total phenolic contents of Piper betel leaves  

PubMed Central

Objective: The study was conducted to investigate the antibacterial and anthelmintic activities and to determine total phenolic contents of methanolic extract of Piper betel leaves. Materials and Methods: The extract was subjected to assay for antibacterial activity using both gram positive and gram negative bacterial strains through disc diffusion method; anthelmintic activity with the determination of paralysis and death time using earthworm (Pheritima posthuma) at five different concentrations and the determination of total phenolic contents using the Folin-ciocalteau method. Results: The extract showed significant (p<0.01) zone of inhibitions against gram positive Staphylococcus aureus [(6.77±0.25) mm] and Gram negative Escherichia coli [(8.53±0.25) mm], Salmonella typhi [(5.20±0.26) mm], Shigella dysenteriae [(11.20±0.26) mm] compared to positive control Azithromycin (ranging from 20.10±0.17 to 25.20±0.35 mm) while no zone inhibitory activity was found for both the extract and the standard drug against Gram positive Bacillus cereus. The extract also showed potent anthelmintic activity requiring less time for paralysis and death compared to the standard drug albendazole (10 mg/ml). At concentrations 10, 20, 40, 60 and 80 mg/ml, leaves extract showed paralysis at mean time of 9.83±0.60, 8.50±0.29, 6.60±0.17, 6.20±0.44 and 4.16±0.60; death at 11.33±0.88, 9.67±0.33, 7.83±0.17, 7.16±0.60 and 5.16±0.72 minutes, respectively. Whereas the standard drug showed paralysis and death at 19.33±0.71 and 51.00±0.23 minutes respectively. The extract confirmed the higher concentration of phenolic contents (124.42±0.14 mg of GAE /g of extract) when screened for total phenolic compounds. Conclusion: As results confirmed potential antibacterial and anthelmintic activities of Piper betel leaves extract, therefore it may be processed for further drug research. PMID:25386394

Akter, Kazi Nahid; Karmakar, Palash; Das, Abhijit; Anonna, Shamima Nasrin; Shoma, Sharmin Akter; Sattar, Mohammad Mafruhi

2014-01-01

184

In vitro antibacterial and antifungal activities of Cassia fistula Linn. fruit pulp extracts  

PubMed Central

Aim of the study is to assess the antimicrobial activity Cassia fistula fruit pulp extracts on some bacterial and fungal strains. Hydro alcohol and chloroform extracts of Cassia fistula fruit pulp were evaluated for the potential antimicrobial activity. The antimicrobial activity was determined in both the extracts using the agar disc diffusion method. Extracts were effective on tested microorganisms. The antibacterial and antifungal activities of solvent extracts (5, 25, 50, 100, 250 ?g/mL) of C. fistula were tested against two gram positive, two gram negative human pathogenic bacteria and three fungi, respectively. Crude extracts of C. fistula exhibited moderate to strong activity against most of the bacteria tested. The tested bacterial strains were Staphylococcus aureus, Streptococcus pyogenes, Escherichia coil, Pseudomonas aeruginosa, and fungal strains were Aspergillus. niger, Aspergillus. clavatus, Candida albicans. The antibacterial potential of the extracts were found to be dose dependent. The antibacterial activities of the C. fistula were due to the presence of various secondary metabolites. Hence, these plants can be used to discover bioactive natural products that may serve as leads in the development of new pharmaceuticals research activities. PMID:23049197

Bhalodia, N. R.; Nariya, P. B.; Acharya, R. N.; Shukla, V. J.

2012-01-01

185

Surface enhanced Raman scattering, antibacterial and antifungal active triangular gold nanoparticles  

NASA Astrophysics Data System (ADS)

Shape controlled syntheses of gold nanoparticles have attracted a great deal of attention as their optical, electronic, magnetic and biological properties are strongly dependent on the size and shape of the particles. Here is a report on the surface enhanced Raman scattering (SERS) activity of Cinnamomum zeylanicum leaf broth reduced gold nanoparticles consisting of triangular and spherical like particles, using 2-aminothiophenol (2-ATP) and crystal violet (CV) as probe molecules. Nanoparticles prepared with a minimum leaf broth concentration, having a greater number of triangular like particles exhibit a SERS activity of the order of 107. The synthesized nanoparticles exhibit efficient antibacterial activity against the tested gram negative bacterium Escherichia coli and gram positive bacterium Staphylococcus aureus. Investigations on the antifungal activity of the synthesized nanoparticles against Aspergillus niger and Fusarium oxysporum positive is also discussed.

Smitha, S. L.; Gopchandran, K. G.

2013-02-01

186

Influence of acetylation degree and molecular weight of homogeneous chitosans on antibacterial and antifungal activities.  

PubMed

The results given in the literature are conflicting when considering the relationship between antimicrobial activity and chitosan characteristics. To be able to clarify, we prepared fifteen homogeneous chitosans with different acetylation degrees (DA) and molecular weights (MW) by reacetylation of a fully deacetylated chitin under homogeneous conditions. They were tested at different pH values for their antimicrobial activities against four Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Salmonella typhi), four Gram-positive bacteria (Staphylococcus aureus, Bacillus cereus, Enterococcus faecalis and Micrococcus luteus) and three fungi (Aspergillus niger, Fusarium oxysporum and Alternaria solani). Chitosans markedly inhibited growth of most bacteria and fungi tested, although the inhibitory effect depends on the type of microorganism and on the chitosan characteristics (DA and MW) with minimum inhibitory concentrations in the range of 0.001 to 0.1 w%. Considering chitosan efficiency on bacteria, our series of data clearly show that the lower DA and the lower pH give the larger efficiency. Antibacterial activity was further enhanced for Gram-negative bacteria with decreasing MW, whereas, opposite effect was observed with the Gram-positive. Concerning the antifungal activity, the influence of chitosan characteristics was dependent on the particular type of fungus. Fungal growth decreased with increasing MW for F. oxysporum and decreasing DA for A. solani, but no MW or DA dependences were observed with A. niger. PMID:24929684

Younes, Islem; Sellimi, Sabrine; Rinaudo, Marguerite; Jellouli, Kemel; Nasri, Moncef

2014-08-18

187

Anaerobic, gram-positive, pleomorphic rods in human gingival crevice.  

PubMed

Sixty-two strains of anaerobic, gram-positive, pleomorphic rods were isolated from the gingival crevice of individuals clinically free from peridontal disease, and examined for biochemical characteristics, cellular and colonial morphology, and acid end-products from glucose fermentation. None of them produced indole, hydrogen sulfide, or catalase, but all hydrolysed esculin. Seven, 10 and 45 of 62 strains were identified as Bifidobacterium, Actinomyces naeslundii, and Actinomyces israelii, respectively, on the basis of biochemical characteristics. PMID:6928807

Maeda, N

1980-03-01

188

Architecture and assembly of the Gram-positive cell wall  

PubMed Central

The bacterial cell wall is a mesh polymer of peptidoglycan – linear glycan strands crosslinked by flexible peptides – that determines cell shape and provides physical protection. While the glycan strands in thin “Gram-negative” peptidoglycan are known to run circumferentially around the cell, the architecture of the thicker “Gram-positive” form remains unclear. Using electron cryotomography, here we show that Bacillus subtilis peptidoglycan is a uniformly dense layer with a textured surface. We further show it rips circumferentially, curls and thickens at free edges, and extends longitudinally when denatured. Molecular dynamics simulations show that only atomic models based on the circumferential topology recapitulate the observed curling and thickening, in support of an “inside-to-outside” assembly process. We conclude that instead of being perpendicular to the cell surface or wrapped in coiled cables (two alternative models), the glycan strands in Gram-positive cell walls run circumferentially around the cell just as they do in Gram-negative cells. Together with providing insights into the architecture of the ultimate determinant of cell shape, this study is important because Gram-positive peptidoglycan is an important antibiotic target crucial to the viability of several important rod-shaped pathogens including Bacillus anthracis, Listeria monocytogenes, and Clostridium difficile. PMID:23600697

Beeby, Morgan; Gumbart, James C.; Roux, Benoit; Jensen, Grant J.

2013-01-01

189

Rational Design of Berberine-Based FtsZ Inhibitors with Broad-Spectrum Antibacterial Activity  

PubMed Central

Inhibition of the functional activity of Filamenting temperature-sensitive mutant Z (FtsZ) protein, an essential and highly conserved bacterial cytokinesis protein, is a promising approach for the development of a new class of antibacterial agents. Berberine, a benzylisoquinoline alkaloid widely used in traditional Chinese and native American medicines for its antimicrobial properties, has been recently reported to inhibit FtsZ. Using a combination of in silico structure-based design and in vitro biological assays, 9-phenoxyalkyl berberine derivatives were identified as potent FtsZ inhibitors. Compared to the parent compound berberine, the derivatives showed a significant enhancement of antibacterial activity against clinically relevant bacteria, and an improved potency against the GTPase activity and polymerization of FtsZ. The most potent compound 2 strongly inhibited the proliferation of Gram-positive bacteria, including methicillin-resistant S. aureus and vancomycin-resistant E. faecium, with MIC values between 2 and 4 µg/mL, and was active against the Gram-negative E. coli and K. pneumoniae, with MIC values of 32 and 64 µg/mL respectively. The compound perturbed the formation of cytokinetic Z-ring in E. coli. Also, the compound interfered with in vitro polymerization of S. aureus FtsZ. Taken together, the chemical modification of berberine with 9-phenoxyalkyl substituent groups greatly improved the antibacterial activity via targeting FtsZ. PMID:24824618

Sun, Ning; Chan, Fung-Yi; Lu, Yu-Jing; Neves, Marco A. C.; Lui, Hok-Kiu; Wang, Yong; Chow, Ka-Yan; Chan, Kin-Fai; Yan, Siu-Cheong; Leung, Yun-Chung; Abagyan, Ruben; Chan, Tak-Hang; Wong, Kwok-Yin

2014-01-01

190

Thermal solvent-free synthesis of chromonyl chalcones, pyrazolines and their in vitro antibacterial, antifungal activities.  

PubMed

A facile and ecofriendly synthesis of new chromonyl chalcones 3a-b from 3-formylchromone 1 and active methyl compounds 2a-b is reported under thermal solvent-free heating condition in good yields. The chromonyl chalcones 3a-b were used as intermediates under green condition for the synthesis of new bioactive pyrazoline derivatives 4a-f. The compounds were tested for antimicrobial activity by disk diffusion assay with slight modifications against Gram-positive, Gram-negative strains of bacteria as well as fungal strains. The investigation of antimicrobial screening revealed that compounds 3a-b and 4a-f showed antibacterial and antifungal activities. PMID:21612378

Siddiqui, Zeba N; Praveen, Shagufta; Musthafa, T N Mohammed; Ahmad, Anis; Khan, Asad U

2012-02-01

191

Anti-bacterial activity and brine shrimp lethality bioassay of methanolic extracts of fourteen different edible vegetables from Bangladesh  

PubMed Central

Objective To investigate the antibacterial and cytotoxic activity of fourteen different edible vegetables methanolic extract from Bangladesh. Methods The antibacterial activity was evaluated using disc diffusion assay method against 12 bacteria (both gram positive and gram negative). The plant extracts were also screened for cytotoxic activity using the brine shrimp lethality bioassay method and the lethal concentrations (LC50) were determined at 95% confidence intervals by analyzing the data on a computer loaded with “Finney Programme”. Results All the vegetable extracts showed low to elevated levels of antibacterial activity against most of the tested strains (zone of inhibition=5-28 mm). The most active extract against all bacterial strains was from Xanthium indicum which showed remarkable antibacterial activity having the diameter of growth inhibition zone ranging from 12 to 28 mm followed by Alternanthera sessilis (zone of inhibition=6-21 mm). All extracts exhibited considerable general toxicity towards brine shrimps. The LC50 value of the tested extracts was within the range of 8.447 to 60.323 µg/mL with respect to the positive control (vincristine sulphate) which was 0.91 µg/mL. Among all studied extracts, Xanthium indicum displayed the highest cytotoxic effect with LC50 value of 8.447 µg/mL. Conclusions The results of the present investigation suggest that most of the studied plants are potentially good source of antibacterial and anticancer agents. PMID:23570009

Ullah, M. Obayed; Haque, Mahmuda; Urmi, Kaniz Fatima; Zulfiker, Abu Hasanat Md.; Anita, Elichea Synthi; Begum, Momtaj; Hamid, Kaiser

2013-01-01

192

Antibacterial and antioxidant activities of Artemisia annua essential oil  

Microsoft Academic Search

The essential oil of Artemisia annua aerial parts, consisting of camphor (44%), germacrene D (16%), trans-pinocarveol (11%), ?-selinene (9%), ?-caryophyllene (9%) and artemisia ketone (3%), was screened for its antimicrobial activity. The essential oil remarkably inhibited the growth of tested Gram-positive bacteria Enterococcus hirae and both tested fungi. This oil has shown an antioxidant activity equivalent to 18% of the

Fabien Juteau; Veronique Masotti; Jean Marie Bessičre; Michel Dherbomez; Josette Viano

2002-01-01

193

Microwave-assisted synthesis of diverse pyrrolo[3,4-c]quinoline-1,3-diones and their antibacterial activities.  

PubMed

With the aim of developing a general and practical method for library production, a novel and efficient two-phase microwave-assisted cascade reaction between isatins and ?-ketoamides in [Bmim]BF4/toluene was developed for the synthesis of pyrrolo[3,4-c]quinoline-1,3-diones. The features of this methodology are, the use of microwave-assisted rapid synthesis, mild reaction conditions, high yields, operational simplicity, facile product separation, and recyclability. Furthermore, the antibacterial activities of the pyrrolo[3,4-c]quinoline-1,3-dione derivatives produced were evaluated against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Enterobacter aerogenes) and Gram-positive bacteria (Bacillus cereus and Staphylococcus aureus). These derivatives showed antibacterial activities against Gram-positive strains that were at least equivalent to that against Gram-negative strains. Compound 7{3,5} displayed the most potent antibacterial activity against P. aeruginosa (MIC = 0.5 ?g/mL) and greater activity than standard ampicillin (MIC = 1 ?g/mL). Compound 7{4,7} exhibited the best inhibitory activity against E. coli and E. aerogenes (MIC = 1 and 0.5 ?g/mL), compared with the standard ampicillin (both MICs = 1 ?g/mL). The synthesized pyrrolo[3,4-c]quinoline-1,3-diones are expected to be widely used as lead compounds for the development of new antibacterial agents. PMID:24749663

Xia, Likai; Idhayadhulla, Akber; Lee, Yong Rok; Kim, Sung Hong; Wee, Young-Jung

2014-07-14

194

Evaluation of antibacterial activity on different solvent extracts of Euphorbia caracasana Boiss and Euphorbia cotinifolia L. (Euphorbiaceae) collected in Venezuela (Evaluación de la actividad antibacteriana en extractos de diferentes solventes de Euphorbia caracasana Boiss y Euphorbia cotinifolia L. (Euphorbiaceae) recolectadas en Venezuela)  

Microsoft Academic Search

In the present investigation the evaluation of the antibacterial activity of Euphorbia caracasana Boiss and Euphorbia cotinifolia L. has been evaluated against Gram positive and Gram negative bacteria using the disc diffusion agar method. E. caracasana and E. cotinifolia leaves were extracted with isopropyl alcohol. These extracts, after concentration, were fractionated by column chromatography and selected fractions, based on their

Janne ROJAS; Judith VELASCO; Antonio MORALES; Tulia DÍAZ; Gina MECCIA

2008-01-01

195

In vitro and in vivo antibacterial activities of CS-834, a novel oral carbapenem.  

PubMed Central

CS-834 is a novel oral carbapenem antibiotic. This compound is an ester-type prodrug of the active metabolite R-95867. The antibacterial activity of R-95867 was tested against 1,323 clinical isolates of 35 species and was compared with those of oral cephems, i.e., cefteram, cefpodoxime, cefdinir, and cefditoren, and that of a parenteral carbapenem, imipenem. R-95867 exhibited a broad spectrum of activity covering both gram-positive and -negative aerobes and anaerobes. Its activity was superior to those of the other compounds tested against most of the bacterial species tested. R-95867 showed potent antibacterial activity against clinically significant pathogens: methicillin-susceptible Staphylococcus aureus including ofloxacin-resistant strains, Streptococcus pneumoniae including penicillin-resistant strains, Clostridium perfringens, Neisseria spp., Moraxella catarrhalis, most members of the family Enterobacteriaceae, and Haemophilus influenzae (MIC at which 90% of strains are inhibited, < or =0.006 to 0.78 microg/ml). R-95867 was quite stable to hydrolysis by most of the beta-lactamases tested except the metallo-beta-lactamases from Stenotrophomonas maltophilia and Bacteroides fragilis. R-95867 showed potent bactericidal activity against S. aureus and Escherichia coli. Penicillin-binding proteins 1 and 4 of S. aureus and 1Bs, 2, 3, and 4 of E. coli had high affinities for R-95867. The in vivo efficacy of CS-834 was evaluated in murine systemic infections caused by 16 strains of gram-positive and -negative pathogens. The efficacy of CS-834 was in many cases superior to those of cefteram pivoxil, cefpodoxime proxetil, cefdinir, and cefditoren pivoxil, especially against infections caused by S. aureus, penicillin-resistant S. pneumoniae, E. coli, Citrobacter freundii, and Proteus vulgaris. Among the drugs tested, CS-834 showed the highest efficacy against experimental pneumonia in mice caused by penicillin-resistant S. pneumoniae. PMID:9420035

Fukuoka, T; Ohya, S; Utsui, Y; Domon, H; Takenouchi, T; Koga, T; Masuda, N; Kawada, H; Kakuta, M; Kubota, M; Ishii, C; Ishii, C; Sakagawa, E; Harasaki, T; Hirasawa, A; Abe, T; Yasuda, H; Iwata, M; Kuwahara, S

1997-01-01

196

In vitro and in vivo antibacterial activities of CS-834, a novel oral carbapenem.  

PubMed

CS-834 is a novel oral carbapenem antibiotic. This compound is an ester-type prodrug of the active metabolite R-95867. The antibacterial activity of R-95867 was tested against 1,323 clinical isolates of 35 species and was compared with those of oral cephems, i.e., cefteram, cefpodoxime, cefdinir, and cefditoren, and that of a parenteral carbapenem, imipenem. R-95867 exhibited a broad spectrum of activity covering both gram-positive and -negative aerobes and anaerobes. Its activity was superior to those of the other compounds tested against most of the bacterial species tested. R-95867 showed potent antibacterial activity against clinically significant pathogens: methicillin-susceptible Staphylococcus aureus including ofloxacin-resistant strains, Streptococcus pneumoniae including penicillin-resistant strains, Clostridium perfringens, Neisseria spp., Moraxella catarrhalis, most members of the family Enterobacteriaceae, and Haemophilus influenzae (MIC at which 90% of strains are inhibited, < or =0.006 to 0.78 microg/ml). R-95867 was quite stable to hydrolysis by most of the beta-lactamases tested except the metallo-beta-lactamases from Stenotrophomonas maltophilia and Bacteroides fragilis. R-95867 showed potent bactericidal activity against S. aureus and Escherichia coli. Penicillin-binding proteins 1 and 4 of S. aureus and 1Bs, 2, 3, and 4 of E. coli had high affinities for R-95867. The in vivo efficacy of CS-834 was evaluated in murine systemic infections caused by 16 strains of gram-positive and -negative pathogens. The efficacy of CS-834 was in many cases superior to those of cefteram pivoxil, cefpodoxime proxetil, cefdinir, and cefditoren pivoxil, especially against infections caused by S. aureus, penicillin-resistant S. pneumoniae, E. coli, Citrobacter freundii, and Proteus vulgaris. Among the drugs tested, CS-834 showed the highest efficacy against experimental pneumonia in mice caused by penicillin-resistant S. pneumoniae. PMID:9420035

Fukuoka, T; Ohya, S; Utsui, Y; Domon, H; Takenouchi, T; Koga, T; Masuda, N; Kawada, H; Kakuta, M; Kubota, M; Ishii, C; Ishii, C; Sakagawa, E; Harasaki, T; Hirasawa, A; Abe, T; Yasuda, H; Iwata, M; Kuwahara, S

1997-12-01

197

A new pentacyclic triterpene with potent antibacterial activity from Limnophila indica Linn. (Druce).  

PubMed

A new pentacyclic triterpenoid constituent, characterized as 3-oxo-olean-12(13),18(19)-dien-29?-carboxylic acid (1) on the basis of detailed spectral studies, was isolated from the aerial parts and roots of Limnophila indica (Scrophulariaceae). Compound 1 exhibited considerable antibacterial activity against three Gram-positive bacteria viz. Bacillus subtilis, Staphylococcus aureus and Listeria monocytogenes (MICs within a range of 25-30 ?g/ml) and moderate activity against four Gram-negative bacteria Salmonella typhimurium, Escherichia coli, Pseudomonas aeruginosa, and Pantoea ananatis (MICs within a range of 30-100 ?g/ml). The plant pathogenic bacterium P. ananatis and human pathogenic S. typhimurium responded at comparatively higher concentrations of the compound 1, which were 75 and 100 ?g/ml respectively. The compound inhibited the growth of Gram-positive B. subtilis and Gram-negative P. aeruginosa completely with a clear bactericidal mode of action at their MIC values. The compound upon treatment on both B. subtilis and P. aeruginosa released substantial amount of nucleic acid in the external medium and also effected the change of morphology towards pleomorphicity, thereby indicating its probable action on cell membrane. Furthermore, the triterpenoid 1 was found not to inhibit a probiotic lactic acid bacterium Lactococcus lactis subsp. lactis LABW4 under in vitro condition and to possess no toxicity in Swiss albino mice. PMID:23876368

Brahmachari, Goutam; Mandal, Narayan C; Roy, Rajiv; Ghosh, Ranjan; Barman, Soma; Sarkar, Sajal; Jash, Shyamal K; Mondal, Sadhan

2013-10-01

198

Antibacterial activity of dentine primer containing MDPB after curing  

Microsoft Academic Search

Objectives: A monomer methacryloyloxydodecylpyridinium bromide (MDPB) has antibacterial activity before polymerization. Furthermore, the antibacterial agent is immobilized by the polymerization of MDPB and the resin-based material incorporating MDPB is able to show an antibacterial effect even after being cured. The purpose of this study was to investigate the antibacterial effect of a dentine primer containing MDPB after curing.Methods: The inhibitory

S. Imazato; A. Ehara; M. Torii; S. Ebisu

1998-01-01

199

Antibiotic-decorated titanium with enhanced antibacterial activity through adhesive polydopamine for dental/bone implant.  

PubMed

Implant-associated infections, which are normally induced by microbial adhesion and subsequent biofilm formation, are a major cause of morbidity and mortality. Therefore, practical approaches to prevent implant-associated infections are in great demand. Inspired by adhesive proteins in mussels, here we have developed a novel antibiotic-decorated titanium (Ti) material with enhanced antibacterial activity. In this study, Ti substrate was coated by one-step pH-induced polymerization of dopamine followed by immobilization of the antibiotic cefotaxime sodium (CS) onto the polydopamine-coated Ti through catechol chemistry. Contact angle measurement and X-ray photoelectron spectroscopy confirmed the presence of CS grafted on the Ti surface. Our results demonstrated that the antibiotic-grafted Ti substrate showed good biocompatibility and well-behaved haemocompatibility. In addition, the antibiotic-grafted Ti could effectively prevent adhesion and proliferation of Escherichia coli (Gram-negative) and Streptococcus mutans (Gram-positive). Moreover, the inhibition of biofilm formation on the antibiotic-decorated Ti indicated that the grafted CS could maintain its long-term antibacterial activity. This modified Ti substrate with enhanced antibacterial activity holds great potential as implant material for applications in dental and bone graft substitutes. PMID:24647910

He, Shu; Zhou, Ping; Wang, Linxin; Xiong, Xiaoling; Zhang, Yifei; Deng, Yi; Wei, Shicheng

2014-06-01

200

Teichoic acids and related cell-wall glycopolymers in Gram-positive physiology and host interactions  

Microsoft Academic Search

Abstract | Most Gram-positive bacteria incorporate membrane- or peptidoglycan-attached carbohydrate-based polymers into their cell envelopes. Such cell-wall glycopolymers (CWGs) often have highly variable structures and have crucial roles in protecting, connecting and controlling the major envelope constituents. Further important roles of CWGs in host-cell adhesion, inflammation and immune activation have also been described in recent years. Identifying and harnessing highly

Christopher Weidenmaier; Andreas Peschel

2008-01-01

201

Synthetic Teichoic Acid Conjugate Vaccine against Nosocomial Gram-Positive Bacteria  

PubMed Central

Lipoteichoic acids (LTA) are amphiphilic polymers that are important constituents of the cell wall of many Gram-positive bacteria. The chemical structures of LTA vary among organisms, albeit in the majority of Gram-positive bacteria the LTAs feature a common poly-1,3-(glycerolphosphate) backbone. Previously, the specificity of opsonic antibodies for this backbone present in some Gram-positive bacteria has been demonstrated, suggesting that this minimal structure may be sufficient for vaccine development. In the present work, we studied a well-defined synthetic LTA-fragment, which is able to inhibit opsonic killing of polyclonal rabbit sera raised against native LTA from Enterococcus faecalis 12030. This promising compound was conjugated with BSA and used to raise rabbit polyclonal antibodies. Subsequently, the opsonic activity of this serum was tested in an opsonophagocytic assay and specificity was confirmed by an opsonophagocytic inhibition assay. The conjugated LTA-fragment was able to induce specific opsonic antibodies that mediate killing of the clinical strains E. faecalis 12030, Enterococcus faecium E1162, and community-acquired Staphylococcus aureus strain MW2 (USA400). Prophylactic immunization with the teichoic acid conjugate and with the rabbit serum raised against this compound was evaluated in active and passive immunization studies in mice, and in an enterococcal endocarditis rat model. In all animal models, a statistically significant reduction of colony counts was observed indicating that the novel synthetic LTA-fragment conjugate is a promising vaccine candidate for active or passive immunotherapy against E. faecalis and other Gram-positive bacteria. PMID:25333799

Laverde, Diana; Wobser, Dominique; Romero-Saavedra, Felipe; Hogendorf, Wouter; van der Marel, Gijsbert; Berthold, Martin; Kropec, Andrea; Codee, Jeroen; Huebner, Johannes

2014-01-01

202

3-Bromo- 4-(1 H-3-indolyl)-2,5-dihydro-1 H-2,5-pyrroledione derivatives as new lead compounds for antibacterially active substances  

Microsoft Academic Search

A number of new compounds containing 3-bromo-2,5-dihydro-1H-2,5-pyrroledione and indole substructures were found to have antibacterial activity against resistant strains of Staphylococcus aureus, Mycobacterium smegmatis and some other Gram positive bacteria. The investigated compounds exhibit minimal inhibition concentrations (MIC's) lower than those of ciprofloxacin, vancomycin and doxycycline resp. A different spectrum of activity, suggests a mechanism of action different to vancomycin

Siavosh Mahboobi; Emerich Eichhorn; Alfred Popp; Andreas Sellmer; Sigurd Elz; Ute Möllmann

2006-01-01

203

Antibacterial activities of Dodonaea viscosa using contact bioautography technique.  

PubMed

The crude ethanolic extract and n-hexane, dichloromethane, ethyl acetate, n-butanol and aqueous fractions of Dodonaea viscosa were analyzed for antibacterial potential against four Gram positive bacteria: Bacillus subtilis, Bacillus cereus, Micrococcus luteus, Staphylococcus aureus, and three Gram negative bacteria: Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa. Preliminary screening showed inhibition against Staphylococcus aureus, Micrococcus luteus, Escherichia coli and Pseudomonas aeruginosa. The thin layer chromatograms of the fractions were then subjected to contact bioautography, which showed inhibition zone at different R(f) values against Bacillus subtilis, Micrococcus luteus, Escherichia coli, Salmonella typhi and Pseudomonas aeruginosa, indicating the presence of antibacterial components. The MIC of each fraction was determined through a 96-well micro-titer plate method. The non-viability of the organisms was ascertained by determining the MBC of the fractions. PMID:19325527

Khurram, Muhammad; Khan, Murad Ali; Hameed, Abdul; Abbas, Naz; Qayum, Abdul; Inayat, Humaira

2009-01-01

204

Antibacterial activity of Pd(II) complexes with salicylaldehyde-amino acids Schiff bases ligands.  

PubMed

Palladium(II) complexes with Schiff bases ligands derived from salicylaldehyde and amino acids (Ala, Gly, Met, Ser, Val) have been synthesized and characterized by Fourier transform (FT)-IR, UV-Vis and (1)H-NMR spectroscopy. The electrospray mass spectrometry (ES-MS) spectrometry confirms the formation of palladium(II) complexes in 1/2 (M/L) molar ratio. All the Pd(II) complexes 1, [Pd(SalAla)2]Cl2; 2, [Pd(SalGly)2]Cl2; 3, [Pd(SalMet)2]Cl2; 4, [Pd(SalSer)2]Cl2; 5, [Pd(SalVal)2]Cl2; have shown antibacterial activity against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli. PMID:24390488

Rîmbu, Cristina; Danac, Ramona; Pui, Aurel

2014-01-01

205

Studies on constituents from Chamaecyparis pisifera and antibacterial activity of diterpenes.  

PubMed

In the course of our research for biologically active constituents from coniferous plants, a chromone derivative (1) and an abietane derivative (2) were isolated along with several diterpenes from Chamaecyparis pisifera. Structures of the new compounds were determined to be 5,7-dihydroxy-2-(1-acetyl-2-methoxycarbonylethyl)-chromone and rel-(8R,10R,20S)-8,10,20-trihydroxy-9(10-->20)-abeo-abieta-9,13-dien-12-one by means of spectral methods including two-dimensional NMR experiments. Some of these abietane-type compounds isolated from this plants showed antibacterial activitv against the gram-positive bacteria Staphylococcus aureus and Bacillus subtilis. PMID:11724244

Xiao, D; Kuroyanagi, M; Itani, T; Matsuura, H; Udayama, M; Murakami, M; Umehara, K; Kawahara, N

2001-11-01

206

Antibacterial nanofiber materials activated by light.  

PubMed

Electrospun polymeric nanofiber materials doped with 5,10,15,20-tetraphenylporphyrin (TPP) photosensitizer were prepared from four different polymers and were characterized with microscopic methods, steady-state, and time-resolved fluorescence and absorption spectroscopy. The polymers used included polyurethane Larithane™ (PUR), polystyrene (PS), polycaprolactone (PCL), and polyamide 6 (PA6). The antibacterial activity of all nanofiber materials against E. coli was activated by visible light and it was dependent on oxygen permeability/diffusion coefficients and the diameter of the polymeric nanofibers. This activity is based on oxidation ability of singlet oxygen O?(ą?(g)) that is generated upon irradiation. All tested nanofiber materials exhibited prolonged antibacterial properties, even in the dark after long-duration irradiation. The post-irradiation effect was explained by the photogeneration of H?O?, which provided the material with long-lasting antibacterial properties. PMID:21972201

Jesenská, So?a; Plíštil, Lukáš; Kubát, Pavel; Lang, Kamil; Brožová, Libuše; Popelka, St?pán; Szatmáry, Lórant; Mosinger, Ji?í

2011-12-15

207

The Antibacterial Activity of Haematin  

Microsoft Academic Search

SUMMARY: Haematin in concentrations of 1 \\/l,OOO,OOO-1\\/2,000,000 inhibited the growth of a number of bacteria most of which were aerobic sporing bacilli. Deutero- haematin and mesohaematin were also inhibitory, but not haematohaematin, urohaematin and a number of iron-free porphyrin derivatives. In a few cases whole blood was inhibitory, but generally only trypsin-digested laked red cells. The mechanism of the antibacterial

W. E. VAN HEYNINGEN

1951-01-01

208

Type IV Pili in Gram-Positive Bacteria  

PubMed Central

SUMMARY Type IV pili (T4P) are surface-exposed fibers that mediate many functions in bacteria, including locomotion, adherence to host cells, DNA uptake (competence), and protein secretion and that can act as nanowires carrying electric current. T4P are composed of a polymerized protein, pilin, and their assembly apparatuses share protein homologs with type II secretion systems in eubacteria and the flagella of archaea. T4P are found throughout Gram-negative bacterial families and have been studied most extensively in certain model Gram-negative species. Recently, it was discovered that T4P systems are also widespread among Gram-positive species, in particular the clostridia. Since Gram-positive and Gram-negative bacteria have many differences in cell wall architecture and other features, it is remarkable how similar the T4P core proteins are between these organisms, yet there are many key and interesting differences to be found as well. In this review, we compare the two T4P systems and identify and discuss the features they have in common and where they differ to provide a very broad-based view of T4P systems across all eubacterial species. PMID:24006467

Craig, Lisa

2013-01-01

209

Teicoplanin in the treatment of gram-positive-bacterial endocarditis.  

