Science.gov

Sample records for gram-positive antibacterial activity

  1. Identification of novel aminopiperidine derivatives for antibacterial activity against Gram-positive bacteria.

    PubMed

    Lee, Hee-Yeol; An, Kyung-Mi; Jung, Juyoung; Koo, Je-Min; Kim, Jeong-Geun; Yoon, Jong-Min; Lee, Myong-Jae; Jang, HyeonSoo; Lee, Hong-Sub; Park, Soobong; Kang, Jae-Hoon

    2016-07-01

    We have previously reported amidopiperidine derivatives as a novel peptide deformylase (PDF) inhibitor and evaluated its antibacterial activity against Gram-positive bacteria, but poor pharmacokinetic profiles have resulted in low efficacy in in vivo mouse models. In order to overcome these weaknesses, we newly synthesized aminopiperidine derivatives with remarkable antimicrobial properties and oral bioavailability, and also identified their in vivo efficacy against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE) and penicillin-resistant Streptococcus pneumoniae (PRSP). PMID:27173797

  2. Triterpene sapogenin-polyarginine conjugates exhibit promising antibacterial activity against Gram-positive strains.

    PubMed

    Na, Heiya; Li, Xiangpeng; Zou, Cunbin; Wang, Chenhong; Wang, Chao; Liu, Keliang

    2016-07-01

    Triterpene sapogenins are a group of biologically active compounds with antibacterial activity. However, the limited solubility and poor bioavailability of triterpene sapogenins restrict their therapeutic application. Polyarginine peptides are small cationic peptides with high affinities for multiple negatively charged cell membranes and possess moderate antibacterial activities. In this study, we designed and synthesized a series of sapogenin-polyarginine conjugates in which the triterpene sapogenin moiety was covalently appended to the positively charged polyarginine via click chemistry. A clear synergistic effect was found, and the conjugates exhibited potent and selective antibacterial activity against Gram-positive strains. Among them, BAc-R3 was the most promising compound, which was also proven to be nontoxic toward mammalian cells as well as stable in plasma. The mechanism of BAc-R3 primarily involves an interaction with the bacterial membrane, similar to that of antimicrobial peptides (AMPs). This scaffold design opens an avenue for the further development of novel antibiotics comprised of the combination of a peptide and a natural product. PMID:27209170

  3. Antibacterial Activity of Stenotrophomonas maltophilia Endolysin P28 against both Gram-positive and Gram-negative Bacteria

    PubMed Central

    Dong, Hongling; Zhu, Chaoyang; Chen, Jingyi; Ye, Xing; Huang, Yu-Ping

    2015-01-01

    Maltocin P28 is a phage-tail like bacteriocin produced by Stenotrophomonas maltophilia P28. The ORF8 of maltocin P28 gene cluster is predicted to encode an endolysin and we name it endolysin P28. Sequence analysis revealed that it contains the lysozyme_like superfamily conserved domain. Endolysin P28 has the four consensus motifs as that of Escherichia coli phage lambda gpR. In this study, endolysin P28 was expressed in E. coli BL21 (DE3) and purified with a C-terminal oligo-histidine tag. The antibacterial activity of endolysin P28 increased as the temperature rose from 25 to 45°C. Thermostability assays showed that endolysin P28 was stable up to 50°C, while its residual activity was reduced by 55% after treatment at 70°C for 30 min. Acidity and high salinity could enhance its antibacterial activity. Endolysin P28 exhibited a broad antibacterial activity against 14 out of 16 tested Gram-positive and Gram-negative bacteria besides S. maltophilia. Moreover, it could effectively lyse intact Gram-negative bacteria in the absence of ethylenediaminetetraacetic acid as an outer membrane permeabilizer. Therefore, the characteristics of endolysin P28 make it a potential therapeutic agent against multi-drug-resistant pathogens. PMID:26635765

  4. Indole trimers with antibacterial activity against Gram-positive organisms produced using combinatorial biocatalysis.

    PubMed

    McClay, Kevin; Mehboob, Shahila; Yu, Jerry; Santarsiero, Bernard D; Deng, Jiangping; Cook, James L; Jeong, Hyunyoung; Johnson, Michael E; Steffan, Robert J

    2015-12-01

    The I100V isoform of toluene-4-monooxygenase was used to catalyze the oxidative polymerization of anthranil and various indoles under mildly acidic conditions, favoring the production of trimers. Compounds produced in sufficient yield were purified and tested for their ability to inhibit the growth of B. anthracis, E. faecalis, L. monocytogenes, S. aureus, and in some cases, F. tularensis. 15 of the compounds displayed promising antibacterial activity (MIC < 5 µg/ml) against one or more of the strains tested, with the best MIC values being <0.8 µg/ml. All of these compounds had good selectivity, showing minimal cytotoxicity towards HepG2 cells. The structure was solved for six of the compounds that could be crystallized, revealing that minimally two classes of indole based trimers were produced. One compound class produced was a group of substituted derivatives of the natural product 2,2-bis(3-indolyl) indoxyl. The other group of compounds identified was classified as tryptanthrin-like compounds, all having multi-ring pendant groups attached at position 11 of tryptanthrin. One compound of particular interest, SAB-J85, had a structure that suggests that any compound, with a ring structure that can be activated by an oxygenase, might serve as a substrate for combinatorial biocatalysis. PMID:26112315

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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

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

    PubMed Central

    2014-01-01

    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

  7. Antibacterial Activity of Sphingoid Bases and Fatty Acids against Gram-Positive and Gram-Negative Bacteria

    PubMed Central

    Fischer, Carol L.; Drake, David R.; Dawson, Deborah V.; Blanchette, Derek R.; Brogden, Kim A.

    2012-01-01

    There is growing evidence that the role of lipids in innate immunity is more important than previously realized. How lipids interact with bacteria to achieve a level of protection, however, is still poorly understood. To begin to address the mechanisms of antibacterial activity, we determined MICs and minimum bactericidal concentrations (MBCs) of lipids common to the skin and oral cavity—the sphingoid bases d-sphingosine, phytosphingosine, and dihydrosphingosine and the fatty acids sapienic acid and lauric acid—against four Gram-negative bacteria and seven Gram-positive bacteria. Exact Kruskal-Wallis tests of these values showed differences among lipid treatments (P < 0.0001) for each bacterial species except Serratia marcescens and Pseudomonas aeruginosa. d-Sphingosine (MBC range, 0.3 to 19.6 μg/ml), dihydrosphingosine (MBC range, 0.6 to 39.1 μg/ml), and phytosphingosine (MBC range, 3.3 to 62.5 μg/ml) were active against all bacteria except S. marcescens and P. aeruginosa (MBC > 500 μg/ml). Sapienic acid (MBC range, 31.3 to 375.0 μg/ml) was active against Streptococcus sanguinis, Streptococcus mitis, and Fusobacterium nucleatum but not active against Escherichia coli, Staphylococcus aureus, S. marcescens, P. aeruginosa, Corynebacterium bovis, Corynebacterium striatum, and Corynebacterium jeikeium (MBC > 500 μg/ml). Lauric acid (MBC range, 6.8 to 375.0 μg/ml) was active against all bacteria except E. coli, S. marcescens, and P. aeruginosa (MBC > 500 μg/ml). Complete killing was achieved as early as 0.5 h for some lipids but took as long as 24 h for others. Hence, sphingoid bases and fatty acids have different antibacterial activities and may have potential for prophylactic or therapeutic intervention in infection. PMID:22155833

  8. Purification of equine neutrophil lysozyme and its antibacterial activity against gram-positive and gram-negative bacteria.

    PubMed

    Pellegrini, A; Waiblinger, S; Von Fellenberg, R

    1991-01-01

    Lysozyme from equine neutrophil granulocytes was isolated in a pure form by fast performance liquid chromatography, i.e. ion-exchange chromatography and reversed-phase chromatography. The lysozyme lysed Micrococcus luteus, Bacillus subtilis and Staphylococcus lentus and was also bactericidal against the Gram-negative bacteria Escherichia coli, Klebsiella pneumoniae, Bordetella bronchiseptica, and Serratia marcescens. Staphylococcus aureus and Staphylococcus epidermidis were not lysed. The lysozyme was only very slightly bactericidal for S. epidermidis and S. aureus. Equine neutrophil lysozyme was found to be bactericidal for Gram-positive as well as for Gram-negative bacteria without further treatment. Equine and chicken egg white lysozymes were found to be immunologically related when examined using specific antisera against each of them. Both lysozymes also had very similar specific enzymatic activities against M. luteus membranes. PMID:1803722

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    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 Å, c = 6.876 Å for x Ag = 0.05, a = b = 9.443 Å, c = 6.875 Å for x Ag = 0.2, and a = b = 9.445 Å, c = 6.877 Å for x Ag = 0.3 are in good agreement with the standard of a = b = 9.418 Å, c = 6.884 Å (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).

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

    PubMed Central

    2012-01-01

    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 Å, c = 6.876 Å for xAg = 0.05, a = b = 9.443 Å, c = 6.875 Å for xAg = 0.2, and a = b = 9.445 Å, c = 6.877 Å for xAg = 0.3 are in good agreement with the standard of a = b = 9.418 Å, c = 6.884 Å (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

  11. Significance of postgrowth processing of ZnO nanostructures on antibacterial activity against gram-positive and gram-negative bacteria

    PubMed Central

    Mehmood, Shahid; Rehman, Malik A; Ismail, Hammad; Mirza, Bushra; Bhatti, Arshad S

    2015-01-01

    In this work, we highlighted the effect of surface modifications of one-dimensional (1D) ZnO nanostructures (NSs) grown by the vapor–solid mechanism on their antibacterial activity. Two sets of ZnO NSs were modified separately – one set was modified by annealing in an Ar environment, and the second set was modified in O2 plasma. Annealing in Ar below 800°C resulted in a compressed lattice, which was due to removal of Zn interstitials and increased O vacancies. Annealing above 1,000°C caused the formation of a new prominent phase, Zn2SiO4. Plasma oxidation of the ZnO NSs caused an expansion in the lattice due to the removal of O vacancies and incorporation of excess O. Photoluminescence (PL) spectroscopy was employed for the quantification of defects associated with Zn and O in the as-grown and processed ZnO NS. Two distinct bands were observed, one in the ultraviolet (UV) region, due to interband transitions, and other in the visible region, due to defects associated with Zn and O. PL confirmed the surface modification of ZnO NS, as substantial decrease in intensities of visible band was observed. Antibacterial activity of the modified ZnO NSs demonstrated that the surface modifications by Ar annealing limited the antibacterial characteristics of ZnO NS against Staphylococcus aureus. However, ZnO NSs annealed at 1,000°C or higher showed a remarkable antibacterial activity against Escherichia coli. O2 plasma–treated NS showed appreciable antibacterial activity against both E. coli and S. aureus. The minimum inhibition concentration was determined to be 0.5 mg/mL and 1 mg/mL for Ar-annealed and plasma-oxidized ZnO NS, respectively. It was thus proved that the O content at the surface of the ZnO NS was crucial to tune the antibacterial activity against both selected gram-negative (E. coli) and gram-positive (S. aureus) bacterial species. PMID:26213466

  12. Blue green alga mediated synthesis of gold nanoparticles and its antibacterial efficacy against Gram positive organisms.

    PubMed

    Suganya, K S Uma; Govindaraju, K; Kumar, V Ganesh; Dhas, T Stalin; Karthick, V; Singaravelu, G; Elanchezhiyan, M

    2015-02-01

    Biofunctionalized gold nanoparticles (AuNPs) play an important role in design and development of nanomedicine. Synthesis of AuNPs from biogenic materials is environmentally benign and possesses high bacterial inhibition and bactericidal properties. In the present study, blue green alga Spirulina platensis protein mediated synthesis of AuNPs and its antibacterial activity against Gram positive bacteria is discussed. AuNPs were characterized using Ultraviolet-visible (UV-vis) spectroscopy, Fluorescence spectroscopy, Fourier Transform-Infrared (FTIR) spectroscopy, Raman spectroscopy, High Resolution-Transmission Electron Microscopy (HR-TEM) and Energy Dispersive X-ray analysis (EDAX). Stable, well defined AuNPs of smaller and uniform shape with an average size of ~ 5 nm were obtained. The antibacterial efficacy of protein functionalized AuNPs were tested against Gram positive organisms Bacillus subtilis and Staphylococcus aureus. PMID:25492207

  13. In vitro antibacterial activity of AZD0914, a new spiropyrimidinetrione DNA gyrase/topoisomerase inhibitor with potent activity against Gram-positive, fastidious Gram-Negative, and atypical bacteria.