PubMed Central

Intravenous teicoplanin has been used to treat 23 cases of gram-positive-bacterial endocarditis, usually with 3 to 7 mg/kg every 12 h on the first day, followed by 3 to 7 mg/kg every 24 h. For some cases (staphylococcal and enterococcal endocarditis), the dosage was 8 to 14.4 mg/kg per day and/or other antibiotics were given. The mean duration was 48.2 days (range, 23 to 130 days). Of 23 patients, 21 (91.3%) had negative cultures or were cured. A total of 18 patients were treated with teicoplanin alone; of these, 4 had surgery, and all (except 2 who relapsed) were cured. Teicoplanin was combined with one or more antibiotics in five cases; in all cases appropriate cultures were negative, but three patients died during therapy or follow-up. Mild renal impairment was seen in two patients; both were receiving teicoplanin in combination with an aminoglycoside. We conclude that intravenous teicoplanin administered once a day at doses of 7 to 14 mg/kg per day is well tolerated, easy to administer, and may represent an efficacious therapy for gram-positive-bacterial endocarditis. PMID:2529815

Martino, P; Venditti, M; Micozzi, A; Brandimarte, C; Gentile, G; Santini, C; Serra, P

1989-01-01

210

Effect of Ester to Amide or N-methyl Amide Substitution on Bacterial Membrane Depolarization and Antibacterial Activity of Novel Cyclic Lipopeptides  

PubMed Central

Cyclic lipopeptides derived from the fusaricidin/LI-F family of naturally occurring antibiotics represent particularly attractive candidates for the development of new antibacterial agents. In comparison to natural products, these derivatives may offer better stability under physiologically relevant conditions and lower nonspecific toxicity, while preserving their antibacterial activity. In this study we have assessed the ability of cyclic lipodepsipeptide 1, and its amide 2, N-methyl amide 3 and linear peptide 4 analogues to interact with the cytoplasmic membranes of selected Gram-positive bacteria, as well as their bacteriostatic/bactericidal modes of action and in vivo potency using a Galleria mellonella model of MRSA infection. Cyclic lipopeptides 1 and 2 depolarize the cytoplasmic membranes of Gram-positive bacteria in a concentration-dependent manner. The degree of membrane depolarization was influenced by the structural and physical properties of 1 and 2, with more flexible and hydrophobic peptide 1 being most efficient. However, membrane depolarization does not correlate with bacterial cell lethality, suggesting that membrane-targeting activity is not the main mode of action for this class of antibacterial peptides. Conversely, substitution of the depsipeptide bond in 1 with an N-methyl amide bond 3, or its hydrolysis 4, lead to a complete loss of antibacterial activity, and indicate that the conformation of cyclic lipopeptides plays a role in their antibacterial activities. Cyclic lipopeptides 1 and 2 are also capable of improving the survival of G. mellonella larvae infected with MRSA with different efficiencies reflecting their in vitro activities. Gaining more insights into the structure-activity-relationship and mode of action of these cyclic lipopeptides may enable the development of new antibiotics of this class with improved antibacterial activity. PMID:23780744

Bionda, Nina; Fleeman, Renee M.; Shaw, Lindsey N.; Cudic, Predrag

2013-01-01

211

Antibacterial activity of selected Malaysian honey  

PubMed Central

Background Antibacterial activity of honey is mainly dependent on a combination of its peroxide activity and non-peroxide components. This study aims to investigate antibacterial activity of five varieties of Malaysian honey (three monofloral; acacia, gelam and pineapple, and two polyfloral; kelulut and tualang) against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa. Methods Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were performed for semi-quantitative evaluation. Agar well diffusion assay was used to investigate peroxide and non-peroxide activities of honey. Results The results showed that gelam honey possessed lowest MIC value against S. aureus with 5% (w/v) MIC and MBC of 6.25% (w/v). Highest MIC values were shown by pineapple honey against E. coli and P. aeruginosa as well as acacia honey against E. coli with 25% (w/v) MIC and 50% (w/v) MBC values. Agar inhibition assay showed kelulut honey to possess highest total antibacterial activity against S. aureus with 26.49 equivalent phenol concentrations (EPC) and non-peroxide activity of 25.74 EPC. Lowest antibacterial activity was observed in acacia honey against E. coli with total activity of 7.85 EPC and non-peroxide activity of 7.59 EPC. There were no significant differences (p?>?0.05) between the total antibacterial activities and non-peroxide activities of Malaysian honey. The intraspecific correlation between MIC and EPC of E. coli (r?=?-0.8559) was high while that between MIC and EPC of P. aeruginosa was observed to be moderate (r?=?-0.6469). S. aureus recorded a smaller correlation towards the opposite direction (r?=?0.5045). In contrast, B.cereus showed a very low intraspecific correlation between MIC and EPC (r?=?-0.1482). Conclusions Malaysian honey, namely gelam, kelulut and tualang, have high antibacterial potency derived from total and non-peroxide activities, which implies that both peroxide and other constituents are mutually important as contributing factors to the antibacterial property of honey. PMID:23758747

2013-01-01

212

Mercury(II) complexes of unsymmetric phosphorus ylides: Synthesis, spectroscopic and antibacterial activity studies  

NASA Astrophysics Data System (ADS)

The reaction of Ph2PCH2PPh2 (dppm) with 2-bromo-3-nitroacetophenone and 2,2?,4?-trichloroacetophenone in chloroform produce the new phosphonium salts [Ph2PCH2PPh2CH2C(O)C6H4NO2]Br (1) and [Ph2PCH2PPh2CH2C(O)C6H3Cl2]Cl (2). Further, by reaction of the monophosphonium salts of dppm with the strong base triethylaminethe corresponding bidentate phosphorus ylides, Ph2PCH2PPh2C(H)C(O)C6H4NO2 (3) and Ph2PCH2PPh2C(H)C(O)C6H3Cl2 (4) were obtained. The reaction of these ligands with mercury(II) halides in dry methanol led to the formation of the mononuclear complexes {HgX2[(Ph2PCH2PPh2C(H)C(O)C6H4NO2)]} [X = Cl (5), Br (6), I (7)] and {HgX2[(Ph2PCH2PPh2C(H)C(O)C6H3Cl2)]} [X = Cl (8), Br (9), I (10)]. Characterization of the obtained compounds was performed by elemental analysis, IR, 1H, 31P and 13C NMR. The structure of compound 1 being unequivocally determined by single crystal X-ray diffraction techniques. The mass spectrum of compound 6 (as an instance) also demonstrates the synthesize of these compounds. In all complexes the title ylides are coordinated through the ylidic carbon and the phosphine atom. These compounds form five membered ring under complexation. The antibacterial effects of DMSO solutions of the ligands and their metal complexes were evaluated by the disc diffusion method against six Gram positive and negative bacteria. All compounds represent antibacterial activity against these bacteria with high levels of inhibitory potency exhibited against the Gram positive species.

Sabounchei, Seyyed Javad; Panahimehr, Mohammad; Hosseinzadeh, Marjan; Karamian, Roya; Asadbegy, Mostafa; Masumi, Azadeh

2014-03-01

213

An insect defensin-derived ?-hairpin peptide with enhanced antibacterial activity.  

PubMed

Insect defensins are a class of small, cysteine-rich antimicrobial peptides primarily active on Gram-positive bacteria. Their roles in maggot therapy for treating chronic wound infection have been reported recently. However, a relatively narrow antibacterial spectrum together with the lack of a cost-effective means of commercial-scale production has limited their application. To further exploit the therapeutic potential of these molecules, we engineered the carboxyl-terminal ?-sheet of navidefensin2-2, an insect defensin from Nasonia vitripennis, based on its structural similarity to naturally occurring microbicidal ?-hairpin peptides. The designed peptide of 14 residues, referred to as NvBH, spans the ?-sheet region of the defensin with two amino acids substituted for assembly of a disulfide-bonded amphipathic ?-hairpin structure. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) combined with circular dichroism (CD) analysis shows that the oxidized NvBH (oNvBH), produced from the synthetic peptide by air oxidization in an alkaline environment, folds into a typical ?-hairpin structure linked by two disulfide bridges (Cys1-Cys4; Cys2-Cys3). However, such a structure appears not to be functionally necessary as synthetic NvBH with a spontaneously oxidized disulfide bridge (Cys2-Cys3) (termed poNvBH) displayed similar antibacterial potency to oNvBH. In comparison with oNvBH, poNvBH exhibited higher serum stability and more resistance on tryptic digestion. These two forms of peptides are capable of killing an array of Gram-positive (including antibiotic-resistant strains of Staphylococcus) and Gram-negative bacterial pathogens at low micromolar concentrations through a membrane disruptive mode of action. Our work indicates that the ?-sheet region of insect defensins is a promising subdomain of proteins in anti-infective drug discovery. PMID:24228718

Gao, Bin; Zhu, Shunyi

2014-02-21

214

Tandem affinity purification vectors for use in gram positive bacteria.  

PubMed

Tandem affinity purification has become a valuable tool for the isolation of protein complexes. Here we describe the construction and use of a series of plasmid vectors for Gram positive bacteria. The vectors utilize the SPA tag as well as variants containing a 3C rather than the TEV protease site as 3C protease has been shown to work efficiently at the low temperatures (4 degrees C) used to isolate protein complexes. In addition, a further vector incorporates a GST moiety in place of the 3xFLAG of the SPA tag which provides an additional tagging option for situations where SPA binding may be inefficient. The vectors are all compatible with previously constructed fluorescent protein fusion vectors enabling construction of a suite of affinity and fluorescently tagged genes using a single PCR product. PMID:18093654

Yang, Xiao; Doherty, Geoff P; Lewis, Peter J

2008-01-01

215

Antibacterial Activity of Honey on Cariogenic Bacteria  

PubMed Central

Objective: Honey has antibacterial activity. The aim of this study was to evaluate the antibacterial activity of honey on Streptococcus mutans and Lactobacillus. Materials and Methods: In this in vitro study, solutions containing 0%, 5%, 10%, 20%, 50% and 100%(w/v) of natural Hamadan honey were prepared. Each blood (nutrient) agar plate was then filled with dilutions of the honey. The strains of bacteria were inoculated in blood agar for 24 hours at 37°C and were adjusted according to the McFarland scale (10×10 cfumcl?1). All assays were repeated 10 times for each of the honey concentrations. Data were analyzed by non parametric Chi-Square test. Statistical significance was set at ?=0.05. Results: Significant antibacterial activity was detected for honey on Streptococcus mutans in concentrations more than 20% and on Lactobacillus in 100% concentration (P<0.05). Conclusion: It seems that antibacterial activity of honey could be used for prevention and reduction of dental caries. PMID:23724198

Ahmadi - Motamayel, Fatemeh; Hendi, Seyedeh Sare; Alikhani, Mohammad Yusof; Khamverdi, Zahra

2013-01-01

216

In vitro and in vivo antibacterial activities of CS-834, a new oral carbapenem.  

PubMed

CS-834 is a prodrug of the carbapenem R-95867, developed by Sankyo Co., Ltd., Tokyo, Japan. To investigate the possibility that CS-834 may be the first carbapenem usable in an oral dosage form, its in vitro antibacterial activity (as R-95867) and in vivo antibacterial activity were compared with those of cefpodoxime proxetil, cefditoren pivoxil, cefdinir, ofloxacin, imipenem, and amoxicillin. R-95867 had high levels of activity against methicillin-susceptible staphylococci and streptococci, including penicillin-resistant Streptococcus pneumoniae, as well as Neisseria gonorrhoeae, Moraxella catarrhalis, the members of the family Enterobacteriaceae (with the exception of Serratia marcescens), Haemophilus influenzae, and Bordetella pertussis; for all these strains, the MICs at which 90% of tested strains are inhibited (MIC90s) were 1.0 microg/ml or less. Against methicillin-resistant staphylococci, enterococci, Serratia marcescens, Burkholderia cepacia, Stenotrophomonas maltophilia, and Acinetobacter calcoaceticus, R-95867 showed activity comparable to or slightly less than that of imipenem, with MIC90s ranging from 2 to >128 microg/ml. The in vivo efficacy of oral CS-834 against experimental mouse septicemia caused by gram-positive and gram-negative bacteria was better than that of comparative drugs. In murine respiratory infection models, the efficacy of CS-834 reflected not only its potent in vitro activity but also the high levels present in the lungs. PMID:9517932

Yamaguchi, K; Domon, H; Miyazaki, S; Tateda, K; Ohno, A; Ishii, K; Matsumoto, T; Furuya, N

1998-03-01

217

In Vitro and In Vivo Antibacterial Activities of CS-834, a New Oral Carbapenem  

PubMed Central

CS-834 is a prodrug of the carbapenem R-95867, developed by Sankyo Co., Ltd., Tokyo, Japan. To investigate the possibility that CS-834 may be the first carbapenem usable in an oral dosage form, its in vitro antibacterial activity (as R-95867) and in vivo antibacterial activity were compared with those of cefpodoxime proxetil, cefditoren pivoxil, cefdinir, ofloxacin, imipenem, and amoxicillin. R-95867 had high levels of activity against methicillin-susceptible staphylococci and streptococci, including penicillin-resistant Streptococcus pneumoniae, as well as Neisseria gonorrhoeae, Moraxella catarrhalis, the members of the family Enterobacteriaceae (with the exception of Serratia marcescens), Haemophilus influenzae, and Bordetella pertussis; for all these strains, the MICs at which 90% of tested strains are inhibited (MIC90s) were 1.0 ?g/ml or less. Against methicillin-resistant staphylococci, enterococci, Serratia marcescens, Brukholderia cepacia, Stenotrophomonas maltophilia, and Acinetobacter calcoaceticus, R-95867 showed activity comparable to or slightly less than that of imipenem, with MIC90s ranging from 2 to >128 ?g/ml. The in vivo efficacy of oral CS-834 against experimental mouse septicemia caused by gram-positive and gram-negative bacteria was better than that of comparative drugs. In murine respiratory infection models, the efficacy of CS-834 reflected not only its potent in vitro activity but also the high levels present in the lungs. PMID:9517932

Yamaguchi, Keizo; Domon, Haruki; Miyazaki, Shuichi; Tateda, Kazuhiro; Ohno, Akira; Ishii, Kazuhiro; Matsumoto, Tetsuya; Furuya, Nobuhiko

1998-01-01

218

In vitro activity of ceftaroline-avibactam against gram-negative and gram-positive pathogens isolated from patients in Canadian hospitals from 2010 to 2012: results from the CANWARD surveillance study.  

PubMed

The in vitro activities of ceftaroline-avibactam, ceftaroline, and comparative agents were determined for a collection of bacterial pathogens frequently isolated from patients seeking care at 15 Canadian hospitals from January 2010 to December 2012. In total, 9,758 isolates were tested by using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method (document M07-A9, 2012), with MICs interpreted by using CLSI breakpoints (document M100-S23, 2013). Ceftaroline-avibactam demonstrated potent activity (MIC90, ? 0.5 ?g/ml) against Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Proteus mirabilis, Enterobacter cloacae, Enterobacter aerogenes, Serratia marcescens, Morganella morganii, Citrobacter freundii, and Haemophilus influenzae; >99% of isolates of E. coli, K. pneumoniae, K. oxytoca, P. mirabilis, M. morganii, C. freundii, and H. influenzae were susceptible to ceftaroline-avibactam according to CLSI MIC interpretative criteria for ceftaroline. Ceftaroline was less active than ceftaroline-avibactam against all species of Enterobacteriaceae tested, with rates of susceptibility ranging from 93.9% (P. mirabilis) to 54.0% (S. marcescens). All isolates of methicillin-susceptible Staphylococcus aureus (MIC90, 0.25 ?g/ml) and 99.6% of methicillin-resistant S. aureus isolates (MIC90, 1 ?g/ml) were susceptible to ceftaroline; the addition of avibactam to ceftaroline did not alter its activity against staphylococci or streptococci. All isolates of Streptococcus pneumoniae (MIC90, 0.03 ?g/ml), Streptococcus pyogenes (MIC90, ? 0.03 ?g/ml), and Streptococcus agalactiae (MIC90, 0.015 ?g/ml) tested were susceptible to ceftaroline. We conclude that combining avibactam with ceftaroline expanded its spectrum of activity to include most isolates of Enterobacteriaceae resistant to third-generation cephalosporins, including extended-spectrum ?-lactamase (ESBL)- and AmpC-producing E. coli and ESBL-producing K. pneumoniae, while maintaining potent activity against staphylococci and streptococci. PMID:23979759

Karlowsky, James A; Adam, Heather J; Baxter, Melanie R; Lagacé-Wiens, Philippe R S; Walkty, Andrew J; Hoban, Daryl J; Zhanel, George G

2013-11-01

219

Biotransformation of the antibiotic agent flumequine by ligninolytic fungi and residual antibacterial activity of the transformation mixtures.  

PubMed

Flumequine, a fluoroquinolone antibiotic, is applied preferably in veterinary medicine, for stock breeding and treatment of aquacultures. Formation of drug resistance is a matter of general concern when antibiotics such as flumquine occur in the environment. Thus, biodegradation of flumequine in solution was investigated using five different ligninolytic fungi. Irpex lacteus, Dichomitus squalens, and Trametes versicolor proved most efficient and transformed more than 90% of flumequine within 6 or even 3 days. Panus tigrinus and Pleurotus ostreatus required up to 14 days to remove >90% of flumequine. Analyses of the metabolites by liquid chromatography-mass spectrometry suggest different transformation pathways for the different fungal strains. Structure proposals were elaborated for 8 metabolites. 7-Hydroxy-flumequine and flumequine ethyl ester were identified as common metabolites produced by all ligninolytic fungi. The largest variety of metabolites was formed by D. squalens. Residual antibacterial activity of the metabolite mixtures was tested using gram-positive and gram-negative bacteria. While for the less efficient P. tigrinus and P. ostreatus cultures the antibacterial activities corresponded to the residual concentrations of flumequine, a remarkable antibacterial activity remained in the D. squalens cultures although flumequine was transformed to more than 90%. Obviously, antibacterially active transformation products were formed by this fungal strain. PMID:24261869

Cvan?arová, Monika; Moeder, Monika; Filipová, Alena; Reemtsma, Thorsten; Cajthaml, Tomáš

2013-12-17

220

Fatty acid composition, antioxidant and antibacterial activities of Adonis wolgensis L. extract  

PubMed Central

Objectives: The objective of this study was to analyze the fatty acid content, antioxidant, and antibacterial activities of hydro-methanolic extract of Adonis wolgensis L. (A. wolgensis L.) growing wild in north of Iran. Materials and Methods: Oils of A. wolgensis L. was obtained by means of Soxhlet apparatus from leaves and stems. Methyl esters were derived from the oily mixtures by trans-esterification process and were analyzed by GC/FID and GC/MS systems. Phenolic compounds extraction was done with aqueous methanol (90%). This extract was investigated for antioxidant activity using DPPH radical scavenging and reducing power methods and was also tested against a panel of microorganisms. Results: Linolenic acid (45.83%) and oleic acid (47.54%) were the most abundant fatty acids in leaves and stems, respectively. Hydro-methanolic extract with the high amount of total phenolics (9.20 ±0.011 mg GAE per dry matter) was the potent antioxidant in the assays. Results obtained from measurements of MIC for extract, indicated that E. coli, S. aureus, and S. enteritidis were the most sensitive microorganisms tested, but no activity was observed against Gram-positive microorganism (B. subtilis). Conclusion: The results obtained from the present study indicated that the oil of A. wolgensis leaves and stems contained a high source of poly-unsaturated fatty acids (PUFAs). These results also showed that hydro-methanolic extract of this plant contained significant antioxidant and antibacterial activities. PMID:25050298

Mohadjerani, Maryam; Tavakoli, Rahmatollah; Hosseinzadeh, Rahman

2014-01-01

221

24-Branched ?5 sterols from Laurencia papillosa red seaweed with antibacterial activity against human pathogenic bacteria.  

PubMed

Methanol extract of thirty-eight seaweeds samples were first screened against Gram-positive (Staphylococcus aureus ATCC 25923 and Bacillus subtilis ATCC 6051) and -negative (Escherichia coli ATCC 8739 and Pseudomonas aerugenosa ATCC 9027) bacteria. Laurencia papillosa (Ceramiales, Rhodomelaceae, Rhodophyta) gave maximum antimicrobial activity against these bacteria. It was finally tested against four clinical Gram-negative isolates (E. coli, P. aerugenosa, Klebsiella pneumoniae and Shigella flexineri) and exhibited antibacterial activity. The extract was fractionated by column chromatography and the active fraction was identified as a cholesterol derivative, 24-propylidene cholest-5-en-3?-ol using gas chromatography mass spectrometry (GC-MS). The electrospray ionization mass spectrometry (ESI-MS) and FT-IR spectroscopic analysis also supported the structure of the compound. The minimum inhibitory concentration ranged from 1.2 to 1.7 ?g/mL (IC50) against clinical isolates. This is the first report of antibacterial activity of this cholesterol derivative. This compound could be exploited as potential lead molecule against broad spectrum drug development. The results also affirm the potential of seaweeds as an important natural source of antimicrobial compounds for pharmaceutical industries. PMID:23910454

Kavita, Kumari; Singh, Vijay Kumar; Jha, Bhavanath

2014-04-01

222

Synthesis, characterization and antibacterial activity of biodegradable films prepared from Schiff bases of zein.  

PubMed

Pure zein is known to be very hydrophobic, but is still inappropriate for coating and film applications because of their brittle nature. In an attempt to improve the flexibility and the antimicrobial activity of these coatings and films, Chemical modification of zein through forming Schiff bases with different phenolic aldhydes was tried. Influence of this modifications on mechanical, topographical, wetting properties and antimicrobial activity of zein films were evaluated. The chemical structure of the Schiff bases films were characterized by ATR-FTIR spectroscopy. The results indicate an improvement in mechanical properties with chemically modification of zein to form Schiff bases leading to a reduction in the elastic modulus. An increase in the elongation at break has been observed, but with slight influence on tensile strength. Plasticized zein films have similar initial contact angle (?40°). An increase in reaction temperature and time increases film's affinity towards water. As shown by contact angle measurements, a noticeable relation was found between film composition and the hydrophilicity. Surface topography also varied by forming Schiff bases, becoming rougher than zein-based films. The antibacterial activities of zein and Schiff bases of zein-based films were investigated against gram-positive bacteria (Listeria innocua, Listeria monocytogenes, Bacillus cereus and Clostridium sporogenes) and gram-negative bacteria (Escherichia coli, Yersinia enterocolitica and Salmonella enterica). It was found that the antibacterial activity of the Schiff bases-based films was more effective than that of zein-based films. PMID:25328181

Soliman, E A; Khalil, A A; Deraz, S F; El-Fawal, G; Elrahman, S Abd

2014-10-01

223

Honey: its medicinal property and antibacterial activity  

PubMed Central

Indeed, medicinal importance of honey has been documented in the world's oldest medical literatures, and since the ancient times, it has been known to possess antimicrobial property as well as wound-healing activity. The healing property of honey is due to the fact that it offers antibacterial activity, maintains a moist wound condition, and its high viscosity helps to provide a protective barrier to prevent infection. Its immunomodulatory property is relevant to wound repair too. The antimicrobial activity in most honeys is due to the enzymatic production of hydrogen peroxide. However, another kind of honey, called non-peroxide honey (viz., manuka honey), displays significant antibacterial effects even when the hydrogen peroxide activity is blocked. Its mechanism may be related to the low pH level of honey and its high sugar content (high osmolarity) that is enough to hinder the growth of microbes. The medical grade honeys have potent in vitro bactericidal activity against antibiotic-resistant bacteria causing several life-threatening infections to humans. But, there is a large variation in the antimicrobial activity of some natural honeys, which is due to spatial and temporal variation in sources of nectar. Thus, identification and characterization of the active principle(s) may provide valuable information on the quality and possible therapeutic potential of honeys (against several health disorders of humans), and hence we discussed the medicinal property of honeys with emphasis on their antibacterial activities. PMID:23569748

Mandal, Manisha Deb; Mandal, Shyamapada

2011-01-01

224

Synthesis, structure-activity relationship studies, and antibacterial evaluation of 4-chromanones and chalcones, as well as olympicin a and derivatives.  

PubMed

On the basis of recently reported abyssinone II and olympicin A, a series of chemically modified flavonoid phytochemicals were synthesized and evaluated against Mycobacterium tuberculosis and a panel of Gram-positive and -negative bacterial pathogens. Some of the synthesized compounds exhibited good antibacterial activities against Gram-positive pathogens including methicillin resistant Staphylococcus aureus with minimum inhibitory concentration as low as 0.39 ?g/mL. SAR analysis revealed that the 2-hydrophobic substituent and the 4-hydrogen bond donor/acceptor of the 4-chromanone scaffold together with the hydroxy groups at 5- and 7-positions enhanced antibacterial activities; the 2',4'-dihydroxylated A ring and the lipophilic substituted B ring of chalcone derivatives were pharmacophoric elements for antibacterial activities. Mode of action studies performed on selected compounds revealed that they dissipated the bacterial membrane potential, resulting in the inhibition of macromolecular biosynthesis; further studies showed that selected compounds inhibited DNA topoisomerase IV, suggesting complex mechanisms of actions for compounds in this series. PMID:25238443

Feng, Li; Maddox, Marcus M; Alam, Md Zahidul; Tsutsumi, Lissa S; Narula, Gagandeep; Bruhn, David F; Wu, Xiaoqian; Sandhaus, Shayna; Lee, Robin B; Simmons, Charles J; Tse-Dinh, Yuk-Ching; Hurdle, Julian G; Lee, Richard E; Sun, Dianqing

2014-10-23

225

Expression, purification and antibacterial activity of the channel catfish hepcidin mature peptide.  

PubMed

Hepcidins are small cysteine-rich cationic antimicrobial peptides. The channel catfish (Ictalurus punctatus) hepcidin cDNA has been characterized, but recombinant protein expression and purification was not reported. I. punctatus hepcidin is comprised of 96 residues, with eight functionally important conserved cysteine residues located in the C-terminal region of the mature peptide, suggesting that this region is responsible for the antibacterial activity. In this study, a cDNA fragment (mCH) encoding the 25 amino acid mature peptide was cloned from channel catfish liver, and inserted into vector pET-32a(+) to produce a construct that expressed a hexahistidine-tagged thioredoxin (trxA) fusion protein that was cleavable using enterokinase. The trxA-mCH fusion protein was expressed in Escherichia coli BL21 (DE3) at 25°C, using 1mM IPTG for induction. Greater than 80% of the fusion protein was expressed solubly, but was not biologically active. Removal of the trxA fusion partner by enterokinase resulted in mCH that exhibited antibacterial activity against two Gram-positive (Listeria monocytogenes and Staphylococcus aureus), and two Gram-negative (E. coli and Pseudomonas aeruginosa) bacteria. PMID:24269761

Tao, Yan; Zhao, Dong-Mei; Wen, Ya

2014-02-01

226

Antioxidant and antibacterial activity of six edible wild plants (Sonchus spp.) in China.  

PubMed

The total phenolic and flavonoid, antioxidant and antibacterial activities of six Sonchus wild vegetables (Sonchus oleraceus L., Sonchus arvensis L., Sonchus asper (L.) Hill., Sonchus uliginosus M.B., Sonchus brachyotus DC. and Sonchus lingianus Shih) in China were investigated. The results revealed that S. arvensis extract and S. oleraceus extract contained the highest amount of phenolic and flavonoid, respectively. Among the methanol extracts of six Sonchus species, S. arvensis extract exhibited the highest radical (DPPH and ABTS+ scavenging power and lipid peroxidation inhibitory power. It also exhibited the highest reducing power at 500?µg?mL?ą by A (700)?=?0.80. The results of antibacterial test indicated that the S. oleraceus extract showed higher activity than the other five Sonchus wild vegetables extracts, both in Gram-negative bacteria (Escherichia coli, Salmonella enterica and Vibrio parahaemolyticus) and in a Gram-positive bacterium (Staphylococcus aureus). These results indicate that Sonchus wild food plants might be applicable in natural medicine and healthy food. PMID:21793765

Xia, Dao-Zong; Yu, Xin-Fen; Zhu, Zhuo-Ying; Zou, Zhuang-Dan

2011-12-01

227

Fabrication of silver nanoparticles doped in the zeolite framework and antibacterial activity  

PubMed Central

Using the chemical reduction method, silver nanoparticles (Ag NPs) were effectively synthesized into the zeolite framework in the absence of any heat treatment. Zeolite, silver nitrate, and sodium borohydride were used as an inorganic solid support, a silver precursor, and a chemical reduction agent, respectively. Silver ions were introduced into the porous zeolite lattice by an ion-exchange path. After the reduction process, Ag NPs formed in the zeolite framework, with a mean diameter of about 2.12–3.11 nm. The most favorable experimental condition for the synthesis of Ag/zeolite nanocomposites (NCs) is described in terms of the initial concentration of AgNO3. The Ag/zeolite NCs were characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, and Fourier transform infrared. The results show that Ag NPs form a spherical shape with uniform homogeneity in the particle size. The antibacterial activity of Ag NPs in zeolites was investigated against Gram-negative bacteria (ie, Escherichia coli and Shigella dysentriae) and Gram-positive bacteria (ie, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus) by disk diffusion method using Mueller–Hinton agar at different sizes of Ag NPs. All of the synthesized Ag/zeolite NCs were found to have antibacterial activity. These results show that Ag NPs in the zeolite framework can be useful in different biological research and biomedical applications. PMID:21383858

Shameli, Kamyar; Ahmad, Mansor Bin; Zargar, Mohsen; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa

2011-01-01

228

Glycopeptide Resistance in Gram-Positive Cocci: A Review  

PubMed Central

Vancomycin-resistant enterococci (VRE) have emerged as important nosocomial pathogens in the past two decades all over the world and have seriously limited the choices available to clinicians for treating infections caused by these agents. Methicillin-resistant Staphylococcus aureus, perhaps the most notorious among the nosocomial pathogens, was till recently susceptible to vancomycin and the other glycopeptides. Emergence of vancomycin nonsusceptible strains of S. aureus has led to a worrisome scenario where the options available for treating serious infections due to these organisms are very limited and not well evaluated. Vancomycin resistance in clinically significant isolates of coagulase-negative staphylococci is also on the rise in many setups. This paper aims to highlight the genetic basis of vancomycin resistance in Enterococcus species and S. aureus. It also focuses on important considerations in detection of vancomycin resistance in these gram-positive bacteria. The problem of glycopeptide resistance in clinical isolates of coagulase-negative staphylococci and the phenomenon of vancomycin tolerance seen in some strains of Streptococcus pneumoniae has also been discussed. Finally, therapeutic options available and being developed against these pathogens have also found a mention. PMID:22778729

Sujatha, S.; Praharaj, Ira

2012-01-01

229

Streptococcus mutans: a new Gram-positive paradigm?  

PubMed Central

Despite the enormous contributions of the bacterial paradigms Escherichia coli and Bacillus subtilis to basic and applied research, it is well known that no single organism can be a perfect representative of all other species. However, given that some bacteria are difficult, or virtually impossible, to cultivate in the laboratory, that some are recalcitrant to genetic and molecular manipulation, and that others can be extremely dangerous to manipulate, the use of model organisms will continue to play an important role in the development of basic research. In particular, model organisms are very useful for providing a better understanding of the biology of closely related species. Here, we discuss how the lifestyle, the availability of suitable in vitro and in vivo systems, and a thorough understanding of the genetics, biochemistry and physiology of the dental pathogen Streptococcus mutans have greatly advanced our understanding of important areas in the field of bacteriology such as interspecies biofilms, competence development and stress responses. In this article, we provide an argument that places S. mutans, an organism that evolved in close association with the human host, as a novel Gram-positive model organism. PMID:23393147

Quivey, Robert G.; Koo, Hyun; Abranches, Jacqueline

2013-01-01

230

Streptococcus mutans: a new Gram-positive paradigm?  

PubMed

Despite the enormous contributions of the bacterial paradigms Escherichia coli and Bacillus subtilis to basic and applied research, it is well known that no single organism can be a perfect representative of all other species. However, given that some bacteria are difficult, or virtually impossible, to cultivate in the laboratory, that some are recalcitrant to genetic and molecular manipulation, and that others can be extremely dangerous to manipulate, the use of model organisms will continue to play an important role in the development of basic research. In particular, model organisms are very useful for providing a better understanding of the biology of closely related species. Here, we discuss how the lifestyle, the availability of suitable in vitro and in vivo systems, and a thorough understanding of the genetics, biochemistry and physiology of the dental pathogen Streptococcus mutans have greatly advanced our understanding of important areas in the field of bacteriology such as interspecies biofilms, competence development and stress responses. In this article, we provide an argument that places S. mutans, an organism that evolved in close association with the human host, as a novel Gram-positive model organism. PMID:23393147

Lemos, José A; Quivey, Robert G; Koo, Hyun; Abranches, Jacqueline

2013-03-01

231

Gram-positive marine bacteria as a potential resource for the discovery of quorum sensing inhibitors.  

PubMed

Inhibitors of bacterial quorum sensing have been proposed as potentially novel therapeutics for the treatment of certain bacterial diseases. We recently reported a marine Halobacillus salinus isolate that secretes secondary metabolites capable of quenching quorum sensing phenotypes in several Gram-negative reporter strains. To investigate how widespread the production of such compounds may be in the marine bacterial environment, 332 Gram-positive isolates from diverse habitats were tested for their ability to interfere with Vibrio harveyi bioluminescence, a cell signaling-regulated phenotype. Rapid assay methods were employed where environmental isolates were propagated alongside the reporter strain. "Actives" were defined as bacteria that interfered with bioluminescence without visible cell-killing effects (antibiotic activity). A total of 49 bacterial isolates interfered with bioluminescence production in the assays. Metabolite extracts were generated from cultures of the active isolates, and 28 reproduced the bioluminescence inhibition against V. harveyi. Of those 28, five extracts additionally inhibited violacein production by Chromobacterium violaceum. Chemical investigations revealed that phenethylamides and a cyclic dipeptide are two types of secondary metabolites responsible for the observed activities. The active bacterial isolates belonged primarily to either the genus Bacillus or Halobacillus. The results suggest that Gram-positive marine bacteria are worthy of further investigation for the discovery of quorum sensing antagonists. PMID:21152942

Teasdale, Margaret E; Donovan, Kellye A; Forschner-Dancause, Stephanie R; Rowley, David C

2011-08-01

232

Synthesis and antibacterial activity of some new 2,3-dimethoxy-3-hydroxy-2-(1-phenyl-3-aryl-4-pyrazolyl)chromanones  

Microsoft Academic Search

Seven new 2,3-dimethoxy-3-hydroxy-2-(1-phenyl-3-aryl-4-pyrazolyl)chromanones (5) have been synthesized by the oxidation of 3-hydroxy-2-(1-phenyl-3-aryl-4-pyrazolyl)chromones (4) with iodobenzene diacetate in methanol. The structures of compounds 5 were established by the combined use of 1H NMR, IR and mass spectra. All the seven compounds (5) were tested in vitro for their antibacterial activity against Gram-positive bacteria namely, Staphylococcus aureus, Staphylococcus epidermidis and Bacillus pumilus

Om Prakash; Rajesh Kumar; Rakesh Sehrawat

2009-01-01

233

Synthesis and in-vitro antibacterial activity of 5-substituted 1-methyl-4-nitro-1H-imidazoles.  

PubMed

A series of 5-substituted 1-methyl-4-nitro-1H-imidazole derivatives were synthesized and evaluated for in-vitro antibacterial activity against a panel of microorganisms including Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Escherichia coli, Klebsiella pneumonia, Enterobacter aerogenes, and Helicobacter pylori using conventional agar dilution method. Among the test compounds, 1-methyl-4-nitro-5-(phenylsulfonyl)-1H-imidazole was the most potent against Gram-positive bacteria, with a MIC value of < or =8 microg/mL. All compounds showed no significant activity against Gram-negative bacteria at concentrations < or =64 microg/mL. The MIC values against 15 clinical isolates of H. pylori indicated that compounds 10 and 11 were the most active compounds in this series in terms of inhibiting the growth of H. pylori (MIC = 2 microg/mL). It was also demonstrated that their corresponding activities were four times larger than that of metronidazole. PMID:18618489

Letafat, Bahram; Emami, Saeed; Aliabadi, Alireza; Mohammadhosseini, Negar; Moshafi, Mohammad Hassan; Asadipour, Ali; Shafiee, Abbas; Foroumadi, Alireza

2008-08-01

234

The antibacterial effect of a polyhydroxylated fucophlorethol from the marine brown alga, Fucus vesiculosus  

Microsoft Academic Search

An antibacterial compound was isolated from the brown alga Fucus vesiculosus. Purification consisted of extraction of plant material with 0.05% trifluoroacetic acid, concentration on a C18 cartridge, and reverse-phase high performance liquid chromatography on a C18 semi-preparative column. The isolated compound exhibited antibacterial activity against both the Gram-positive and the Gram-negative bacteria tested. Killing studies conducted indicated that the activity

Erling Sandsdalen; Tor Haug; Klara Stensvĺg; Olaf B. Styrvold

2003-01-01

235

Terrestrial actinomycetes from diverse locations of Uttarakhnad, India: Isolation and screening for their antibacterial activity  

PubMed Central

Background and Objective Uttarakhand region is less explored, but possess a great biodiversity. This diversity can be explored for isolation and characterization of new actinomycetes strains for seeking antimicrobial molecules. It can therefore be predicted that novel bioactive metabolite producing actinomycetes can be discovered to combat multidrug resistant bacterial pathogens. Materials and Methods Variations in the viable count of actinomycetes were accessed in different altitudes. Actinomycetes were isolated, indentified and screened for their antibacterial activity. Results The highest viable counts of actinomycetes were recorded in valleys followed by mid hills and high hills. A total of 512 actinomycetes were isolated which were found to belong the 14 different genera of actinomycetes. Mainly the genus Streptomyces was dominant in all the soil samples. Out of 512 isolates recovered, 23.44% exhibited antibacterial activity against one or more tested bacterial pathogens. Of these 56.67% showed activity against Gram-positive bacteria, 26.67% against Gram-negative bacteria while 16.67% showed broad spectrum activity. Isolate DV1S and GR9a-5 showed highest antibacterial properties against several multi-drug resistant bacterial pathogens and were identified using polyphasic approach. DV1S and GR9a-5 were found to be most closely related with S. massasporeus NBRC 12796T and Nocardia nova JCM 6044T respectively. Conclusion The results of this study strongly support the idea that the viable count of actinomycetes varied greatly with altitude. The actinomycetes species isolated from valleys, mid hills and high hills possess significant capacity to produce compounds which are active against several drug resistant bacterial pathogens. PMID:24475340

Kumar, Vijay; Bisht, Gajraj Singh; Gusain, Omprakash

2013-01-01

236

Purification and characterization of an antibacterial factor from snail mucus.  

PubMed

The antibacterial factor from the body surface of the African giant snail, Achatina fulica Férussac, was isolated by DEAE-Toyopearl 650M ion exchange chromatography. The isolated preparation exhibited highly positive antibacterial activity both for the Gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus and for the Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, but it lost such activity when heated at 75 degrees C for 5 min. The antibacterial factor of the snail mucus was a glycoprotein whose molecular weight (MW) was about 160,000. It was composed of two subunits of MW 70,000-80,000. PMID:2866907

Kubota, Y; Watanabe, Y; Otsuka, H; Tamiya, T; Tsuchiya, T; Matsumoto, J J

1985-01-01

237

Chemical Composition and Antibacterial and Cytotoxic Activities of Allium hirtifolium Boiss  

PubMed Central

Allium hirtifolium Boiss. known as Persian shallot, is a spice used as a traditional medicine in Iran and, Mediterranean region. In this study, the chemical composition of the hydromethanolic extract of this plant was analyzed using GC/MS. The result showed that 9-hexadecenoic acid, 11,14-eicosadienoic acid, and n-hexadecanoic acid are the main constituents. The antibacterial activity of the shallot extract was also examined by disk diffusion and microdilution broth assays. It was demonstrated that Persian shallot hydromethanolic extract was effective against 10 different species of pathogenic bacteria including methicillin resistant Staphylococcus aureus (MRSA), methicillin sensitive Staphylococcus aureus (MSSA), Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Escherichia coli, Escherichia coli O157:H7, Salmonella typhimurium, Proteus mirabilis, and Klebsiella pneumoniae. Specifically, the minimum concentration of the extract which inhibited bacterial growth (MIC values) was 1.88?mg/mL for most of the gram-positive bacteria. This concentration was not much different from the concentration that was safe for mammalian cells (1.50?mg/mL) suggesting that the hydromethanolic extract of Persian shallot may be a safe and strong antibacterial agent. PMID:23484141

Ismail, Salmiah; Jalilian, Farid Azizi; Talebpour, Amir Hossein; Zargar, Mohsen; Shameli, Kamyar; Sekawi, Zamberi; Jahanshiri, Fatemeh

2013-01-01

238

One-step synthesis of silver nanoparticles in an aqueous solution and their antibacterial activities  

NASA Astrophysics Data System (ADS)

A one-step simple synthesis of silver colloid nanoparticles with controllable sizes is presented in this research. In the synthesis, an amino-terminated hyperbranched polymer (HBP-NH2) was applied as a stabilizer and a reductant. The syntheses, performed at various initial AgNO3 concentrations (0.28-0.56 g/l) in a 2 g/l HBP-NH2 aqueous solution, produced silver colloid nanoparticles having average sizes from 3 to 30 nm with narrow size distributions. The formation of silver colloid nanoparticles was characterized by Fourier Transform Infrared Spectrophotometry (FTIR), Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), UV/Visible Absorption Spectrophotometry, and X-ray Diffraction (XRD) measurements. The results indicated that both particle size and the UV absorption are strongly dependent on the initial AgNO3 concentrations. The silver colloid nanoparticles, prepared with a 0.35 g/l AgNO3 aqueous solution in the presences of 2 g/l HBP-NH2, showed good antibacterial activities against Gram-negative bacteria ( Escherichia coli) and Gram-positive bacteria ( Staphylococcus aureus). A very low concentration of nano-silver (as low as 3.0 ug/ml Ag) also gave excellent antibacterial performance.

Zhang, Guangyu; Zhang, Feng; Morikawa, Hideaki; Chen, Yueyue

2014-03-01

239

In-vitro and in-vivo antibacterial activities of CS-834, a new oral carbapenem.  

PubMed

We evaluated the in-vitro and in-vivo antibacterial activities of R-95867 and CS-834, a new oral carbapenem which is an ester-type prodrug of R-95867. Against Gram-positive bacteria, R-95867 was as active or two to 256 times more active than cefpodoxime, cefdinir, cefditoren and ofloxacin, while its activity was similar to or two to eight times lower than that of imipenem. Against most Gram-negative bacteria it was as active or two to 1024 times more active than the other compounds tested. Against Helicobacter pylori it was two to 64 times more active than orally active anti-H. pylori agents, i.e. amoxycillin, clarithromycin and lansoprazole. It also showed potent bactericidal activity against Staphylococcus aureus and Escherichia coli. R-95867 induced a spherical form in E. coli and showed high affinity for PBP 2 in E. coli. Against systemic infections in mice caused by various bacteria, CS-834 showed an excellent protective effect and its in-vivo efficacy correlated well with the in-vitro activity of R-95867. These results suggest that CS-834 may be effective in the therapy of various bacterial infections. PMID:9818740

Sakagawa, E; Otsuki, M; Oh, T; Nishino, T; Ou, T

1998-10-01

240

Antiviral and antibacterial polyurethanes of various modalities.  

PubMed

We have prepared and characterized a new polyurethane-based antimicrobial material, N,N-dodecyl,methyl-polyurethane (Quat-12-PU). It exhibits strong antiviral and antibacterial activities when coated (as an organic solution or an aqueous nanosuspension) onto surfaces and antibacterial activity when electrospun into nanofibers. Quat-12-PU surfaces are able to kill airborne Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria, as well as inactivate the enveloped influenza virus (but not the non-enveloped poliovirus). PMID:23306899

Park, Daewon; Larson, Alyssa M; Klibanov, Alexander M; Wang, Yadong

2013-02-01

241

Chemical composition and in vitro antioxidant and antibacterial activity of Heracleum transcaucasicum and Heracleum anisactis roots essential oil  

PubMed Central

Introduction: In vitro antioxidant and antibacterial activity and volatile compositions of two Heracleum species (Apiaceae) including Heracleum transcaucasicum and Heracleum anisactis roots Essential Oil (EO) were investigated. Methods: The volatile compositions of EOs were analyzed by GC/Mass spectroscopy. To detect the antioxidant activity of essential oils TLC-bioautography and DPPH radical scavenging assay by spectrophotometry was performed. Additionally, the antibacterial activity of two essential oils were studied and compared against four pathogenic bacteria by agar disc diffusion method and MIC values of the EOs were determined using the broth dilution method. Results: Myristicin was the dominant component in both EOs. It was identified as 96.87% and 95.15% of the essential oil composition of H. transcaucasicum and H. anisactis roots, respectively. The TLC-bioautography showed antioxidant spots in both EOs and IC50 of H. anisactis and H. transcaucasicum EO was found to be 54 ?g × ml (-1) and 77 ?g × ml (-1), respectively. Regarding the antimicrobial assay, H. anisactis EO exhibited weak to moderate antibacterial activity against gram-positive bacteria and also Escherichia coli, whereas the essential oil from H. transcaucasicum was inactive. Conclusion: Based on the results from this study, both tested EOs mainly consist of myristicin. Despite the presence of myristicin with known antibacterial property, the EO from H. transcacausicum showed no antibacterial activity. Thus it is supposed that the biological activity of plants is remarkably linked to the extracts’ chemical profile and intercomponents’ synergistic or antagonistic effect could play a crucial role in bioactivity of EOs and other plant extracts. PMID:25035849

Torbati, Mohammadali; Nazemiyeh, Hossein; Lotfipour, Farzaneh; Nemati, Mahboob; Asnaashari, Solmaz; Fathiazad, Fatemeh

2014-01-01

242

Antibacterial Activities and In Vitro Anti-Inflammatory (Membrane Stability) Properties of Methanolic Extracts of Gardenia coronaria Leaves  

PubMed Central

This work is carried out with Gardenia coronaria leaves that belong to the family Rubiaceae, which is a small-to-medium-sized but tall, deciduous tree, 7.6–9?m high on an average. Leaves are used for the treatment of rheumatic pain and bronchitis. The leaf of the plant consists of coronalolide, coronalolic acid, coronalolide methyl ester, ethyl coronalolate acetate triterpenes (secocycloartanes), and so forth. Methanol extract from the leaves of Gardenia coronaria was completely screened for membrane stability and antibacterial activity. The lower concentrations of Methanolic leaf extract of Gardenia coronaria gave good antimicrobial and anti-inflammatory activity, but higher concentrations gave relatively more projecting antibacterial activity in vitro as compared with Kanamycin. The crude drug's anti-inflammatory effects were compared with those of Aspirin as positive control. The Methanolic extracts of Gardenia coronaria leaves possessed a broad spectrum antibacterial activity against a variety of both Gram-negative and Gram-positive organisms like Streptococcus agalactiae, Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, Shigella sonnei, Shigella boydii, and Proteus mirabilis, with a zone of inhibition from 10 to 16?mm. The extract also showed good membrane stability to be considered as having significant anti-inflammatory action. PMID:24695677

Jainul, Mohammed Abdullah; Faruq, Kazi Omar; Islam, Atiqul

2014-01-01

243

Is Mycobacterium tuberculosis a closer relative to Gram-positive or Gram–negative bacterial pathogens?  

Microsoft Academic Search

The phylogenetic position of Mycobacterium tuberculosis relative to other bacteria is controversial. Its cell wall has characteristics of both Gram-positive and Gram-negative bacteria. In the standard reference of bacterial phylogeny based on 16S ribosomal RNA sequence comparison, M. tuberculosis belongs to the high G+C Gram-positive bacteria that form a monophyletic group with the low G+C Gram-positive bacteria such as Bacillus

L. M Fu; C. S Fu-Liu

2002-01-01

244

In vitro screening of Circium arvense for potential antibacterial and antifungal activities.  

PubMed

The antimicrobial activities of Circium arvense extracts were evaluated against two human gram positive (Staphylococcus aureus, Micrococcus luteus) and four gram negative pathogen (Escherichia coli, pseudomonas aeruginosa, Enterobacter, Klebsiella pneumoniae). The Methanol extracts of Circium arvense were used to obtain various fractions (X1) n-hexane, (X2) chloroform, (X3) ethyl acetate and (X4) n-butanol. The agar well diffusion assay and agar dilution susceptibility testing were carried out to determine the zone of inhibitions and the minimum inhibitory concentration respectively. Antifungal activity was employed by agar well diffusion method. The Ampicilline, Ofloxacine and Itraconazole were used as standard agents. Almost all fractions exhibited more or less antimicrobial activity. The X2 (Chloroform) fraction was reported as highly active fraction with good antimicrobial activity MIC 0.312 mg/ml against staphylococcus areous. The MBC values of fraction X2 (chloroform) was 2 times the MIC. Similarly all fractions exhibited good inhibitory activities against Aspergillus niger. The fraction X1(n-hexane) was found highly active 6(±0.11), followed by X2 (chloroform) fraction 5 (±0.17). Present study provides a base to explore the antimicrobial potential of Circium arvense. It is concluded that the Circium arvense having potential antibacterial and antifungal activities, irrespective of fact that the MIC values reported were high. Further investigations are recommended to exploit the hidden medicinal value of plant. PMID:21959814

Khan, Arifullah; Amin, Adnan; Khan, Muhammad Ayaz; Ali, Irshad

2011-10-01

245

Green synthesis of silver nanoparticles, their characterization, application and antibacterial activity.  

PubMed

Our research focused on the production, characterization and application of silver nanoparticles (AgNPs), which can be utilized in biomedical research and environmental cleaning applications. We used an environmentally friendly extracellular biosynthetic technique for the production of the AgNPs. The reducing agents used to produce the nanoparticles were from aqueous extracts made from the leaves of various plants. Synthesis of colloidal AgNPs was monitored by UV-Visible spectroscopy. The UV-Visible spectrum showed a peak between 417 and 425 nm corresponding to the Plasmon absorbance of the AgNPs. The characterization of the AgNPs such as their size and shape was performed by Atom Force Microscopy (AFM), and Transmission Electron Microscopy (TEM) techniques which indicated a size range of 3 to 15 nm. The anti-bacterial activity of AgNPs was investigated at concentrations between 2 and 15 ppm for Gram-negative and Gram-positive bacteria. Staphylococcus aureus and Kocuria rhizophila, Bacillus thuringiensis (Gram-positive organisms); Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhimurium (Gram-negative organisms) were exposed to AgNPs using Bioscreen C. The results indicated that AgNPs at a concentration of 2 and 4 ppm, inhibited bacterial growth. Preliminary evaluation of cytotoxicity of biosynthesized silver nanoparticles was accomplished using the InQ™ Cell Research System instrument with HEK 293 cells. This investigation demonstrated that silver nanoparticles with a concentration of 2 ppm and 4 ppm were not toxic for human healthy cells, but inhibit bacterial growth. PMID:24157517

Okafor, Florence; Janen, Afef; Kukhtareva, Tatiana; Edwards, Vernessa; Curley, Michael

2013-10-01

246

Antibacterial and Antifungal Activities of Stereum ostrea, an Inedible Wild Mushroom  

PubMed Central

Antibacterial and antifungal activities of liquid culture filtrate, water and ethanol extract (solid culture) of Stereum ostrea were evaluated against 5 bacteria and 3 plant pathogenic fungi. To determine the minimal inhibitory concentration (MIC), we studied 5~300 mg/ml concentrations against bacteria and fungi separately. The MIC was 10 mg/ml for Bacillus subtilis and 40 mg/ml for Colletotrichum gloeosporioides and Colletotrichum miyabeanus. Liquid culture filtrate was more effective against Gram positive than Gram negative bacteria, and Staphylococcus aureus was the most inhibited (20.3 mm) bacterium. Water and ethanol extracts were effective against both Gram positive and Gram negative bacteria, and water extract was better than ethanol extract. In water and ethanol extract, inhibition zones were 23.6 and 21.0 mm (S. aureus) and 26.3 and 22.3 mm (Pseudomonas aeruginosa), respectively. For plant pathogenic fungi, the highest and lowest percent inhibition of mycelial growth (PIMG) was found 82.8 and 14.4 against C. miyabeanus and Botrytis cinerea in liquid culture filtrate, respectively. In water extract, the PIMG was found to be the highest 85.2 and lowest 41.7 for C. miyabeanus and C. gloeosporioides, respectively. The inhibitory effect of ethanol extract was better against C. miyabeanus than C. gloeosporioides and B. cinerea. Among 3 samples, water extract was the best against tested pathogenic fungi. This study offers that the extracts isolated from S. ostrea contain potential compounds which inhibit the growth of both bacteria and fungi. PMID:24015099

Imtiaj, Ahmed; Jayasinghe, Chandana; Lee, Geon Woo

2007-01-01

247

Biological Sciences INVITRO ANTIBACTERIAL ACTIVITY OF SARGASSUM WIGHTII  

E-print Network

The antibacterial activity of Sargassum weightti was screened against human bacterial pathogens like bacillus cereus, Klebsiella pneumonia, Streptococcus pyogenes, Vibrio cholerae, E. coli, Proteus vulgaris and Salmonella typhi. The maximum activity was recorded from the extract of Sargassum weightti against K. pnuemoniae and minimum activity against streptococcus pyogenes. KEY WORDS Antibacterial activity, Mandapam coast, human bacterial pathogens.

P. Vengadesan; S. Ahmed John

248

The laboratory identification of gram-positive anaerobic cocci.  

PubMed

A collection of 256 clinical strains and 40 reference strains of gram-positive anaerobic cocci (GPAC) was studied, to characterise the recognised species more fully and to define groups of strains which might correspond to previously undescribed species. The methods used were: gas-liquid chromatography (GLC) for the detection of volatile fatty acids (VFAs); determination of the pre-formed enzyme profile with a commercially available kit, ATB 32A; microscopic appearance; colonial morphology; and antibiotic sensitivity tests. Strains were placed in one of five VFA groups according to their GLC profile; 96% of strains were further assigned to 12 groups by their enzyme profile. There was less than 99% agreement between the two methods. Of 111 clinical strains in the VFA-negative group, 110 gave one of three distinct enzyme profiles corresponding to Peptostreptococcus magnus, P. micros and P. heliotrinreducens. The assignment of strains to groups based on their microscopic appearance and colonial morphology agreed well with groupings according to enzyme profile. Identification of butyrate-producing GPAC was unsatisfactory because it relied heavily on the enzyme profile; testing for indole production was of limited discriminative value. Most strains of P. asaccharolyticus and P. indolicus were very similar in enzyme profile, microscopic appearance and colonial morphology, but a sub-group of P. asaccharolyticus could be distinguished. A further indole-positive group corresponding to Hare group III was also noted. Strains of P. prevotii and P. tetradius were very similar, but easily distinguished from other butyrate-producing GPAC. However, 45% of the butyrate-producing cocci could not be assigned to recognised species; most of these were assigned to one of two new groups, the ADH group and the bGAL group, by their enzyme profile, microscopic appearance and smell. Four strains that produced a terminal VFA peak of isovaleric acid formed a new group designated 'ivoricus'. Reliable features for the identification of P. anaerobius were GLC (all GPAC that produced isocaproic acid were identified as P. anaerobius), enzyme profile and sensitivity to SPS. Two clinical strains that produced caproci acid were identified as Hare group VIII; they were distinguished from Peptococcus niger by their enzyme profile and colonial morphology. A phenotypic classification based on GLC and enzyme profile is presented, with a method for the identification of most strains of GPAC within 48 h of primary isolation. PMID:2030504

Murdoch, D A; Mitchelmore, I J

1991-05-01

249

Protein secretion biotechnology in Gram-positive bacteria with special emphasis on Streptomyces lividans.  

PubMed

Proteins secreted by Gram-positive bacteria are released into the culture medium with the obvious benefit that they usually retain their native conformation. This property makes these host cells potentially interesting for the production of recombinant proteins, as one can take full profit of established protocols for the purification of active proteins. Several state-of-the-art strategies to increase the yield of the secreted proteins will be discussed, using Streptomyces lividans as an example and compared with approaches used in some other host cells. It will be shown that approaches such as increasing expression and translation levels, choice of secretion pathway and modulation of proteins thereof, avoiding stress responses by changing expression levels of specific (stress) proteins, can be helpful to boost production yield. In addition, the potential of multi-omics approaches as a tool to understand the genetic background and metabolic fluxes in the host cell and to seek for new targets for strain and protein secretion improvement is discussed. It will be shown that S. lividans, along with other Gram-positive host cells, certainly plays a role as a production host for recombinant proteins in an economically viable way. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey. PMID:24412306

Anné, Jozef; Vrancken, Kristof; Van Mellaert, Lieve; Van Impe, Jan; Bernaerts, Kristel

2014-08-01

250

Chemical composition, antioxidant and antibacterial activities of the leaf essential oil of Juglans regia L. and its constituents.  

PubMed

The essential oil from the leaves of Juglans regia L. (Juglandaceae) growing wild in Kashmir (India) was obtained by hydrodistillation and analysed by a combination of capillary GC-FID and GC-MS. A total of 38 compounds, representing 92.7% of the oil, were identified and the major components were found to be ?-pinene (15.1%), ?-pinene (30.5%), ?-caryophyllene (15.5%) germacrene D (14.4%) and limonene (3.6%). The essential oil and the main individual constituents were screened for antibacterial activity and the essential oil evaluated for antioxidant activity. Antibacterial activity was evaluated using the disc diffusion and microdilution methods against a group of clinically significant Gram-positive (Staphylococcus epidermidis MTCC-435, Bacillus subtilis MTCC-441, Staphylococcus aureus) and Gram-negative bacteria (Proteus vulgaris MTCC-321, Pseudomonas aeruginosa MTCC-1688, Salmonella typhi, Shigella dyssenteriae, Klebsiella pneumonia and Escherichia coli). The essential oil and its major components exhibited broad spectrum inhibition against all the bacterial strains with Gram-positive being more susceptible to the oil than Gram-negative bacteria. Antioxidant activity of the oil was evaluated by the scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) and hydroxyl radicals. In general, the essential oil exhibited high antioxidant activity which was comparable to the reference standards at the same dose (ascorbic acid and butylated hydroxyl toluene, BHT) with IC(50) values of 34.5 and 56.4?g/ml calculated by DPPH and hydroxyl radical scavenging assays respectively. PMID:22951389

Rather, Manzoor A; Dar, Bilal A; Dar, Mohd Yousuf; Wani, Bilal A; Shah, Wajahat A; Bhat, Bilal A; Ganai, Bashir A; Bhat, Khursheed A; Anand, Rajneesh; Qurishi, Mushtaq A

2012-10-15

251

Essential oils: their antibacterial properties and potential applications in foods—a review  

Microsoft Academic Search

In vitro studies have demonstrated antibacterial activity of essential oils (EOs) against Listeria monocytogenes, Salmonella typhimurium, Escherichia coli O157:H7, Shigella dysenteria, Bacillus cereus and Staphylococcus aureus at levels between 0.2 and 10 ?l ml?1. Gram-negative organisms are slightly less susceptible than gram-positive bacteria. A number of EO components has been identified as effective antibacterials, e.g. carvacrol, thymol, eugenol, perillaldehyde, cinnamaldehyde

Sara Burt

2004-01-01

252

Chemical composition and antibacterial activity of the essential oil from green huajiao (Zanthoxylum schinifolium) against selected foodborne pathogens.  

PubMed

Green huajiao, which is the ripe pericarp of the fruit of Zanthoxylum schinifolium Sieb. et Zucc, is widely consumed in Asia as a spice. In this work, the chemical composition of the essential oil from green huajiao was analyzed by gas chromatography (GC) and GC/mass spectrometry (MS), and the majority of components were identified. Linalool (28.2%), limonene (13.2%), and sabinene (12.1%) were found to be the major components. The antibacterial activity, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of the essential oil were evaluated against selected bacteria, including food-borne pathogens. The results showed that the sensitivities to the essential oil were different for different bacteria tested, and the susceptibility of Gram-positive bacteria tested was observed to be greater than that of Gram-negative bacteria. The antibacterial activity of the essential oil was particularly strong against Staphylococcus epidermidis , with MIC and MBC values of 2.5 and 5.0 mg/mL, respectively. A postcontact effect assay also confirmed the essential oil had a significant effect on the growth rate of surviving S. epidermidis . The antibacterial activity of the essential oil from green huajiao may be due to the increase in permeability of cell membranes, and the leakage of intracellular constituents, on the basis of the cell constituents' release assay and electron microscopy observations. PMID:23758080

Diao, Wen-Rui; Hu, Qing-Ping; Feng, Sai-Sai; Li, Wei-Qin; Xu, Jian-Guo

2013-06-26

253

Synthesis and antibacterial activity of some new 2,3-dimethoxy-3-hydroxy-2-(1-phenyl-3-aryl-4-pyrazolyl)chromanones.  

PubMed

Seven new 2,3-dimethoxy-3-hydroxy-2-(1-phenyl-3-aryl-4-pyrazolyl)chromanones (5) have been synthesized by the oxidation of 3-hydroxy-2-(1-phenyl-3-aryl-4-pyrazolyl)chromones (4) with iodobenzene diacetate in methanol. The structures of compounds 5 were established by the combined use of (1)H NMR, IR and mass spectra. All the seven compounds (5) were tested in vitro for their antibacterial activity against gram-positive bacteria namely, Staphylococcus aureus, Staphylococcus epidermidis and Bacillus pumilus and two gram-negative bacteria namely, Salmonella typhi and Pseudomonas aeruginosa. Three compounds, 5d, 5f and 5g, have displayed antibacterial activity comparable to the commercial antibiotics, Linezolid, Cefaclor and Cefuroxime axetial. PMID:18504062

Prakash, Om; Kumar, Rajesh; Sehrawat, Rakesh

2009-04-01

254

Screening seeds of Scottish plants for antibacterial activity  

Microsoft Academic Search

Based on ethnopharmacological and taxonomic information, seeds of 21 Scottish plant species from 14 different families were obtained from authentic seed suppliers. Their n-hexane, dichloromethane and methanol extracts were assessed for antibacterial activity against 11 pathogenic bacterial species. Methanol extracts of 11 plant species showed significant antibacterial activity. Malva moschata and Prunus padus were active against five bacterial species, Reseda

Yashodharan Kumarasamy; Philip John Cox; Marcel Jaspars; Lutfun Nahar; Satyajit Dey Sarker

2002-01-01

255

Synthesis, characterization and magnetic properties of hematite (?-Fe2O3) nanoparticles on polysaccharide templates and their antibacterial activity  

NASA Astrophysics Data System (ADS)

The present study is to synthesize iron oxide nanoparticles on different polysaccharide templates calcined at controlled temperature, characterizing them for spectroscopic and magnetic studies leading to evaluate their antibacterial property. The synthesized iron oxide nanoparticles were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy, high resolution scanning electron microscopy (HRSEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer. The iron oxide nanoparticles were tested for antibacterial activity against gram-positive and gram-negative bacterial species. The XRD confirms the crystalline nature of iron oxide nanoparticles with the mean crystallite size of 10 nm. The functional groups of the synthesized iron oxide nanoparticles were 547, 543 and 544 cm-1 characterizing the Fe-O and the broad bands at 3,398, 3,439 and 3,427 cm-1 were attributed to the stretching vibrations of hydroxyl group absorbed by iron oxide nanoparticles. HRTEM analyses revealed that the average particle size of the hematite nanoparticles are about 85, 92 and 77 nm for AF, DF and GF, respectively, which was a coincident with the results obtained from the HRSEM analysis. Magnetic measurement exhibited ferromagnetic behavior of the ?-Fe2O3 at the room temperature with higher coercivity of H C = 2,303, 2,333 and 1,019 Oe for AF, DF and GF, respectively. Antibacterial test showed the inhibition against Aeromonas hydrophila and Escherichia coli with significant antagonistic activity.

Rafi, M. Mohamed; Ahmed, K. Syed Zameer; Nazeer, K. Prem; Siva Kumar, D.; Thamilselvan, M.

2014-08-01

256

Synthesis and antibacterial and cytotoxic activities of new N-3 substituted thiazolidine-2,4-dione derivatives bearing the pyrazole moiety.  

PubMed

Two new series of N-3 substituted thiazolidine-2,4-dione derivatives bearing the pyrazole moiety (5a-j and 7a-j) were synthesized and assessed in vitro for their efficacy as antibacterial agents against gram-positive and gram-negative bacterial strains. Among the tested compounds, 7b, 7c, 7i, and 7j were found to be active against gram-positive bacteria (Staphylococcus aureus and Streptococcus pyogenes) with minimum inhibitory concentration (MIC) values in the range of 6.25-25 µg/mL, and some compounds were also tested against methicillin-resistant S. aureus (MRSA). Compounds 7c and 7j inhibited the growth of MRSA at MIC values of 6.25 and 12.5 µg/mL, respectively. The influence of the lipophilicity (C log P) on the biological profile (MIC) of the prepared products was also discussed. From the standpoint of structure-activity relationship studies, it was observed that the lipophilic profiles of the compounds were crucial for their antibacterial activities. Further, the results of the MTT cytotoxicity studies on a human cervical cancer cell line (HeLa) and a mouse embryonic fibroblast cell line (NIH 3T3) suggested that compounds 7b, 7c, 7i, and 7j were endowed with low levels of cytotoxicity. PMID:24729458

Desai, Nisheeth C; Satodiya, Hitesh M; Kotadiya, Ghanshyam M; Vaghani, Hasit V

2014-07-01

257

Antibacterial activity of Aristolochia paucinervis Pomel.  

PubMed

Several fractions of the methanolic extract of the rhizome or the leaves of Aristolochia paucinervis Pomel were screened for antibacterial activity using the agar dilution method against fourteen reference bacterial strains. Only three fractions (defatted chloroformic rhizome fraction: APRC, rhizome ethyl acetate fraction: APRE and leaf chloroform fraction: APLC) showed an activity against at least one of the microorganisms tested. The minimum inhibitory concentration (MIC) determination showed that APRC was the most active against Clostridium perfringens, Clostridium difficile, Enterococcus faecalis, Micrococcus luteus and Bacillus subtilis. The high bacteriostatic activity of APRC was confirmed by its MIC determination against clinical strains of C. perfringens (n = 32), C. difficile (n = 31), and E. faecalis (n = 22). Results of this study suggest the potential interest of this highly active fraction and support the use of A. paucinervis Pomel in Moroccan traditional medicine to treat skin and soft-tissue infections, especially gas gangrene and intestinal diseases. PMID:10616964

Gadhi, C A; Weber, M; Mory, F; Benharref, A; Lion, C; Jana, M; Lozniewski, A

1999-10-01

258

Wound-dressing materials with antibacterial activity from electrospun polyurethane-dextran nanofiber mats containing ciprofloxacin HCl.  