    PubMed

    Huband, Michael D; Bradford, Patricia A; Otterson, Linda G; Basarab, Gregory S; Kutschke, Amy C; Giacobbe, Robert A; Patey, Sara A; Alm, Richard A; Johnstone, Michele R; Potter, Marie E; Miller, Paul F; Mueller, John P

    2015-01-01

    AZD0914 is a new spiropyrimidinetrione bacterial DNA gyrase/topoisomerase inhibitor with potent in vitro antibacterial activity against key Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes, and Streptococcus agalactiae), fastidious Gram-negative (Haemophilus influenzae and Neisseria gonorrhoeae), atypical (Legionella pneumophila), and anaerobic (Clostridium difficile) bacterial species, including isolates with known resistance to fluoroquinolones. AZD0914 works via inhibition of DNA biosynthesis and accumulation of double-strand cleavages; this mechanism of inhibition differs from those of other marketed antibacterial compounds. AZD0914 stabilizes and arrests the cleaved covalent complex of gyrase with double-strand broken DNA under permissive conditions and thus blocks religation of the double-strand cleaved DNA to form fused circular DNA. Whereas this mechanism is similar to that seen with fluoroquinolones, it is mechanistically distinct. AZD0914 exhibited low frequencies of spontaneous resistance in S. aureus, and if mutants were obtained, the mutations mapped to gyrB. Additionally, no cross-resistance was observed for AZD0914 against recent bacterial clinical isolates demonstrating resistance to fluoroquinolones or other drug classes, including macrolides, β-lactams, glycopeptides, and oxazolidinones. AZD0914 was bactericidal in both minimum bactericidal concentration and in vitro time-kill studies. In in vitro checkerboard/synergy testing with 17 comparator antibacterials, only additivity/indifference was observed. The potent in vitro antibacterial activity (including activity against fluoroquinolone-resistant isolates), low frequency of resistance, lack of cross-resistance, and bactericidal activity of AZD0914 support its continued development. PMID:25385112

  14. In Vitro Antibacterial Activity of AZD0914, a New Spiropyrimidinetrione DNA Gyrase/Topoisomerase Inhibitor with Potent Activity against Gram-Positive, Fastidious Gram-Negative, and Atypical Bacteria

    PubMed Central

    Bradford, Patricia A.; Otterson, Linda G.; Basarab, Gregory S.; Kutschke, Amy C.; Giacobbe, Robert A.; Patey, Sara A.; Alm, Richard A.; Johnstone, Michele R.; Potter, Marie E.; Miller, Paul F.; Mueller, John P.

    2014-01-01

    AZD0914 is a new spiropyrimidinetrione bacterial DNA gyrase/topoisomerase inhibitor with potent in vitro antibacterial activity against key Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes, and Streptococcus agalactiae), fastidious Gram-negative (Haemophilus influenzae and Neisseria gonorrhoeae), atypical (Legionella pneumophila), and anaerobic (Clostridium difficile) bacterial species, including isolates with known resistance to fluoroquinolones. AZD0914 works via inhibition of DNA biosynthesis and accumulation of double-strand cleavages; this mechanism of inhibition differs from those of other marketed antibacterial compounds. AZD0914 stabilizes and arrests the cleaved covalent complex of gyrase with double-strand broken DNA under permissive conditions and thus blocks religation of the double-strand cleaved DNA to form fused circular DNA. Whereas this mechanism is similar to that seen with fluoroquinolones, it is mechanistically distinct. AZD0914 exhibited low frequencies of spontaneous resistance in S. aureus, and if mutants were obtained, the mutations mapped to gyrB. Additionally, no cross-resistance was observed for AZD0914 against recent bacterial clinical isolates demonstrating resistance to fluoroquinolones or other drug classes, including macrolides, β-lactams, glycopeptides, and oxazolidinones. AZD0914 was bactericidal in both minimum bactericidal concentration and in vitro time-kill studies. In in vitro checkerboard/synergy testing with 17 comparator antibacterials, only additivity/indifference was observed. The potent in vitro antibacterial activity (including activity against fluoroquinolone-resistant isolates), low frequency of resistance, lack of cross-resistance, and bactericidal activity of AZD0914 support its continued development. PMID:25385112

  15. Non-Aqueous Glycerol Monolaurate Gel Exhibits Antibacterial and Anti-Biofilm Activity against Gram-Positive and Gram-Negative Pathogens

    PubMed Central

    Mueller, Elizabeth A.; Schlievert, Patrick M.

    2015-01-01

    Background Skin and surgical infections due to Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii are causes of patient morbidity and increased healthcare costs. These organisms grow planktonically and as biofilms, and many strains exhibit antibiotic resistance. This study examines the antibacterial and anti-biofilm activity of glycerol monolaurate (GML), as solubilized in a non-aqueous vehicle (5% GML Gel), as a novel, broadly-active topical antimicrobial. The FDA has designated GML as generally recognized as safe for human use, and the compound is commonly used in the cosmetic and food industries. Methods In vitro, bacterial strains in broths and biofilms were exposed to GML Gel, and effects on bacterial colony-forming units (CFUs) were assessed. In vivo,subcutaneous incisions were made in New Zealand white rabbits; the incisions were closed with four sutures. Bacterial strains were painted onto the incision sites, and then GML Gel or placebo was liberally applied to cover the sites completely. Rabbits were allowed to awaken and were examined for CFUs as a function of exposure time. Results In vitro, GML Gel was bactericidal for all broth culture and biofilm organisms in <1 hour and <4 hour, respectively; no CFUs were detected after the entire 24 h test period. In vivo, GML Gel inhibited bacterial growth in the surgical incision sites, compared to no growth inhibition in controls. GML Gel significantly reduced inflammation, as viewed by lack of redness in and below the incision sites. Conclusions Our findings suggest that 5% GML Gel is useful as a potent topical antibacterial and anti-inflammatory agent for prevention of infections. PMID:25799455

  16. Robenidine Analogues as Gram-Positive Antibacterial Agents.

    PubMed

    Abraham, Rebecca J; Stevens, Andrew J; Young, Kelly A; Russell, Cecilia; Qvist, Anastasia; Khazandi, Manouchehr; Wong, Hui San; Abraham, Sam; Ogunniyi, Abiodun D; Page, Stephen W; O'Handley, Ryan; McCluskey, Adam; Trott, Darren J

    2016-03-10

    Robenidine, 1 (2,2'-bis[(4-chlorophenyl)methylene]carbonimidic dihydrazide), was active against MRSA and VRE with MIC's of 8.1 and 4.7 μM, respectively. SAR revealed tolerance for 4-Cl isosteres with 4-F (8), 3-F (9), 3-CH3 (22), and 4-C(CH3)3 (27) (23.7-71 μM) and with 3-Cl (3), 4-CH3 (21), and 4-CH(CH3)2 (26) (8.1-13.0 μM). Imine carbon alkylation identified a methyl/ethyl binding pocket that also accommodated a CH2OH moiety (75; 2,2'-bis[1-(4-chlorophenyl)-2-hydroxyethylidene]carbonimidic dihydrazide). Analogues 1, 27 (2,2'-bis{[4-(1,1-dimethylethyl)phenyl]methylene}carbonimidic dihydrazide), and 69 (2,2'-bis[1-(4-chlorophenyl)ethylidene]carbonimidic dihydrazide hydrochloride) were active against 24 clinical MRSA and MSSA isolates. No dose-limiting cytotoxicity at ≥2× MIC or hemolysis at ≥8× MIC was observed. Polymyxin B addition engendered Escherichia coli and Pseudomonas aeruginosa Gram-negative activity MIC's of 4.2-21.6 μM. 1 and 75 displayed excellent microsomal stability, intrinsic clearance, and hepatic extraction ratios with T1/2 > 247 min, CLint < 7 μL/min/mg protein, and EH < 0.22 in both human and mouse liposomes for 1 and in human liposomes for 75. PMID:26765953

  17. Biosynthesis of silver nanoparticles and its antibacterial and antifungal activities towards Gram-positive, Gram-negative bacterial strains and different species of Candida fungus.

    PubMed

    Rahisuddin; Al-Thabaiti, Shaeel Ahmed; Khan, Zaheer; Manzoor, Nikhat

    2015-09-01

    Biomimetic and economic method for the synthesis of silver nanoparticles (AgNPs) with controlled size has been reported in presence of shape-directing cetlytrimethylammonium bromide (CTAB). Biochemical reduction of Ag(+) ions in micellar solution with an aqueous lemon extract produced spherical and polyhedral AgNPs with size ranging from 15 to 30 nm. The influence of [CTAB] and [lemon extract] on the size of particles, fraction of metallic silver and their antimicrobial properties is discussed. The AgNPs were evaluated for their antimicrobial activities (antibacterial and antifungal) against different pathogenic organisms. For this purpose, AgNPs were tested against two model bacteria (Staphylococcus aureus (MTCC3160) and Escherichia coli (MTCC405)) and three species of Candida fungus (Candida albicans (ATCC90028), Candida glabrata (ATCC90030) and Candida tropicalis (ATCC750). AgNPs were found to be highly toxic towards both bacteria. The inhibition action was due to the structural changes in the protein cell wall. PMID:26017756

  18. Development of a five-hour radiometric serum antibacterial assay for gram-positive cocci

    SciTech Connect

    Beckwith, D.G.; Guidon, P.T. Jr.

    1981-03-01

    A preliminary report on a 5-hr radiometric serum antibacterial assay (ABA) for Gram-positive cocci is presented. The method agreed within +- one twofold dilution with static ABA endpoints in 24/26 (92%) of the assays and with cidal ABA end-points in 23/26 (88%) of the assays performed.

  19. Three novel B-type mannose-specific lectins of Cynoglossus semilaevis possess varied antibacterial activities against Gram-negative and Gram-positive bacteria.

    PubMed

    Sun, Yuan-yuan; Liu, Li; Li, Jun; Sun, Li

    2016-02-01

    Lectins are a group of sugar-binding proteins that are important factors of the innate immune system. In this study, we examined, in a comparative manner, the expression and function of three Bulb-type (B-type) mannose-specific lectins (named CsBML1, CsBML2, and CsBML3) from tongue sole. All three lectins possess three repeats of the conserved mannose binding motif QXDXNXVXY. Expression of CsBML1, CsBML2, and CsBML3 was most abundant in liver and upregulated by bacterial infection. Recombinant (r) CsBML1, CsBML2, and CsBML3 bound to a wide arrange of bacteria in a dose-dependent manner and with different affinities. All three lectins displayed mannose-specific and calcium-dependent agglutinating capacities but differed in agglutinating profiles. rCsBML1 and rCsBML2, but not rCsBML3, killed target bacteria in vitro and inhibited bacterial dissemination in fish tissues in vivo. These results indicate for the first time that in teleost, different members of B-type mannose-specific lectins likely play different roles in antibacterial immunity. PMID:26455466

  20. Antibacterial Efficacy of Eravacycline In Vivo against Gram-Positive and Gram-Negative Organisms.

    PubMed

    Monogue, Marguerite L; Thabit, Abrar K; Hamada, Yukihiro; Nicolau, David P

    2016-08-01

    Members of the tetracycline class are frequently classified as bacteriostatic. However, recent findings have demonstrated an improved antibacterial killing profile, often achieving ≥3 log10 bacterial count reduction, when such antibiotics have been given for periods longer than 24 h. We aimed to study this effect with eravacycline, a novel fluorocycline, given in an immunocompetent murine thigh infection model over 72 h against two methicillin-resistant Staphylococcus aureus (MRSA) isolates (eravacycline MICs = 0.03 and 0.25 μg/ml) and three Enterobacteriaceae isolates (eravacycline MICs = 0.125 to 0.25 μg/ml). A humanized eravacycline regimen, 2.5 mg/kg of body weight given intravenously (i.v.) every 12 h (q12h), demonstrated progressively enhanced activity over the 72-h study period. A cumulative dose response in which bacterial density was reduced by more than 3 log10 CFU at 72 h was noted over the study period in the two Gram-positive isolates, and eravacycline performed similarly to comparator antibiotics (tigecycline, linezolid, and vancomycin). A cumulative dose response with eravacycline and comparators (tigecycline and meropenem) over the study period was also observed in the Gram-negative isolates, although more variability in bacterial killing was observed for all antibacterial agents. Overall, a bacterial count reduction of ≥3 log was achieved in one of the three isolates with both eravacycline and tigecycline, while meropenem achieved a similar endpoint against two of the three isolates. Bactericidal activity is typically defined in vitro over 24 h; however, extended regimen studies in vivo may demonstrate an improved correlation with clinical outcomes by better identification of antimicrobial effects. PMID:27353265

  1. Activity of quinolones against gram-positive cocci: clinical features.

    PubMed

    Giamarellou, H

    1995-01-01

    The potential role of the commercially available fluoroquinolones in the treatment of Gram-positive infections is discussed on the basis of data obtained from animal experiments and clinical trials. In respiratory tract infections, and particularly in community-acquired pneumonia, it is evident that the presently available quinolones cannot be prescribed empirically as first-line therapy because of their borderline activity against Streptococcus pneumoniae and anaerobes. Reports of pneumococcal seeding in other tissues during quinolone therapy render their administration a debatable issue. Experience in endocarditis is limited to the use of ciprofloxacin plus rifampicin in intravenous drug users with right-sided Staphylococcus aureus endocarditis. Patients with staphylococcal osteomyelitis are included among cases of other bone infections. In noncontrolled studies ciprofloxacin, ofloxacin and pefloxacin attained a staphylococcal eradication rate ranging from 70 to 100%, while the addition of rifampicin has been proven to reduce the emergence of resistant mutants during therapy. In soft tissue and skin structure infections that also involve Gram-negative bacteria, ciprofloxacin and ofloxacin eradicated 72.6 and 89% of staphylococci, respectively; however, the presence of diabetes or vascular disease compromised the success of treatment. In staphylococcal peritonitis complicating continuous ambulatory peritoneal dialysis, results with ciprofloxacin given intravenously or intraperitoneally were promising. In infections in neutropenic hosts, success of prophylaxis or therapy is still not clear, since colonisation and breakthrough bacteraemias with viridans streptococci and staphylococci have been reported. Furthermore, therapeutic results are compromised by the low response rate in Gram-positive infections. Despite the reported clinical efficacy of the newer fluoroquinolones, physicians should be alerted to the emergence of staphylococci resistant to fluoroquinolones

  2. [Comparative urinary bactericidal activity of oral antibiotics against gram-positive pathogens].