PubMed

Dextran is a versatile biomacromolecule for preparing electrospun nanofibrous membranes by blending with either water-soluble bioactive agents or hydrophobic biodegradable polymers for biomedical applications. In this study, an antibacterial electrospun scaffold was prepared by electrospinning of a solution composed of dextran, polyurethane (PU) and ciprofloxacin HCl (CipHCl) drug. The obtained nanofiber mats have good morphology. The mats were characterized by various analytical techniques. The interaction parameters between fibroblasts and the PU-dextran and PU-dextran-drug scaffolds such as viability, proliferation, and attachment were investigated. The results indicated that the cells interacted favorably with the scaffolds especially the drug-containing one. Moreover, the composite mat showed good bactericidal activity against both of Gram-positive and Gram-negative bacteria. Overall, our results conclude that the introduced scaffold might be an ideal biomaterial for wound dressing applications. PMID:22944448

Unnithan, Afeesh R; Barakat, Nasser A M; Pichiah, P B Tirupathi; Gnanasekaran, Gopalsamy; Nirmala, R; Cha, Youn-Soo; Jung, Che-Hun; El-Newehy, Mohamed; Kim, Hak Yong

2012-11-01

259

[Thrombin inhibitors which display antibacterial activity].  

PubMed

The investigation of cytotoxicity and antibacterial activity of the novel thrombin inhibitors containing retro-D-sequences -D-Arg-D-Phe--modified by D-arginine amino group by the residues of lauric acid or chromone-contained substituent, in comparison with known cationic preservative Nalpha-lauroyl-L-arginine ethyl ester (LAE) have been carried out. It has been shown that compound Laur-D-Arg-D-Phe-OMe has a similar cytotoxicity with LAE, and Chrom-D-Arg-D-Phe-OMe has almost twice higher toxicity than it fatty moiety contained analogues. Antibacterial activity of Laur-D-Arg-D-Phe-OMe against Staphylococcus aureus and Bacillus subtilis is close in action to LAE. It is assumed that ability of thrombin inhibitors to suppress the growth of some microorganisms can be explained by their ability to suppress activity of trypsin-like serine proteinases, which participate in the infection process of Staphylococcus aureus and influence on Bacillus subtilis sporulation. These findings open new prospects for exploring efficient antimicrobial agents among synthetic low-molecular trypsin-like serine proteinase inhibitors. PMID:20684237

Poiarkov, A A; Timoshok, N A; Spivak, N Ia; Poiarkova, S A

2010-01-01

260

Di-alkylated paromomycin derivatives: targeting the membranes of gram positive pathogens that cause skin infections.  

PubMed

A collection of paromomycin-based di-alkylated cationic amphiphiles differing in the lengths of their aliphatic chain residues were designed, synthesized, and evaluated against 14 Gram positive pathogens that are known to cause skin infections. Paromomycin derivatives that were di-alkylated with C7 and C8 linear aliphatic chains had improved antimicrobial activities relative to the parent aminoglycoside as well as to the clinically used membrane-targeting antibiotic gramicidin D; several novel derivatives were at least 16-fold more potent than the parent aminoglycoside paromomycin. Comparison between a di-alkylated and a mono-alkylated paromomycin indicated that the di-alkylation strategy leads to both an improvement in antimicrobial activity and to a dramatic reduction in undesired red blood cell hemolysis caused by many aminoglycoside-based cationic amphiphiles. Scanning electron microscopy provided evidence for cell surface damage by the reported di-alkylated paromomycins. PMID:23602621

Berkov-Zrihen, Yifat; Herzog, Ido M; Feldman, Mark; Sonn-Segev, Adar; Roichman, Yael; Fridman, Micha

2013-06-15

261

Cytotoxicity and antibacterial activity of extractives from Wedelia calendulacea  

Microsoft Academic Search

The cytotoxicity and antibacterial activity of petroleum ether, chloroform and methanol extracts of Wedelia calendulacea were assayed by brine shrimp lethality bioassay and standardized disk diffusion method against 19 bacterial strains. Three diterpenes isolated from the plant were also evaluated for in vitro antibacterial activities. The LC50 for the crude extracts against the brine shrimp nauplii were found to be

A. K. M Mottakin; R Chowdhury; M. S Haider; K. M Rahman; C. M Hasan; M. A Rashid

2004-01-01

262

Screening of some Palestinian medicinal plants for antibacterial activity  

Microsoft Academic Search

Antibacterial activity of organic and aqueous extracts of 15 Palestinian medicinal plants were carried against eight different species of bacteria: Bacillus subtilis, two Escherichia coli species, Staphylococcus aureus (methicillin resistant), two S. aureus (methicillin sensitive) species, Pseudomonas aeruginosa, and Enterococcus fecalis. Of the 15 plants tested, eight showed antibacterial activity. Each plant species has unique against different bacteria. The most

T Essawi; M Srour

2000-01-01

263

Saccharomicins, Novel Heptadecaglycoside Antibiotics Produced by Saccharothrix espanaensis: Antibacterial and Mechanistic Activities  

PubMed Central

Saccharomicins A and B, two new heptadecaglycoside antibiotics, were isolated from the fermentation broth of the rare actinomycete Saccharothrix espanaensis. They represent a novel class of bactericidal antibiotics that are active both in vitro and in vivo against bacteria and yeast (MICs: Staphylococcus aureus, <0.12 to 0.5; vancomycin-resistant enterococci, 0.25 to 16; gram-negative bacteria, 0.25 to >128; and yeast, >128 ?g/ml), including multiply resistant strains. Saccharomicins protected mice from lethal challenges by staphylococci (subcutaneous 50% effective dose range of 0.06 to 2.6 mg/kg of body weight, depending on the S. aureus strain). The 50% lethal dose by the subcutaneous route was 16 mg/kg. Mechanistic studies with Escherichia coli imp and Bacillus subtilis suggested complete, nonspecific inhibition of DNA, RNA, and protein biosynthesis within 10 min of drug treatment. Microscopic examination of drug-treated cells also suggested cell lysis. These data are consistent with a strong membrane-disruptive activity. The antibacterial activities of the saccharomicins against gram-positive bacteria were unaffected by the presence of Ca2+ or Mg2+, but activity against gram-negative bacteria was substantially reduced. PMID:10898690

Singh, M. P.; Petersen, P. J.; Weiss, W. J.; Kong, F.; Greenstein, M.

2000-01-01

264

Antibacterial activity of eravacycline (TP-434), a novel fluorocycline, against hospital and community pathogens.  

PubMed

Eravacycline (TP-434 or 7-fluoro-9-pyrrolidinoacetamido-6-demethyl-6-deoxytetracycline) is a novel fluorocycline that was evaluated for antimicrobial activity against panels of recently isolated aerobic and anaerobic Gram-negative and Gram-positive bacteria. Eravacycline showed potent broad-spectrum activity against 90% of the isolates (MIC90) in each panel at concentrations ranging from ?0.008 to 2 ?g/ml for all species panels except those of Pseudomonas aeruginosa and Burkholderia cenocepacia (MIC90 values of 32 ?g/ml for both organisms). The antibacterial activity of eravacycline was minimally affected by expression of tetracycline-specific efflux and ribosomal protection mechanisms in clinical isolates. Furthermore, eravacycline was active against multidrug-resistant bacteria, including those expressing extended-spectrum ?-lactamases and mechanisms conferring resistance to other classes of antibiotics, including carbapenem resistance. Eravacycline has the potential to be a promising new intravenous (i.v.)/oral antibiotic for the empirical treatment of complicated hospital/health care infections and moderate-to-severe community-acquired infections. PMID:23979750

Sutcliffe, J A; O'Brien, W; Fyfe, C; Grossman, T H

2013-11-01

265

Antibacterial Activity of Eravacycline (TP-434), a Novel Fluorocycline, against Hospital and Community Pathogens  

PubMed Central

Eravacycline (TP-434 or 7-fluoro-9-pyrrolidinoacetamido-6-demethyl-6-deoxytetracycline) is a novel fluorocycline that was evaluated for antimicrobial activity against panels of recently isolated aerobic and anaerobic Gram-negative and Gram-positive bacteria. Eravacycline showed potent broad-spectrum activity against 90% of the isolates (MIC90) in each panel at concentrations ranging from ?0.008 to 2 ?g/ml for all species panels except those of Pseudomonas aeruginosa and Burkholderia cenocepacia (MIC90 values of 32 ?g/ml for both organisms). The antibacterial activity of eravacycline was minimally affected by expression of tetracycline-specific efflux and ribosomal protection mechanisms in clinical isolates. Furthermore, eravacycline was active against multidrug-resistant bacteria, including those expressing extended-spectrum ?-lactamases and mechanisms conferring resistance to other classes of antibiotics, including carbapenem resistance. Eravacycline has the potential to be a promising new intravenous (i.v.)/oral antibiotic for the empirical treatment of complicated hospital/health care infections and moderate-to-severe community-acquired infections. PMID:23979750

O'Brien, W.; Fyfe, C.; Grossman, T. H.

2013-01-01

266

Antibacterial activity of Artemisia nilagirica leaf extracts against clinical and phytopathogenic bacteria  

PubMed Central

Background The six organic solvent extracts of Artemisia nilagirica were screened for the potential antimicrobial activity against phytopathogens and clinically important standard reference bacterial strains. Methods The agar disk diffusion method was used to study the antibacterial activity of A. nilagirica extracts against 15 bacterial strains. The Minimum Inhibitory Concentration (MIC) of the plant extracts were tested using two fold agar dilution method at concentrations ranging from 32 to 512 ?g/ml. The phytochemical screening of extracts was carried out for major phytochemical derivatives in A. nilagirica. Results All the extracts showed inhibitory activity for gram-positive and gram-negative bacteria except for Klebsiella pneumoniae, Enterococcus faecalis and Staphylococcus aureus. The hexane extract was found to be effective against all phytopathogens with low MIC of 32 ?g/ml and the methanol extract exhibited a higher inhibition activity against Escherichia coli, Yersinia enterocolitica, Salmonella typhi, Enterobacter aerogenes, Proteus vulgaris, Pseudomonas aeruginosa (32 ?g/ml), Bacillus subtilis (64 ?g/ml) and Shigella flaxneri (128 ?g/ml). The phytochemical screening of extracts answered for the major derivative of alkaloids, amino acids, flavonoids, phenol, quinines, tannins and terpenoids. Conclusion All the extracts showed antibacterial activity against the tested strains. Of all, methanol and hexane extracts showed high inhibition against clinical and phytopathogens, respectively. The results also indicate the presence of major phytochemical derivatives in the A. nilagirica extracts. Hence, the isolation and purification of therapeutic potential compounds from A. nilagirica could be used as an effective source against bacterial diseases in human and plants. PMID:20109237

2010-01-01

267

In Vitro Antibacterial Activity of Essential Oils against Streptococcus pyogenes.  

PubMed

Streptococcus pyogenes plays an important role in the pathogenesis of tonsillitis. The present study was conducted to evaluate the in vitro antibacterial activities of 18 essential oils chemotypes from aromatic medicinal plants against S. pyogenes. Antibacterial activity of essential oils was investigated using disc diffusion method. Minimum Inhibitory Concentration of essential oils showing an important antibacterial activity was measured using broth dilution method. Out of 18 essential oils tested, 14 showed antibacterial activity against S. pyogenes. Among them Cinnamomum verum, Cymbopogon citratus, Thymus vulgaris CT thymol, Origanum compactum, and Satureja montana essential oils exhibited significant antibacterial activity. The in vitro results reported here suggest that, for patients suffering from bacterial throat infections, if aromatherapy is used, these essential oils, considered as potential antimicrobial agents, should be preferred. PMID:23662123

Sfeir, Julien; Lefrançois, Corinne; Baudoux, Dominique; Derbré, Séverine; Licznar, Patricia

2013-01-01

268

Cobra Cytotoxins: Structural Organization and Antibacterial Activity  

PubMed Central

Cardiotoxins (cytotoxins, CT) are ?-structured proteins isolated from the venom of cobra. They consist of 59–61 amino acid residues, whose antiparallel chains form three ‘fingers’. In contrast to neurotoxins with an overall similar fold, CTs are amphiphilic. The amphiphilicity is caused by positively charged lysine and arginine residues flanking the tips of the loops that consist primarily of hydrophobic amino acids. A similar distribution of amino acid residues is typical for linear (without disulfide bonds) cationic cytolytic peptides from the venoms of other snakes and insects. Many of them are now considered to be lead compounds in combatting bacterial infections and cancer. In the present review, we summarize the data on the antibacterial activity of CTs and compare it to the activity of linear peptides. PMID:25349711

Dubovskii, P. V.; Utkin, Y. N.

2014-01-01

269

Antibiotics for gram-positive bacterial infection: vancomycin, teicoplanin, quinupristin/dalfopristin, oxazolidinones, daptomycin, telavancin, and ceftaroline.  

PubMed

An overview of the mechanism of action, dosing, clinical indications, and toxicities of the glycopeptide vancomycin is provided. The emerging gram-positive bacterial resistance to antimicrobials and its mechanisms are reviewed. Strategies to control this emergence of resistance are expected to be proposed. Newer antimicrobial agents that have activity against vancomycin-resistant organisms are now available and play a critical role in the treatment of life-threatening infections. PMID:21679789

Nailor, Michael D; Sobel, Jack D

2011-07-01

270

Synthesis, structure and structure-activity relationship analysis of 3-tert-butoxycarbonyl-2-arylthiazolidine-4-carboxylic acid derivatives as potential antibacterial agents.  

PubMed

Nine 2-arylthiazolidine-4-carboxylic acid derivatives and nine 3-tert-butoxycarbonyl-2-arylthiazolidine-4-carboxylic acid derivatives were synthesized to screen for their antibacterial activities. Compounds 5, 14-18 were first reported. Their chemical structures were clearly determined by (1)H NMR, (13)C NMR, ESI mass spectra and elemental analyses, coupled with one selected single-crystal structure. All the compounds were assayed for antibacterial activities against two Gram-positive bacterial strains (Bacillus subtilis ATCC 6633 and Staphylococcus aureus ATCC 6538) and two Gram-negative bacterial strains (Escherichia coli ATCC 35218 and Pseudomonas aeruginosa ATCC 13525) by MTT method. Most of the 3-tert-butoxycarbonyl-2-arylthiazolidine-4-carboxylic acid derivatives exhibited better antibacterial activities against the four bacterial strains than relative 2-arylthiazolidine-4-carboxylic acid derivatives. Compound (2RS,4R)-3-(tert-butoxycarbonyl)-2-(5-fluoro-2-hydroxyphenyl)thiazolidine-4-carboxylic acid (14) showed powerful antibacterial activities against P. aeruginosa with IC(50) value of 0.195 microg/mL, which was superior to the positive controls Penicillin G and Kanamycin B, respectively. On the basis of the biological results, structure-activity relationships were discussed. PMID:19423200

Song, Zhong-Cheng; Ma, Gao-Yuan; Lv, Peng-Cheng; Li, Huan-Qiu; Xiao, Zhu-Ping; Zhu, Hai-Liang

2009-10-01

271

Antibacterial activity of cefquinome against equine bacterial pathogens  

Microsoft Academic Search

Cefquinome is known for its use as an antibacterial drug in cattle and pigs. The objective of this study was to evaluate the antibacterial activity of cefquinome against equine pathogenic bacteria. The minimum inhibitory concentration (MIC) of cefquinome was determined for a total of 205 strains, which had recently been isolated in Europe from diseased horses (respiratory infection, foal septicaemia).

E. Thomas; V. Thomas; C. Wilhelm

2006-01-01

272

A novel beta-defensin structure: a potential strategy of big defensin for overcoming resistance by Gram-positive bacteria.  

PubMed

Big defensin is a 79-residue peptide derived from hemocytes of the Japanese horseshoe crab. It has antimicrobial activities against Gram-positive and -negative bacteria. The amino acid sequence of big defensin can be divided into an N-terminal hydrophobic half and a C-terminal cationic half. Interestingly, the trypsin cleaves big defensin into two fragments, the N-terminal and C-terminal fragments, which are responsible for antimicrobial activity against Gram-positive and -negative bacteria, respectively. To explore the antimicrobial mechanism of big defensin, we determined the solution structure of mature big defensin and performed a titration experiment with DPC micelles. Big defensin has a novel defensin structure; the C-terminal domain adopts a beta-defensin structure, and the N-terminal domain forms a unique globular conformation. It is noteworthy that the hydrophobic N-terminal domain undergoes a conformational change in micelle solution, while the C-terminal domain remains unchanged. Here, we propose that the N-terminal domain achieves its antimicrobial activity in a novel fashion and explain that big defensin has developed a strategy different from those of other beta-defensins to suppress the growth of Gram-positive bacteria. PMID:18785751

Kouno, Takahide; Fujitani, Naoki; Mizuguchi, Mineyuki; Osaki, Tsukasa; Nishimura, Shin-ichiro; Kawabata, Shun-ichiro; Aizawa, Tomoyasu; Demura, Makoto; Nitta, Katsutoshi; Kawano, Keiichi

2008-10-01

273

Extracellular vesicles produced by the Gram-positive bacterium Bacillus subtilis are disrupted by the lipopeptide surfactin.  

PubMed

Previously, extracellular vesicle production in Gram-positive bacteria was dismissed due to the absence of an outer membrane, where Gram-negative vesicles originate, and the difficulty in envisioning how such a process could occur through the cell wall. However, recent work has shown that Gram-positive bacteria produce extracellular vesicles and that the vesicles are biologically active. In this study, we show that Bacillus subtilis produces extracellular vesicles similar in size and morphology to other bacteria, characterized vesicles using a variety of techniques, provide evidence that these vesicles are actively produced by cells, show differences in vesicle production between strains, and identified a mechanism for such differences based on vesicle disruption. We found that in wild strains of B. subtilis, surfactin disrupted vesicles while in laboratory strains harbouring a mutation in the gene sfp, vesicles accumulated in the culture supernatant. Surfactin not only lysed B. subtilis vesicles, but also vesicles from Bacillus anthracis, indicating a mechanism that crossed species boundaries. To our knowledge, this is the first time a gene and a mechanism has been identified in the active disruption of extracellular vesicles and subsequent release of vesicular cargo in Gram-positive bacteria. We also identify a new mechanism of action for surfactin. PMID:24826903

Brown, Lisa; Kessler, Anne; Cabezas-Sanchez, Pablo; Luque-Garcia, Jose L; Casadevall, Arturo

2014-07-01

274

Environmentally friendly antibacterial cotton textiles finished with siloxane sulfopropylbetaine.  

PubMed

This paper reports a novel environmentally friendly antibacterial cotton textile finished with reactive siloxane sulfopropylbetaine(SSPB). The results show that SSPB can be covalently bound onto the cotton textile surface, imparting perdurable antibacterial activity. The textiles finished with SSPB have been investigated systematically from the mechanical properties, thermal stability, hydrophilic properties and antibacterial properties. It is found that the hydrophilicity and breaking strength are improved greatly after the cotton textiles are finished with SSPB. Additionally, the cotton textiles finished with SSPB exhibit good antibacterial activities against gram-positive bacteria Staphylococcus aureus (S.aureus, ATCC 6538), gram-negative bacteria Escherichia coli (E.coli, 8099) and fungi Candida albicans (C.albicans, ATCC 10231). Moreover, SSPB is nonleachable from the textiles, and it does not induce skin stimulation and is nontoxic to animals. Thus, SSPB is ideal candidate for environmentally friendly antibacterial textile applications. PMID:21417413

Chen, Shiguo; Chen, Shaojun; Jiang, Song; Xiong, Meiling; Luo, Junxuan; Tang, Jiaoning; Ge, Zaochuan

2011-04-01

275

Ligational behavior of Schiff bases towards transition metal ion and metalation effect on their antibacterial activity  

NASA Astrophysics Data System (ADS)

New Schiff bases pyrazine-2-carboxylicacid (phenyl-pyridin-2-yl-methylene)-hydrazide (Hpch-bp) HL1 and pyrazine-2-carboxylicacid (pyridin-2-ylmethylene)-hydrazide (Hpch-pc) HL2 derived from condensation of pyrazine carboxylic hydrazide (Hpch) with 2-benzoyl pyridine (bp) or pyridine 2-carbaldehyde (pc) and their transition metal complexes of type ML(1-2)2 have been synthesized, where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). Characterization of ligands and their metal complexes was carried out by elemental analysis, conductimetric studies, magnetic susceptibility, spectroscopic techniques (IR, UV-VIS, NMR, ESR, Mass) and thermogravimetric analysis. The physico-chemical studies revealed octahedral geometry or distorted octahedral geometry around metal ion. These azomethine Schiff base ligands acted as tridentate ? coordinating through carbonyl, azomethine and pyridine nitrogen present in the ligand. The thermodynamic and thermal properties of the complexes have been investigated and it was observed on the basis of these studies that thermal stability of complexes follows the order Mn < Zn < Cu < Co < Ni. The ligands and their complexes were tested for in vitro antibacterial activity at different concentrations against bacteria viz. Gram positive Bacillus subtilis, Micrococcus luteus and Gram negative Pseudomonas aeruginosa, Pseudomonas mendocina. A marked enhancement in biocidal activity of the ligands under similar experimental conditions was observed as a consequence of coordination with metal ions. The trend of growth inhibition in the complexes was found to be in the order: Cu > Mn > Ni > Co > Zn.

Devi, Jai; Batra, Nisha; Malhotra, Rajesh

2012-11-01

276

Antibacterial activity of selected fatty acids and essential oils against six meat spoilage organisms.  

PubMed

The antibacterial activity of selected fatty acids and essential oils was examined against two gram-negative (Pseudomonas fluorescens and Serratia liquefaciens) and four gram-positive (Brochothrix thermosphacta, Carnobacterium piscicola, Lactobacillus curvatus, and Lactobacillus sake) bacteria involved in meat spoilage. Various amounts of each preservative were added to brain heart infusion or MRS (deMan, Rogosa and Sharpe) agars, and the minimum inhibitory concentration was determined for each organism. Essential oils were analysed by gas-liquid chromatography to determine the concentration of selected components commonly found in spices. B. thermosphacta, P. fluorescens and S. liquefaciens were not affected by fatty acids, and generally overcame the inhibitory effect of essential oils after 24 h of exposure. Among the fatty acids, lauric and palmitoleic acids exhibited the greatest inhibitory effect with minimum inhibitory concentrations of 250 to 500 micrograms/ml, while myristic, palmitic, stearic and oleic acids were completely ineffective. For essential oils, clove, cinnamon, pimento, and rosemary were found to be the most active. The 1/100 dilution of those oils inhibited at least five of the six tested organisms. A relationship was found between the inhibitory effect of essential oils and the presence of eugenol and cinnamaldehyde. PMID:9310850

Ouattara, B; Simard, R E; Holley, R A; Piette, G J; Bégin, A

1997-07-22

277

Antibacterial activity of the essential oil from Cymbopogon nervatus inflorescence  

Microsoft Academic Search

Antibacterial activity of essential oil of dried inflorescence of Cymbopogon nervatus was investigated. The essential oil remarkably inhibited the growth of tested bacteria except for Salmonella typhi. The maximum activity was against Shigella dysenteriae and Klebsiella pneumoniae.

H. H. EL-Kamali; M. A. Hamza; M. Y. EL-Amir

2005-01-01

278

Essential oil composition and antibacterial activity of Origanum vulgare subsp. glandulosum Desf. at different phenological stages.  

PubMed

Variation in the quantity and quality of the essential oil (EO) of wild population of Origanum vulgare at different phenological stages, including vegetative, late vegetative, and flowering set, is reported. The oils of air-dried samples were obtained by hydrodistillation. The yield of oils (w/w%) at different stages were in the order of late vegetative (2.0%), early vegetative (1.7%), and flowering (0.6%) set. The oils were analyzed by gas chromatography (GC) and GC-mass spectrometry (GC-MS). In total, 36, 33, and 16 components were identified and quantified in vegetative, late vegetative, and flowering set, representing 94.47%, 95.91%, and 99.62% of the oil, respectively. Carvacrol was the major compound in all samples. The ranges of major constituents were as follows: carvacrol (61.08-83.37%), p-cymene (3.02-9.87%), and ?-terpinene (4.13-6.34%). Antibacterial activity of the oils was tested against three Gram-positive and two Gram-negative bacteria by the disc diffusion method and determining their diameter of inhibition and the minimum inhibitory concentration (MIC) values. The inhibition zones and MIC values for bacterial strains, which were sensitive to the EO of O. vulgare subsp. glandulosum, were in the range of 9-36 mm and 125-600 ?g/mL, respectively. The oils of various phenological stages showed high activity against all tested bacteria, of which Bacillus subtilis was the most sensitive and resistant strain, respectively. Thus, they represent an inexpensive source of natural antibacterial substances that exhibited potential for use in pathogenic systems. PMID:24320986

Béjaoui, Afef; Chaabane, Hédia; Jemli, Maroua; Boulila, Abdennacer; Boussaid, Mohamed

2013-12-01

279

Antibacterial, anti-inflammatory, anti-cholinesterase and mutagenic effects of extracts obtained from some trees used in South African traditional medicine  

Microsoft Academic Search

Extracts obtained from 10 trees used in South African traditional medicine were screened for antibacterial, anti-inflammatory (COX-1 and COX-2) and anti-cholinesterase activities and investigated for potential mutagenic effects using the Ames test. Antibacterial activity was detected using the disc-diffusion and micro-dilution assays. The extracts were tested against Gram-positive bacteria: Bacillus subtilis, Staphylococcus aureus, Micrococcus luteus and Gram-negative bacteria: Escherichia coli

I. M. S. Eldeen; E. E. Elgorashi; J. van Staden

2005-01-01

280

Synthesis and antibacterial activity of N-[2-[5-(methylthio)thiophen-2-yl]-2-oxoethyl] and N-[2-[5-(methylthio)thiophen-2-yl]-2-(oxyimino)ethyl]piperazinylquinolone derivatives.  

PubMed

A number of N-substituted piperazinylquinolone derivatives were synthesized and evaluated for antibacterial activity against Gram-positive and Gram-negative bacteria. Preliminary results indicated that most compounds tested in this study demonstrated comparable or better activity against Staphylococcus aureus and Staphylococcus epidermidis than their parent piperazinylquinolones as reference drugs. Among these derivatives, ciprofloxacin derivative 5a, containing N-[2-[5-(methylthio)thiophen-2-yl]-2-oxoethyl] residue, showed significant improvement of potency against staphylococci, maintaining Gram-negative coverage. PMID:16427290

Foroumadi, Alireza; Oboudiat, Mehdi; Emami, Saeed; Karimollah, Alireza; Saghaee, Lotfollah; Moshafi, Mohammad Hassan; Shafiee, Abbas

2006-05-15

281

Induction of nitric oxide production by polyosides from the cell walls of Streptococcus mutans OMZ 175, a gram-positive bacterium, in the rat aorta.  

PubMed Central

The cardiovascular dysfunctions associated with septic shock induced by gram-negative or gram-positive bacteria (gram-positive or gram-negative septic shock) are comparable. In gram-negative septic shock, lipopolysaccharide (LPS) induces nitric oxide (NO) synthase, which contributes to the vascular hypotension and hyporeactivity to vasoconstrictors. The role of NO in gram-positive septic shock and the nature of the bacterial wall components responsible for the vascular effects of gram-positive bacteria are not well known. This study investigated the vascular effects of cell wall serotype polyosides, rhamnose glucose polymers (RGPs), from Streptococcus mutans, in comparison with lipoteichoic acid (LTA) from Staphylococcus aureus, on the induction of NO synthase activity in the rat aorta. We show that 10 microg of both RGPs and LTA per ml induced hyporeactivity to noradrenaline, L-arginine-induced relaxation, increases of 2.2- and 7.8-fold, respectively, of cyclic GMP production, and increases of 7- and 12-fold in nitrite release. All of these effects appeared after several hours of incubation and were inhibited by N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthase. Electron paramagnetic resonance spin trapping experiments demonstrated directly that RGPs and LTA induced NO overproduction (four- to eightfold, respectively) in rat aortic rings; this production was inhibited by L-NAME and prevented by dexamethasone. These results demonstrate directly the induction of NO production in vascular tissue by LTA and show that another, chemically different component of gram-positive bacteria can also have these properties. This result suggests that different components of the gram-positive bacterial wall could be implicated in the genesis of cardiovascular dysfunctions observed in gram-positive septic shock. PMID:9169734

Martin, V; Kleschyov, A L; Klein, J P; Beretz, A

1997-01-01

282

Streptomyces tunisiensis sp. nov., a novel Streptomyces species with antibacterial activity.  

PubMed

A novel actinomycete strain designated CN-207(T) was isolated from northern Tunisian soil. This strain exhibited potent broad spectrum antibacterial activity against clinical isolates of methicillin-resistant Staphylococcus species and several other Gram-positive and Gram-negative bacteria. Strain CN-207(T) developed greyish aerial mycelium and pale grey substrate mycelium on yeast extract/malt agar. The isolate produced branching vegetative mycelia with sporangiophores bearing sporangia developing at a late stage of growth. The sporangia contained smooth, non-motile spores. Chemotaxonomic characteristics of strain CN-207(T) were typical of the Streptomyces genus. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain CN-207(T) belonged to the genus Streptomyces, and was most closely related to Streptomyces griseoincarnatus DSM 40274(T), Streptomyces variabilis DSM 40179(T), Streptomyces labedae DSM 41446(T) and Streptomyces erythrogriseus DSM 40116(T). Low DNA-DNA relatedness values were recorded between strain CN-207(T) and its closest phylogenetic neighbours. Strain CN-207(T) was also distinguished from the nearest phylogenetic neighbours using a combination of morphological and phenotypic characteristics. On the basis of its phenotypic and molecular properties, strain CN-207(T) is considered as a novel species of the Streptomyces genus, for which the name Streptomyces tunisiensis sp. nov. is proposed. The type strain is CN-207(T) (=JCM 17589(T) = DSM 42037(T)). PMID:24306769

Slama, Nedra; Mankai, Houda; Ayed, Ameni; Mezhoud, Karim; Rauch, Catherine; Lazim, Hadeer; Barkallah, Insaf; Gtari, Maher; Limam, Ferid

2014-02-01

283

Ligand effects on the structural dimensionality and antibacterial activities of silver-based coordination polymers.  

PubMed

Four Ag-based coordination polymers [Ag(Bim)] (1), [Ag2(NIPH)(HBim)] (2), [Ag6(4-NPTA)(Bim)4] (3) and [Ag2(3-NPTA)(bipy)0.5(H2O)] (4) (HBim = 1H-benzimidazole, bipy = 4,4'-bipyridyl, H2NIPH = 5-nitroisophthalic acid, H2NPTA = 3-/4-nitrophthalic acid) have been synthesized by hydrothermal reaction of Ag(i) salts with N-/O-donor ligands. Single-crystal X-ray diffraction indicated that these coordination polymers constructed from mononuclear or polynuclear silver building blocks exhibit three typical structure features from 1-D to 3-D frameworks. These compounds favour a slow release of Ag(+) ions leading to excellent and long-term antimicrobial activities, which is distinguished by their different topological structures, towards both Gram-negative bacteria, Escherichia coli (E. coli) and Gram-positive bacteria, Staphylococcus aureus (S. aureus). In addition, these compounds show good thermal stability and light stability under UV-vis and visible light, which are important characteristics for their further application in antibacterial agents. PMID:24871812

Lu, Xinyi; Ye, Junwei; Sun, Yuan; Bogale, Raji Feyisa; Zhao, Limei; Tian, Peng; Ning, Guiling

2014-07-14

284

Surface multiheme c-type cytochromes from Thermincola potens: Implications for dissimilatory metal reduction by Gram-positive bacteria  

NASA Astrophysics Data System (ADS)

Almost nothing is known about the mechanisms of dissimilatory metal reduction by Gram-positive bacteria, although they have been shown to be the dominant species in some environments. Thermincola potens strain JR was isolated from the anode of a microbial fuel cell inoculated with anaerobic digester sludge and operated at 55 °C. Preliminary characterization revealed that T. potens coupled acetate oxidation to the reduction of hydrous ferric oxides (HFO) or the humic substances analog, anthraquinone-2,6-disulfonate (AQDS). The genome of T. potens was recently sequenced, and the abundance of multiheme c-type cytochromes (MHCs) is unusual for a Gram-positive bacterium. We present evidence from trypsin shaving LC-MS/MS experiments and surface-enhanced Raman spectroscopy (SERS) that indicates the expression of a number of MHCs during T. potens growth on either HFO or AQDS and that several MHCs are localized to the cell wall or cell surface of T. potens. Furthermore, one of the MHCs can be extracted from cells with low pH or denaturants suggesting a loose association with the cell wall or cell surface. Electron microscopy does not reveal an S-layer, and the precipitation of silver metal on the cell surface is inhibited by cyanide, supporting the involvement of surface-localized redox-active heme proteins in dissimilatory metal reduction. These results are the first direct evidence for cell-wall associated cytochromes and MHC involvement in conducting electrons across the cell envelope of a Gram-positive bacterium.

Carlson, H. K.; Iavarone, A. T.; Gorur, A.; Yeo, B. S.; Tran, R.; Melnyk, R. A.; Mathies, R. A.; Auer, M.; Coates, J. D.

2011-12-01

285

Towards long-lasting antibacterial stainless steel surfaces by combining double glow plasma silvering with active screen plasma nitriding.  

PubMed

Antibacterial surface modification of biomedical materials has evolved as a potentially effective method for preventing bacterial proliferation on the surfaces of devices. However, thin antibacterial coatings or modified layers can be easily worn down when interacting with other surfaces in relative motion, thus leading to a low durability of the antibacterial surface. To this end, novel biomaterial surfaces with antibacterial Ag agents and a wear-resistant S-phase have been generated on stainless steel by duplex plasma silvering-nitriding techniques for application to load-bearing medical devices. The chemical composition, microstructure, surface topography, roughness and wettability of SS surfaces were characterised using glow discharge optical emission spectroscopy, energy-dispersive spectroscopy/wavelength dispersive spectrometry (WDS), X-ray diffraction, atomic force microscopy and a contact angle goniometer. Optimal surface design for high antimicrobial activity and prolonged durability has been achieved, as evidenced by rapid bacterial killing rates (within 6h), an ultra hard matrix (875 ± 25 Hv), high load-bearing capacity (critical load 37 N) and excellent wear resistance (wear rate 4.9 × 10?? mmł m?ą). Ag embedded in the hard substrate of fcc compounds M(4)N (M=Fe, Cr, Ag, etc.) and the expanded fcc nitrogen S-phase shows deep infiltration of 6 ± 1 ?m, and provides bactericidal activity against both Gram-negative Escherichia coli NCTC 10418 and Gram-positive Staphylococcus epidermidis NCTC 11047 of over 97% and 90%, respectively, within 6h. The presence of silver in the surface before and after scratching under a progressive load applied up to 60 N using a diamond stylus was confirmed by WDS. PMID:20727993

Dong, Y; Li, X; Tian, L; Bell, T; Sammons, R L; Dong, H

2011-01-01

286

Facile green synthesis of silver nanoparticles using seed aqueous extract of Pistacia atlantica and its antibacterial activity.  

PubMed

In the present work, we describe the synthesis of silver nanoparticles (Ag-NPs) using seed aqueous extract of Pistacia atlantica (PA) and its antibacterial activity. UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infra red spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray energy dispersive spectrophotometer (EDAX) were performed to ascertain the formation of Ag-NPs. It was observed that the growths of Ag-NPs are stopped within 35 min of reaction time. The synthesized Ag-NPs were characterized by a peak at 446 nm in the UV-visible spectrum. XRD confirmed the crystalline nature of the nanoparticles of 27 nm size. The XRD peaks at 38°, 44°, 64° and 77° can be indexed to the (111), (200), (220) and (311) Bragg's reflections of cubic structure of metallic silver, respectively. The FTIR result clearly showed that the extracts containing OH as a functional group act in capping the nanoparticles synthesis. Antibacterial activities of Ag-NPs were tested against the growth of Gram-positive (S. aureus) using SEM. The inhibition was observed in the Ag-NPs against S. aureus. The results suggest that the synthesized Ag-NPs act as an effective antibacterial agent. It is confirmed that Ag-NPs are capable of rendering high antibacterial efficacy and hence has a great potential in the preparation of used drugs against bacterial diseases. The scanning electron microscopy (SEM), indicated that, the most strains of S. aureus was damaged and extensively disappeared by addition of Ag-NPs. The results confirmed that the (PA) is a very good eco friendly and nontoxic source for the synthesis of Ag-NPs as compared to the conventional chemical/physical methods. PMID:25022505

Sadeghi, Babak; Rostami, Amir; Momeni, S S

2015-01-01

287

Antibacterial activity of sucralfate versus aluminum chloride in simulated gastric fluid  

Microsoft Academic Search

Studies have previously demonstrated that sucralfate possesses intrinsic antibacterial activity. This study was designed to indirectly assess whether aluminum is the active antibacterial component of sucralfate and to further evaluate factors that may influence this agent's antibacterial activity. Utilizing an in vitro model, the antibacterial activity of sucralfate, an equivalent quantity of aluminum in the form of aluminum chloride, and

L. Welage; P. Carver; K. Welch

1994-01-01

288

A Comparative Genome Analysis Identifies Distinct Sorting Pathways in Gram-Positive Bacteria  

Microsoft Academic Search

Surface proteins in gram-positive bacteria are frequently required for virulence, and many are attached to the cell wall by sortase enzymes. Bacteria frequently encode more than one sortase enzyme and an even larger number of potential sortase substrates that possess an LPXTG-type cell wall sorting signal. In order to elucidate the sorting pathways present in gram-positive bacteria, we performed a

David Comfort; Robert T. Clubb

2004-01-01

289

Antibiotic-Resistant Gram-Positive Cocci: Implications for Surgical Practice  

Microsoft Academic Search

. Gram-positive infections are causing more serious infections than ever before in surgical patients, who are increasingly\\u000a aged, ill, and debilitated. Invasive procedures disrupt natural barriers to bacterial invasion, and indwelling catheters may\\u000a act as conduits for infection. The use of broad-spectrum antibiotics selects for the emergence of resistant pathogens. Potential\\u000a sites of nosocomial gram-positive infections include the urinary tract,

Philip S. Barie

1998-01-01

290

Widespread Abundance of Functional Bacterial Amyloid in Mycolata and Other Gram-Positive Bacteria  

Microsoft Academic Search

Until recently, extracellular functional bacterial amyloid (FuBA) has been detected and characterized in only a few bacterial species, including Escherichia coli, Salmonella, and the gram-positive organism Streptomyces coelicolor. Here we probed gram-positive bacteria with conformationally specific antibodies and revealed the existence of FuBA in 12 of 14 examined mycolata species, as well as six other distantly related species examined belonging

Peter Bruun Jordal; Morten Simonsen Dueholm; Poul Larsen; Steen Vang Petersen; Jan Johannes Enghild; Gunna Christiansen; P. Hojrup; Per Halkjćr Nielsen; Daniel Erik Otzen

2009-01-01

291

Antibacterial activity of some plant extracts used in folk medicine.  

PubMed

In the present work, selected plants were screened for their potential antibacterial activity. For evaluating antibacterial activity, both aqueous and organic solvent methanol was used. The plants screened were Ocimum sanctum, Jatropha gossypifolia, Boerhavia diffusa, Azadirachta indica, Solidago virgaurea, and Commelina benghalensis. The antibacterial activity was assessed against six bacterial strains--Pseudomonas testosteroni, Staphylococcus epidermidis, Klebsiella pneumoniae, Bacillus subtilis, Proteus morganii, Micrococcus flavus. Agar disc diffusion method and Agar ditch diffusion method were used to study the antibacterial activity of all these plants. Ps. testosteroni and K. pneumoniae were the most resistant bacterial strains. A. indica showed strong activity against tested bacterial strains. Therefore, we conclude that A. indica may prove to be a promising agent, and further exploration into this compound should be performed to determine its full therapeutic potential. In addition, its leaf extract can also be used as a lead molecule in combating the diseases caused by the studied bacterial strains. PMID:18928141

Nair, Rathish; Kalariya, Tamanna; Chanda, Sumitra

2007-01-01

292

Assessment of phytochemical content, polyphenolic composition, antioxidant and antibacterial activities of Leguminosae medicinal plants in Peninsular Malaysia  

PubMed Central

Background Many medicinal plants from Leguminosae family can be found easily in Malaysia. These plants have been used as traditional medicines by local ethnic groups, where they are prepared as decoction, pastes for wound infections, and some have been eaten as salad. This paper focused on the assessment of antioxidant potential, antibacterial activity and classes of phytochemicals of nine plants from the Leguminosae family. Methods Acacia auriculiformis, Bauhinia kockiana, Bauhinia purpurea, Caesalpinia pulcherrima, Calliandra tergemina, Cassia surattensis, Leucaena leucocephala, Peltophorum pterocarpum, and Samanea saman were extracted with aqueous methanol and dichloromethane:methanol mixture to test for antioxidant and antibacterial activities. The Folin-Ciocalteu assay was conducted to quantify the total phenolic content and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to determine the free radical quenching capacity. Antibacterial activity was assessed using disc diffusion (Kirby-Bauer) assay. Screening for major classes of phytochemical was done using standard chemical tests. Results B. kockiana flowers and C. pulcherrima leaves contained high total phenolic content (TPC) and strong DPPH radical scavenging ability with TPC of 8280 ± 498 mg GAE/100 g, IC50 of 27.0 ± 5.0 ?g/mL and TPC of 5030 ± 602 mg GAE/100 g, IC50 of 50.0 ± 5.0 ?g/mL respectively. Positive correlation was observed between TPC and free radical scavenging ability. Most extracts showed antibacterial activity against Gram positive bacteria at 1 mg, while none showed activity against Gram negative bacteria at the same dose. All extracts (except Samanea saman flower) showed antibacterial activity against two strains of methicillin resistant Staphylococcus aureus (MRSA) with MID values ranging between 100 ?g/disc and 500 ?g/disc. Conclusion The potential source of antioxidant and antibacterial agents, especially for MRSA infection treatments were found in B. kockiana, C. pulcherrima, C. tergemina and P. pterocarpum. These preliminary results would be a guide in the selection of potential candidates for further pharmacological study and in search of new drug candidate in treating MRSA infections. PMID:21306653

2011-01-01

293

Molecular characterization of a novel hepcidin (HepcD) from Camelus dromedarius. Synthetic peptide forms exhibit antibacterial activity.  

PubMed

Hepcidin is a cysteine-rich peptide widely characterized in immunological processes and antimicrobial activity in several vertebrate species. Obviously, this hormone plays a central role in the regulation of systemic iron homeostasis. However, its role in camelids' immune response and whether it is involved in antibacterial immunity have not yet been proven. In this study, we characterized the Arabian camel hepcidin nucleotide sequence with an open reading frame of 252 bp encoding an 83-amino acid preprohepcidin peptide. Eight cysteine key residues conserved in all mammalian hepcidin sequences were identified. The model structure analysis of hepcidin-25 peptide showed a high homology structure and sequence identity to the human hepcidin. Two different hepcidin-25 analogs manually synthesized by SPPS shared significant cytotoxic capacity toward the Gram-negative bacterium Escherichia coli American Type Culture Collection (ATCC) 8739 as well as the Gram-positive bacteria Bacillus subtilis ATCC 11779 and Staphylococcus aureus ATCC 6538 in vitro. The three disulfide bridges hepcidin analog demonstrated bactericidal activity, against B.?subtilis ATCC 11779 and S.?aureus ATCC 6538 strains, at the concentration of 15 ?M (50 µg/ml) or above at pH 6.2. This result correlates with the revealed structural features suggesting that camel hepcidin is proposed to be involved in antibacterial process of innate immune response. PMID:24895313

Boumaiza, Mohamed; Ezzine, Aymen; Jaouen, Maryse; Sari, Marie-Agnes; Marzouki, Mohamed Nejib

2014-09-01

294

Antibacterial activities of surface modified electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) fibrous membranes  

NASA Astrophysics Data System (ADS)

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) membrane, with its excellent chemical and mechanical properties, has good potential for broad applications. However, due to its hydrophobic nature, microbial colonization is commonly encountered. In this work, electrospun PVDF-HFP fibrous membranes were surface modified by poly(4-vinyl- N-alkylpyridinium bromide) to achieve antibacterial activities. The membranes were first subjected to plasma pretreatment followed by UV-induced surface graft copolymerization of 4-vinylpyridine (4VP) and quaternization of the grafted pyridine groups with hexylbromide. The chemical composition of the surface modified PVDF-HFP electrospun membranes was studied by X-ray photoelectron spectroscopy (XPS). The morphology and mechanical properties of pristine and surface modified PVDF-HFP fibrous membranes were characterized by scanning electron microscopy (SEM) and tensile test, respectively. The antibacterial activities of the modified electrospun PVDF-HFP fibrous membranes were assessed against Gram-positive Staphylococcus aureus ( S. aureus) and Gram-negative Escherichia coli ( E. coli). The results showed that the PVDF-HFP fibrous membranes modified with quaternized pyridinium groups are highly effective against both bacteria with killing efficiency as high as 99.9999%.

Yao, Chen; Li, Xinsong; Neoh, K. G.; Shi, Zhilong; Kang, E. T.

2009-01-01

295

Proteolytically activated anti-bacterial hydrogel microspheres.  

PubMed

Hydrogels are finding increased clinical utility as advances continue to exploit their favorable material properties. Hydrogels can be adapted for many applications, including surface coatings and drug delivery. Anti-infectious surfaces and delivery systems that actively destroy invading organisms are alternative ways to exploit the favorable material properties offered by hydrogels. Sterilization techniques are commonly employed to ensure the materials are non-infectious upon placement, but sterilization is not absolute and infections are still expected. Natural, anti-bacterial proteins have been discovered which have the potential to act as anti-infectious agents; however, the proteins are toxic and need localized release to have therapeutic efficacy without toxicity. In these studies, we explore the use of the glutathione s-transferase (GST) to anchor the bactericidal peptide, melittin, to the surface of poly(ethylene glycol) diacrylate (PEGDA) hydrogel microspheres. We show that therapeutic levels of protein can be anchored to the surface of the microspheres using the GST anchor. We compared the therapeutic efficacy of recombinant melittin released from PEGDA microspheres to melittin. We found that, when released by an activating enzyme, thrombin, recombinant melittin efficiently inhibits growth of the pathogenic bacterium Streptococcus pyogenes as effectively as melittin created by solid phase peptide synthesis. We conclude that a GST protein anchor can be used to immobilize functional protein to PEGDA microspheres and the protein will remain immobilized under physiological conditions until the protein is enzymatically released. PMID:23816641

Buhrman, Jason S; Cook, Laura C; Rayahin, Jamie E; Federle, Michael J; Gemeinhart, Richard A

2013-11-10

296

Composition and Antibacterial Activity of Achillea chrysocoma Essential Oil  

Microsoft Academic Search

Essential oil of Achillea chrysocoma Friv. was investigated for composition and antibacterial activity. Twenty-eight identified compounds constituted 91.5% of the oil. The main compounds of the oil were borneol (10.1%), terpinen-4-ol (9.2%), cis-p-menth-2-en-1-ol (8.2%) and trans-p-menth-2-en-1-ol (7.9%). Antibacterial tests showed pronounced activity of the oil against Gram-negative bacteria Klebsiella pneumoniae and Pseudomonas aeruginosa.

Nebojsa Simic; Radosav Palic; Vlatka Vajs; Slobodan Milosavljevic; Dejan Djokovic

2000-01-01

297

Antibacterial activity of some Indian medicinal plants  

Microsoft Academic Search

Aqueous extracts of ten medicinal plants were examined for their antibacterial potential against some reference strains of\\u000a human pathogenic bacteria. Anethum graveolens, Elettaria cardamomum, Foeniculum vulgare, Trachyspermum ammi and Viola odorata were found to be better\\/equally effective compared to standard antibiotics. V. odorata was the most effective antibacterial with minimum inhibitory concentration values ranging from 1 to 2%. The results

Daljit Singh Arora; Gurinder Jeet Kaur

2007-01-01

298

Gas chromatography-mass spectroscopy analysis of bioactive petalostigma extracts: Toxicity, antibacterial and antiviral activities  

PubMed Central

Background: Petalostigma pubescens and Petalostigma triloculare were common components of pharmacopeia's of multiple Australian Aboriginal tribal groupings which traditionally inhabited the areas in which they grow. Among these groups, they had a myriad of medicinal uses in treating a wide variety of bacterial, fungal and viral infections. This study was undertaken to test P. pubescens and P. triloculare leaf and fruit extracts for the ability to inhibit bacterial and viral growth and thus validate Australian Aboriginal usage of these plants in treating bacterial and fungal diseases. Materials and Methods: P. pubescens, and P. triloculare leaves and fruit were extracted and tested for antimicrobial, antiviral activity and toxicity. The bioactive extracts were further examined by RP-HPLC and GC-MS to identify the component compounds. Results: The methanol, water and ethyl acetate leaf and fruit extracts of displayed potent antibacterial activity. The methanol and ethyl acetate extracts displayed the broadest specificity, inhibiting the growth of 10 of the 14 bacteria tested (71%) for the leaf extract and 9 of the 14 bacteria tested (64%) for the fruit extracts. The water extracts also had broad spectrum antibacterial activity, inhibiting the growth of 8 (57%) and 7 (50%) of the 14 bacteria tested, respectively. All antibacterial extracts were approximately equally effective against Gram-positive and Gram-negative bacteria, inhibiting the growth of 50-75% of the bacteria tested. The methanol, water and ethyl acetate extracts also displayed antiviral activity in the MS2 plaque reduction assay. The methanol and water extracts inhibited 26.6-49.0% and 85.4-97.2% of MS2 plaque formation, respectively, with the fruit extracts being more potent inhibitors. All ethyl acetate extracts inhibited 100% of MS2 plaque formation. All extracts were also non-toxic or of low toxicity. Analysis of these extracts by RP-HPLC showed that the P. triloculare ethyl acetate fruit extract was the least complex of the bioactive extracts. Subsequent analysis of this extract by GC-MS revealed that it contained 9 main compounds: acetic acid; 2,2-dimethoxybutane; 4-methyl-1,3-dioxane; decane; unadecane; 2-furanmethanol; 1,2-benzenediol; 1,2,3-benzenetriol; and benzoic acid. Conclusion: These studies validate Australian Aboriginal therapeutic usage of Petalostigma species and indicate their medicinal potential. PMID:24914307

Kalt, F. R.; Cock, I. E.

2014-01-01

299

Thermophilic Gram-Positive Biocatalysts for Biomass Conversion to Ethanol  

SciTech Connect

Production of energy from renewable sources is receiving increased attention due to the finite nature of fossil fuels and the environmental impact associated with the continued large scale use of fossil energy sources. Biomass, a CO2-neutral abundant resource, is an attractive alternate source of energy. Biomass-derived sugars, such as glucose, xylose, and other minor sugars, can be readily fermented to fuel ethanol and commodity chemicals. Extracellular cellulases produced by fungi are commercially developed for depolymerization of cellulose in biomass to glucose for fermentation by appropriate biocatalysts in a simultaneous saccharification and fermentation (SSF) process. Due to the differences in the optimum conditions for the activity of the fungal cellulases and the growth and fermentation characteristics of the current industrial biocatalysts, SSF of cellulose is envisioned at conditions that are not optimal for the fungal cellulase activity leading to higher than required cost of cellulase in SSF. We have isolated bacterial biocatalysts whose growth and fermentation requirements match the optimum conditions for commercial fungal cellulase activity (pH 5.0 and 50 deg. C). These isolates fermented both glucose and xylose, major components of cellulose and hemicellulose, respectively, to L(+)-lactic acid. Xylose was metabolized through the pentose-phosphate pathway by these organisms as evidenced by the fermentation profile and analysis of the fermentation products of 13C1-xylose by NMR. As expected for the metabolism of xylose by the pentose-phosphate pathway, 13C-lactate accounted for more than 90% of the total 13C-labeled products. All three strains fermented crystalline cellulose to lactic acid with the addition of fungal cellulase (Spezyme CE) (SSF) at an optimum of about 10 FPU/g cellulose. These isolates also fermented cellulose and sugar cane bagasse hemicellulose acid hydrolysate simultaneously. Based on fatty acid profile and 16S rRNA sequence, these isolates cluster with Bacillus coagulans although B. coagulans type strain, ATCC 7050, failed to utilize xylose as a carbon source. For successful production of ethanol from pyruvate, both pyruvate decarboxylase (PDC) and alcohol dehydrogenase (AHD) need to be produced at optimal levels in these biocatalysts. A plasmid containing the S. ventriculi pdc gene and the adh gene from geobacillus stearothermophilus was constructed using plasmid pWH1520 that was successfully used for expression of pdc in B. megaterium. The resulting portable ethanol (PET) plasmid, pJAM423, was transformed into B. megaterium. After xylose induction, a significant fraction of cell cytoplasm was composed of the S. ventriculi PDC and G. stearothermophilus ADH proteins. In preliminary experiments, the amount of ethanol produced by b. megaterium with plasmid pJAM423 was about twice (20 mM) of the bacterium without the plasmid. These results show that the PET operon is functional in B. megaterium but high level ethanol production needs further genetic and metabolic engineering. A genetic transfer system for the second generation biocatalysts needs to be developed for transferring the plasmid pJAM423 and its derivatives for engineering these organisms for ethanol production from biomass derived sugars and cellulose to ethanol. One of the new biocatalysts, strain P4-102B was found to be transformable with plasmids and the method for introducing plasmid pJAM423 into this strain and expression of the encoded DNA is being optimized. These new second generation biocatalysts have the potential to reduce the cost of SSF by minimizing the amount of fungal cellulases, a significant cost component in the use of biomass as a renewable resource for production of fuels and chemicals.

Shanmugam, K.T.; Ingram, L.O.; Maupin-Furlow, J.A.; Preston, J.F.; Aldrich, H.C.

2003-12-01

300

Synthesis, molecular docking and biological evaluation of metronidazole derivatives containing piperazine skeleton as potential antibacterial agents.  

PubMed

Metronidazole has a broad-spectrum antibacterial activity. Hereby a series of novel metronidazole derivatives were designed and synthesized based on nitroimidazole scaffold in order to find some more potent antibacterial drugs. For these compounds which were reported for the first time, their antibacterial activities against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus were tested. These compounds showed good antibacterial activities against Gram-positive strains. Compound 4m represented the most potent antibacterial activity against S. aureus ATCC 25923 with MIC of 0.003 ?g/mL and it showed the most potent activity against S. aureus TyrRS with IC50 of 0.0024 ?M. Molecular docking of 4m into S. aureus tyrosyl-tRNA synthetase active site were also performed to determine the probable binding mode. PMID:24680059

Wang, She-Feng; Yin, Yong; Qiao, Fang; Wu, Xun; Sha, Shao; Zhang, Li; Zhu, Hai-Liang

2014-04-15

301

The Effect of Substituent, Degree of Acetylation and Positioning of the Cationic Charge on the Antibacterial Activity of Quaternary Chitosan Derivatives  

PubMed Central

A series of water-soluble cationic chitosan derivatives were prepared by chemoselective functionalization at the amino group of five different parent chitosans having varying degrees of acetylation and molecular weight. The quaternary moieties were introduced at different alkyl spacer lengths from the polymer backbone (C-0, C-2 and C-6) with the aid of 3,6-di-O-tert-butyldimethylsilyl protection of the chitosan backbone, thus allowing full (100%) substitution of the free amino groups. All of the derivatives were characterized using 1H-NMR, 1H-1H COSY and FT-IR spectroscopy, while molecular weight was determined by GPC. Antibacterial activity was investigated against Gram positive S. aureus and Gram negative E. coli. The relationship between structure and activity/toxicity was defined, considering the effect of the cationic group’s structure and its distance from the polymer backbone, as well as the degree of acetylation within a molecular weight range of 7–23 kDa for the final compounds. The N,N,N-trimethyl chitosan with 100% quaternization showed the highest antibacterial activity with moderate cytotoxicity, while increasing the spacer length reduced the activity. Trimethylammoniumyl quaternary ammonium moieties contributed more to activity than 1-pyridiniumyl moieties. In general, no trend in the antibacterial activity of the compounds with increasing molecular weight or degree of acetylation up to 34% was observed. PMID:25196937

Sahariah, Priyanka; Gaware, Vivek S.; Lieder, Ramona; Jonsdottir, Sigri?ur; Hjalmarsdottir, Martha A.; Sigurjonsson, Olafur E.; Masson, Mar

2014-01-01

302

Antibacterial properties and corrosion resistance of AISI 420 stainless steels implanted by silver and copper ions  

NASA Astrophysics Data System (ADS)

Silver or copper ions are often chosen as antibacterial agents. But a few reports are concerned with these two antibacterial agents for preparation of antibacterial stainless steel (SS). The antibacterial properties and corrosion resistance of AISI 420 stainless steel implanted by silver and copper ions were investigated. Due to the cooperative antibacterial effect of silver and copper ions, the Ag/Cu implanted SS showed excellent antibacterial activities against both Gram-negative Escherichia coli ( E. coli) and Gram-positive Staphylococcus aureus ( S. aureus) at a total implantation dose of 2×1017 ions/cm2. Electrochemical polarization curves revealed that the corrosion resistance of Ag/Cu implanted SS was slightly enhanced as compared with that of un-implanted SS. The implanted layer was characterized by X-ray photoelectron spectroscopy (XPS). Core level XPS spectra indicate that the implanted silver and copper ions exist in metallic state in the implanted layer.

Ni, Hong-wei; Zhang, Han-shuang; Chen, Rong-sheng; Zhan, Wei-ting; Huo, Kai-fu; Zuo, Zhen-yu

2012-04-01

303

Transport Capabilities of Eleven Gram-positive Bacteria: Comparative Genomic Analyses  

PubMed Central

The genomes of eleven Gram-positive bacteria that are important for human health and the food industry, nine low G+C lactic acid bacteria and two high G+C Gram-positive organisms, were analyzed for their complement of genes encoding transport proteins. Thirteen to eighteen percent of their genes encode transport proteins, larger percentages than observed for most other bacteria. All of these bacteria possess channel proteins, some of which probably function to relieve osmotic stress. Amino acid uptake systems predominate over sugar and peptide cation symporters, and of the sugar uptake porters, those specific for oligosaccharides and glycosides often outnumber those for free sugars. About 10% of the total transport proteins are constituents of putative multidrug efflux pumps with Major Facilitator Superfamily (MFS)-type pumps (55%) being more prevalent than ATP-binding cassette (ABC)-type pumps (33%), which, however, usually greatly outnumber all other types. An exception to this generalization is Streptococcus thermophilus with 54% of its drug efflux pumps belonging to the ABC superfamily and 23% belonging each to the Multidrug/Oligosaccharide/Polysaccharide (MOP) superfamily and the MFS. These bacteria also display peptide efflux pumps that may function in intercellular signalling, and macromolecular efflux pumps, many of predictable specificities. Most of the bacteria analyzed have no pmf-coupled or transmembrane flow electron carriers. The one exception is Brevibacterium linens, which in addition to these carriers, also has transporters of several families not represented in the other ten bacteria examined. Comparisons with the genomes of organisms from other bacterial kingdoms revealed that lactic acid bacteria possess distinctive proportions of recognized transporter types (e.g., more porters specific for glycosides than reducing sugars). Some homologues of transporters identified had previously been identified only in Gram-negative bacteria or in eukaryotes. Our studies reveal unique characteristics of the lactic acid bacteria such as the universal presence of genes encoding mechanosensitive channels, competence systems and large numbers of sugar transporters of the phosphotransferase system. The analyses lead to important physiological predictions regarding the preferred signalling and metabolic activities of these industrially important bacteria. PMID:17490609

Lorca, Graciela L.; Barabote, Ravi D.; Zlotopolski, Vladimir; Tran, Can; Winnen, Brit; Hvorup, Rikki N.; Stonestrom, Aaron J.; Nguyen, Elizabeth; Huang, Li-Wen; Kim, David S.; Saier, Milton H.

2007-01-01

304

Mechanistic antimicrobial approach of extracellularly synthesized silver nanoparticles against gram positive and gram negative bacteria.  

PubMed

The development of eco-friendly and reliable processes for the synthesis of nanoparticles has attracted considerable interest in nanotechnology. In this study, an extracellular enzyme system of a newly isolated microorganism, Exiguobacterium sp. KNU1, was used for the reduction of AgNO? solutions to silver nanoparticles (AgNPs). The extracellularly biosynthesized AgNPs were characterized by UV-vis spectroscopy, Fourier transform infra-red spectroscopy and transmission electron microscopy. The AgNPs were approximately 30 nm (range 5-50 nm) in size, well-dispersed and spherical. The AgNPs were evaluated for their antimicrobial effects on different gram negative and gram positive bacteria using the minimum inhibitory concentration method. Reasonable antimicrobial activity against Salmonella typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was observed. The morphological changes occurred in all the microorganisms tested. In particular, E. coli exhibited DNA fragmentation after being treated with the AgNPs. Finally, the mechanism for their bactericidal activity was proposed according to the results of scanning electron microscopy and single cell gel electrophoresis. PMID:23867968

Tamboli, Dhawal P; Lee, Dae Sung

2013-09-15

305

Antibacterial and antifungal activity of Indonesian ethnomedical plants.  

PubMed

Methylene chloride and methanol extracts of 20 Indonesian plants with ethnomedical uses have been assessed for in vitro antibacterial and antifungal properties by disk diffusion method. Extracts of the six plants: Terminalia catappa, Swietenia mahagoni Jacq., Phyllanthus acuminatus, Ipomoea spp., Tylophora asthmatica and Hyptis brevipes demonstrated high activity in this bioassay system. These findings should stimulate the search for novel, natural product such as new antibacterial and antifungal agents. PMID:12946723

Goun, E; Cunningham, G; Chu, D; Nguyen, C; Miles, D

2003-09-01

306

Antibacterial activity of plastics coated with silver-doped organic-inorganic hybrid coatings prepared by sol-gel processes.  

PubMed

Silver-doped organic-inorganic hybrid coatings were prepared starting from tetraethoxysilane- and triethoxysilane-terminated poly(ethylene glycol)-block-polyethylene by the sol-gel process. They were applied as a thin layer (0.6-1.1 microm) to polyethylene (PE) and poly(vinyl chloride) (PVC) films and the antibacterial activity of the coated films was tested against Gram-negative (Escherichia coli ATCC 25922) and Gram-positive (Staphylococcus aureus ATCC 6538) bacteria. The effect of several factors (such as organic-inorganic ratio, type of catalyst, time of post-curing, silver ion concentration, etc.) was investigated. Measurements at different contact times showed a rapid decrease of the viable count for both tested strains. The highest antibacterial activity [more than 6 log reduction within 6 h starting from 106 colony-forming units (cfu) mL-1] was obtained for samples with an organic-inorganic weight ratio of 80:20 and 5 wt % silver salt with respect to the coating. For the coatings prepared by an acid-catalyzed process, a high level of permanence of the antibacterial activity of the coated films was demonstrated by repeatedly washing the samples in warm water or by immersion in physiological saline solution at 37 degrees C for 3 days. The release of silver ions per square meter of coating is very similar to that previously observed for polyamides filled with metallic silver nanoparticles; however, when compared on the basis of Ag content, the concentration of silver ions released from the coating is much higher than that released from 1 mm thick specimens of polyamide (PA) filled with silver nanoparticles. Transparency and good adhesion of the coating to PE and PVC plastic substrates without any previous surface treatment are further interesting features. PMID:17335284

Marini, M; De Niederhausern, S; Iseppi, R; Bondi, M; Sabia, C; Toselli, M; Pilati, F

2007-04-01

307

Preparation of active antibacterial LDPE surface through multistep physicochemical approach: I. Allylamine grafting, attachment of antibacterial agent and antibacterial activity assessment  

Microsoft Academic Search

Low-density polyethylene (LDPE) samples were treated in air plasma discharge, coated by polyallyamine brush thought copolymeric grafting surface-from reaction and deposited four common antibacterial agents (benzalkonium chloride, bronopol, chlorhexidine and triclosan) to gain material with active antibacterial properties. Surface characteristics were evaluated by static contact angle measurement with surface energy evaluation ATR-FTIR, X-ray Photoelectron Spectroscopy (XPS) and SEM analysis. Inhibition

František Bílek; Tá?a K?ížová; Marián Lehocký

2011-01-01

308

Injectable bioadhesive hydrogels with innate antibacterial properties.  

PubMed

Surgical site infections cause significant postoperative morbidity and increased healthcare costs. Bioadhesives used to fill surgical voids and support wound healing are typically devoid of antibacterial activity. Here we report novel syringe-injectable bioadhesive hydrogels with inherent antibacterial properties prepared from mixing polydextran aldehyde and branched polyethylenimine. These adhesives kill both Gram-negative and Gram-positive bacteria, while sparing human erythrocytes. An optimal composition of 2.5?wt% oxidized dextran and 6.9?wt% polyethylenimine sets within seconds forming a mechanically rigid (~1,700?Pa) gel offering a maximum adhesive stress of ~2.8?kPa. A murine infection model showed that the adhesive is capable of killing Streptococcus pyogenes introduced subcutaneously at the bioadhesive's surface, with minimal inflammatory response. The adhesive was also effective in a cecal ligation and puncture model, preventing sepsis and significantly improving survival. These bioadhesives represent novel, inherently antibacterial materials for wound-filling applications. PMID:24958189

Giano, Michael C; Ibrahim, Zuhaib; Medina, Scott H; Sarhane, Karim A; Christensen, Joani M; Yamada, Yuji; Brandacher, Gerald; Schneider, Joel P

2014-01-01

309

The antibacterial activity and stability of acetic acid.  

PubMed

Acetic acid has been shown to have good antibacterial activity against micro-organisms such as Pseudomonas aeruginosa. This study examined the activity against a range of bacterial pathogens and also assessed any reduction in antibacterial activity due to evaporation or inactivation by organic material in dressings. Acetic acid was active at dilutions as low as 0.166% and the activity was not reduced by evaporation nor by inactivation by cotton swabs. Burn injuries are a major problem in countries with limited resources. Acetic acid is an ideal candidate for use in patients who are treated in those parts of the world. PMID:23747099

Fraise, A P; Wilkinson, M A C; Bradley, C R; Oppenheim, B; Moiemen, N

2013-08-01

310

Emergence of resistance to fluoroquinolones among gram positive and gram negative clinical isolates.  