    PubMed

    Bedenić, Branka; Budimir, Ana; Gverić, Ana; Plecko, Vanda; Vranes, Jasmina; Bubonja-Sonje, Marina; Kalenić, Smilja

    2012-01-01

    In routine bacteriological laboratories the antibacterial activity of antibiotics is determined by in vitro testing, usually by disk-diffusion test. However, in vitro testing does not always reflect antibacterial efficiency of antibiotics in vivo. In this investigation, the urine samples obtained in a single oral dose pharmacokinetic study were examined for their bactericidal activity against a range of relevant Gram-positive urinary tract pathogens. Urinary bactericidal activity of linezolid had been previously compared with ciprofloxacin but not with other oral antibiotics such as beta-lactams. Linezolid showed satisfactory urinary bactericidal titres throughout the whole testing period against all Gram-positive cocci. Fluoroquinolones displayed high and persisting levels of urinary bactericidal activity against staphylococci, but their activity against enterococci was weaker. According to the results of ex-vivo testing amoxycillin could be recommended only for infections caused by E. faecalis. Amoxycillin combined with clavulanic acid can be considered as a therapeutic option for infections caused by S. saprophyticus and E. faecalis. Older cephalosporins had high titres only against S. saprophyticus. Their drawback is a short elimination half-time in urine resulting in rapid decrease of urinary bactericidal titers during dosing interval. Furthermore, they do not show activity against enterococci due to their intrinsic resistance to cephalosporins. PMID:22930932

  3. Charged Nonclassical Antifolates with Activity Against Gram-Positive and Gram-Negative Pathogens.

    PubMed

    Scocchera, Eric; Reeve, Stephanie M; Keshipeddy, Santosh; Lombardo, Michael N; Hajian, Behnoush; Sochia, Adrienne E; Alverson, Jeremy B; Priestley, Nigel D; Anderson, Amy C; Wright, Dennis L

    2016-07-14

    Although classical, negatively charged antifolates such as methotrexate possess high affinity for the dihydrofolate reductase (DHFR) enzyme, they are unable to penetrate the bacterial cell wall, rendering them poor antibacterial agents. Herein, we report a new class of charged propargyl-linked antifolates that capture some of the key contacts common to the classical antifolates while maintaining the ability to passively diffuse across the bacterial cell wall. Eight synthesized compounds exhibit extraordinary potency against Gram-positive S. aureus with limited toxicity against mammalian cells and good metabolic profile. High resolution crystal structures of two of the compounds reveal extensive interactions between the carboxylate and active site residues through a highly organized water network. PMID:27437079

  4. Lipoglycopeptide Antibacterial Agents in Gram-Positive Infections: A Comparative Review.

    PubMed

    Van Bambeke, Françoise

    2015-12-01

    Oritavancin, telavancin, and dalbavancin are recently marketed lipoglycopeptides that exhibit remarkable differences to conventional molecules. While dalbavancin inhibits the late stages of peptidoglycan synthesis by mainly impairing transglycosylase activity, oritavancin and telavancin anchor in the bacterial membrane by the lipophilic side chain linked to their disaccharidic moiety, disrupting membrane integrity and causing bacteriolysis. Oritavancin keeps activity against vancomycin-resistant enterocococci, being a stronger inhibitor of transpeptidase than of transglycosylase activity. These molecules have potent activity against Gram-positive organisms, most notably staphylococci (including methicillin-resistant Staphylococcus aureus and to some extent vancomycin-intermediate S. aureus), streptococci (including multidrug-resistant pneumococci), and Clostridia. All agents are indicated for the treatment of acute bacterial skin and skin structure infections, and telavancin, for hospital-acquired and ventilator-associated bacterial pneumonia. While telavancin is administered daily at 10 mg/kg, the remarkably long half-lives of oritavancin and dalbavancin allow for infrequent dosing (single dose of 1200 mg for oritavancin and 1000 mg at day 1 followed by 500 mg at day 8 for dalbavancin), which could be exploited in the future for outpatient therapy. Among possible safety issues evidenced during clinical development were an increased risk of developing osteomyelitis with oritavancin; taste disturbance, nephrotoxicity, and risk of corrected QT interval prolongation (especially in the presence of at-risk co-medications) with telavancin; and elevation of hepatic enzymes with dalbavancin. Interference with coagulation tests has been reported with oritavancin and telavancin. These drugs proved non-inferior to conventional treatments in clinical trials but their advantages may be better evidenced upon future evaluation in more severe infections. PMID:26603874

  5. Gram-negative and gram-positive antibacterial properties of the whole plant extract of willow herb (Epilobium angustifolium).

    PubMed

    Bartfay, Wally J; Bartfay, Emma; Johnson, Julia Green

    2012-01-01

    The emergence of new pathogens and the increase in the number of multidrug-resistant strains in well-established pathogens during the past decade represent a growing public health concern globally. With the current lack of research and development of new antibiotics by large pharmaceutical companies due to poor financial returns, new alternatives need to be explored including natural herbal or plant-based extracts with reported antibacterial properties. Willow herb (Epilobium angustifolium) preparations have been used in traditional aboriginal and folk medicine preparations externally as an antiphlogistic to treat prostate and gastrointestinal disorders and as an antiseptic to treat infected wounds. The authors hypothesized that a whole plant extract of willow herb would exhibit antimicrobial properties on a variety of both Gram-positive and gram-negative bacteria in culture. The authors found that, in comparison to growth controls, willow herb extract significantly inhibited the growth of Micrococcus luteus (p < .01), Staphylococcus aureus (p < .05), Escherichia coli (p < .001), and Pseudomonas aeruginosa (p < .001). They also found that willow herb extract inhibited the growth of bacteria in culture more effectively than vancomycin (p < .05) or tetracycline (p < .004). These results provide preliminary support for the traditional folkloric claim that the plant willow herb possesses antibacterial properties against a variety of gram-positive and gram-negative bacteria. Given that whole plant extract was utilized for this study, further investigations are warranted to determine which specific part of the plant (i.e., leaves, stem, roots, and flowers) possess the antibacterial properties. PMID:21208973

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

    PubMed Central

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

    2013-01-01

    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 μL 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

  7. Armadillidin: a novel glycine-rich antibacterial peptide directed against gram-positive bacteria in the woodlouse Armadillidium vulgare (Terrestrial Isopod, Crustacean).

    PubMed

    Herbinière, Juline; Braquart-Varnier, Christine; Grève, Pierre; Strub, Jean-Marc; Frère, Jacques; Van Dorsselaer, Alain; Martin, Gilbert

    2005-01-01

    We report the isolation and the characterization of a novel antibacterial peptide from hemocytes of the woodlouse Armadillidium vulgare, naturally infected or uninfected by Wolbachia, an intracellular Gram-negative bacterium. This molecule displays antibacterial activity against Gram-positive bacteria despite its composition which classes it into the glycine-rich antibacterial peptide family, usually directed against fungi and Gram-negative bacteria. The complete sequence was determined by a combination of Edman degradation, mass spectrometry and cDNA cloning using a hemocyte library. The mature peptide (53 residues) has a 5259 Da molecular mass and is post-translationally modified by a C-terminal amidation. This peptide is characterized by a high level of glycine (47%) and a fivefold repeated motif GGGFH(R/S). As no evident sequence homology to other hitherto described antibacterial peptides has been found out, this antibacterial peptide was named armadillidin. Armadillidin is constitutively expressed in hemocytes and appears to be specific of A. vulgare. PMID:15752546

  8. Two Active Forms of UDP-N-Acetylglucosamine Enolpyruvyl Transferase in Gram-Positive Bacteria

    PubMed Central

    Du, Wensheng; Brown, James R.; Sylvester, Daniel R.; Huang, Jianzhong; Chalker, Alison F.; So, Chi Y.; Holmes, David J.; Payne, David J.; Wallis, Nicola G.

    2000-01-01

    Gene sequences encoding the enzymes UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) from many bacterial sources were analyzed. It was shown that whereas gram-negative bacteria have only one murA gene, gram-positive bacteria have two distinct genes encoding these enzymes which have possibly arisen from gene duplication. The two murA genes of the gram-positive organism Streptococcus pneumoniae were studied further. Each of the murA genes was individually inactivated by allelic replacement. In each case, the organism was viable despite losing one of its murA genes. However, when attempts were made to construct a double-deletion strain, no mutants were obtained. This indicates that both genes encode active enzymes that can substitute for each other, but that the presence of a MurA function is essential to the organism. The two genes were further cloned and overexpressed, and the enzymes they encode were purified. Both enzymes catalyzed the transfer of enolpyruvate from phosphoenolpyruvate to UDP-N-acetylglucosamine, confirming they are both active UDP-N-acetylglucosamine enolpyruvyl transferases. The catalytic parameters of the two enzymes were similar, and they were both inhibited by the antibiotic fosfomycin. PMID:10894720

  9. Effect of kojic acid-grafted-chitosan oligosaccharides as a novel antibacterial agent on cell membrane of gram-positive and gram-negative bacteria.

    PubMed

    Liu, Xiaoli; Xia, Wenshui; Jiang, Qixing; Xu, Yanshun; Yu, Peipei

    2015-09-01

    Our work here, for the first time, reported the antibacterial activity of kojic acid-grafted-chitosan oligosaccharides (COS/KA) against three gram-positive and three gram-negative bacteria. Integrity of cell membrane, outer membrane (OM) and inner membrane (IM) permeabilization assay, alkaline phosphatase (ALP) and glucose-6-phosphate dehydrogenase (G6PDH) assay, and SDS-PAGE assay techniques were used to investigate the interactions between COS/KA and bacterial membranes. The antibacterial activity of COS/KA was higher than those of unmodified COS. The electric conductivity of bacteria suspensions increased, followed by increasing of the units of average release for ALP and G6PDH. COS/KA can also rapidly increase the 1-N-phenylanphthylamine (NPN) uptake and the release of β-galactosidase via increasing the permeability of OM and IM in Escherichia coli. SDS-PAGE indicated the content of cellular soluble proteins decreased significantly in COS/KA-treated bacteria. Hence, COS/KA has potential in food industry and biomedical sciences. PMID:25682520

  10. 18β-Glycyrrhetinic Acid Derivatives Possessing a Trihydroxylated A Ring Are Potent Gram-Positive Antibacterial Agents.

    PubMed

    Huang, Li-Rong; Hao, Xiao-Jiang; Li, Qi-Ji; Wang, Dao-Ping; Zhang, Jian-Xin; Luo, Heng; Yang, Xiao-Sheng

    2016-04-22

    The oleanane-type triterpene 18β-glycyrrhetinic acid (1) was modified chemically through the introduction of a trihydroxylated A ring and an ester moiety at C-20 to enhance its antibacterial activity. Compounds 22, 23, 25, 28, 29, 31, and 32 showed more potent inhibitory activity against Streptomyces scabies than the positive control, streptomycin. Additionally, the inhibitory activity of the most potent compound, 29, against Bacillus subtilis, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus was greater than that of the positive controls. The antibacterial mode of action of the active derivatives involved the regulation of the expression of genes associated with peptidoglycans, the respiratory metabolism, and the inherent virulence factors found in bacteria, as determined through a quantitative real-time reverse transcriptase PCR assay. PMID:26928299

  11. Gramicidin A Mutants with Antibiotic Activity against Both Gram-Positive and Gram-Negative Bacteria.

    PubMed

    Zerfas, Breanna L; Joo, Yechaan; Gao, Jianmin

    2016-03-17

    Antimicrobial peptides (AMPs) have shown potential as alternatives to traditional antibiotics for fighting infections caused by antibiotic-resistant bacteria. One promising example of this is gramicidin A (gA). In its wild-type sequence, gA is active by permeating the plasma membrane of Gram-positive bacteria. However, gA is toxic to human red blood cells at similar concentrations to those required for it to exert its antimicrobial effects. Installing cationic side chains into gA has been shown to lower its hemolytic activity while maintaining the antimicrobial potency. In this study, we present the synthesis and the antibiotic activity of a new series of gA mutants that display cationic side chains. Specifically, by synthesizing alkylated lysine derivatives through reductive amination, we were able to create a broad selection of structures with varied activities towards Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). Importantly, some of the new mutants were observed to have an unprecedented activity towards important Gram-negative pathogens, including Escherichia coli, Klebsiella pneumoniae and Psuedomonas aeruginosa. PMID:26918268

  12. Design and characterization of novel antimicrobial peptides, R-BP100 and RW-BP100, with activity against Gram-negative and Gram-positive bacteria.