PubMed

Fluoroquinolones are broad-spectrum antibiotics that are considered as first line drugs to treat infectious diseases. In order to find out useful fluoroquinolones, the antibiotic resistance of fluoroquinolones, namely, ofloxacin (OFL), ciprofloxacin (CIP), norfloxacin (NRF), enoxacin (ENX), pefloxacin (PFL) and levofloxacin (LVF) was investigated against ninety five clinical isolates that includes Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae and Proteus mirabilis. In vitro activity of these isolates was carried out by agar dilution method. All Staphylococcus aureus were sensitive to OFL at 2 ?g/ml. About 6% isolates of Klebsiella pneumoniae were found to be resistance to LVF and ENX, 6% to CIP, OFL and PFL and none of the isolates were resistant to LVF and ENX. Percentage resistance of P. aeruginosa was found to be 4.35% to CIP, 7% to OFL and 2.2% to NRF, whereas 8.69% to ENX, 0% to PFL and 17.4% to LVF, respectively. The present study provides the data about the emergence of resistance to fluoroquinolones among gram positive and gram negative bacteria and strongly recommends the rational and appropriate use of these antibiotics. PMID:23010009

Nesar, Shagufta; Shoaib, Muhammad Harris; Rahim, Najia; Rehman, Rabia

2012-10-01

311

[Resistance to "last resort" antibiotics in Gram-positive cocci: The post-vancomycin era].  

PubMed

New therapeutic alternatives have been developed in the last years for the treatment of multidrug-resistant Gram-positive infections. Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are considered a therapeutic challenge due to failures and lack of reliable antimicrobial options. Despite concerns related to the use of vancomycin in the treatment of severe MRSA infections in specific clinical scenarios, there is a paucity of solid clinical evidence that support the use of alternative agents (when compared to vancomycin). Linezolid, daptomycin and tigecycline are antibiotics approved in the last decade and newer cephalosporins (such as ceftaroline and ceftobiprole) and novel glycopeptides (dalvavancin, telavancin and oritavancin) have reached clinical approval or are in the late stages of clinical development. This review focuses on discussing these newer antibiotics used in the "post-vancomycin" era with emphasis on relevant chemical characteristics, spectrum of antimicrobial activity, mechanisms of action and resistance, as well as their clinical utility. PMID:24968051

Rincón, Sandra; Panesso, Diana; Díaz, Lorena; Carvajal, Lina P; Reyes, Jinnethe; Munita, José M; Arias, César A

2014-04-01

312

Cytotoxic, antioxidant and antibacterial activities of Varthemia iphionoides Boiss. extracts  

Microsoft Academic Search

The hexane, ethyl acetate, chloroform, ethanol and water extracts of aerial parts of Varthemia, Varthemia iphionoides, were investigated for cytotoxic activity against human myelocytic leukemia (HL-60) cells; DPPH radical-scavenging activity; antioxidative activity in the linoleic acid system; reducing power; antibacterial activity; the contents of phenolic compounds. A pronounced cytotoxic effect on human leukemia (HL-60) cells was shown in the hexane,

Maher M. Al-Dabbas; Toshihiko Suganuma; Kanefumi Kitahara; De-Xing Hou; Makoto Fujii

2006-01-01

313

Antibacterial and Antioxidant Activity of Essential Oil Terpenes against Pathogenic and Spoilage-Forming Bacteria and Cell Structure-Activity Relationships Evaluated by SEM Microscopy.  

PubMed

The antibacterial activity and antioxidant effect of the compounds ?-terpineol, linalool, eucalyptol and ?-pinene obtained from essential oils (EOs), against pathogenic and spoilage forming bacteria were determined. The antibacterial activities of these compounds were observed in vitro on four Gram-negative and three Gram-positive strains. S. putrefaciens was the most resistant bacteria to all tested components, with MIC values of 2% or higher, whereas E. coli O157:H7 was the most sensitive strain among the tested bacteria. Eucalyptol extended the lag phase of S. Typhimurium, E. coli O157:H7 and S. aureus at the concentrations of 0.7%, 0.6% and 1%, respectively. In vitro cell growth experiments showed the tested compounds had toxic effects on all bacterial species with different level of potency. Synergistic and additive effects were observed at least one dose pair of combination against S. Typhimurium, E. coli O157:H7 and S. aureus, however antagonistic effects were not found in these combinations. The results of this first study are encouraging for further investigations on mechanisms of antimicrobial activity of these EO components. PMID:25372394

Zengin, Hatice; Baysal, Ayse H

2014-01-01

314

Studies on the antibacterial activity of dodecylglycerol  

SciTech Connect

The antimicrobial activity of lipids has been known for many years, with dodecanoylglycerol (dodecanoic acid esterified to glycerol) being one of the most potential. However, the antibacterial potency of dodecylglycerol (DDG), the corresponding 1-O-alkyl glycerol ether, is considerably greater. The superior efficacy of DDG can be attributed, at least in part, to the greater chemical and metabolic stability of the ether bond as compared to esters. In an attempt towards elucidating the mode of action of DDG, the effect of DDG on bacterial lipid metabolism was examined using Streptococcus mutans BHT, a tolerant bacterium. The metabolic fate of the ether was also determined with the use of three radioactive tracers, /sup 14/C-glycerol, /sup 32/Pi, and /sup 14/C-DDG. Treatment of exponentially growing cultures of S. mutans BHI with growth inhibitory concentrations of DDG (10 and 20 ..mu..g/ml) inhibited the incorporation of /sup 14/C-glycerol into lipid. In vivo studies using /sup 14/C-DDG showed that the /sup 14/C-ether was readily incorporated almost exclusively into phosphatidic (PA) and lysophosphatidic (LPA) acids. When cells prelabelled with either /sup 14/C-glycerol or /sup 32/Pi were exposed to 10 and 20 /sup +/g/ml DDG for 2 h, the accumulation of PA and diphosphatidylglycerol (diPG) was greatly stimulated. However, diPG accumulated at the expense of its precursor, glycerol, which greatly decreased. These data suggest that the ether-containing PA inhibits the synthesis of CDP-diglyceride. Moreover, these results clearly demonstrate that DDG functions as a metabolic rather than physical effector, disputing the conventional notion that bactericidal lipids act as detergents, physically dissolving the cellular envelope.

Brissette, J.L.

1985-01-01

315

Turicibacter sanguinis gen. nov., sp. nov., a novel anaerobic, Gram-positive bacterium.  

PubMed

An unknown, strictly anaerobic, Gram-positive, rod-shaped bacterium (strain MOL361T) was isolated from a blood culture of a febrile patient with acute appendicitis and characterized using phenotypic and molecular methods. Fatty acid analysis and biochemical examination indicated that the isolate most closely resembles members of the Gram-positive bacteria with low DNA G+C content. 16S rDNA sequencing revealed a relatively high overall similarity (97%) to an uncultured bacterium, but these two strains both exhibit low (<87%) 16S rDNA similarity to other bacteria. Phylogenetic analysis with different treeing methods showed that this strain forms a novel line of descent within the Gram-positive bacteria with low G+C content. Strain MOL361T is described as the type strain of a novel species within a new genus, Turicibacter sanguinis gen. nov., sp. nov. PMID:12148638

Bosshard, Philipp P; Zbinden, Reinhard; Altwegg, Martin

2002-07-01

316

An examination of the medicinal potential of Scaevola spinescens: Toxicity, antibacterial, and antiviral activities  

PubMed Central

Background: Scaevola spinescens is an endemic Australian native plant with a history of use as a medicinal agent by indigenous Australians. Yet the medicinal bioactivities of this plant are poorly studied. Materials and Methods: S. spinescens solvent extracts were tested for antimicrobial activity, antiviral activity and toxicity in vitro. Results: All extracts displayed antibacterial activity in the disc diffusion assay. The methanol extract proved to have the broadest specificity, inhibiting the growth of 7 of the 14 bacteria tested (50%). The water, ethyl acetate, chloroform, and hexane extracts inhibited the growth of 6 (42.9%), 5 (35.7%), 5 (35.7%), and 4 (28.6%) of the 14 bacteria tested, respectively. S. spinescens methanolic extracts were equally effective against Gram-positive (50%) and Gram-negative bacteria (50%). All other extracts were more effective at inhibiting the growth of Gram-negative bacteria. All extracts also displayed antiviral activity in the MS2 plaque reduction assay with the methanol, water, ethyl acetate, chloroform, and hexane extracts inhibiting 95.2 ± 1.8%, 72.3 ± 6.3%, 82.6 ± 4.5%, 100 ± 0% and 47.7 ± 12.9% of plaque formation, respectively. All S. spinescens extracts were nontoxic in the Artemia fransiscana bioassay with no significant increase in mortality induced by any extract at 24 and 48 h. The only increase in mortality was seen for the water extract at 72 h, although even this extract displayed low toxicity, inducing only 41.7 ± 23.3% mortality. Conclusions: The lack of toxicity of the S. spinescens extracts and their inhibitory bioactivity against bacteria and viruses validate the Australian Aboriginal usage of S. spinescens and indicates its medicinal potential. PMID:21772751

Cock, Ian E.; Kukkonen, Liisa

2011-01-01

317

Antibacterial and catalytic activities of green synthesized silver nanoparticles.  

PubMed

The aqueous beetroot extract was used as reducing agent for silver nanoparticles synthesis. The synthesized nanoparticles were characterized using UV-visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The surface plasmon resonance peak of synthesized nanoparticles was observed at 438nm. As the concentration of beetroot extract increases, absorption spectra shows blue shift with decreasing particle size. The prepared silver nanoparticles were well dispersed, spherical in shape with the average particle size of 15nm. The prepared silver nanoparticles are effective in inhibiting the growth of both gram positive and gram negative bacteria. The prepared silver nanoparticles reveal faster catalytic activity. This natural method for synthesis of silver nanoparticles offers a valuable contribution in the area of green synthesis and nanotechnology avoiding the presence of hazardous and toxic solvents and waste. PMID:25093965

Bindhu, M R; Umadevi, M

2015-01-25

318

Investigation of antibacterial activity of cotton fabric incorporating nano silver colloid  

Microsoft Academic Search

In this work, silver nanoparticles were prepared by polyol process with microwave heating and incorporated on cotton fabric surfaces. The antibacterial performance of the antibacterial cotton fabric was tested for different concentration of nano-sized silver colloid, contact time germs, and washing times. It was found that antibacterial activity increased with the increasing concentration of nano-sized silver colloid. The antibacterial fabric

Ngo Vo Ke Thanh; Nguyen Thi Phuong Phong

2009-01-01

319

Quorum sensing in gram-positive bacteria: assay protocols for staphylococcal agr and enterococcal fsr systems.  

PubMed

A thiolactone/lactone peptide-mediated quorum sensing (QS) system is commonly employed in gram-positive bacteria to control the expression of a variety of phenotypes, including the production of virulence factors and biofilm formation. Here, we describe assay protocols for the well-studied QS systems (agr and fsr) of two representative gram-positive pathogens, Staphylococcus aureus and Enterococcus faecalis. These convenient assay systems are useful for the screening of QS inhibitors as well as for basic research to address the mechanism of these QS systems. PMID:24664824

Shojima, Akane; Nakayama, Jiro

2014-01-01

320

Screening seeds of Scottish plants for antibacterial activity.  

PubMed

Based on ethnopharmacological and taxonomic information, seeds of 21 Scottish plant species from 14 different families were obtained from authentic seed suppliers. Their n-hexane, dichloromethane and methanol extracts were assessed for antibacterial activity against 11 pathogenic bacterial species. Methanol extracts of 11 plant species showed significant antibacterial activity. Malva moschata and Prunus padus were active against five bacterial species, Reseda lutea against four, Centaurium erythraea and Crithmum maritimum against three, Calluna vulgaris against two, and Armeria maritima, Centaurea scabiosa, Daucus carota, Rosa canina and Stellaria holostea against one bacterial species. C. erythraea and P. padus were also active against methicillin resistant Staphylococcus aureus. PMID:12413709

Kumarasamy, Yashodharan; Cox, Philip John; Jaspars, Marcel; Nahar, Lutfun; Sarker, Satyajit Dey

2002-11-01

321

Synthesis and Antibacterial Activities of Antibacterial Peptides with a Spiropyran Fluorescence Probe  

PubMed Central

In this report, antibacterial peptides1-3 were prepared with a spiropyran fluorescence probe. The probe exhibits a change in fluorescence when isomerized from a colorless spiro-form (spiropyran, Sp) to a colored open-form (merocyanine, Mc) under different chemical environments, which can be used to study the mechanism of antimicrobial activity. Peptides 1-3 exhibit a marked decrease in antimicrobial activity with increasing alkyl chain length. This is likely due to the Sp-Mc isomers in different polar environments forming different aggregate sizes in TBS, as demonstrated by time-dependent dynamic light scattering (DLS). Moreover, peptides 1-3 exhibited low cytotoxicity and hemolytic activity. These probe-modified peptides may provide a novel approach to study the effect of structural changes on antibacterial activity, thus facilitating the design of new antimicrobial agents to combat bacterial infection. PMID:25358905

Chen, Lei; Zhu, Yu; Yang, Danling; Zou, Rongfeng; Wu, Junchen; Tian, He

2014-01-01

322

8-Azatetracyclines: Synthesis and Evaluation of a Novel Class of Tetracycline Antibacterial Agents  

PubMed Central

A novel series of fully synthetic 8-azatetracyclines was prepared and evaluated for antibacterial activity. Compounds were identified that overcome both efflux (tet(K)) and ribosomal protection (tet(M)) tetracycline resistance mechanisms and are active against Gram-positive and Gram-negative organisms. Two compounds were identified that exhibit comparable efficacy to marketed tetracyclines in in vivo models of bacterial infection. PMID:21302930

2011-01-01

323

Nanosilver on nanostructured silica: Antibacterial activity and Ag surface area  

PubMed Central

Nanosilver is one of the first nanomaterials to be closely monitored by regulatory agencies worldwide motivating research to better understand the relationship between Ag characteristics and antibacterial activity. Nanosilver immobilized on nanostructured silica facilitates such investigations as the SiO2 support hinders the growth of nanosilver during its synthesis and, most importantly, its flocculation in bacterial suspensions. Here, such composite Ag/silica nanoparticles were made by flame spray pyrolysis of appropriate solutions of Ag-acetate or Ag-nitrate and hexamethyldisiloxane or tetraethylorthosilicate in ethanol, propanol, diethylene glucolmonobutyl ether, acetonitrile or ethylhexanoic acid. The effect of solution composition on nanosilver characteristics and antibacterial activity against the Gram negative Escherichia coli was investigated by monitoring their recombinantly synthesized green fluorescent protein. Suspensions with identical Ag mass concentration exhibited drastically different antibacterial activity pointing out that the nanosilver surface area concentration rather than its mass or molar or number concentration determine best its antibacterial activity. Nanosilver made from Ag-acetate showed a unimodal size distribution, while that made from inexpensive Ag-nitrate exhibited a bimodal one. Regardless of precursor composition or nanosilver size distribution, the antibacterial activity of nanosilver was correlated best with its surface area concentration in solution. PMID:23730198

Sotiriou, Georgios A.; Teleki, Alexandra; Camenzind, Adrian; Krumeich, Frank; Meyer, Andreas; Panke, Sven; Pratsinis, Sotiris E.

2013-01-01

324

Extraction of Essential Oil from Nigella sativa Using Supercritical Carbon Dioxide: Study of Antibacterial Activity  

Microsoft Academic Search

The antimicrobial activity of N. sativa essential oil obtained by supercritical fluid extraction by carbon dioxide was investigated against Gram Positive and Gram negative strains, isolated from clinical specimens. Best conditions for Black cumin oil extraction are obtained at 400 bar, 40°C and a solvent flow rate of 25 g min -1 . The seed extracts were prepared by supercritical

Nagi A. Alhaj; Mariana N. Shamsudin; Hana F. Zamri; Rasedee Abdullah

2008-01-01

325

Protamine-induced permeabilization of cell envelopes of gram-positive and gram-negative bacteria  

Microsoft Academic Search

The inhibitory effect of the cationic peptide protamine on Listeria monocytogenes, Escherichia coli, and Shewanella putrefacienshas been studied in detail. The addition of protamine (10 to 1,000 mg\\/ml) resulted in inhibition of oxygen consumption after less than 1 min and loss of intracellular carboxyfluorescein and ATP after 2 to 5 min. Maximum antibacterial activity was reached at alkaline pH and

CHARLOTTE JOHANSEN; ANNETTE VERHEUL; LONE GRAM; TOM GILL; T. Abee

1997-01-01

326

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

PubMed Central

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

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

2013-01-01

327

Anti-tyrosinase, antioxidant, and antibacterial activities of novel 5-hydroxy-4-acetyl-2,3-dihydronaphtho[1,2-b]furans.  

PubMed

Novel 5-hydroxy-4-acetyl-2,3-dihydronaphtho[1,2-b]furans (7a-k) were synthesized using ceric ammonium nitrate (CAN)-catalyzed formal [3 + 2] cycloaddition. Synthesized compounds were evaluated for their tyrosinase inhibitory, antioxidant, and antibacterial activities. A modified spectrophotometric method using l-DOPA as substrate was used to determine tyrosinase inhibitory activities, and a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay was used to evaluate antioxidant properties. Antibacterial activities against gram-negative Escherichia coli (KCTC-1924) and gram-positive Staphylococcus aureus (KCTC-1916) were evaluated using the disc diffusion technique. Of the synthesized compounds, 7b with a 4-acetyl and an electron-enriched dihydronaphthofuran ring showed the highest tyrosinase-inhibition activity (IC50 = 8.91 ?g/mL), which was comparable with that of standard kojic acid (IC50 = 10.16 ?g/mL), potent antioxidant activity (IC50 = 3.33 ?g/mL), which was comparable with that of BHT (IC50 = 34.67 ?g/mL), and excellent antibacterial activities (MICs: 0.50 ?g/mL against E. coli and S. aureus strains). A mechanistic analysis of 7b demonstrated that its tyrosinase inhibitory activity was reversible and competitive. Compounds 7c and 7d showed potent antioxidant activities (IC50: 6.30 and 5.01 ?g/mL), and compound 7d also exhibited potent inhibitory activity against E. coli with a MIC of 0.5 ?g/mL. Furthermore, compounds 7a, 7e, 7f, and 7i showed potent antibacterial activities against S. aureus with MICs of 0.5 ?g/mL, which was comparable to that of ampicillin (MIC = 0.5 ?g/mL). PMID:25218909

Xia, Likai; Idhayadhulla, Akber; Lee, Yong Rok; Wee, Young-Jung; Kim, Sung Hong

2014-10-30

328

Ligational behavior of Schiff bases towards transition metal ion and metalation effect on their antibacterial activity.  

PubMed

New Schiff bases pyrazine-2-carboxylicacid (phenyl-pyridin-2-yl-methylene)-hydrazide (Hpch-bp) HL(1) and pyrazine-2-carboxylicacid (pyridin-2-ylmethylene)-hydrazide (Hpch-pc) HL(2) derived from condensation of pyrazine carboxylic hydrazide (Hpch) with 2-benzoyl pyridine (bp) or pyridine 2-carbaldehyde (pc) and their transition metal complexes of type ML((1-2)2) have been synthesized, where M=Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). Characterization of ligands and their metal complexes was carried out by elemental analysis, conductimetric studies, magnetic susceptibility, spectroscopic techniques (IR, UV-VIS, NMR, ESR, Mass) and thermogravimetric analysis. The physico-chemical studies revealed octahedral geometry or distorted octahedral geometry around metal ion. These azomethine Schiff base ligands acted as tridentate coordinating through carbonyl, azomethine and pyridine nitrogen present in the ligand. The thermodynamic and thermal properties of the complexes have been investigated and it was observed on the basis of these studies that thermal stability of complexes follows the order Mnantibacterial activity at different concentrations against bacteria viz. Gram positive Bacillus subtilis, Micrococcus luteus and Gram negative Pseudomonas aeruginosa, Pseudomonas mendocina. A marked enhancement in biocidal activity of the ligands under similar experimental conditions was observed as a consequence of coordination with metal ions. The trend of growth inhibition in the complexes was found to be in the order: Cu>Mn>Ni>Co>Zn. PMID:22813991

Devi, Jai; Batra, Nisha; Malhotra, Rajesh

2012-11-01

329

A Technology for Developing Synbodies with Antibacterial Activity  

PubMed Central

The rise in antibiotic resistance has led to an increased research focus on discovery of new antibacterial candidates. While broad-spectrum antibiotics are widely pursued, there is evidence that resistance arises in part from the wide spread use of these antibiotics. Our group has developed a system to produce protein affinity agents, called synbodies, which have high affinity and specificity for their target. In this report, we describe the adaptation of this system to produce new antibacterial candidates towards a target bacterium. The system functions by screening target bacteria against an array of 10,000 random sequence peptides and, using a combination of membrane labeling and intracellular dyes, we identified peptides with target specific binding or killing functions. Binding and lytic peptides were identified in this manner and in vitro tests confirmed the activity of the lead peptides. A peptide with antibacterial activity was linked to a peptide specifically binding Staphylococcus aureus to create a synbody with increased antibacterial activity. Subsequent tests showed that this peptide could block S. aureus induced killing of HEK293 cells in a co-culture experiment. These results demonstrate the feasibility of using the synbody system to discover new antibacterial candidate agents. PMID:23372679

Domenyuk, Valeriy; Loskutov, Andrey; Johnston, Stephen Albert; Diehnelt, Chris W.

2013-01-01

330

Small molecule inhibitor of lipoteichoic acid synthesis is an antibiotic for Gram-positive bacteria  

PubMed Central

The current epidemic of infections caused by antibiotic-resistant Gram-positive bacteria requires the discovery of new drug targets and the development of new therapeutics. Lipoteichoic acid (LTA), a cell wall polymer of Gram-positive bacteria, consists of 1,3-polyglycerol-phosphate linked to glycolipid. LTA synthase (LtaS) polymerizes polyglycerol-phosphate from phosphatidylglycerol, a reaction that is essential for the growth of Gram-positive bacteria. We screened small molecule libraries for compounds inhibiting growth of Staphylococcus aureus but not of Gram-negative bacteria. Compound 1771 [2-oxo-2-(5-phenyl-1,3,4-oxadiazol-2-ylamino)ethyl 2-naphtho[2,1-b]furan-1-ylacetate] blocked phosphatidylglycerol binding to LtaS and inhibited LTA synthesis in S. aureus and in Escherichia coli expressing ltaS. Compound 1771 inhibited the growth of antibiotic-resistant Gram-positive bacteria and prolonged the survival of mice with lethal S. aureus challenge, validating LtaS as a target for the development of antibiotics. PMID:23401520

Richter, Stefan G.; Elli, Derek; Kim, Hwan Keun; Hendrickx, Antoni P. A.; Sorg, Joseph A.; Schneewind, Olaf; Missiakas, Dominique

2013-01-01

331

Postantibiotic Leukocyte Enhancement of Meropenem against Gram-Positive and Gram-Negative Strains  

Microsoft Academic Search

The pharmacodynamic aspects of antimicrobial drugs, such as the postantibiotic effect (PAE), have been extensively stud- ied in the last 15 years with gram-positive and gram-negative bacteria in order to analyze their possible influence on antibi- otic dosage regimens (3). Bacterial susceptibility to leukocyte phagocytosis and killing is usually enhanced when organisms are in the PAE phase (11, 12, 19,

ANDREA NOVELLI; STEFANIA FALLANI; MARIA IRIS CASSETTA; SILVIA CONTI; TERESITA MAZZEI

2000-01-01

332

Microarray-Based Detection of 90 Antibiotic Resistance Genes of Gram-Positive Bacteria  

Microsoft Academic Search

A disposable microarray was developed for detection of up to 90 antibiotic resistance genes in gram-positive bacteria by hybridization. Each antibiotic resistance gene is represented by two specific oligonucleotides chosen from consensus sequences of gene families, except for nine genes for which only one specific oligonucleotide could be developed. A total of 137 oligonucleotides (26 to 33 nucleotides in length

Vincent Perreten; Lorianne Vorlet-Fawer; Peter Slickers; Ralf Ehricht; Peter Kuhnert; Joachim Frey

2005-01-01

333

STUDIES ON RIFAMYCIN SV : IN VITRO SUSCEPTIBILITY OF GRAM-POSITIVE PATHOGENS  

E-print Network

characteristics on agar containing4p. 100 sheep red blood cells, by their CAMP reaction and by their inabilitySTUDIES ON RIFAMYCIN SV : IN VITRO SUSCEPTIBILITY OF GRAM-POSITIVE PATHOGENS OF BOVINE UDDER ORIGIN ; TIMBAI&dquo; PAI,I,ANZA and CARNITI, I96I). Studies using this anti- biotic in the treatment of bovine

Paris-Sud XI, Université de

334

Antibacterial anthranilic acid derivatives from Geijera parviflora.  

PubMed

Five anthranilic acid derivatives, a mixture I of three new compounds 11'-hexadecenoylanthranilic acid (1), 9'-hexadecenoylanthranilic acid (2), and 7'-hexadecenoylanthranilic acid (3), as well as a new compound 9,12,15-octadecatrienoylanthranilic acid (4) together with a new natural product, hexadecanoylanthranilic acid (5), were isolated from Geijera parviflora Lindl. (Rutaceae). Their structures were elucidated by extensive spectroscopic measurements, and the positions of the double bonds in compounds 1-3 of the mixture I were determined by tandem mass spectrometry employing ozone-induced dissociation. The mixture I and compound 5 showed good antibacterial activity against several Gram-positive strains. PMID:24370663

Shou, Qingyao; Banbury, Linda K; Maccarone, Alan T; Renshaw, Dane E; Mon, Htwe; Griesser, Stefani; Griesser, Hans J; Blanksby, Stephen J; Smith, Joshua E; Wohlmuth, Hans

2014-03-01

335

Identification of Surprisingly Diverse Type IV Pili, across a Broad Range of Gram-Positive Bacteria  

PubMed Central

Background In Gram-negative bacteria, type IV pili (TFP) have long been known to play important roles in such diverse biological phenomena as surface adhesion, motility, and DNA transfer, with significant consequences for pathogenicity. More recently it became apparent that Gram-positive bacteria also express type IV pili; however, little is known about the diversity and abundance of these structures in Gram-positives. Computational tools for automated identification of type IV pilins are not currently available. Results To assess TFP diversity in Gram-positive bacteria and facilitate pilin identification, we compiled a comprehensive list of putative Gram-positive pilins encoded by operons containing highly conserved pilus biosynthetic genes (pilB, pilC). A surprisingly large number of species were found to contain multiple TFP operons (pil, com and/or tad). The N-terminal sequences of predicted pilins were exploited to develop PilFind, a rule-based algorithm for genome-wide identification of otherwise poorly conserved type IV pilins in any species, regardless of their association with TFP biosynthetic operons (http://signalfind.org). Using PilFind to scan 53 Gram-positive genomes (encoding >187,000 proteins), we identified 286 candidate pilins, including 214 in operons containing TFP biosynthetic genes (TBG+ operons). Although trained on Gram-positive pilins, PilFind identified 55 of 58 manually curated Gram-negative pilins in TBG+ operons, as well as 53 additional pilin candidates in operons lacking biosynthetic genes in ten species (>38,000 proteins), including 27 of 29 experimentally verified pilins. False positive rates appear to be low, as PilFind predicted only four pilin candidates in eleven bacterial species (>13,000 proteins) lacking TFP biosynthetic genes. Conclusions We have shown that Gram-positive bacteria contain a highly diverse set of type IV pili. PilFind can be an invaluable tool to study bacterial cellular processes known to involve type IV pilus-like structures. Its use in combination with other currently available computational tools should improve the accuracy of predicting the subcellular localization of bacterial proteins. PMID:22216142

Roos, David S.; Pohlschroder, Mechthild

2011-01-01

336

Multistep Resistance Development Studies of Ceftaroline in Gram-Positive and -Negative Bacteria?  

PubMed Central

Ceftaroline, the active component of the prodrug ceftaroline fosamil, is a novel broad-spectrum cephalosporin with bactericidal activity against Gram-positive and -negative isolates. This study evaluated the potential for ceftaroline and comparator antibiotics to select for clones of Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, Moraxella catarrhalis, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecalis with elevated MICs. S. pneumoniae and S. pyogenes isolates in the present study were highly susceptible to ceftaroline (MIC range, 0.004 to 0.25 ?g/ml). No streptococcal strains yielded ceftaroline clones with increased MICs (defined as an increase in MIC of >4-fold) after 50 daily passages. Ceftaroline MICs for H. influenzae and M. catarrhalis were 0.06 to 2 ?g/ml for four strains and 8 ?g/ml for a ?-lactamase-positive, efflux-positive H. influenzae with a mutation in L22. One H. influenzae clone with an increased ceftaroline MIC (quinolone-resistant, ?-lactamase-positive) was recovered after 20 days. The ceftaroline MIC for this isolate increased 16-fold, from 0.06 to 1 ?g/ml. MICs for S. aureus ranged from 0.25 to 1 ?g/ml. No S. aureus isolates tested with ceftaroline had clones with increased MIC (>4-fold) after 50 passages. Two E. faecalis isolates tested had ceftaroline MICs increased from 1 to 8 ?g/ml after 38 days and from 4 to 32 ?g/ml after 41 days, respectively. The parental ceftaroline MIC for the one K. pneumoniae extended-spectrum ?-lactamase-negative isolate tested was 0.5 ?g/ml and did not change after 50 daily passages. PMID:21343467

Clark, Catherine; McGhee, Pamela; Appelbaum, Peter C.; Kosowska-Shick, Klaudia

2011-01-01

337

One of Two Human Lactoferrin Variants Exhibits Increased Antibacterial and Transcriptional Activation Activities and Is Associated with Localized Juvenile Periodontitis  

PubMed Central

The iron-binding protein lactoferrin is a ubiquitous and abundant constituent of human exocrine secretions. Lactoferrin inhibits bacterial growth by sequestering essential iron and also exhibits non-iron-dependent antibacterial, antifungal, antiviral, antitumor, anti-inflammatory, and immunoregulatory activities. All of these non-iron-dependent activities are mediated by the highly charged N terminus of lactoferrin. In this study we characterized a Lys/Arg polymorphism at position 29 in the N-terminal region of human lactoferrin that results from a single nucleotide polymorphism in exon 1 of the human lactoferrin gene. We expressed cDNAs encoding both lactoferrin variants in insect cells and purified the two proteins by ion exchange chromatography. The two lactoferrin variants exhibited nearly identical iron-binding and iron-releasing activities and equivalent bactericidal activities against a strain of the gram-negative bacterium Actinobacillus actinomycetemcomitans. When tested against the gram-positive species Streptococcus mutans and Streptococcus mitis, however, lactoferrin containing Lys at position 29 exhibited significantly greater bactericidal activity than did lactoferrin containing Arg. In addition, the Lys-containing lactoferrin stimulated bovine tracheal epithelial cells to synthesize much higher levels of tracheal antimicrobial peptide mRNA than did the Arg-containing variant. A genotyping assay that distinguished between the two alleles based on a polymorphic EarI restriction site showed that the Lys and Arg alleles had frequencies of 24% and 76%, respectively, among 17 healthy human subjects, and 72% and 28%, respectively, among nine patients with localized juvenile periodontitis. Our findings suggest that these two lactoferrin variants are functionally different and that these differences may contribute to the pathogenesis of localized juvenile periodontitis. PMID:14573629

Velliyagounder, Kabilan; Kaplan, Jeffrey B.; Furgang, David; Legarda, Diana; Diamond, Gill; Parkin, Ruth E.; Fine, Daniel H.

2003-01-01

338

One of two human lactoferrin variants exhibits increased antibacterial and transcriptional activation activities and is associated with localized juvenile periodontitis.  

PubMed

The iron-binding protein lactoferrin is a ubiquitous and abundant constituent of human exocrine secretions. Lactoferrin inhibits bacterial growth by sequestering essential iron and also exhibits non-iron-dependent antibacterial, antifungal, antiviral, antitumor, anti-inflammatory, and immunoregulatory activities. All of these non-iron-dependent activities are mediated by the highly charged N terminus of lactoferrin. In this study we characterized a Lys/Arg polymorphism at position 29 in the N-terminal region of human lactoferrin that results from a single nucleotide polymorphism in exon 1 of the human lactoferrin gene. We expressed cDNAs encoding both lactoferrin variants in insect cells and purified the two proteins by ion exchange chromatography. The two lactoferrin variants exhibited nearly identical iron-binding and iron-releasing activities and equivalent bactericidal activities against a strain of the gram-negative bacterium Actinobacillus actinomycetemcomitans. When tested against the gram-positive species Streptococcus mutans and Streptococcus mitis, however, lactoferrin containing Lys at position 29 exhibited significantly greater bactericidal activity than did lactoferrin containing Arg. In addition, the Lys-containing lactoferrin stimulated bovine tracheal epithelial cells to synthesize much higher levels of tracheal antimicrobial peptide mRNA than did the Arg-containing variant. A genotyping assay that distinguished between the two alleles based on a polymorphic EarI restriction site showed that the Lys and Arg alleles had frequencies of 24% and 76%, respectively, among 17 healthy human subjects, and 72% and 28%, respectively, among nine patients with localized juvenile periodontitis. Our findings suggest that these two lactoferrin variants are functionally different and that these differences may contribute to the pathogenesis of localized juvenile periodontitis. PMID:14573629

Velliyagounder, Kabilan; Kaplan, Jeffrey B; Furgang, David; Legarda, Diana; Diamond, Gill; Parkin, Ruth E; Fine, Daniel H

2003-11-01

339

On the antibacterial activity of roots of Capparis spinosa L.  