    PubMed

    Torcato, Inês M; Huang, Yen-Hua; Franquelim, Henri G; Gaspar, Diana; Craik, David J; Castanho, Miguel A R B; Troeira Henriques, Sónia

    2013-03-01

    BP100 is a short cationic antimicrobial peptide with a mechanism of action dependent on peptide-lipid interactions and microbial surface charge neutralization. Although active against Gram-negative bacteria, BP100 is inactive against Gram-positive bacteria. In this study we report two newly designed BP100 analogues, RW-BP100 and R-BP100 that have the Tyr residue replaced with a Trp and/or the Lys residues replaced with an Arg. The new analogues in addition to being active against Gram-negative bacteria, possess activity against all tested Gram-positive bacteria. Mechanistic studies using atomic force microscopy, surface plasmon resonance and fluorescence methodologies reveal that the antibacterial efficiency follows the affinity for bacterial membrane. The studies suggest that the activity of BP100 and its analogues against Gram-negative bacteria is mainly driven by electrostatic interactions with the lipopolysaccharide layer and is followed by binding to and disruption of the inner membrane, whereas activity against Gram-positive bacteria, in addition to electrostatic attraction to the exposed lipoteichoic acids, requires an ability to more deeply insert in the membrane environment, which is favoured with Arg residues and is facilitated in the presence of a Trp residue. Knowledge on the mechanism of action of these antimicrobial peptides provides information that assists in the design of antimicrobials with higher efficacy and broader spectra of action, but also on the design of peptides with higher specificity if required. PMID:23246973

  13. Tedizolid: a novel oxazolidinone with potent activity against multidrug-resistant gram-positive pathogens.

    PubMed

    Zhanel, George G; Love, Riley; Adam, Heather; Golden, Alyssa; Zelenitsky, Sheryl; Schweizer, Frank; Gorityala, Bala; Lagacé-Wiens, Philippe R S; Rubinstein, Ethan; Walkty, Andrew; Gin, Alfred S; Gilmour, Matthew; Hoban, Daryl J; Lynch, Joseph P; Karlowsky, James A

    2015-02-01

    Tedizolid phosphate is a novel oxazolidinone prodrug (converted to the active form tedizolid by phosphatases in vivo) that has been developed and recently approved (June 2014) by the United States FDA for the treatment of acute bacterial skin and skin structure infections (ABSSSIs) caused by susceptible Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). Tedizolid is an oxazolidinone, but differs from other oxazolidinones by possessing a modified side chain at the C-5 position of the oxazolidinone nucleus which confers activity against certain linezolid-resistant pathogens and has an optimized C- and D-ring system that improves potency through additional binding site interactions. The mechanism of action of tedizolid is similar to other oxazolidinones and occurs through inhibition of bacterial protein synthesis by binding to 23S ribosomal RNA (rRNA) of the 50S subunit of the ribosome. As with other oxazolidinones, the spontaneous frequency of resistance development to tedizolid is low. Tedizolid is four- to eightfold more potent in vivo than linezolid against all species of staphylococci, enterococci, and streptococci, including drug-resistant phenotypes such as MRSA and vancomycin-resistant enterococci (VRE) and linezolid-resistant phenotypes. Importantly, tedizolid demonstrates activity against linezolid-resistant bacterial strains harboring the horizontally transmissible cfr gene, in the absence of certain ribosomal mutations conferring reduced oxazolidinone susceptibility. With its half-life of approximately 12 h, tedizolid is dosed once daily. It demonstrates linear pharmacokinetics, has a high oral bioavailability of approximately 90 %, and is primarily excreted by the liver as an inactive, non-circulating sulphate conjugate. Tedizolid does not require dosage adjustment in patients with any degree of renal dysfunction or hepatic dysfunction. Studies in animals have demonstrated that the pharmacodynamic parameter most closely

  14. In Vitro Activities of the Ketolide HMR 3647 against Recent Gram-Positive Clinical Isolates and Haemophilus influenzae

    PubMed Central

    Barry, Arthur L.; Fuchs, Peter C.; Brown, Steven D.

    1998-01-01

    The ketolide HMR 3647 (previously RU 66647) was evaluated against 2,563 recent clinical isolates of gram-positive pathogens and 200 Haemophilus influenzae isolates. HMR 3647 was active against macrolide-resistant streptococci, including pneumococci, but was not active against macrolide- or lincosamide-resistant staphylococci. Against H. influenzae, the potency of HMR 3647 was similar to that of azithromycin. PMID:9687424

  15. In Vitro Activity of Ozenoxacin against Quinolone-Susceptible and Quinolone-Resistant Gram-Positive Bacteria

    PubMed Central

    López, Y.; Tato, M.; Espinal, P.; Garcia-Alonso, F.; Gargallo-Viola, D.; Cantón, R.

    2013-01-01

    In vitro activity of ozenoxacin, a novel nonfluorinated topical (L. D. Saravolatz and J. Leggett, Clin. Infect. Dis. 37:1210–1215, 2003) quinolone, was compared with the activities of other quinolones against well-characterized quinolone-susceptible and quinolone-resistant Gram-positive bacteria. Ozenoxacin was 3-fold to 321-fold more active than other quinolones. Ozenoxacin could represent a first-in-class nonfluorinated quinolone for the topical treatment of a broad range of dermatological infections. PMID:24080666

  16. Biosynthetic Pathway for Mannopeptimycins, Lipoglycopeptide Antibiotics Active against Drug-Resistant Gram-Positive Pathogens

    PubMed Central

    Magarvey, Nathan A.; Haltli, Brad; He, Min; Greenstein, Michael; Hucul, John A.

    2006-01-01

    The mannopeptimycins are a novel class of lipoglycopeptide antibiotics active against multidrug-resistant pathogens with potential as clinically useful antibacterials. This report is the first to describe the biosynthesis of this novel class of mannosylated lipoglycopeptides. Included here are the cloning, sequencing, annotation, and manipulation of the mannopeptimycin biosynthetic gene cluster from Streptomyces hygroscopicus NRRL 30439. Encoded by genes within the mannopeptimycin biosynthetic gene cluster are enzymes responsible for the generation of the hexapeptide core (nonribosomal peptide synthetases [NRPS]) and tailoring reactions (mannosylation, isovalerylation, hydroxylation, and methylation). The NRPS system is noncanonical in that it has six modules utilizing only five amino acid-specific adenylation domains and it lacks a prototypical NRPS macrocyclizing thioesterase domain. Analysis of the mannopeptimycin gene cluster and its engineering has elucidated the mannopeptimycin biosynthetic pathway and provides the framework to make new and improved mannopeptimycins biosynthetically. PMID:16723579

  17. Biosynthetic pathway for mannopeptimycins, lipoglycopeptide antibiotics active against drug-resistant gram-positive pathogens.

    PubMed

    Magarvey, Nathan A; Haltli, Brad; He, Min; Greenstein, Michael; Hucul, John A

    2006-06-01

    The mannopeptimycins are a novel class of lipoglycopeptide antibiotics active against multidrug-resistant pathogens with potential as clinically useful antibacterials. This report is the first to describe the biosynthesis of this novel class of mannosylated lipoglycopeptides. Included here are the cloning, sequencing, annotation, and manipulation of the mannopeptimycin biosynthetic gene cluster from Streptomyces hygroscopicus NRRL 30439. Encoded by genes within the mannopeptimycin biosynthetic gene cluster are enzymes responsible for the generation of the hexapeptide core (nonribosomal peptide synthetases [NRPS]) and tailoring reactions (mannosylation, isovalerylation, hydroxylation, and methylation). The NRPS system is noncanonical in that it has six modules utilizing only five amino acid-specific adenylation domains and it lacks a prototypical NRPS macrocyclizing thioesterase domain. Analysis of the mannopeptimycin gene cluster and its engineering has elucidated the mannopeptimycin biosynthetic pathway and provides the framework to make new and improved mannopeptimycins biosynthetically. PMID:16723579

  18. In Vitro Activities of a New Lipopeptide, HMR 1043, against Susceptible and Resistant Gram-Positive Isolates

    PubMed Central

    Bemer, Pascale; Juvin, Marie-Emmanuelle; Bryskier, Andre; Drugeon, Henri

    2003-01-01

    The purpose of this study was to compare the activity of HMR 1043 with those of daptomycin and teicoplanin against gram-positive isolates. Susceptibility tests were performed for 52 strains, 26 parental strains, including staphylococcal, streptococcal, enterococcal, and listerial strains, and 26 HMR 1043-resistant mutants obtained from parental strains by using the Szybalski method. Agar dilution and disk diffusion susceptibility tests were performed by the procedures outlined by the NCCLS. HMR 1043 demonstrated good activity against susceptible and resistant gram-positive bacteria. The activity of HMR 1043 in vitro was less influenced by the presence of calcium ions than that of daptomycin. Susceptibility test breakpoints were not defined because of the poor correlation coefficients obtained with the different disks tested. PMID:12937020

  19. In Vitro Activities of Dalbavancin and Nine Comparator Agents against Anaerobic Gram-Positive Species and Corynebacteria

    PubMed Central

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

    2003-01-01

    Dalbavancin is a novel semisynthetic glycopeptide with enhanced activity against gram-positive species. Its comparative in vitro activities and those of nine comparator agents, including daptomycin, vancomycin, linezolid, and quinupristin-dalfopristin, against 290 recent gram-positive clinical isolates strains, as determined by the NCCLS agar dilution method, were studied. The MICs of dalbavancin at which 90% of various isolates tested were inhibited were as follows: Actinomyces spp., 0.5 μg/ml; Clostridium clostridioforme, 8 μg/ml; C. difficile, 0.25 μg/ml; C. innocuum, 0.25 μg/ml; C. perfringens, 0.125 μg/ml; C. ramosum, 1 μg/ml; Eubacterium spp., 1 μg/ml; Lactobacillus spp., >32 μg/ml, Propionibacterium spp., 0.5 μg/ml; and Peptostreptococcus spp., 0.25 μg/ml. Dalbavancin was 1 to 3 dilutions more active than vancomycin against most strains. Dalbavancin exhibited excellent activity against gram-positive strains tested and warrants clinical evaluation. PMID:12760876

  20. Isolation of Highly Active Monoclonal Antibodies against Multiresistant Gram-Positive Bacteria

    PubMed Central

    Rossmann, Friederike S.; Laverde, Diana; Kropec, Andrea; Romero-Saavedra, Felipe; Meyer-Buehn, Melanie; Huebner, Johannes

    2015-01-01

    Multiresistant nosocomial pathogens often cause life-threatening infections that are sometimes untreatable with currently available antibiotics. Staphylococci and enterococci are the predominant Gram-positive species associated with hospital-acquired infections. These infections often lead to extended hospital stay and excess mortality. In this study, a panel of fully human monoclonal antibodies was isolated from a healthy individual by selection of B-cells producing antibodies with high opsonic killing against E. faecalis 12030. Variable domains (VH and VL) of these immunoglobulin genes were amplified by PCR and cloned into an eukaryotic expression vector containing the constant domains of a human IgG1 molecule and the human lambda constant domain. These constructs were transfected into CHO cells and culture supernatants were collected and tested by opsonophagocytic assay against E. faecalis and S. aureus strains (including MRSA). At concentrations of 600 pg/ml, opsonic killing was between 40% and 70% against all strains tested. Monoclonal antibodies were also evaluated in a mouse sepsis model (using S. aureus LAC and E. faecium), a mouse peritonitis model (using S. aureus Newman and LAC) and a rat endocarditis model (using E. faecalis 12030) and were shown to provide protection in all models at a concentration of 4 μg/kg per animal. Here we present a method to produce fully human IgG1 monoclonal antibodies that are opsonic in vitro and protective in vivo against several multiresistant Gram-positive bacteria. The monoclonal antibodies presented in this study are significantly more effective compared to another monoclonal antibody currently in clinical trials. PMID:25706415

  1. Design, synthesis and biological evaluation of 4-benzoyl-1-dichlorobenzoylthiosemicarbazides as potent Gram-positive antibacterial agents.