PubMed

A decoction of Capparis spinosa L. roots, widely used in the traditional folk medicine of southern Italy, was prepared and submitted to antibacterial activity tests, which showed an interesting bacteriostatic activity on the growth of Deinococcus radiophilus. Heterocyclic compounds were also recovered from the chloroformic extract of the roots. PMID:21328135

Boga, Carla; Forlani, Luciano; Calienni, Rocco; Hindley, Teresa; Hochkoeppler, Alejandro; Tozzi, Silvia; Zanna, Nicola

2011-02-01

340

On the antibacterial activity of roots of Capparis spinosa L  

Microsoft Academic Search

A decoction of Capparis spinosa L. roots, widely used in the traditional folk medicine of southern Italy, was prepared and submitted to antibacterial activity tests, which showed an interesting bacteriostatic activity on the growth of Deinococcus radiophilus. Heterocyclic compounds were also recovered from the chloroformic extract of the roots.

Carla Boga; Luciano Forlani; Rocco Calienni; Teresa Hindley; Alejandro Hochkoeppler; Silvia Tozzi; Nicola Zanna

2011-01-01

341

Antibacterial activities of some mosses including Hylocomium splendens from South Western British Columbia  

Microsoft Academic Search

The antibacterial activity of methanol extracts of ten moss species and fractions prepared from 80% methanol extract of Hylocomium splendens were evaluated by disk diffusion method. Nine moss species showed antibacterial activity against Gram (+) bacteria, in particular H. splendens and its ethyl acetate fractions showed stronger activity. Enhancement of antibacterial activity against Staphylococci by UV-A light irradiation was demonstrated

S. J. Kang; S. H. Kim; P. Liu; E. Jovel; G. H. N. Towers

2007-01-01

342

[Bioessay with brine Artemia to predict antibacterial and pharmacologic activity].  

PubMed

The Brine Shrimp Test (BST) is a simple and inexpensive method to test cytotoxity, to biodirect phytochemical fractionation of natural products and as a predictor for antitumor and pesticidal activity. In this work, the BST test, an antibacterial test and the rat hippocratic screening test were used on 25 plant extracts and fractions, to evaluate the correlation, if any, between the BST and the others. Preliminary results show that the BST is not a predictor of antibacterial activity nor the hippocratic screening test. PMID:8475339

Sánchez, C; Gupta, M; Vásquez, M; de Noriega, Y M; Montenegro, G

1993-01-01

343

Antibacterial activity of various leaf extracts of Merremia emarginata  

PubMed Central

Objective To investigate the antibacterial activity and phytochemical screening of the aqueous, methanol and petroleum ether leaf extracts of Merremia emarginata (M. emarginata). Methods The antibacterial activity of leaf extracts of M. emarginata were evaluated by agar well diffusion method against four selected bacterial species. Results The presence of tannins, flavonoids, amino acids, starch, glycosides and carbohydrates in the different leaf extracts was established. The methanol extract was more effective against Bacillus cereus and Escherichia coli, whereas aqueous extract was more effective against Staphylococcus aureus and Pseudomonas aeruginosa. Conclusions : The results in the present study suggest that M. emarginata leaf can be used in treating diseases caused by the tested organisms. PMID:23569802

Elumalai, EK; Ramachandran, M; Thirumalai, T; Vinothkumar, P

2011-01-01

344

Caenorhabditis elegans Immune Conditioning with the Probiotic Bacterium Lactobacillus acidophilus Strain NCFM Enhances Gram-Positive Immune Responses  

PubMed Central

Although the immune response of Caenorhabditis elegans to microbial infections is well established, very little is known about the effects of health-promoting probiotic bacteria on evolutionarily conserved C. elegans host responses. We found that the probiotic Gram-positive bacterium Lactobacillus acidophilus NCFM is not harmful to C. elegans and that L. acidophilus NCFM is unable to colonize the C. elegans intestine. Conditioning with L. acidophilus NCFM significantly decreased the burden of a subsequent Enterococcus faecalis infection in the nematode intestine and prolonged the survival of nematodes exposed to pathogenic strains of E. faecalis and Staphylococcus aureus, including multidrug-resistant (MDR) isolates. Preexposure of nematodes to Bacillus subtilis did not provide any beneficial effects. Importantly, L. acidophilus NCFM activates key immune signaling pathways involved in C. elegans defenses against Gram-positive bacteria, including the p38 mitogen-activated protein kinase pathway (via TIR-1 and PMK-1) and the ?-catenin signaling pathway (via BAR-1). Interestingly, conditioning with L. acidophilus NCFM had a minimal effect on Gram-negative infection with Pseudomonas aeruginosa or Salmonella enterica serovar Typhimurium and had no or a negative effect on defense genes associated with Gram-negative pathogens or general stress. In conclusion, we describe a new system for the study of probiotic immune agents and our findings demonstrate that probiotic conditioning with L. acidophilus NCFM modulates specific C. elegans immunity traits. PMID:22585961

2012-01-01

345

Antibacterial activity of long-chain polyunsaturated fatty acids against Propionibacterium acnes and Staphylococcus aureus.  

PubMed

New compounds are needed to treat acne and superficial infections caused by Propionibacterium acnes and Staphylococcus aureus due to the reduced effectiveness of agents used at present. Long-chain polyunsaturated fatty acids (LC-PUFAs) are attracting attention as potential new topical treatments for Gram-positive infections due to their antimicrobial potency and anti-inflammatory properties. This present study aimed to investigate the antimicrobial effects of six LC-PUFAs against P. acnes and S. aureus to evaluate their potential to treat infections caused by these pathogens. Minimum inhibitory concentrations were determined against P. acnes and S. aureus, and the LC-PUFAs were found to inhibit bacterial growth at 32-1024 mg/L. Generally, P. acnes was more susceptible to the growth inhibitory actions of LC-PUFAs, but these compounds were bactericidal only for S. aureus. This is the first report of antibacterial activity attributed to 15-hydroxyeicosapentaenoic acid (15-OHEPA) and 15-hydroxyeicosatrienoic acid (HETrE), while the anti-P. acnes effects of the six LC-PUFAs used herein are novel observations. During exposure to the LC-PUFAs, S. aureus cells were killed within 15-30 min. Checkerboard assays demonstrated that the LC-PUFAs did not antagonise the antimicrobial potency of clinical agents used presently against P. acnes and S. aureus. However, importantly, synergistic interactions against S. aureus were detected for combinations of benzoyl peroxide with 15-OHEPA, dihomo-?-linolenic acid (DGLA) and HETrE; and neomycin with 15-OHEPA, DGLA, eicosapentaenoic acid, ?-linolenic acid and HETrE. In conclusion, LC-PUFAs warrant further evaluation as possible new agents to treat skin infections caused by P. acnes and S. aureus, especially in synergistic combinations with antimicrobial agents already used clinically. PMID:24232668

Desbois, Andrew P; Lawlor, Keelan C

2013-01-01

346

Isolation and partial characterization of an antibacterial substance produced by Enterococcus faecium  

Microsoft Academic Search

A strain ofEnterococcus faecium isolated from Bulgarian yellow cheese “kashkaval” produced a bacteriocin-like substance named enterococcin A 2000. The antibacterial\\u000a substance had a low molar mass (<2 kDa), was relatively stable toward heat but was sensitive to selected proteolytic enzymes.\\u000a It was active against Gram-positive bacteria including enterococci, such asListeria, Bacillus andStreptococcus, and also against Gram-negativeE. coli. Production of enterococcin

A. Pantev; P. Kabadjova; M. Dalgalarrondo; T. Haertlé; I. Ivanova; X. Dousset; H. Prévost; J.-M. Chobert

2002-01-01

347

Assessment of antibacterial effects of flavonoids by estimation of generation times in liquid bacterial cultures  

Microsoft Academic Search

Antibacterial activities of various flavonoids, a group of natural plant substances, have been reported previously, however,\\u000a there are contradictory data, published by various authors, regarding sensitivity of particular bacterial species to these\\u000a compounds. These problems arose apparently because of using different methods by various researchers. Here we tested sensitivity\\u000a of several bacterial species (Gram-positive: Bacillus subtilis, Micrococcus luteus, Sarcina sp.

Katarzyna Ulanowska; Anna Majchrzyk; Marta Moskot; Joanna Jakóbkiewicz-Banecka; Grzegorz Wţegrzyn

2007-01-01

348

Antibacterial activity of some actinomycetes from Tamil Nadu, India  

PubMed Central

Objective To isolate novel actinomycetes and to evaluate their antibacterial activity. Methods Three soil samples were collected from Vengodu (village) in Kanchipuram district, Tamil Nadu, India. Actinomycetes were isolated using serial dilution and plating method on actinomycetes isolation agar. Results Totally 35 isolates were obtained on the basis of colony characteristics on actinomycetes isolation agar. All the isolates were screened for antibacterial activity by cross streak method. Medium and optimization of day were done for the potent strains using Nathan's agar well diffusion method. Isolation of bioactive compounds from significant active isolates was done by using different media. The most active isolate VAS 10 was identified as Actinobacterium Loyola PBT VAS 10 (accession No. JF501398) using 16s rRNA sequence method. The hexane, ethyl acetate, dichloromethane and butanol extracts of VAS 10 were tested against bacteria. The maximum antibacterial activity was observed in dichloromethane and ethyl acetate; maximum zones of inhibition were observed against Enterococcus durans. The rRNA secondary structure and the restriction sites of Actinobacterium Loyola VAS 10 were predicted using Genebee and NEBCutter online tools respectively. Conclusions The present study showed that among the isolated actinomycetes, Actinobacterium Loyola PBT VAS 10 (accession No. JF501398) showed good antibacterial activity against the tested bacteria. PMID:23593572

Kumar, Pachaiyappan Saravana; Raj, John Poonga Preetam; Duraipandiyan, Veeramuthu; Ignacimuthu, Savarimuthu

2012-01-01

349

Antibacterial, antifungal and antioxidant activities of the ethanol extract of the stem bark of Clausena heptaphylla  

PubMed Central

Background There is wide spread interest in drugs derived from plants as green medicine is believed to be safe and dependable, compared with costly synthetic drugs that have adverse effects. Methods We have attempted to evaluate the antioxidant, In vitro thrombolytic, antibacterial, antifungal and cytotoxic effects of Clausena heptaphylla (Rutaceae) stem bark extract ethanol extract. Results Ethanolic stem bark extract of Clausena heptaphylla (CHET) contains flavonoids, alkaloids, saponins and steroids but it lacks tannins, anthraquinones and resins. Phenol content of the extract was 13.42 mg/g and flavonoid content was 68.9 mg/g. CHET exhibited significant DPPH free radical scavenging activity with IC50 value of 3.11 ?g/ml. Reducing power of CHET was also moderately stronger. In the cytotoxicity assay, LC50 and Chi-square value of the ethanolic extract against brine shrimp nauplii were 144.1461 ?g/ml and 0.8533 demonstrating potent cytotoxic effect of the extract. In vitro thrombolytic activity of CHET is significant with 45.38% clot lysis capability compared to that of Streptokinase (65.78%). In antibacterial screening, moderate zone of inhibition (6.5-9.0 mm in diameter) was observed against gram-positive Bacillus subtilis ATCC 11774, Bacillus cereus ATCC 10876, Staphylococcus aureus ATCC 25923, Bacillus polymyxa ATCC 842 and Bacillus megaterium ATCC 13578 and less promising zone of inhibition (3.0-4.5 mm in diameter) against gram-negative Salmonella typhi ATCC 65154, Shigella flexneri ATCC 12022, Proteus vulgaris ATCC 13315 and Escherichia coli ATCC 25922. Shigella sonnei ATCC 8992 did not show any sensitivity. The MIC values against these bacteria were ranged from 2,000 to 3,500 ?g/ml. The extract showed significant zone of inhibition against Rhizopus oryzae DSM 2200, Aspergillus niger DSM 737 and Aspergillus ochraceus DSM 824 in antifungal assay. Conclusions Further advanced research is necessary to isolate and characterize the chemical components responsible for the therapeutic properties of the plant. PMID:23181593

2012-01-01

350

In vitro activities of U-100592 and U-100766, novel oxazolidinone antibacterial agents.  

PubMed

Oxazolidinones make up a relatively new class of antimicrobial agents which possess a unique mechanism of bacterial protein synthesis inhibition. U-100592 (S)-N-[[3-[3-fluoro-4-[4-(hydroxyacetyl)-1-piperazinyl]- phenyl]-2-oxo-5-oxazolidinyl]methyl]-acetamide and U-100766 (S)-N-[[3-[3-fluoro-4-(4-morpholinyl)phenyl]- 2-oxo-5-oxazolidinyl]methyl]-acetamide are novel oxazolidinone analogs from a directed chemical modification program. MICs were determined for a variety of bacterial clinical isolates; the respective MICs of U-100592 and U-100766 at which 90% of isolates are inhibited were as follows: methicillin-susceptible Staphylococcus aureus, 4 and 4 micrograms/ml; methicillin-resistant S. aureus, 4 and 4 micrograms/ml; methicillin-susceptible Staphylococcus epidermidis, 2 and 2 micrograms/ml; methicillin-resistant S. epidermidis, 1 and 2 micrograms/ml; Enterococcus faecalis, 2 and 4 micrograms/ml; Enterococcus faecium, 2 and 4 micrograms/ml; Streptococcus pyogenes, 1 and 2 micrograms/ml; Streptococcus pneumoniae, 0.50 and 1 microgram/ml; Corynebacterium spp., 0.50 and 0.50 micrograms/ml; Moraxella catarrhalis, 4 and 4 micrograms/ml; Listeria monocytogenes, 8 and 2 micrograms/ml; and Bacteroides fragilis, 16 and 4 micrograms/ml. Most strains of Mycobacterium tuberculosis and the gram-positive anaerobes were inhibited in the range of 0.50 to 2 micrograms/ml. Enterococcal strains resistant to vancomycin (VanA, VanB, and VanC resistance phenotypes), pneumococcal strains resistant to penicillin, and M. tuberculosis strains resistant to common antitubercular agents (isoniazid, streptomycin, rifampin, ethionamide, and ethambutol) were not cross-resistant to the oxazolidinones. The presence of 10, 20, and 40% pooled human serum did not affect the antibacterial activities of the oxazolidinones. Time-kill studies demonstrated a bacteriostatic effect of the analogs against staphylococci and enterococci but a bactericidal effect against streptococci. The spontaneous mutation frequencies of S. aureus ATCC 29213 were <3.8 x 10(-10) and <8 x 10(-11) for U-100592 and U-100766, respectively. Serial transfer of three staphylococcal and two enterococcal strains on drug gradient plates produced no evidence of rapid resistance development. Thus, these new oxazolidinone analogs demonstrated in vitro antibacterial activities against a variety of clinically important human pathogens. PMID:8849237

Zurenko, G E; Yagi, B H; Schaadt, R D; Allison, J W; Kilburn, J O; Glickman, S E; Hutchinson, D K; Barbachyn, M R; Brickner, S J

1996-04-01

351

Comparative antibacterial activity of L-695,256, a carbapenem active against methicillin-resistant staphylococci.  

PubMed Central

The activity of a new prototype carbapenem, L-695,256, against clinical isolates of gram-positive and gram-negative aerobes was studied in vitro by agar dilution. L-695,256 was highly active against methicillin-resistant and -susceptible isolates of staphylococci (MICs, 0.016 to 2 micrograms/ml) and against penicillin-resistant pneumococci (MICs, 0.016 to 0.064 micrograms/ml), irrespective of penicillin susceptibility. Activity against members of the family Enterobacteriaceae was less than that of imipenem, while Proteus mirabilis and Morganella morganii were more susceptible to L-695,256. PMID:7625810

Rylander, M; Rollof, J; Jacobsson, K; Norrby, S R

1995-01-01

352

ZAAPS International Surveillance Program (2007) for linezolid resistance: results from 5591 Gram-positive clinical isolates in 23 countries.  

PubMed

The 2007 ZAAPS Program reports the results from the 6th year of oxazolidinone (linezolid) resistance surveillance among Gram-positive pathogens from 23 nations. For 2007, a total of 5591 organisms were systematically sampled from Asia, Australia, Canada, Europe, and Latin America including Staphylococcus aureus (3000 isolates, 38.2% methicillin resistant), coagulase-negative staphylococci (CoNS, 716 isolates), enterococci (906 isolates), Streptococcus pneumoniae (452 isolates), viridans group streptococci (155 isolates), and beta-hemolytic streptococci (362 isolates). The overall linezolid MIC distribution (MIC(50) and MIC(90) at 1 and 2 microg/mL, respectively) was unchanged since 2002. At published linezolid breakpoints (, or = 2 microg/mL), all streptococci were susceptible; however, resistance was observed very rarely among S. aureus (0.03%), CoNS (0.28%), and the enterococci (0.11%, 0.55% intermediate). These oxazolidinone-nonsusceptible isolates occurred in Ireland, Italy, China, and Brazil (9 strains), and the rate was not increased since 2006. The detected mechanism of resistance was G2576 target mutations; no cfr-mediated patterns were observed. Clonal outbreaks with patient-to-patient dissemination were documented in 1 Italian site. Linezolid appears to retain excellent activity against monitored Gram-positive pathogens at a level of >99.8%. PMID:19500528

Jones, Ronald N; Kohno, Shigeru; Ono, Yasuo; Ross, James E; Yanagihara, Katsunori

2009-06-01

353

Antibacterial activities in vitro and in vivo and pharmacokinetics of cefquinome (HR 111V), a new broad-spectrum cephalosporin.  

PubMed Central

Cefquinome is a new injectable aminothiazolyl cephalosporin derivative. It is stable against chromosomally and plasmid-encoded beta-lactamases and has a broad antibacterial spectrum. Staphylococcus aureus, streptococci, Pseudomonas aeruginosa, and members of the family Enterobacteriaceae (Escherichia coli, Salmonella spp., Klebsiella spp., Enterobacter spp., Citrobacter spp., and Serratia marcescens) are inhibited at low concentrations. Cefquinome is also active against many strains of methicillin-resistant staphylococci and enterococci. Its in vitro activity against gram-negative anaerobes is very limited. The high in vitro activity of cefquinome is reflected by its high in vivo efficacy against experimental septicemia due to different gram-positive and gram-negative bacteria. We studied the pharmacokinetic properties of cefquinome in mice, dogs, pigs, and calves. After single parenteral administrations, cefquinome displayed high peak levels, declining with half-lives of about 0.5, 0.9, 1.2, and 1.3 h, respectively. The areas under the concentration-time curve determined for dogs and mice showed linear correlations to the given doses. In dogs the urinary recovery was more than 70% within 24 h of dosing. Images PMID:2014969

Limbert, M; Isert, D; Klesel, N; Markus, A; Seeger, K; Seibert, G; Schrinner, E

1991-01-01

354

In vitro antibacterial activity of Tabernaemontana alternifolia (Roxb) stem bark aqueous extracts against clinical isolates of methicillin resistant Staphylococcus aureus  

PubMed Central

Background The rise of antibiotic resistance among methicillin resistant Staphylococcus aureus (MRSA), have caused concerns for the treatment of MRSA infections. Hence, search for an alternative therapy for these infections is inevitable. Folk Indian medicine refers to the use of leaf and stem bark powder of Tabernaemontana alternifolia (Roxb) in treatment of skin infections, but no scientific report establishes its antibacterial activity. Methods Direct aqueous extracts and sequential aqueous extracts of the stem bark of T. alternifolia (using petroleum ether and ethyl acetate as other solvents) were prepared by soxhlet extraction. The antibiotic sensitivity profiles of the clinical isolates were determined against 18 antibiotics using disc diffusion method. The isolates were identified by 16S rRNA gene sequencing. The methicillin resistance among S. aureus (MRSA) was confirmed by PCR amplification of mecA gene. The disc diffusion method was used to determine the antibacterial activity of the extracts. The micro-dilution method was used to determine the minimum inhibitory concentration (MIC) of the extract against the test organism. To further evaluate the therapeutic potential of the extract, cell cytotoxicity was checked on Vero cells by MTT assay. Chemical profiling of the extract was done by HPTLC method. Results The aqueous extracts of T. alternifolia stem bark exhibited antibacterial activity against Gram-positive microorganisms, particularly against clinical isolates of MRSA and vancomycin resistant S. aureus (VRSA). The minimum inhibitory concentration (MIC) of extract against the isolates ranged from 600–800 ?g/ml. The extract did not exhibit cytotoxic activity against Vero cells even at the concentration of 4 mg/ml. The chemical profiling revealed presence of alkaloids, flavonoids, coumarins, saponins and steroids. Petroleum ether and ethyl acetate extracts did not exhibit antibacterial activity. Conclusion Our results offer a scientific basis for the traditional use of T. alternifolia in the treatment of skin infections, showing that the plant extract has an enormous potential as a prospective alternative therapy against MRSA skin infections. The present study lays the basis for future studies, to validate the possible use of T. alternifolia as a candidate in the treatment of MRSA infections. PMID:24066905

2013-01-01

355

[Triclocarban antibacterial activity on resistant staphylococci, streptococci, and enterococci].  

PubMed

Triclocarban is an antiseptic of the anilide family. Its antibacterial activity was re-assessed in vitro against various susceptible and antibiotic resistant staphylococcus, streptococcus, and enterococcus strains. The results of this study show that, in vitro, the effectiveness of triclocarban antibacterial is maintained at very low MICs ranging from 0.5 to 8 mg/L for the various resistant strains studied. Triclocarban remains still very effective for the treatment of either initially bacterial skin and mucosal infections, or skin and mucosal at risk of super infection. PMID:22626523

Drugeon, H-B; Rouveix, B; Michaud-Nerard, A

2012-06-01

356

Light-activated antibacterial surfaces comprise photosensitizers.  

PubMed

Antibacterial surfaces were prepared using a base polyethylene sheet topped with a layer containing a mixed powder of poly (vinylidene fluoride) and photosensitizers (PSs). A crimpled stamp was placed on the mixed powder, and then it was passed through a heating and pressing device. The three chosen PSs were rose bengal, toluidine blue O and methylene blue. Scanning electron microscope analysis showed that the PS surface texture was coarse and highly developed. Measurement of the apparent contact angles of the droplets deposited on the PS surfaces using goniometry showed that all three surfaces were hydrophobic. Photodynamic analysis of the surfaces into which the PSs were incorporated indicated significant reactive oxygen species formation after illumination with light fluency rate of 1.46 mW cm(-2) for 30 min. Photodynamic inactivation assays performed in nutrient broth demonstrated more than 4 log reduction of the attached Escherichia coli after illumination (1.46 mW cm(-2)) for 24 h when the inoculum was 10(3) CFU mL(-1). However, more than 4 log reduction of Staphylococcus aureus occurred even when the cultures were illuminated for only 6 h. Our results provide an inexpensive, simple, state-of-the-art method for preparing antibacterial surfaces that may help prevent infections in hospital surroundings and in some medical devices. PMID:21883241

Cahan, Rivka; Schwartz, Ronen; Langzam, Yakov; Nitzan, Yeshayahu

2011-01-01

357

Antibacterial Activity of Fullerene Water Suspensions: Effects of  

E-print Network

Antibacterial Activity of Fullerene Water Suspensions: Effects of Preparation Method and Particle and Department of Chemistry, Rice University, Houston, Texas 77005 Fullerene research in biological systems has to aggregate, forming stable fullerene water suspensions (FWS) whose properties differ from those of bulk solid

Alvarez, Pedro J.

358

Activity of endodontic antibacterial agents against selected anaerobic bacteria  

Microsoft Academic Search

The antimicrobial activity of substances used as antibacterial agents (solutions of 10% calcium hydroxide, camphorated paramono- chlorophenol - PMCC, 2% chlorhexidine digluconate and 10% castor oil plant detergent) on anaerobic bacteria (Fusobacterium nucleatum ATCC 25586, Prevotella nigrescens ATCC 33563, Clostridium perfringens ATCC 13124 and Bacteroides fragilis ATCC 25285), using a broth dilution technique, was evaluated in vitro. For determination of

Cláudio Maniglia Ferreira; Odila Pereira da Silva; Sérgio Aparecido Torres; Flaviana Bombarda de Andrade Ferreira; Norberti Bernardinelli

2002-01-01

359

In Vitro and In Vivo Antibacterial Activities of DC-159a, a New Fluoroquinolone?  

PubMed Central

DC-159a is a new 8-methoxy fluoroquinolone that possesses a broad spectrum of antibacterial activity, with extended activity against gram-positive pathogens, especially streptococci and staphylococci from patients with community-acquired infections. DC-159a showed activity against Streptococcus spp. (MIC90, 0.12 ?g/ml) and inhibited the growth of 90% of levofloxacin-intermediate and -resistant strains at 1 ?g/ml. The MIC90s of DC-159a against Staphylococcus spp. were 0.5 ?g/ml or less. Against quinolone- and methicillin-resistant Staphylococcus aureus strains, however, the MIC90 of DC-159a was 8 ?g/ml. DC-159a was the most active against Enterococcus spp. (MIC90, 4 to 8 ?g/ml) and was more active than the marketed fluoroquinolones, such as levofloxacin, ciprofloxacin, and moxifloxacin. The MIC90s of DC-159a against Haemophilus influenzae, Moraxella catarrhalis, and Klebsiella pneumoniae were 0.015, 0.06, and 0.25 ?g/ml, respectively. The activity of DC-159a against Mycoplasma pneumoniae was eightfold more potent than that of levofloxacin. The MICs of DC-159a against Chlamydophila pneumoniae were comparable to those of moxifloxacin, and DC-159a was more potent than levofloxacin. The MIC90s of DC-159a against Peptostreptococcus spp., Clostridium difficile, and Bacteroides fragilis were 0.5, 4, and 2 ?g/ml, respectively; and among the quinolones tested it showed the highest level of activity against anaerobic organisms. DC-159a demonstrated rapid bactericidal activity against quinolone-resistant Streptococcus pneumoniae strains both in vitro and in vivo. In vitro, DC-159a showed faster killing than moxifloxacin and garenoxacin. The bactericidal activity of DC-159a in a murine muscle infection model was revealed to be superior to that of moxifloxacin. These activities carried over to the in vivo efficacy in the murine pneumonia model, in which treatment with DC-159a led to bactericidal activity superior to those of the other agents tested. PMID:17938194

Hoshino, Kazuki; Inoue, Kazue; Murakami, Yoichi; Kurosaka, Yuichi; Namba, Kenji; Kashimoto, Yoshinori; Uoyama, Saori; Okumura, Ryo; Higuchi, Saito; Otani, Tsuyoshi

2008-01-01

360

Discovery of inhibitors of Escherichia coli methionine aminopeptidase with the Fe(II)-form selectivity and antibacterial activity  

PubMed Central

Methionine aminopeptidase (MetAP) is a promising target to develop novel antibiotics, because all bacteria express MetAP from a single gene that carries out the essential function of removing N-terminal methionine from nascent proteins. Divalent metal ions play a critical role in the catalysis, and there is an urgent need to define the actual metal used by MetAP in bacterial cells. By high throughput screening, we identified a novel class of catechol-containing MetAP inhibitors that display selectivity for the Fe(II)-form of MetAP. X-ray structure revealed that the inhibitor binds to MetAP at the active site with the catechol coordinating to the metal ions. Importantly, some of the inhibitors showed antibacterial activity at low micromolar concentration on Gram-positive and Gram-negative bacteria. Our data indicate that Fe(II) is the likely metal used by MetAP in the cellular environment, and MetAP inhibitors need to inhibit this metalloform of MetAP effectively to be therapeutically useful. PMID:18785729

Wang, Wen-Long; Chai, Sergio C.; Huang, Min; He, Hong-Zhen; Hurley, Thomas D.; Ye, Qi-Zhuang

2009-01-01

361

Antibacterial Activity of the Alkaloid-Enriched Extract from Prosopis juliflora Pods and Its Influence on in Vitro Ruminal Digestion  

PubMed Central

The purpose of this study was to assess the in vitro antimicrobial activity of alkaloid-enriched extracts from Prosopis juliflora (Fabaceae) pods in order to evaluate them as feed additives for ruminants. As only the basic chloroformic extract (BCE), whose main constituents were juliprosopine (juliflorine), prosoflorine and juliprosine, showed Gram-positive antibacterial activity against Micrococcus luteus (MIC = 25 ?g/mL), Staphylococcus aureus (MIC = 50 ?g/mL) and Streptococcus mutans (MIC = 50 ?g/mL), its influence on ruminal digestion was evaluated using a semi-automated in vitro gas production technique, with monensin as the positive control. Results showed that BCE has decreased gas production as efficiently as monensin after 36 h of fermentation, revealing its positive influence on gas production during ruminal digestion. Since P. juliflora is a very affordable plant, this study points out this alkaloid enriched extract from the pods of Prosopis juliflora as a potential feed additive to decrease gas production during ruminal digestion. PMID:23595000

dos Santos, Edilene T.; Pereira, Mara Lucia A.; da Silva, Camilla Flavia P.G.; Souza-Neta, Lourdes C.; Geris, Regina; Martins, Dirceu; Santana, Antonio Euzebio G.; Barbosa, Luiz Claudio A.; Silva, Heryma Giovane O.; Freitas, Giovana C.; Figueiredo, Mauro P.; de Oliveira, Fernando F.; Batista, Ronan

2013-01-01

362

Modified bamboo rayon-copper nanoparticle composites as antibacterial textiles.  

PubMed

In the current study the bamboo rayon fabric grafted with acrylamide was utilized as a backbone to immobilize copper nanoprticles. The grafted bamboo rayon was first treated with CuSO4 followed by chemical reduction. The modified product was characterized using FTIR, TGA and SEM. The characteristic color developed after reduction was measured spectrophotometrically. The grafted bamboo rayon with Cu nanoparticles was then evaluated for antibacterial activity against both gram positive and gram negative bacteria and the durability of their antibacterial activity after washing. The product showed antibacterial activity against both types of bacterias which was found to be durable till 50 washes. The material can be claimed as suitable candidate for medical textile applications to prevent cross-infections. PMID:23916646

Teli, M D; Sheikh, Javed

2013-10-01

363

Atmospheric growth requirements for Alloiococcus species and related gram-positive cocci.  

PubMed

The growth of Alloiococcus otitis under different atmospheres and nutritional conditions was studied. The growth rates of 25 strains of gram-positive cocci representing five genera on heart infusion agar plates containing 5% rabbit blood and on brucella agar plates with and without sheep blood under aerobic, increased CO2, and anaerobic atmospheres were compared. Eight strains of alloiococci plated on heart infusion agar with rabbit blood and on brucella sheep blood agar grew under aerobic and candle jar atmospheres. Two of these strains showed poor anaerobic growth after 7 days. Strains of Aerococcus viridans, Aerococcus urinae, Helcococci kunzi, Dolosigranulum pigrum, Gemella haemolysans, and Gemella morbillorum grew well under all three atmospheres and on the three types of media and in thioglycolate broth. These results confirm all the aerobic atmospheric requirements for Alloiococcus strains and show that aerobic growth characteristics help distinguish the alloiococci from the other gram-positive cocci that are facultatively anaerobic. PMID:8815077

Miller, P H; Facklam, R R; Miller, J M

1996-04-01

364

Atmospheric growth requirements for Alloiococcus species and related gram-positive cocci.  

PubMed Central

The growth of Alloiococcus otitis under different atmospheres and nutritional conditions was studied. The growth rates of 25 strains of gram-positive cocci representing five genera on heart infusion agar plates containing 5% rabbit blood and on brucella agar plates with and without sheep blood under aerobic, increased CO2, and anaerobic atmospheres were compared. Eight strains of alloiococci plated on heart infusion agar with rabbit blood and on brucella sheep blood agar grew under aerobic and candle jar atmospheres. Two of these strains showed poor anaerobic growth after 7 days. Strains of Aerococcus viridans, Aerococcus urinae, Helcococci kunzi, Dolosigranulum pigrum, Gemella haemolysans, and Gemella morbillorum grew well under all three atmospheres and on the three types of media and in thioglycolate broth. These results confirm all the aerobic atmospheric requirements for Alloiococcus strains and show that aerobic growth characteristics help distinguish the alloiococci from the other gram-positive cocci that are facultatively anaerobic. PMID:8815077

Miller, P H; Facklam, R R; Miller, J M

1996-01-01

365

Protein transport across the cell wall of monoderm Gram-positive bacteria  

PubMed Central

Summary In monoderm (single membrane) Gram-positive bacteria, the majority of secreted proteins are first translocated across the cytoplasmic membrane into the inner wall zone. For a subset of these proteins, final destination is within the cell envelope either as membrane-anchored or cell wall-anchored proteins, whereas another subset of proteins is destined to be transported across the cell wall into the extracellular milieu. Although the cell wall is a porous structure, there is evidence that, for some proteins, transport is a regulated process. This review aims at describing what is known about the mechanisms that regulate the transport of proteins across the cell wall of monoderm Gram-positive bacteria. PMID:22471582

Forster, Brian M.; Marquis, Helene

2012-01-01

366

Survival of gram positive anaerobic cocci on swabs and their isolation from the mouth and vagina.  

PubMed Central

The survival of Gram positive anaerobic cocci on plain cotton wool and albumin coated swabs held in various transport media was investigated. Results suggested that in most cases Amies', Stuart's and VMGII media do not offer any more protection to the bacteria than storing swabs dry in their containers. A technique was developed for the isolation and identification of Gram positive anaerobic cocci from the mouth and vagina, incorporating bicozamycin in the medium as a selective agent. Few strains were recovered from the oral cavity, but larger numbers were isolated from the vagina. Using a minimum number of antibiotic sensitivity and biochemical tests, including analysis of end products by gas-liquid chromatography, most isolates were identified to species level. PMID:3950035

Smith, G L; Cumming, C G; Ross, P W

1986-01-01

367

Rapid identification of obligately anaerobic gram-positive cocci using high-performance liquid chromatography.  