    PubMed

    Paneth, Agata; Plech, Tomasz; Kaproń, Barbara; Hagel, Dominika; Kosikowska, Urszula; Kuśmierz, Edyta; Dzitko, Katarzyna; Paneth, Piotr

    2016-01-01

    Twelve 4-benzoyl-1-dichlorobenzoylthiosemicarbazides have been tested as potential antibacterials. All the compounds had MICs between 0.49 and 15.63 µg/ml toward Micrococcus luteus, Bacillus cereus, Bacillus subtilis and Staphylococcus epidermidis indicating, in most cases, equipotent or even more effective action than cefuroxime. In order to clarify if the observed antibacterial effects are universal, further research were undertaken to test inhibitory potency of two most potent compounds 3 and 11 on clinical isolates of Staphylococcus aureus. Compound 11 inhibited the growth of methicillin-sensitive S. aureus (MSSA) at MICs of 1.95-7.81 µg/ml, methicillin-resistant S. aureus (MRSA) at MICs of 0.49-1.95 µg/ml and MDR-MRSA at MIC of 0.98 and 3.90 µg/ml, respectively. Finally, inhibitory efficacy of 3 and 11 on planktonic cells and biofilms formation in clinical isolates of S. aureus and Haemophilus parainfluenzae was tested. The majority of cells in biofilm populations of MSSA and MRSA were eradicated at low level of 3, with MBICs in the range of 7.82-15.63 µg/ml. PMID:25897586

  2. Bacteriocins of gram-positive bacteria.

    PubMed Central

    Jack, R W; Tagg, J R; Ray, B

    1995-01-01

    posttranslational modification and depending on the pH, the molecules may either be released into the environment or remain bound to the cell wall. The antibacterial action against a sensitive cell of a gram-positive strain is produced principally by destabilization of membrane functions. Under certain conditions, gram-negative bacterial cells can also be sensitive to some of these molecules. By application of site-specific mutagenesis, bacteriocin variants which may differ in their antimicrobial spectrum and physicochemical characteristics can be produced. Research activity in this field has grown remarkably but sometimes with an undisciplined regard for conformity in the definition, naming, and categorization of these molecules and their genetic effectors. Some suggestions for improved standardization of nomenclature are offered. PMID:7603408

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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 1.6μm 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

  4. Thusin, a Novel Two-Component Lantibiotic with Potent Antimicrobial Activity against Several Gram-Positive Pathogens

    PubMed Central

    Xin, Bingyue; Zheng, Jinshui; Liu, Hualin; Li, Junhua; Ruan, Lifang; Peng, Donghai; Sajid, Muhammad; Sun, Ming

    2016-01-01

    Due to the rapidly increasing prevalence of multidrug-resistant bacterial strains, the need for new antimicrobial drugs to treat infections has become urgent. Bacteriocins, which are antimicrobial peptides of bacterial origin, are considered potential alternatives to conventional antibiotics and have attracted widespread attention in recent years. Among these bacteriocins, lantibiotics, especially two-component lantibiotics, exhibit potent antimicrobial activity against some clinically relevant Gram-positive pathogens and have potential applications in the pharmaceutical industry. In this study, we characterized a novel two-component lantibiotic termed thusin that consists of Thsα, Thsβ, and Thsβ' (mutation of Thsβ, A14G) and that was isolated from a B. thuringiensis strain BGSC 4BT1. Thsα and Thsβ (or Thsβ') exhibit optimal antimicrobial activity at a 1:1 ratio and act sequentially to affect target cells, and they are all highly thermostable (100°C for 30 min) and pH tolerant (pH 2.0 to 9.0). Thusin shows remarkable efficacy against all tested Gram-positive bacteria and greater activities than two known lantibiotics thuricin 4A-4 and ticin A4, and one antibiotic vancomycin against various bacterial pathogens (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus (MRSA), Staphylococcus sciuri, Enterococcus faecalis, and Streptococcus pneumoniae). Moreover, thusin is also able to inhibit the outgrowth of B. cereus spores. The potent antimicrobial activity of thusin against some Gram-positive pathogens indicates that it has potential for the development of new drugs. PMID:27486447

  5. Thusin, a Novel Two-Component Lantibiotic with Potent Antimicrobial Activity against Several Gram-Positive Pathogens.

    PubMed

    Xin, Bingyue; Zheng, Jinshui; Liu, Hualin; Li, Junhua; Ruan, Lifang; Peng, Donghai; Sajid, Muhammad; Sun, Ming

    2016-01-01

    Due to the rapidly increasing prevalence of multidrug-resistant bacterial strains, the need for new antimicrobial drugs to treat infections has become urgent. Bacteriocins, which are antimicrobial peptides of bacterial origin, are considered potential alternatives to conventional antibiotics and have attracted widespread attention in recent years. Among these bacteriocins, lantibiotics, especially two-component lantibiotics, exhibit potent antimicrobial activity against some clinically relevant Gram-positive pathogens and have potential applications in the pharmaceutical industry. In this study, we characterized a novel two-component lantibiotic termed thusin that consists of Thsα, Thsβ, and Thsβ' (mutation of Thsβ, A14G) and that was isolated from a B. thuringiensis strain BGSC 4BT1. Thsα and Thsβ (or Thsβ') exhibit optimal antimicrobial activity at a 1:1 ratio and act sequentially to affect target cells, and they are all highly thermostable (100°C for 30 min) and pH tolerant (pH 2.0 to 9.0). Thusin shows remarkable efficacy against all tested Gram-positive bacteria and greater activities than two known lantibiotics thuricin 4A-4 and ticin A4, and one antibiotic vancomycin against various bacterial pathogens (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus (MRSA), Staphylococcus sciuri, Enterococcus faecalis, and Streptococcus pneumoniae). Moreover, thusin is also able to inhibit the outgrowth of B. cereus spores. The potent antimicrobial activity of thusin against some Gram-positive pathogens indicates that it has potential for the development of new drugs. PMID:27486447

  6. The bactericidal activities of HMR 3004, HMR 3647 and erythromycin against gram-positive bacilli and development of resistance.

    PubMed

    Fernández-Roblas, R; Calvo, R; Esteban, J; Bryskier, A; Soriano, F

    1999-02-01

    The bactericidal activities of two new ketolides, HMR 3004 and HMR 3647, and the potential to develop resistance to these two antibiotics were studied in Gram-positive bacilli. As judged by time-kill kinetics both ketolides were mostly bacteriostatic, being bactericidal against only highly susceptible isolates of Corynebacterium striatum (two isolates) and Corynebacterium minutissimum (one isolate). Spontaneous resistant mutants were detected in seven of 30 strains tested, mainly in Rhodococcus equi, C. minutissimum and C. striatum, with a very low frequency of mutation (10(-12)-10(-15)). PMID:11252337

  7. Telavancin activity tested against a contemporary collection of Gram-positive pathogens from USA Hospitals (2007-2009).

    PubMed

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

    2012-01-01

    This study updates the activity of telavancin against Gram-positive pathogens collected from USA hospitals (2007-2009). Telavancin (MIC(50/90), 0.12/0.25 μg/mL) was active against coagulase-negative staphylococci and methicillin-resistant Staphylococcus aureus (100% susceptible), for which only daptomycin (MIC(50/90), 0.25/0.5 μg/mL; 99% susceptible) and quinupristin/dalfopristin (MIC(50/90), ≤ 0.25-0.5/0.5 μg/mL; 99% susceptible) exhibited similar activity. Telavancin (MIC(50/90), 0.25/0.5 μg/mL) inhibited 96.5% of Enterococcus faecalis at the Food and Drug Administration breakpoint (MIC, ≤ 1 μg/mL), where ampicillin (99.9% susceptible), daptomycin (99.9% susceptible), and linezolid (100% susceptible) also demonstrated high-level coverage. Telavancin inhibited, respectively, 100.0% and 91.7% of VanB-phenotype E. faecalis and E. faecium at ≤ 1 μg/mL, whereas it was less active against VanA strains. Telavancin was uniformly active against Streptococcus pneumoniae and resistant subsets, and demonstrated good potency (MIC(90), 0.06-0.12 μg/mL) against other streptococci, regardless of resistance to other drugs. This assessment reveals potent activity of telavancin against Gram-positive isolates collected from USA hospitals with no evidence of emergence of resistance. PMID:22078909

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

    PubMed

    Quiles-Puchalt, Nuria; Tormo-Más, María Ángeles; Campoy, Susana; Toledo-Arana, Alejandro; Monedero, Vicente; Lasa, Iñigo; Novick, Richard P; Christie, Gail E; Penadés, José R

    2013-08-01

    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

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

    PubMed Central

    Quiles-Puchalt, Nuria; Tormo-Más, María Ángeles; Campoy, Susana; Toledo-Arana, Alejandro; Monedero, Vicente; Lasa, Íñigo; Novick, Richard P.; Christie, Gail E.; Penadés, José R.

    2013-01-01

    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

  10. Structure-Activity Analysis of Gram-positive Bacterium-producing Lasso Peptides with Anti-mycobacterial Activity

    PubMed Central

    Inokoshi, Junji; Koyama, Nobuhiro; Miyake, Midori; Shimizu, Yuji; Tomoda, Hiroshi

    2016-01-01

    Lariatin A, an 18-residue lasso peptide encoded by the five-gene cluster larABCDE, displays potent and selective anti-mycobacterial activity. The structural feature is an N-terminal macrolactam ring, through which the C-terminal passed to form the rigid lariat-protoknot structure. In the present study, we established a convergent expression system by the strategy in which larA mutant gene-carrying plasmids were transformed into larA-deficient Rhodococcus jostii, and generated 36 lariatin variants of the precursor protein LarA to investigate the biosynthesis and the structure-activity relationships. The mutational analysis revealed that four amino acid residues (Gly1, Arg7, Glu8, and Trp9) in lariatin A are essential for the maturation and production in the biosynthetic machinery. Furthermore, the study on structure-activity relationships demonstrated that Tyr6, Gly11, and Asn14 are responsible for the anti-mycobacterial activity, and the residues at positions 15, 16 and 18 in lariatin A are critical for enhancing the activity. This study will not only provide a useful platform for genetically engineering Gram-positive bacterium-producing lasso peptides, but also an important foundation to rationally design more promising drug candidates for combatting tuberculosis. PMID:27457620

  11. Structure-Activity Analysis of Gram-positive Bacterium-producing Lasso Peptides with Anti-mycobacterial Activity

    NASA Astrophysics Data System (ADS)

    Inokoshi, Junji; Koyama, Nobuhiro; Miyake, Midori; Shimizu, Yuji; Tomoda, Hiroshi

    2016-07-01

    Lariatin A, an 18-residue lasso peptide encoded by the five-gene cluster larABCDE, displays potent and selective anti-mycobacterial activity. The structural feature is an N-terminal macrolactam ring, through which the C-terminal passed to form the rigid lariat-protoknot structure. In the present study, we established a convergent expression system by the strategy in which larA mutant gene-carrying plasmids were transformed into larA-deficient Rhodococcus jostii, and generated 36 lariatin variants of the precursor protein LarA to investigate the biosynthesis and the structure-activity relationships. The mutational analysis revealed that four amino acid residues (Gly1, Arg7, Glu8, and Trp9) in lariatin A are essential for the maturation and production in the biosynthetic machinery. Furthermore, the study on structure-activity relationships demonstrated that Tyr6, Gly11, and Asn14 are responsible for the anti-mycobacterial activity, and the residues at positions 15, 16 and 18 in lariatin A are critical for enhancing the activity. This study will not only provide a useful platform for genetically engineering Gram-positive bacterium-producing lasso peptides, but also an important foundation to rationally design more promising drug candidates for combatting tuberculosis.

  12. Production of a bacteriocin by a poultry derived Campylobacter jejuni isolate with antimicrobial activity against Clostridium perfringens and other Gram positive bacteria.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have purified a bacteriocin peptide (termed CUV-3), produced by a poultry cecal isolate of Campylobacter jejuni (strain CUV-3) with inhibitory activity against Gram positive bacteria including Clostridium perfringens (38 strains), Staphylococcus aureus, Staphylococcus epidermidis and Listeria mon...

  13. Antimicrobial and Efflux Pump Inhibitory Activity of Caffeoylquinic Acids from Artemisia absinthium against Gram-Positive Pathogenic Bacteria

    PubMed Central

    Fiamegos, Yiannis C.; Kastritis, Panagiotis L.; Exarchou, Vassiliki; Han, Haley; Bonvin, Alexandre M. J. J.; Vervoort, Jacques; Lewis, Kim; Hamblin, Michael R.; Tegos, George P.

    2011-01-01

    Background Traditional antibiotics are increasingly suffering from the emergence of multidrug resistance amongst pathogenic bacteria leading to a range of novel approaches to control microbial infections being investigated as potential alternative treatments. One plausible antimicrobial alternative could be the combination of conventional antimicrobial agents/antibiotics with small molecules which block multidrug efflux systems known as efflux pump inhibitors. Bioassay-driven purification and structural determination of compounds from plant sources have yielded a number of pump inhibitors which acted against gram positive bacteria. Methodology/Principal Findings In this study we report the identification and characterization of 4′,5′-O-dicaffeoylquinic acid (4′,5′-ODCQA) from Artemisia absinthium as a pump inhibitor with a potential of targeting efflux systems in a wide panel of Gram-positive human pathogenic bacteria. Separation and identification of phenolic compounds (chlorogenic acid, 3′,5′-ODCQA, 4′,5′-ODCQA) was based on hyphenated chromatographic techniques such as liquid chromatography with post column solid-phase extraction coupled with nuclear magnetic resonance spectroscopy and mass spectroscopy. Microbial susceptibility testing and potentiation of well know pump substrates revealed at least two active compounds; chlorogenic acid with weak antimicrobial activity and 4′,5′-ODCQA with pump inhibitory activity whereas 3′,5′-ODCQA was ineffective. These intitial findings were further validated with checkerboard, berberine accumulation efflux assays using efflux-related phenotypes and clinical isolates as well as molecular modeling methodology. Conclusions/Significance These techniques facilitated the direct analysis of the active components from plant extracts, as well as dramatically reduced the time needed to analyze the compounds, without the need for prior isolation. The calculated energetics of the docking poses supported the

  14. Arginine Patch Predicts the RNA Annealing Activity of Hfq from Gram-Negative and Gram-Positive Bacteria.

    PubMed

    Zheng, Amy; Panja, Subrata; Woodson, Sarah A

    2016-06-01

    The Sm-protein Hfq facilitates interactions between small non-coding RNA (sRNA) and target mRNAs. In enteric Gram-negative bacteria, Hfq is required for sRNA regulation, and hfq deletion results in stress intolerance and reduced virulence. By contrast, the role of Hfq in Gram-positive is less established and varies among species. The RNA binding and RNA annealing activity of Hfq from Escherichia coli, Pseudomonas aeruginosa, Listeria monocytogenes, Bacillus subtilis, and Staphylococcus aureus were compared using minimal RNAs and fluorescence spectroscopy. The results show that RNA annealing activity increases with the number of arginines in a semi-conserved patch on the rim of the Hfq hexamer and correlates with the previously reported requirement for Hfq in sRNA regulation. Thus, the amino acid sequence of the arginine patch can predict the chaperone function of Hfq in sRNA regulation in different organisms. PMID:27049793

  15. Evaluation of the in vitro activity of tigecycline against multiresistant Gram-positive cocci containing tetracycline resistance determinants.

    PubMed

    Borbone, Sonia; Lupo, Agnese; Mezzatesta, Maria Lina; Campanile, Floriana; Santagati, Maria; Stefani, Stefania

    2008-03-01

    This study was undertaken to test the in vitro activity of tigecycline against 117 clinically relevant Gram-positive pathogens and to correlate this activity with their resistance gene content. Overall, tigecycline showed a minimal inhibitory concentration (MIC) range of 0.015-0.5mg/L, able to inhibit potently all multiresistant streptococci, enterococci and MR staphylococci. Tigecycline was active against methicillin-resistant Staphylococcus aureus (MRSA) and enterococci, with MICs for 90% of the organisms (MIC(90)) of 0.25 mg/L and 0.12 mg/L, respectively, being more active than linezolid (MIC(90)=2 mg/L) and quinupristin/dalfopristin (MIC(90)=0.5 and 2-4 mg/L, respectively). Molecular characterisation of resistance determinants demonstrated the concomitant presence of different classes of genes: in particular, tet(M), erm(B) and erm(C) in Streptococcus agalactiae; tet(O), variably associated with different erm genes, in Streptococcus pyogenes; vanA, tet(M) and erm(B) in Enterococcus faecalis, and vanA and erm(B) in Enterococcus faecium. All the MRSA strains harboured SCCmec and erm genes and 50% possessed tet(K) with tet(M) genes. Staphylococcus epidermidis strains were only resistant to erythromycin. These results clearly demonstrate that tigecycline has a MIC(90) range of 0.015-0.5 mg/L both against tetracycline-susceptible and -resistant isolates carrying other resistance determinants, suggesting that this drug could play an important role in the treatment of infections caused by these multiresistant Gram-positive pathogens. PMID:17646087

  16. In vitro activity of tedizolid against gram-positive bacteria in patients with skin and skin structure infections and hospital-acquired pneumonia: a Korean multicenter study.

    PubMed

    Lee, Yangsoon; Hong, Sung Kuk; Choi, Sunghak; Im, Weonbin; Yong, Dongeun; Lee, Kyungwon

    2015-09-01

    We compared the activities of tedizolid to those of linezolid and other commonly used antimicrobial agents against gram-positive cocci recovered from patients with skin and skin structure infections (SSSIs) and hospital-acquired pneumonia (HAP) in Korean hospitals. Gram-positive isolates were collected from 356 patients with SSSIs and 144 patients with HAP at eight hospitals in Korea from 2011 to 2014. SSSIs included impetigo, cellulitis, erysipelas, furuncles, abscesses, and infected burns. Antimicrobial susceptibility was tested by using the CLSI agar dilution method. All of the gram-positive isolates were inhibited by ≤1 μg/mL tedizolid. The minimum inhibitory concentration [MIC]₉₀ of tedizolid was 0.5 μg/mL for methicillin-resistant Staphylococcus aureus, which was 4-fold lower than that of linezolid. Tedizolid may become a useful option for the treatment of SSSIs and HAP caused by gram-positive bacteria. PMID:26206690

  17. Antimicrobial activity of Enterococcus Faecium Fair-E 198 against gram-positive pathogens

    PubMed Central

    do Nascimento, Maristela da Silva; Moreno, Izildinha; Kuaye, Arnaldo Yoshiteru

    2010-01-01

    ABSTRACT This study investigated the antimicrobial activity of Enterococcus faecium FAIR-E 198 against Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus. Using the critical-dilution method, the bacteriocin produced by E. faecium FAIR-E 198 inhibited all L. monocytogenes strains evaluated (1,600 to 19,200 AU mL-1). However, none of the B. cereus and S. aureus strains investigated were inhibited. The maximum activity of this bacteriocin (800 AU mL-1) was observed in MRS broth, while the activity in milk was 100 AU mL-1. In the co-cultivation test in milk, B. cereus K1-B041 was reduced to below the detection limit (1.00 log CFU mL-1) after 48 h. E. faecium reduced the initial L. monocytogenes Scott A population by 1 log CFU mL-1 after 3 h at 35°C, However, the pathogen regained growth, reaching 3.68 log CFU mL-1 after 48 h. E. faecium did not influence the growth of S. aureus ATCC 27154 during the 48 h of co-cultivation, Therefore, it can be concluded that the effectiveness of the antimicrobial activity of E. faecium FAIR-E 198 is strictly related to the species and strain of the target microorganism and to the culture medium, PMID:24031466

  18. Antimicrobial activity of cationic gemini surfactant containing an oxycarbonyl group in the lipophilic portion against gram-positive and gram-negative microorganisms.

    PubMed

    Tatsumi, Taiga; Imai, Yoshitane; Kawaguchi, Kakuhiro; Miyano, Naoko; Ikeda, Isao

    2014-01-01

    We evaluated the antimicrobial activities of a cationic Gemini surfactant, trans-1,4-bis[2-(alkanoyloxy)ethyldimethylammonio]-2-butene dichloride [II-m-2(t-butene)] and its derivatives against Gram-positive and Gram-negative microorganisms. The II-m-2(t-butene) compound was previously shown to have good surface activity and biodegradability. A dodecanoyloxy derivative (m = 12) of II-m-2(t-butene) showed excellent antimicrobial activity against Gram-positive Streptococcus aureus [minimum inhibitory concentration (MIC): 7.8 μg/mL] and Gram-negative Escherichia coli (MIC: 31.2 μg/mL). PMID:24420061

  19. A poultry-intestinal isolate of Campylobacter jejuni produces a bacteriocin (CUV-3) active against a range of Gram positive bacterial pathogens including Clostridium perfringens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A newly isolated bacteriocin, CUV-3, produced by a poultry cecal isolate of Campylobacter jejuni strain CUV-3 had inhibitory activity against several Gram positive bacteria including Clostridium perfringens (38 strains), Staphylococcus aureus, Staph.epidermidis and Listeria monocytogenes. The pept...

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

    PubMed Central

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

    1995-01-01

    ) 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

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

    PubMed

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

    1995-12-01

    ) 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

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

    PubMed

    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

    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

  3. Comparison of the Immunostimulatory and Proinflammatory Activities of Candidate Gram-Positive Endotoxins, Lipoteichoic Acid, Peptidoglycan, and Lipopeptides in Murine and Human Cells

    PubMed Central

    Kimbrell, Matthew R.; Warshakoon, Hemamali; Cromer, Jens R.; Malladi, Subbalakshmi; Hood, Jennifer D.; Balakrishna, Rajalakshmi; Scholdberg, Tandace A.; David, Sunil A.

    2008-01-01

    1. Summary The role of lipopolysaccharide (LPS) in the pathogenesis of Gram-negative septic shock is well established. The corresponding proinflammatory and immunostimulatory molecule(s) on the Gram-positive bacteria is less well understood, and their identification and characterization would be a key prerequisite in designing specific sequestrants of the Gram-positive endotoxin(s). We report in this paper the comparison of NF-κB-, cytokine- and chemokine-inducing activities of the TLR2 ligands, lipoteichoic acid (LTA), peptidoglycan (PGN), and lipopeptides, to LPS, a prototype TLR4 agonist, in murine macrophage cell-lines as well as in human blood. In murine cells, di- and triacyl liopopeptides are equipotent in their NF-κB inducing activity relative to LPS, but elicit much lower proinflammatory cytokines. However, both LPS and the lipopeptides potently induce the secretion of a pattern of chemokines that is suggestive of the engagement of a TLR4-independent TRIF pathway. In human blood, although the lipopeptides induce p38 MAP kinase phosphorylation and CD11b upregulation in granulocytes at ng/ml concentrations, they do not elicit proinflammatory cytokine production even at very high doses; LTA, however, activates neutrophils and induces cytokine secretion, although its potency is considerably less than that of LPS, presumably due to its binding to plasma proteins. We conclude that, in human blood, the pattern of immunostimulation and proinflammatory mediator production elicited by LTA parallels that of LPS. PMID:18468694

  4. Facile synthesis of gold nanoparticles on propylamine functionalized SBA-15 and effect of surface functionality of its enhanced bactericidal activity against gram positive bacteria

    NASA Astrophysics Data System (ADS)

    Bhuyan, Diganta; Gogoi, Animesh; Saikia, Mrinal; Saikia, Ratul; Saikia, Lakshi

    2015-07-01

    The facile synthesis of an SBA-15-pr-+NH3.Au0 nano-hybrid material by spontaneous autoreduction of aqueous chloroaurate anions on propylamine functionalized SBA-15 was successfully demonstrated. The as-synthesized SBA-15-pr-+NH3.Au0 nano-hybrid material was well characterized using low and wide angle x-ray diffraction (XRD), N2 adsorption-desorption isotherms, Fourier transform infrared (FTIR), transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX), x-ray photoelectron spectroscopy (XPS), UV-Visible spectroscopy and atomic absorption spectroscopy (AAS). The activity of the nano-hybrid material as a potent bactericidal agent was successfully tested against Gram positive/negative bacteria viz. Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The colony killing percentage of Gram positive bacteria was found to be higher than Gram negative bacteria due to the stronger electrostatic interaction between the positively-charged amine functionality of SBA-15 and the negatively charged functionality of the bacterial cell wall.

  5. Occurrence of ferredoxin:NAD(+) oxidoreductase activity and its ion specificity in several Gram-positive and Gram-negative bacteria.

    PubMed

    Hess, Verena; Gallegos, Rene; Jones, J Andrew; Barquera, Blanca; Malamy, Michael H; Müller, Volker

    2016-01-01

    A ferredoxin:NAD(+) oxidoreductase was recently discovered as a redox-driven ion pump in the anaerobic, acetogenic bacterium Acetobacterium woodii. The enzyme is assumed to be encoded by the rnf genes. Since these genes are present in the genomes of many bacteria, we tested for ferredoxin:NAD(+) oxidoreductase activity in cytoplasmic membranes from several different Gram-positive and Gram-negative bacteria that have annotated rnf genes. We found this activity in Clostridium tetanomorphum, Clostridium ljungdahlii, Bacteroides fragilis, and Vibrio cholerae but not in Escherichia coli and Rhodobacter capsulatus. As in A. woodii, the activity was Na(+)-dependent in C. tetanomorphum and B. fragilis but Na(+)-independent in C. ljungdahlii and V. cholerae. We deleted the rnf genes from B. fragilis and demonstrated that the mutant has greatly reduced ferredoxin:NAD(+) oxidoreductase activity. This is the first genetic proof that the rnf genes indeed encode the reduced ferredoxin:NAD(+) oxidoreductase activity. PMID:26793417

  6. Occurrence of ferredoxin:NAD+ oxidoreductase activity and its ion specificity in several Gram-positive and Gram-negative bacteria

    PubMed Central

    Hess, Verena; Gallegos, Rene; Jones, J Andrew; Barquera, Blanca; Malamy, Michael H

    2016-01-01

    A ferredoxin:NAD+ oxidoreductase was recently discovered as a redox-driven ion pump in the anaerobic, acetogenic bacterium Acetobacterium woodii. The enzyme is assumed to be encoded by the rnf genes. Since these genes are present in the genomes of many bacteria, we tested for ferredoxin:NAD+ oxidoreductase activity in cytoplasmic membranes from several different Gram-positive and Gram-negative bacteria that have annotated rnf genes. We found this activity in Clostridium tetanomorphum, Clostridium ljungdahlii, Bacteroides fragilis, and Vibrio cholerae but not in Escherichia coli and Rhodobacter capsulatus. As in A. woodii, the activity was Na+-dependent in C. tetanomorphum and B. fragilis but Na+-independent in C. ljungdahlii and V. cholerae. We deleted the rnf genes from B. fragilis and demonstrated that the mutant has greatly reduced ferredoxin:NAD+ oxidoreductase activity. This is the first genetic proof that the rnf genes indeed encode the reduced ferredoxin:NAD+ oxidoreductase activity. PMID:26793417

  7. 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

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

    2003-01-01

    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 μg/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 μg/ml were inhibited by <1 μg of daptomycin per ml. Daptomycin MICs were ≥4 μg/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 μg of daptomycin per ml. For two strains of “Corynebacterium aquaticum,” 8 μg 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

  8. Highly selective antibacterial activities of silver nanoparticles against Bacillus subtilis.

    PubMed

    Li, Ju; Rong, Kaifeng; Zhao, Huiping; Li, Fei; Lu, Zhong; Chen, Rong

    2013-10-01

    Silver nanoparticles (AgNPs) with different sizes (5, 15 and 55 nm) were synthesized via simple method, and characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray microanalysis (EDX) and ultraviolet-visible absorption spectroscopy (UV-Vis). The antibacterial activities of the prepared AgNPs against Gram-negative Escherichia coli (E. coli), Gram-positive Staphylococcus aureus (S. aureus) and Bacillus subtilis (B. subtilis) were evaluated by inhibition zone, inhibition curve, and colony counting methods. The results showed that the AgNPs exhibited obvious bacterium-selective and size-dependent antibacterial activities. The Gram-positive bacteria S. aureus and B. subtilis were more sensitive to AgNPs than Gram-negative bacterium E. coli. Interestingly, AgNPs displayed remarkably antibacterial activities against B. subtilis among Gram-positive bacteria, regardless of whether in separately or cocultured bacteria. It also showed that AgNPs with 5 nm in size presented the highest antibacterial activity against both Gram-negative and Gram-positive bacteria. The effects of AgNPs on the membrane leakage of the reducing sugars from three bacteria were also measured by 3,5-dinitrosalicylic acid method. The leakage amount of reducing sugars from B. subtilis was the highest among the tested bacteria, indicating that AgNPs could damage the structure of bacteria cell membrane and resulted in the leakage of reducing sugars, leading to the death of bacteria. PMID:24245147

  9. Elafin (elastase-specific inhibitor) has anti-microbial activity against gram-positive and gram-negative respiratory pathogens.