PubMed Central

High-performance liquid chromatography was evaluated as a rapid means of identifying obligately anaerobic gram-positive cocci of medical interest. Isolates were inoculated into a defined chemical medium consisting primarily of amino acids and were incubated aerobically for 1 h at 35 degrees C. After removal of organisms, the supernatant fluids were derivatized for 1 min at room temperature by the addition of o-phthalaldehyde. The total time required to run a chromatogram was approximately 50 min. Standardized peak heights for each medium component and any new peaks formed were calculated for each isolate and compared with those for uninoculated control medium. Multiple isolates of various species of anaerobic gram-positive cocci gave consistent patterns of medium utilization that could be used for identification purposes. This method can easily be adapted for laboratory use and has the potential for automated microbial identification. PMID:3597760

Harpold, D J; Wasilauskas, B L

1987-01-01

368

Antibacterial activity of plant extracts from Brazil against fish pathogenic bacteria  

PubMed Central

The aim of this work was to evaluate the antibacterial activity of Brazilian plants extracts against fish pathogenic bacteria. Forty six methanolic extracts were screened to identify their antibacterial properties against Streptococcus agalactiae, Flavobacterium columnare and Aeromonas hydrophila. Thirty one extracts showed antibacterial activity. PMID:24031303

Castro, S.B.R.; Leal, C.A.G.; Freire, F.R.; Carvalho, D.A.; Oliveira, D.F.; Figueiredo, H.C.P.

2008-01-01

369

The complete genome sequence of the gram-positive bacterium Bacillus subtilis  

Microsoft Academic Search

Bacillus subtilis is the best-characterized member of the Gram-positive bacteria. Its genome of 4,214,810 base pairs comprises 4,100 protein-coding genes. Of these protein-coding genes, 53% are represented once, while a quarter of the genome corresponds to several gene families that have been greatly expanded by gene duplication, the largest family containing 77 putative ATP-binding transport proteins. In addition, a large

F. Kunst; N. Ogasawara; I. Moszer; A. M. Albertini; G. Alloni; V. Azevedo; M. G. Bertero; P. Bessičres; A. Bolotin; S. Borchert; R. Borriss; L. Boursier; A. Brans; M. Braun; S. C. Brignell; S. Bron; S. Brouillet; C. V. Bruschi; B. Caldwell; V. Capuano; N. M. Carter; S.-K. Choi; J.-J. Codani; I. F. Connerton; A. Danchin

1997-01-01

370

Genome Sequence of the Diazotrophic Gram-Positive Rhizobacterium Paenibacillus riograndensis SBR5T  

PubMed Central

Paenibacillus riograndensis SBR5T, a nitrogen-fixing Gram-positive rhizobacterium isolated from a wheat field in the south of Brazil, has a great potential for agricultural applications due to its plant growth promotion effects. Here we present the draft genome sequence of P. riograndensis SBR5T. Its 7.37-Mb genome encodes determinants of the diazotrophic lifestyle and plant growth promotion, such as nitrogen fixation, antibiotic resistance, nitrate utilization, and iron uptake. PMID:22038959

Beneduzi, Anelise; Campos, Samanta; Ambrosini, Adriana; de Souza, Rocheli; Granada, Camille; Costa, Pedro; Arruda, Leticia; Moreira, Fernanda; Vargas, Luciano K.; Weiss, Vinicius; Tieppo, Eduardo; Faoro, Helisson; de Souza, Emanuel M.; Pedrosa, Fabio O.; Passaglia, Luciane M. P.

2011-01-01

371

Susceptibility of Gram-positive bacteria from ICU patients in UK hospitals to antimicrobial agents  

Microsoft Academic Search

Microbiologists in 25 sentinel laboratories were each asked to refer up to 100 clinically-significant Gram-positive bacteria isolated from consecutive intensive care unit (ICU) patients. A total of 1595 isolates were collected from patients in 23 hospitals; these included Staphylococcus aureus (47.6%), coagulase-negative staphylococci (CNS) (30.6%), enterococci (14.3%), pneumococci (2.8%) and other streptococci (3.5%). A few coryneforms, other bacilli and a

A. P Johnson; C Henwood; S Mushtaq; D James; M Warner; D. M Livermore

2003-01-01

372

Isolation and Characterization of Four Gram-Positive Nickel-Tolerant Microorganisms from Contaminated Sediments  

Microsoft Academic Search

Microbial communities from riparian sediments contaminated with high levels of Ni and U were examined for metal-tolerant microorganisms.\\u000a Isolation of four aerobic Ni-tolerant, Gram-positive heterotrophic bacteria indicated selection pressure from Ni. These isolates\\u000a were identified as Arthrobacter oxydans NR-1, Streptomyces galbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatospora cystarginea NR-4 based on partial 16S rDNA sequences. A functional gene microarray containing

Joy D. Van Nostrand; Tatiana V. Khijniak; Terry J. Gentry; Michelle T. Novak; Andrew G. Sowder; Jizhong Z. Zhou; Paul M. Bertsch; Pamela J. Morris

2007-01-01

373

Rose Bengal-decorated silica nanoparticles as photosensitizers for inactivation of gram-positive bacteria  

Microsoft Academic Search

A new type of photosensitizer, made from Rose Bengal (RB)-decorated silica (SiO2-NH2-RB) nanoparticles, was developed to inactivate gram-positive bacteria, including Methicillin-resistant Staphylococcus aureus (MRSA), with high efficiency through photodynamic action. The nanoparticles were characterized microscopically and spectroscopically to confirm their structures. The characterization of singlet oxygen generated by RB, both free and immobilized on a nanoparticle surface, was performed in

Yanyan Guo; Snezna Rogelj; Peng Zhang

2010-01-01

374

Identification of Aerobic Gram-Positive Bacilli by Use of Vitek MS  

PubMed Central

The accuracy of Vitek MS mass spectrometric identifications was assessed for 206 clinically significant isolates of aerobic Gram-positive bacilli representing 20 genera and 38 species. The Vitek MS identifications were correct for 85% of the isolates (56.3% to the species level, 28.6% limited to the genus level), with misidentifications occurring for 7.3% of the isolates. PMID:24501030

Navas, Maria; Pincus, David H.; Wilkey, Kathy; Sercia, Linda; LaSalvia, Margaret; Wilson, Deborah; Procop, Gary W.

2014-01-01

375

Control of the spread of multi-resistant Gram-positive organisms  

Microsoft Academic Search

Antibiotic-resistant bacteria have always restricted the use of antibiotics, but in recent years such organisms have caused increasing concern as the development of new classes of antimicrobial has slowed, whilst the ability of bacteria to become resistant has not. Multiple antibiotic-resistant Gram-positive organisms represent a microbiological problem quite different from their Gram-negative counterparts. In the case of the Gram-negative bacteria,

S. P. Barrett

1999-01-01

376

Different subcellular locations of secretome components of Gram-positive bacteria  

Microsoft Academic Search

Gram-positive bacteria contain different types of secretion systems for the transport of proteins into or across the cytoplasmic membrane. Recent studies on subcellular localization of specific components of these secretion systems and their substrates have shown that they can be present at various locations in the cell. The translocons of the general Sec secretion system in the rod-shaped bacterium Bacillus

Girbe Buist; Anja N. J. A. Ridder; Jan Kok; Oscar P. Kuipers

2006-01-01

377

Gram-Positive Marine Bacteria as a Potential Resource for the Discovery of Quorum Sensing Inhibitors  

Microsoft Academic Search

Inhibitors of bacterial quorum sensing have been proposed as potentially novel therapeutics for the treatment of certain bacterial\\u000a diseases. We recently reported a marine Halobacillus salinus isolate that secretes secondary metabolites capable of quenching quorum sensing phenotypes in several Gram-negative reporter\\u000a strains. To investigate how widespread the production of such compounds may be in the marine bacterial environment, 332 Gram-positive

Margaret E. Teasdale; Kellye A. Donovan; Stephanie R. Forschner-Dancause; David C. Rowley

378

Synthesis and antibacterial activity of aminosugar-functionalized intercalating agents.  

PubMed

A series of previously reported amino sugar-functionalized intercalating agents, 3-14, were evaluated in two antibacterial assays (paper disk diffusion and 96-well microdilution) against Bacillus atrophaeus, ATCC 9372 and Escherichia coli, ATCC 47076. Although none of the compounds were active against this E. coli strain, several showed activity against B. atrophaeus. In anticipation of the need for larger amounts of these compounds for future structure-activity relationship studies, improved routes to 11-14 were developed. PMID:19926076

Shi, Wei; Marcus, Sandra L; Lowary, Todd L

2010-01-11

379

Susceptibilities of 428 gram-positive and -negative anaerobic bacteria to Bay y3118 compared with their susceptibilities to ciprofloxacin, clindamycin, metronidazole, piperacillin, piperacillin-tazobactam, and cefoxitin.  

PubMed Central

The susceptibilities of 428 gram-negative and gram-positive anaerobes (including selected cefoxitin-resistant strains) to Bay y3118 (a new fluoroquinolone), ciprofloxacin, clindamycin, metronidazole, cefoxitin, piperacillin, and piperacillin-tazobactam were tested. Organisms comprised 115 Bacteroides fragilis group, 116 non-B. fragilis Bacteroides, Prevotella, and Porphyromonas spp., 40 fusobacteria, 58 peptostreptococci, 48 gram-positive non-spore-forming rods, and 51 clostridia. beta-Lactamase production was demonstrated in 87% of the gram-negative rods but in none of the gram-positive organisms. Overall, Bay y3118 was the most active agent, with all organisms inhibited at an MIC of < or = 2.0 micrograms/ml (MICs for 50% [MIC50] and 90% [MIC90] of strains tested, 0.125 and 0.5 microgram/ml, respectively). By contrast, ciprofloxacin was much less active, with only 42% of strains susceptible at a breakpoint of 2.0 micrograms/ml (MIC50, 4.0 micrograms/ml; MIC90, 16.0 micrograms/ml). Metronidazole was active against all gram-negative rods, but 7% of peptostreptococci, 83% of gram-positive non-spore-forming rods, and 4% of non-Clostridium perfringens, non-Clostridium difficile clostridia were resistant to this agent (MICs, > 16.0 micrograms/ml). Clindamycin was active against 94% of Bacteroides, Prevotella, and Porphyromonas spp., 91% of peptostreptococci, and 100% of gram-positive non-spore-forming rods, but was active against only 70% of fusobacteria and 53% of clostridia. Cefoxitin was active against > or = 90% of all groups except the B. fragilis group and non-Propionibacterium acnes gram-positive non-spore-forming rods (both 85%) and C. difficile (20%). Significant enhancement of piperacillin by tazobactam was seen in all beta-lactamase-positive strains (99% susceptible; MIC90, 8.0 micrograms/ml), and all beta-lactamase-negative strains were susceptible to piperacillin (MIC90, 8.0 micrograms/ml). Clinical studies are required to delineate the role of Bay y3118 in the treatment of anaerobic infections. PMID:8215278

Pankuch, G A; Jacobs, M R; Appelbaum, P C

1993-01-01

380

Antimicrobial activity of the extract of stem bark of diplotropis ferruginea benth.  

PubMed

This is the first report about the antibacterial activity of Diplotropis ferruginea Benth. In this study, the ethanol extract of D. ferruginea was tested for its antimicrobial activity against strains gram-positive and gram-negative. In order to determine the minimal inhibitory concentration, assays were carried out by micro dilution method. The extract was screened for antimicrobial activity, and it showed antibacterial activity against Escherichia coli and Pseudomonas aeruginosa. PMID:22224034

Cerqueira, Gs; Rocha, Nfm; Almeida, Jrgs; de Freitas, Apf; Lima, Eo; Filho, Jmb; de Freitas, Rm; Diniz, Melo Mff

2011-10-01

381

Widespread Abundance of Functional Bacterial Amyloid in Mycolata and Other Gram-Positive Bacteria?  

PubMed Central

Until recently, extracellular functional bacterial amyloid (FuBA) has been detected and characterized in only a few bacterial species, including Escherichia coli, Salmonella, and the gram-positive organism Streptomyces coelicolor. Here we probed gram-positive bacteria with conformationally specific antibodies and revealed the existence of FuBA in 12 of 14 examined mycolata species, as well as six other distantly related species examined belonging to the phyla Actinobacteria and Firmicutes. Most of the bacteria produced extracellular fimbriae, sometimes copious amounts of them, and in two cases large extracellular fibrils were also produced. In three cases, FuBA was revealed only after extensive removal of extracellular material by saponification, indicating that there is integrated attachment within the cellular envelope. Spores of species in the genera Streptomyces, Bacillus, and Nocardia were all coated with amyloids. FuBA was purified from Gordonia amarae (from the cell envelope) and Geodermatophilus obscurus, and they had the morphology, tinctorial properties, and ?-rich structure typical of amyloid. The presence of approximately 9-nm-wide amyloids in the cell envelope of G. amarae was visualized by transmission electron microscopy analysis. We conclude that amyloid is widespread among gram-positive bacteria and may in many species constitute a hitherto overlooked integral part of the spore and the cellular envelope. PMID:19395568

Jordal, Peter Bruun; Dueholm, Morten Simonsen; Larsen, Poul; Petersen, Steen Vang; Enghild, Jan Johannes; Christiansen, Gunna; Hřjrup, Peter; Nielsen, Per Halkjćr; Otzen, Daniel Erik

2009-01-01

382

High benzene concentrations can favour Gram-positive bacteria in groundwaters from a contaminated aquifer.  

PubMed

Exposure to pollution exerts strong selective pressure on microbial communities, which may affect their potential to adapt to current or future environmental challenges. In this microcosm study, we used DNA fingerprinting based on 16S rRNA genes to document the impact of high concentrations of benzene on two bacterial communities from a benzene-contaminated aquifer situated below a petrochemical plant (SIReN, UK). The two groundwaters harboured distinct aerobic benzene-degrading communities able to metabolize benzene to below detection levels (1 microg L(-1)). A benzene concentration of 100 mg L(-1) caused a major shift from Betaproteobacteria to Actinobacteria, in particular Arthrobacter spp. A similar shift from Betaproteobacteria to Arthrobacter spp. and Rhodococcus erythropolis was observed in minimal medium (MM) inoculated with a third groundwater. These Gram-positive-dominated communities were able to grow on benzene at concentrations up to 600 mg L(-1) in groundwater and up to 1000 mg L(-1) in MM, concentrations that cause significant solvent stress to cellular systems. Therefore, Gram-positive bacteria were better competitors than Gram-negative organisms under experimental conditions of high benzene loads, which suggests that solvent-tolerant Gram-positive bacteria can play a role in the natural attenuation of benzene or the remediation of contaminated sites. PMID:18540887

Fahy, Anne; Ball, Andrew S; Lethbridge, Gordon; McGenity, Terry J; Timmis, Kenneth N

2008-09-01

383

A Comparative Genome Analysis Identifies Distinct Sorting Pathways in Gram-Positive Bacteria  

PubMed Central

Surface proteins in gram-positive bacteria are frequently required for virulence, and many are attached to the cell wall by sortase enzymes. Bacteria frequently encode more than one sortase enzyme and an even larger number of potential sortase substrates that possess an LPXTG-type cell wall sorting signal. In order to elucidate the sorting pathways present in gram-positive bacteria, we performed a comparative analysis of 72 sequenced microbial genomes. We show that sortase enzymes can be partitioned into five distinct subfamilies based upon their primary sequences and that most of their substrates can be predicted by making a few conservative assumptions. Most bacteria encode sortases from two or more subfamilies, which are predicted to function nonredundantly in sorting proteins to the cell surface. Only ?20% of sortase-related proteins are most closely related to the well-characterized Staphylococcus aureus SrtA protein, but nonetheless, these proteins are responsible for anchoring the majority of surface proteins in gram-positive bacteria. In contrast, most sortase-like proteins are predicted to play a more specialized role, with each anchoring far fewer proteins that contain unusual sequence motifs. The functional sortase-substrate linkage predictions are available online (http://www.doe-mbi.ucla.edu/Services/Sortase/) in a searchable database. PMID:15102780

Comfort, David; Clubb, Robert T.

2004-01-01

384

Green synthesis of silver/montmorillonite/chitosan bionanocomposites using the UV irradiation method and evaluation of antibacterial activity  

PubMed Central

In this study, silver nanoparticles (Ag-NPs) were synthesized using a green physical synthetic route into the lamellar space of montmorillonite (MMT)/chitosan (Cts) utilizing the ultraviolet (UV) irradiation reduction method in the absence of any reducing agent or heat treatment. Cts, MMT, and AgNO3 were used as the natural polymeric stabilizer, solid support, and silver precursor, respectively. The properties of Ag/MMT/Cts bionanocomposites (BNCs) were studied as the function of UV irradiation times. UV irradiation disintegrated the Ag-NPs into smaller sizes until a relatively stable size and size distribution were achieved. Meanwhile, the crystalline structure and d-spacing of the MMT interlayer, average size and size distribution, surface morphology, elemental signal peaks, functional groups, and surface plasmon resonance of Ag/MMT/Cts BNCs were determined by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, Fourier transform infrared, and UV-visible spectroscopy. The antibacterial activity of Ag-NPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria (ie, Escherichia coli) by the disk diffusion method on Muller–Hinton Agar at different sizes of Ag-NPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different biologic research and biomedical applications, such as surgical devices and drug delivery vehicles. PMID:21116328

Shameli, Kamyar; Ahmad, Mansor Bin; Yunus, Wan Md Zin Wan; Rustaiyan, Abdolhossein; Ibrahim, Nor Azowa; Zargar, Mohsen; Abdollahi, Yadollah

2010-01-01

385

Synthesis and characterization of silver/montmorillonite/chitosan bionanocomposites by chemical reduction method and their antibacterial activity  

PubMed Central

Silver nanoparticles (AgNPs) of a small size were successfully synthesized using the wet chemical reduction method into the lamellar space layer of montmorillonite/chitosan (MMT/Cts) as an organomodified mineral solid support in the absence of any heat treatment. AgNO3, MMT, Cts, and NaBH4 were used as the silver precursor, the solid support, the natural polymeric stabilizer, and the chemical reduction agent, respectively. MMT was suspended in aqueous AgNO3/Cts solution. The interlamellar space limits were changed (d-spacing = 1.24–1.54 nm); therefore, AgNPs formed on the interlayer and external surface of MMT/Cts with d-average = 6.28–9.84 nm diameter. Characterizations were done using different methods, ie, ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence spectrometry, and Fourier transform infrared spectroscopy. Silver/montmorillonite/chitosan bionanocomposite (Ag/MMT/Cts BNC) systems were examined. The antibacterial activity of AgNPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria, ie, Escherichia coli, E. coli O157:H7, and Pseudomonas aeruginosa by the disc diffusion method using Mueller Hinton agar at different sizes of AgNPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different biological research and biomedical applications, including surgical devices and drug delivery vehicles. PMID:21499424

Shameli, Kamyar; Ahmad, Mansor Bin; Zargar, Mohsen; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa; Shabanzadeh, Parvaneh; Moghaddam, Mansour Ghaffari

2011-01-01

386

Evaluation of the Antibacterial Activity of Patchouli Oil  

PubMed Central

In the present study, the antimicrobial tests of patchouli oil were studied by using molecular docking technology and antimicrobial test in vitro. Five biological macromolecule enzymes, required by the bacteria in the process of biosynthesis were selected as target molecules. Five antibiotics benzylpenicillin, sulfadiazine, trimethoprim, rifampicin and ciprofloxacin, which are generally acknowledged as antibacterial drugs, were selected as reference compounds. The 3 three-dimensional (3D) structures of the 5 reference compounds and 26 compounds from patchouli oil were established by using surflex-dock software (8.1). And the 3D structures of five biological macromolecule enzymes derived from Protein Data Bank (PDB). Molecular docking was carried out between the 31 chemical compounds (ligands) and the 5 enzymes (receptors) by using surflex-dock function. Furthermore, the antibacterial effects of 31 chemical compounds were investigated by the scoring function after molecular docking was completed. By comparing the scoring result of 26 compounds in patchouli oil with 5 compared components, we inferred antibacterial activity in about 26 compounds in patchouli oil. On the other hand, six frequently-used pathogenic bacteria were selected for antimicrobial test in vitro, patchouli oil and its two major compounds: (-)-patchouli alcohol and pogostone, which their contents exceeded 60% in patchouli oil samples, were selected antibacterial agents. Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) were also determined. Molecular docking technology and antimicrobial test in vitro proved that patchouli oil had strong antimicrobial effects. Particularly, pogostone and (-)-patchouli alcohol have potent antimicrobial activity. PMID:24250637

Yang, Xian; Zhang, Xue; Yang, Shui-Ping; Liu, Wei-Qi

2013-01-01

387

Antibacterial activity of Nymphaea nouchali (Burm. f) flower  

PubMed Central

Background The present work aimed to find out the antibacterial activity of Nymphaea nouchali flower on human and plant pathogenic bacteria. Methods Antibacterial potency of methanol, acetone, ethyl acetate and petroleum spirit extracts of Nymphaea nouchali flower has been tested against four human pathogenic bacteria Bacillus subtilis (FO 3026) Escherichia coli (IFO 3007), Klebsiella pneumonia (ATTC 10031) and Sarcina lutea (IFO 3232) and one plant pathogenic bacterium Xanthomonas campestris (IAM 1671) by disc diffusion assay. Zone of inhibition produced by different extracts against the test bacteria was measured and compared with standard antibiotic disc. Results Methanol extract possessed better antibacterial activity against two pathogenic bacteria, B. subtilis (FO 3026) and S. lutea (IFO 3232) than commercial antibiotic nalidixic acid. Acetone extract showed moderate sensitivity whereas B. subtilis (FO 3026), S. lutea (IFO 3232) and X. campestris (IAM 1671) showed resistance to ethyl acetate and petroleum spirit extracts. The minimum inhibitory concentrations of various extracts were ranged between 128–2048 ?gml-1. Conclusions Nymphaea nouchali flower could be a potential candidate for future development of novel broad spectrum antibacterial herbal formulation. PMID:24099586

2013-01-01

388

Antibacterial immune response in Astacus leptodactylus (Crustacea, Decapoda).  

PubMed

Antibacterial substances (ABS) in the hemolymph of Astacus leptodactylus were studied by agar-plate lysis and inhibition tests. The results demonstrate ABS against Gram-positive and Gram-negative bacteria. ABS against Gram-positive bacteria were identified as a lysozyme with a molecular weight of 14 kDa, heat resistance (< 50 degrees C) and lability to freezing. ABS against Gram-negative bacteria lost 50% of their activity at 50 degrees C and completely at 70 degrees C but were stable to freezing. Both ABS are inducible; they are produced and stored in the granular and semigranular hemocytes. Lysozyme is found in treated and untreated animals, ABS against Gram-negative bacteria only after induction. PMID:9179616

Xylander, W E; Ullrich, G; Kaiser, H E

1997-01-01

389

Innate immune defense of the sponge Suberites domuncula against gram-positive bacteria: induction of lysozyme and AdaPTin  

Microsoft Academic Search

Sponges are filter feeders that are exposed to large amounts of bacteria present in their surrounding aqueous milieu. The characteristic cell wall component of gram-positive bacteria, peptidoglycan (PPG), was used as a model molecule to study the responsiveness of cells from the marine demosponge Suberites domuncula toward gram-positive bacteria. The sponge lysozyme, which hydrolyzes PPG, was isolated from the living

N. L. Thakur; S. Perovi?-Ottstadt; R. Batel; M. Korzhev; B. Diehl-Seifert; I. M. Müller; W. E. G. Müller

2005-01-01

390

Antibacterial and antifungal activity of Avarone and Avarol.  

PubMed

The sesquiterpenoid hydroquinone and quinone, Avarol and Avarone, were previously found to be potent antitumor agents (Müller et al., 1984). In the present study it is reported that in aqueous solution (pH 7.2), in the presence of dimethylsulfoxide, Avarol is converted to Avarone. Avarone and to a smaller extent also Avarol were active against a variety of grampositive bacterial species. The highest activity was determined for Streptococcus pneumoniae and Erysipelothrix rhusiopathiae (MIC 0.781 mg/l). The antibacterial activity can be augmented 2 to 4-fold by lowering the pH in the culture medium from 7.0 to 6.0. The efficiency of Avarone and Avarol was abolished in the presence of serum. No antibacterial activity was determined in gramnegative bacterial species. In addition, Avarol and to a smaller extent also Avarone displayed an antifungal activity on Trichophyton species and Microsporum canis (MIC: 15.6-62.5 mg/l), while Avarone and not Avarol was active on Aspergillus niger, no activity was found against Candida species. These data indicate that the antitumor agents Avarol/Avarone display also antibacterial- and antifungal activities against a limited range of microorganisms. PMID:3841441

Seibert, G; Raether, W; Dogovi?, N; Gasi?, M J; Zahn, R K; Müller, W E

1985-11-01

391

Evaluation of antibacterial and antioxidant activities of Artemisia campestris ( Astraceae) and Ziziphus lotus ( Rhamnacea)  

Microsoft Academic Search

The present work quantitatively evaluates the antimicrobial and antioxidant potentials of two Libyan folk medicinal plants [Artemisia campestris (Astraceae) and Ziziphus lotus (Rhamnacea)] that commonly grow in the south of Libya. The crude methanolic leaves extracts of both plants are appreciably active against Gram-positive species, associated with week anti-Gram-negative activity. These two plant extracts also showed reasonably high contents of

Mahboba B. Naili; Rabia O. Alghazeer; Nabil A. Saleh; Asma Y. Al-Najjar

2010-01-01

392

Range of antibacterial activity of antibiotics at subminimal inhibitory concentrations: the ratio of minimal inhibitory concentration to minimal antibiotic concentration.  

PubMed

The range of activity of subminimal inhibitory concentrations of some beta-lactam and aminoglycoside antibiotics against both gram-negative and gram-positive bacteria was determined and expressed as the ratio of the minimal inhibitory concentration (MIC) to the minimal antibiotic concentration (MAC). Ten strains of Staphylococcus aureus were tested with ampicillin, cefamandole, and cefoxitin. The mean MIC/MAC ratios were 9.4, 14.0, and 2.9, respectively. The mean MIC/MAC ratios for 10 strains of Escherichia coli that were tested with the same three antibiotics were 20.6, 25.2, and 15.1, respectively. The same strains of E. coli and S. aureus were tested with amikacin, gentamicin, and tobramycin. The respective mean MIC/MAC ratios were 13.1, 6.2, and 7.4 for E. coli and 3.7, 5.1, and 3.1 for S. aureus. Ten strains of Serratia marcescens were tested with amikacin, chloramphenicol, and these two drugs combined. The mean MIC/MAC ratios for amikacin and chloramphenicol were 6.8 and 2.1, respectively. For the combination, the mean MIC/MAC ratio was 9.2, a finding that indicates synergism. Determinations of MIC/MAC ratios could provide valuable information for the monitoring of antibacterial therapy, especially when drugs of significant toxicity are used. PMID:396635

Ezrow, L; Saceanu, C; Dabydeen, H

1979-01-01

393

Essential oil composition and antibacterial activity of the different parts of Thymus maroccanus Ball: an endemic species in Morocco.  

PubMed

Three essential oils from three samples: stems, leaves and inflorescences of Thymus maroccanus Ball, obtained by hydrodistillation, were analysed by gas chromatography and gas chromatography coupled to mass spectrometry. The oils of stems, leaves and inflorescences afforded 68, 49 and 51 constituents, respectively. Quantitative and qualitative differences have been found between the analysed parts. The most abundant components in the stems oil included carvacrol (60.8%), ?-terpineol (4.7%) and p-cymene (2.4%), while carvacrol (33%), p-cymene (25.3%) and ?-pinene (11.6%) were the main components in the leaves. In the inflorescences, carvacrol (84.9%) is the major component. Antibacterial activity of the T. maroccanus Ball leaves oil was tested against eight Gram-positive and Gram-negative bacteria by the disc diffusion method. The values of inhibition zones for bacterial strains, which were sensitive to the essential oil of T. maroccanus leaves, were in the range of 11-43 mm. PMID:23425125

Belaqziz, R; Bahri, F; Romane, A; Antoniotti, S; Fernandez, X; Duńach, E

2013-01-01

394

Anti-bacterial activity of ethanolic extract of Indoneesiella echioides (L) nees. evaluated by the filter paper disc method.  

PubMed

The study was carried out to investigate the antibacterial activity of the ethanolic extracts of Indoneesiella echioides (L) Nees. was evaluated by the filter paper disc method. This method is based on the diffusion of an antibiotic from a filter paper disc through the solidified culture media of a Petri dish used for study. The growth of inoculated is inhibited entirely in a circular area "Zone around the filter" paper disc containing a solution of antibiotic and the plant extract. The microorganisms used were: 1. Staphylococcus aureus (Gram positive 2. Escherichia coli (Gram negative). The organisms were maintained on nutrient agar slants. These were tested using nutrient broth. One loop full of the respective cultures was taken in slants which were maintained below 40 degrees C were taken and inoculated in the broth and incubated at 37 degrees C for 24 hrs and were observed for the growth of the organism with naked eye for their turbid nature. It was compared with that of sterile broth. The presence of turbidity indicated growth and suitability of the culture for further work. PMID:19339219

Qadrie, Zulfkar Latief; Jacob, Beena; Anandan, R; Rajkapoor, B; Rahamathulla, Mohammed

2009-04-01

395

Extracellular biosynthesis of CdTe quantum dots by the fungus Fusarium oxysporum and their anti-bacterial activity  

NASA Astrophysics Data System (ADS)

The growing demand for semiconductor [quantum dots (Q-dots)] nanoparticles has fuelled significant research in developing strategies for their synthesis and characterization. They are extensively investigated by the chemical route; on the other hand, use of microbial sources for biosynthesis witnessed the highly stable, water dispersible nanoparticles formation. Here we report, for the first time, an efficient fungal-mediated synthesis of highly fluorescent CdTe quantum dots at ambient conditions by the fungus Fusarium oxysporum when reacted with a mixture of CdCl2 and TeCl4. Characterization of these biosynthesized nanoparticles was carried out by different techniques such as Ultraviolet-visible (UV-Vis) spectroscopy, Photoluminescence (PL), X-ray Diffraction (XRD), X-ray Photoelectron spectroscopy (XPS), Transmission Electron Microscopy (TEM) and Fourier Transformed Infrared Spectroscopy (FTIR) analysis. CdTe nanoparticles shows antibacterial activity against Gram positive and Gram negative bacteria. The fungal based fabrication provides an economical, green chemistry approach for production of highly fluorescent CdTe quantum dots.

Syed, Asad; Ahmad, Absar

2013-04-01

396

Preparation and characterization of ZnO-deposited DBD plasma-treated PP packaging film with antibacterial activities  

NASA Astrophysics Data System (ADS)

Zinc oxide (ZnO)-deposited polypropylene (PP) packaging film was prepared with the aid of dielectric barrier discharge (DBD) plasma treatment. The surface hydrophilicity of PP film was found to increase after the DBD plasma treatment due to the presence of oxygen-containing functional groups on the DBD plasma-treated PP surface. Although the surface roughness of the DBD plasma-treated PP film gradually increased with increasing plasma treatment time, the DBD plasma treatment insignificantly affected the mechanical properties of the PP film. The DBD plasma treatment time was found to be optimized at 10 s. The DBD plasma-treated PP film was further immersed in an aqueous zinc nitrate (Zn(NO3)2) solution at different concentrations before being converted to ZnO particles with the use of a 2.5 M sodium hydroxide (NaOH) solution, followed by sonication. The highest amount of ZnO deposited on the DBD plasma-treated PP surface was about 0.26 wt.% at the optimum Zn(NO3)2 concentration of 0.5 M. The ZnO-deposited DBD plasma-treated PP film showed good antibacterial activities against gram-positive Staphylococcus auerus and gram-negative Escherichia coli.

Paisoonsin, Sutida; Pornsunthorntawee, Orathai; Rujiravanit, Ratana

2013-05-01

397

Antimycobacterial and Antibacterial Activity of Allium sativum Bulbs.  

PubMed

Tuberculosis is one of the major public health problems faced globally. Resistance of Mycobacterium tuberculosis to antitubercular agents has called for an urgent need to investigate newer drugs to combat tuberculosis. Garlic (Allium sativum) is an edible plant which has generated a lot of curiosity throughout human history as a medicinal plant. Garlic contains sulfur compounds like allicin, ajoene, allylmethyltrisulfide, diallyltrisulfide, diallyldisulphide and others which exhibit various biological properties like antimicrobial, anticancer, antioxidant, immunomodulatory, antiinflammatory, hypoglycemic, and cardiovascular effects. According to various traditional systems of medicine, garlic is one of the established remedies for tuberculosis. The objective of the current study was to investigate in vitro antimycobacterial activity as well as anti-bacterial activity of various extracts rich in specific phytoconstituents from garlic. Preparation of garlic extracts was done based on the chemistry of the constituents and their stability. The estimation of in vitro antimycobacterial activity of different garlic extracts was done using Resazurin microtire plate assay technique whereas activity of garlic oil was evaluated by colony count method. The antibacterial activity of extracts and oil was estimated by zone of inhibition method. Extracts of garlic rich in allicin and ajoene showed appreciable antimycobacterial activity as compared to standard drugs. Garlic oil demonstrated significant antibacterial activity, particularly against methicillin-resistant Staphylococcus aureus. PMID:25035540

Viswanathan, V; Phadatare, A G; Mukne, Alka

2014-05-01