    PubMed

    Simpson, A J; Maxwell, A I; Govan, J R; Haslett, C; Sallenave, J M

    1999-06-11

    Elafin (elastase-specific inhibitor) is a low molecular weight inhibitor of neutrophil elastase which is secreted in the lung. Using synthetic peptides corresponding to full-length elafin (H2N-1AVT.....95Q-OH), the NH2-terminal domain (H2N-1AVT.....50K-OH) and the COOH-terminal domain (H2N-51PGS.....95Q-OH), we demonstrate that elafin's anti-elastase activity resides exclusively in the COOH-terminus. Several characteristics of elafin suggest potential anti-microbial activity. The anti-microbial activity of elafin, and of its two structural domains, was tested against the respiratory pathogens Pseudomonas aeruginosa and Staphylococcus aureus. Elafin killed both bacteria efficiently, with 93% killing of P. aeruginosa by 2.5 microM elafin and 48% killing of S. aureus by 25 microM elafin. For both organisms, full-length elafin was required to optimise bacterial killing. These findings represent the first demonstration of co-existent anti-proteolytic and anti-microbial functions for elafin. PMID:10386612

  10. In vitro activity of dalbavancin and five comparator agents against common and uncommon Gram-positive organisms isolated from cancer patients.

    PubMed

    Rolston, Kenneth V I; Wang, Weiqun; Nesher, Lior; Shelburne, Samuel A; Prince, Randall A

    2016-05-01

    Dalbavancin is a long acting, bactericidal lipoglycopeptide. Its in vitro activity was compared with that of vancomycin, daptomycin, linezolid, trimethoprim/sulfamethoxazole (TMP/SMX) and levofloxacin against 241 Gram-positive organisms isolated from cancer patients. The rank order of potency for the glycopeptides based on MIC90 (μg ml(-1)), that is, the concentration of antimicrobial agent required to inhibit 90% of isolates tested was dalbavancin (0.12 μg ml(-1))>daptomycin (1.0 μg ml(-1))>vancomycin (2.0 μg ml(-1)) for coagulase-negative staphylococci and Staphylococcus aureus isolates (including methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) strains). Dalbavancin had potent activity against staphylococcal isolates with vancomycin MICs⩾1.0 μg ml(-1). TMP/SMX also had potent activity against staphylococci including methicillin-resistant strains, whereas levofloxacin had moderate to poor anti-staphylococcal activity. Dalbavancin also exhibited more potent activity than vancomycin and daptomycin against Bacillus spp., Corynebacterium spp., Micrococcus spp. and various streptococci (including Streptococcus pneumoniae, viridans group streptococci (VGS), beta-hemolytic streptococci and gamma-hemolytic streptococci). MBC determinations showed that dalbavancin had potent bactericidal activity against MRSA with no tolerance being detected. These data suggest that dalbavancin may be considered as an alternative to vancomycin, especially in institutions wherein a substantial proportion of infections are caused by organisms with vancomycin MICs⩾1.0 μg ml(-1). PMID:26626876

  11. Antimicrobial activity of daptomycin tested against Gram-positive pathogens collected in Europe, Latin America, and selected countries in the Asia-Pacific Region (2011).

    PubMed

    Sader, Helio S; Flamm, Robert K; Jones, Ronald N

    2013-04-01

    We report the results of the international daptomycin surveillance programs for Europe, Latin America, and selected Asia-Pacific nations. A total of 7948 consecutive Gram-positive organisms of clinical significance were collected in 2011 and susceptibility tested against daptomycin and various comparator agents by Clinical and Laboratory Standards Institute (Clinical and Laboratory Standards Institute. M07-A9. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically; approved standard: ninth edition Wayne, PA: CLSI. 2012.; Cubicin Package Insert 2012. Cubist Pharmaceuticals, Inc, Lexington, MA. Available at http://www.cubicin.com/pdf/PrescribingInformation.pdf. Accessed January 1, 2012.) broth microdilution methods. The test medium was adjusted to contain physiological levels of calcium (50 mg/L) when testing daptomycin. Daptomycin exhibited potent activity against methicillin-susceptible and -resistant Staphylococcus aureus overall and for each region (MIC(50/90), 0.25-0.5/0.5 μg/mL), with susceptibility rates at 100.0% in Latin America, Australia/New Zealand, and India, and at 99.9% in Europe. The daptomycin MIC(50/90) for coagulase-negative staphylococci was also at 0.25-0.5/0.5 μg/mL, and only 1 isolate was considered nonsusceptible with a MIC value at 2 μg/mL. Daptomycin was also highly active against Enterococcus faecalis (MIC(50/90), 1/1-2 μg/mL) and E. faecium (MIC(50/90), 2/2 μg/mL for both vancomycin-susceptible and -resistant isolates). All enterococcal isolates were susceptible to daptomycin (MIC, ≤4 μg/mL) and tigecycline. Susceptibility to linezolid for E. faecalis was at 100.0%, while for E. faecium regional susceptibility rates were at 100.0% except in Europe (99.0%). Viridans group streptococci (MIC(50/90), 0.25/1 μg/mL) and β-haemolytic streptococci (MIC(50/90), ≤0.06/0.25 μg/mL) continue to be very susceptible to daptomycin. In summary, the results of this investigation document the high potency and

  12. Growth of Ag-nanoparticles in an aqueous solution and their antimicrobial activities against Gram positive, Gram negative bacterial strains and Candida fungus.

    PubMed

    Aazam, Elham Shafik; Zaheer, Zoya

    2016-04-01

    Silver nanoparticles (AgNPs) were synthesized using Ocimum sanctum (Tulsi) leaves aqueous extract as reducing as well as a capping agent in absence and presence of cetyltrimethylammonium bromide (CTAB). The resulting nanomaterials were characterized by UV-visible spectrophotometer, and transmission electron microscope. The UV-Vis spectroscopy revealed the formation of AgNPs at 400-450 nm. TEM photographs indicate that the truncated triangular silver nanoplates and/or spherical morphology of the AgNPs with an average diameter of 25 nm have been distorted markedly in presence of CTAB. The AgNPs were almost mono disperse in nature. Antimicrobial activities of AgNPs were determined by using two bacteria (Gram positive Staphylococcus aureus MTCC-3160), Gram negative Escherichia coli MTCC-450) and one species of Candida fungus (Candida albicans ATCC 90030) with Kirby-Bauer or disc diffusion method. The zone of inhibition seems extremely good showing a relatively large zone of inhibition in both Staphylococcus aureus, Escherichia coli, and Candida albicans strains. PMID:26796584

  13. A metal-repressed promoter from gram-positive Bacillus subtilis is highly active and metal-induced in gram-negative Cupriavidus metallidurans.

    PubMed

    Ribeiro-dos-Santos, Gabriela; Biondo, Ronaldo; Quadros, Oeber de Freitas; Vicente, Elisabete José; Schenberg, Ana Clara Guerrini

    2010-10-15

    A synthetic version of the metal-regulated gene A (mrgA) promoter from Bacillus subtilis, which in this Gram-positive bacterium is negatively regulated by manganese, iron, cobalt, or copper turned out to promote high level of basal gene expression that is further enhanced by Co(II), Cd(II), Mn(II), Zn(II), Cu(II), or Ni(II), when cloned in the Gram-negative bacterium Cupriavidus metallidurans. Promoter activity was monitored by expression of the reporter gene coding for the enhanced green fluorescent protein (EGFP), and cellular intensity fluorescence was quantified by flow cytometry. Expression levels in C. metallidurans driven by the heterologous promoter, here called pan, ranged from 20- to 53-fold the expression level driven by the Escherichia coli lac promoter (which is constitutively expressed in C. metallidurans), whether in the absence or presence of metal ions, respectively. The pan promoter did also function in E. coli in a constitutive pattern, regardless of the presence of Mn(II) or Fe(II). In conclusion, the pan promoter proved to be a powerful tool to express heterologous proteins in Gram-negative bacteria, especially in C. metallidurans grown upon high levels of toxic metals, with potential applications in bioremediation. PMID:20517979

  14. 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

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

    2012-01-01

    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 μg/ml), coagulase-negative staphylococci (MIC50/90, 0.06/0.12 μg/ml), β-hemolytic streptococci (MIC50/90, 0.03/0.06 μg/ml), viridans group streptococci (MIC50/90, 0.12/0.5 μg/ml), and Enterococcus faecium (including vancomycin-nonsusceptible strains) (MIC50/90, 0.12/2 μg/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

  15. Cyclohexane triones, novel membrane-active antibacterial agents.

    PubMed Central

    Lloyd, W J; Broadhurst, A V; Hall, M J; Andrews, K J; Barber, W E; Wong-Kai-In, P

    1988-01-01

    The cyclohexane triones are a novel group of synthetic antibacterial agents that are active against gram-positive bacteria, Haemophilus influenzae, and Mycobacterium smegmatis. In general, these compounds behaved in a manner similar to that of hexachlorophene, inhibiting the transport of low-molecular-weight hydrophilic substances into bacteria. Unlike cationic detergents, such as chlorhexidine, they did not cause disruption of the bacterial cytoplasmic membrane over a short time period. The most potent antibacterial cyclohexane trione studied had a reduced ability to inhibit solute transport in comparison with certain less active analogs. Cyclohexane triones may express more than a single type of antibacterial effect. PMID:3137860

  16. Bacillus subtilis subsp. subtilis CBMDC3f with antimicrobial activity against Gram-positive foodborne pathogenic bacteria: UV-MALDI-TOF MS analysis of its bioactive compounds.

    PubMed

    Torres, M J; Petroselli, G; Daz, M; Erra-Balsells, R; Audisio, M C

    2015-06-01

    In this work a new Bacillus sp. strain, isolated from honey, was characterized phylogenetically. Its antibacterial activity against three relevant foodborne pathogenic bacteria was studied; the main bioactive metabolites were analyzed using ultraviolet matrix assisted laser desorption-ionization mass spectrometry (UV-MALDI MS). Bacillus CBMDC3f was phylogenetically characterized as Bacillus subtilis subsp. subtilis after rRNA analysis of the 16S subunit and the gyrA gene (access codes Genbank JX120508 and JX120516, respectively). Its antibacterial potential was evaluated against Listeria monocytogenes (9 strains), B. cereus (3 strains) and Staphylococcus aureus ATCC29213. Its cell suspension and cell-free supernatant (CFS) exerted significant anti-Listeria and anti-S. aureus activities, while the lipopeptides fraction (LF) also showed anti-B. cereus effect. The UV-MALDI-MS analysis revealed surfactin, iturin and fengycin in the CFS, whereas surfactin predominated in the LF. The CFS from CBMDC3f contained surfactin, iturin and fengycin with four, two and four homologues per family, respectively, whereas four surfactin, one iturin and one fengycin homologues were identified in the LF. For some surfactin homologues, their UV-MALDI-TOF/TOF (MS/MS; Laser Induced Decomposition method, LID) spectra were also obtained. Mass spectrometry analysis contributed with relevant information about the type of lipopeptides that Bacillus strains can synthesize. From our results, surfactin would be the main metabolite responsible for the antibacterial effect. PMID:25820813

  17. Antimicrobial activity of Calendula officinalis petal extracts against fungi, as well as Gram-negative and Gram-positive clinical pathogens.

    PubMed

    Efstratiou, Efstratios; Hussain, Abdullah I; Nigam, Poonam S; Moore, John E; Ayub, Muhammad A; Rao, Juluri R

    2012-08-01

    The aim of the present study was to assess the antimicrobial activity of methanol and ethanol extracts of pot marigold (Calendula officinalis) petals against clinical pathogens. The antimicrobial potential of C. officinalis extracts was evaluated against a panel of microorganisms isolated from patients at the Belfast City Hospital (BCH), including bacteria and fungi, using disc diffusion assay. Methanol extract of C. officinalis exhibited better antibacterial activity against most of the bacteria tested, than ethanol extract. Both methanol and ethanol extracts showed excellent antifungal activity against tested strains of fungi, while comparing with Fluconazole. PMID:22789794

  18. Gram-Positive Anaerobic Cocci

    PubMed Central

    Murdoch, D. A.

    1998-01-01

    Gram-positive anaerobic cocci (GPAC) are a heterogeneous group of organisms defined by their morphological appearance and their inability to grow in the presence of oxygen; most clinical isolates are identified to species in the genus Peptostreptococcus. GPAC are part of the normal flora of all mucocutaneous surfaces and are often isolated from infections such as deep organ abscesses, obstetric and gynecological sepsis, and intraoral infections. They have been little studied for several reasons, which include an inadequate classification, difficulties with laboratory identification, and the mixed nature of the infections from which they are usually isolated. Nucleic acid studies indicate that the classification is in need of radical revision at the genus level. Several species of Peptostreptococcus have recently been described, but others still await formal recognition. Identification has been based on carbohydrate fermentation tests, but most GPAC are asaccharolytic and use the products of protein degradation for their metabolism; the introduction of commercially available preformed enzyme kits affords a physiologically more appropriate method of identification, which is simple and relatively rapid and can be used in routine diagnostic laboratories. Recent reports have documented the isolation in pure culture of several species, notably Peptostreptococcus magnus, from serious infections. Studies of P. magnus have elucidated several virulence factors which correlate with the site of infection, and reveal some similarities to Staphylococcus aureus. P. micros is a strongly proteolytic species; it is increasingly recognized as an important pathogen in intraoral infections, particularly periodontitis, and mixed anaerobic deep-organ abscesses. Comparison of antibiotic susceptibility patterns reveals major differences between species. Penicillins are the antibiotics of choice, although some strains of P. anaerobius show broad-spectrum β-lactam resistance. PMID:9457430

  19. Antibacterial activity of resin rich plant extracts

    PubMed Central

    Shuaib, Mohd; Ali, Abuzer; Ali, Mohd; Panda, Bibhu Prasad; Ahmad, Mohd Imtiyaz

    2013-01-01

    Background: The in vitro antibacterial activity of resin rich methanolic extracts (RRMEs) of Commiphora myrrha, Operculina turpethum, and Pinus roxburghii. Materials and Methods: Different concentration were studied by agar-well diffusion method against Gram-positive (Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus, Enterococcus faecalis) and Gram-negative bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Shigella dysenteriae). Results: Among all the bacterial strains tested, E. faecalis was most sensitive and S. typhi was resistant to C. myrrha and P. roxburghii. The extracts of O. turpethum were active against all tested strains in which B. subtilis and S. aureus were the most sensitive. Conclusion: This suggested that the antibacterial activity of RRMEs of O. turpethum was more than C. myrrha and P. roxburghii. This probably explains the potential of these plants against a number of infections caused by bacterial strains tested. PMID:24302834

  20. Transformation of gram positive bacteria by sonoporation

    DOEpatents

    Yang, Yunfeng; Li, Yongchao

    2014-03-11

    The present invention provides a sonoporation-based method that can be universally applied for delivery of compounds into Gram positive bacteria. Gram positive bacteria which can be transformed by sonoporation include, for example, Bacillus, Streptococcus, Acetobacterium, and Clostridium. Compounds which can be delivered into Gram positive bacteria via sonoporation include nucleic acids (DNA or RNA), proteins, lipids, carbohydrates, viruses, small organic and inorganic molecules, and nano-particles.

  1. Collagen-binding Microbial Surface Components Recognizing Adhesive Matrix Molecule (MSCRAMM) of Gram-positive Bacteria Inhibit Complement Activation via the Classical Pathway*

    PubMed Central

    Kang, Mingsong; Ko, Ya-Ping; Liang, Xiaowen; Ross, Caná L.; Liu, Qing; Murray, Barbara E.; Höök, Magnus

    2013-01-01

    Members of a family of collagen-binding microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) from Gram-positive bacteria are established virulence factors in several infectious diseases models. Here, we report that these adhesins also can bind C1q and act as inhibitors of the classical complement pathway. Molecular analyses of Cna from Staphylococcus aureus suggested that this prototype MSCRAMM bound to the collagenous domain of C1q and interfered with the interactions of C1r with C1q. As a result, C1r2C1s2 was displaced from C1q, and the C1 complex was deactivated. This novel function of the Cna-like MSCRAMMs represents a potential immune evasion strategy that could be used by numerous Gram-positive pathogens. PMID:23720782

  2. Developing of a novel antibacterial agent by functionalization of graphene oxide with guanidine polymer with enhanced antibacterial activity

    NASA Astrophysics Data System (ADS)

    Li, Ping; Sun, Shiyu; Dong, Alideertu; Hao, Yanping; Shi, Shuangqiang; Sun, Zijia; Gao, Ge; Chen, Yuxin

    2015-11-01

    New materials with excellent antibacterial activity attract numerous research interests. Herein, a facile synthetic method of polyethylene glycol (PEG) and polyhexamethylene guanidine hydrochloride (PHGC) dual-polymer-functionalized graphene oxide (GO) (GO-PEG-PHGC), a novel antibacterial material, was reported. The as-prepared products were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray pattern (XRD) and elemental analysis. The antibacterial effect on the bacterial strain was investigated by incubating both Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus). The results show that GO-PEG-PHGC has enhanced antibacterial activity when compared to GO, GO-PEG or GO-PHGC alone. The improved antibacterial activity was described to be related to a better dispersion of GO-PEG-PHGC in the presence of PEG. This better dispersion leads to a greater contact between the bacteria membrane and nanomaterials, therefore leading to greater cell damage. Not only Gram-negative bacteria but also Gram-positive bacteria are greatly inhibited by this antibacterial agent. With the powerful antibacterial activity as well as its low cost and facile preparation, the GO-PEG-PHGC as a novel antibacterial agent can find potential application in the areas of healthcare and environmental engineering.

  3. Identification of proteins capable of metal reduction from the proteome of the Gram-positive bacterium Desulfotomaculum reducens MI-1 using an NADH-based activity assay

    SciTech Connect

    Otwell, Annie E.; Sherwood, Roberts; Zhang, Sheng; Nelson, Ornella D.; Li, Zhi; Lin, Hening; Callister, Stephen J.; Richardson, Ruth E.

    2015-01-01

    Metal reduction capability has been found in numerous species of environmentally abundant Gram-positive bacteria. However, understanding of microbial metal reduction is based almost solely on studies of Gram-negative organisms. In this study, we focus on Desulfotomaculum reducens MI-1, a Gram-positive metal reducer whose genome lacks genes with similarity to any characterized metal reductase. D. reducens has been shown to reduce not only Fe(III), but also the environmentally important contaminants U(VI) and Cr(VI). By extracting, separating, and analyzing the functional proteome of D. reducens, using a ferrozine-based assay in order to screen for chelated Fe(III)-NTA reduction with NADH as electron donor, we have identified proteins not previously characterized as iron reductases. Their function was confirmed by heterologous expression in E. coli. These are the protein NADH:flavin oxidoreductase (Dred_2421) and a protein complex composed of oxidoreductase FAD/NAD(P)-binding subunit (Dred_1685) and dihydroorotate dehydrogenase 1B (Dred_1686). Dred_2421 was identified in the soluble proteome and is predicted to be a cytoplasmic protein. Dred_1685 and Dred_1686 were identified in both the soluble as well as the insoluble (presumably membrane) protein fraction, suggesting a type of membrane-association, although PSORTb predicts both proteins are cytoplasmic. Furthermore, we show that these proteins have the capability to reduce soluble Cr(VI) and U(VI) with NADH as electron donor. This study is the first functional proteomic analysis of D. reducens, and one of the first analyses of metal and radionuclide reduction in an environmentally relevant Gram-positive bacterium.

  4. Antibacterial activity of silver bionanocomposites synthesized by chemical reduction route

    PubMed Central

    2012-01-01

    Background The aim of this study is to investigate the functions of polymers and size of nanoparticles on the antibacterial activity of silver bionanocomposites (Ag BNCs). In this research, silver nanoparticles (Ag NPs) were incorporated into biodegradable polymers that are chitosan, gelatin and both polymers via chemical reduction method in solvent in order to produce Ag BNCs. Silver nitrate and sodium borohydride were employed as a metal precursor and reducing agent respectively. On the other hand, chitosan and gelatin were added as a polymeric matrix and stabilizer. The antibacterial activity of different sizes of silver nanoparticles was investigated against Gram-positive and Gram-negative bacteria by the disk diffusion method using Mueller-Hinton Agar. Results The properties of Ag BNCs were studied as a function of the polymer weight ratio in relation to the use of chitosan and gelatin. The morphology of the Ag BNCs films and the distribution of the Ag NPs were also characterized. The diameters of the Ag NPs were measured and their size is less than 20 nm. The antibacterial trait of silver/chitosan/gelatin bionanocomposites was investigated. The silver ions released from the Ag BNCs and their antibacterial activities were scrutinized. The antibacterial activities of the Ag BNC films were examined against Gram-negative bacteria (E. coli and P. aeruginosa) and Gram-positive (S. aureus and M. luteus) by diffusion method using Muller-Hinton agar. Conclusions The antibacterial activity of Ag NPs with size less than 20 nm was demonstrated and showed positive results against Gram-negative and Gram-positive bacteria. The Ag NPs stabilized well in the polymers matrix. PMID:22967920

  5. Identification of proteins capable of metal reduction from the proteome of the Gram-positive bacterium Desulfotomaculum reducens MI-1 using an NADH-based activity assay

    PubMed Central

    Otwell, A.E.; Sherwood, R.W.; Zhang, S.; Nelson, O.D.; Li, Z.; Lin, H.; Callister, S.J.; Richardson, R.E.

    2015-01-01

    Summary Understanding of microbial metal reduction is based almost solely on studies of Gram-negative organisms. In this study, we focus on Desulfotomaculum reducens MI-1, a Gram-positive metal reducer whose genome lacks genes with similarity to any characterized metal reductase. Using non-denaturing separations and mass spectrometry identification, in combination with a colorimetric screen for chelated Fe(III)-NTA reduction with NADH as electron donor, we have identified proteins from the D. reducens proteome not previously characterized as iron reductases. Their function was confirmed by heterologous expression in E. coli. Furthermore, we show that these proteins have the capability to reduce soluble Cr(VI) and U(VI) with NADH as electron donor. The proteins identified are NADH:flavin oxidoreductase (Dred_2421) and a protein complex composed of oxidoreductase FAD/NAD(P)-binding subunit (Dred_1685) and dihydroorotate dehydrogenase 1B (Dred_1686). Dred_2421 was identified in the soluble proteome and is predicted to be a cytoplasmic protein. Dred_1685 and Dred_1686 were identified in both the soluble as well as the insoluble protein fraction, suggesting a type of membrane-association, although PSORTb predicts both proteins are cytoplasmic. This study is the first functional proteomic analysis of D. reducens and one of the first analyses of metal and radionuclide reduction in an environmentally relevant Gram-positive bacterium. PMID:25389064

  6. Antibacterial activity of lichen Usnea rubrotincta, Ramalina dumeticola, and Cladonia verticillata

    NASA Astrophysics Data System (ADS)

    Gunasekaran, Saranyapiriya; Rajan, Vinoshene Pillai; Samsudin, Mohd. Wahid; Din, Laily; Ramanathan, Surash; Murugaiyah, Vikneswaran

    2015-09-01

    The present study was carried out to evaluate the antibacterial activity of extract and chemical constituents of Usnea rubrotincta, Ramalina dumeticola and Cladonia verticillata. Extracts of U. rubrotincta and R. dumeticola showed promising antibacterial activity against gram positive bacteria Staphylococcus aureus and Bacillus subtilis. The lowest value of MIC (15.63 μg/mL) was observed for the acetone extract of U. rubrotincta against B. subtilis. While extract of C. verticillata was neither active against gram positive nor gram negative bacteria at the highest tested concentration of 500 μg/m. This is the first evaluation of antibacterial activity of lichens found in Malaysia and to our knowledge, this is the first report of antibacterial

  7. Zn or O? An Atomic Level Comparison on Antibacterial Activities of Zinc Oxides.

    PubMed

    Yu, Fen; Fang, Xuan; Jia, Huimin; Liu, Miaoxing; Shi, Xiaotong; Xue, Chaowen; Chen, Tingtao; Wei, Zhipeng; Fang, Fang; Zhu, Hui; Xin, Hongbo; Feng, Jing; Wang, Xiaolei

    2016-06-01

    For the first time, the influence of different types of atoms (Zn and O) on the antibacterial activities of nanosized ZnO was quantitatively evaluated with the aid of a 3D-printing-manufactured evaluation system. Two different outermost atomic layers were manufactured separately by using an ALD (atomic layer deposition) method. Interestingly, we found that each outermost atomic layer exhibited certain differences against gram-positive or gram-negative bacterial species. Zinc atoms as outermost layer (ZnO-Zn) showed a more pronounced antibacterial effect towards gram-negative E. coli (Escherichia coli), whereas oxygen atoms (ZnO-O) showed a stronger antibacterial activity against gram-positive S. aureus (Staphylococcus aureus). A possible antibacterial mechanism has been comprehensively discussed from different perspectives, including Zn(2+) concentrations, oxygen vacancies, photocatalytic activities and the DNA structural characteristics of different bacterial species. PMID:27124263

  8. Suicin 90-1330 from a Nonvirulent Strain of Streptococcus suis: a Nisin-Related Lantibiotic Active on Gram-Positive Swine Pathogens

    PubMed Central

    LeBel, Geneviève; Vaillancourt, Katy; Frenette, Michel; Gottschalk, Marcelo

    2014-01-01

    Streptococcus suis serotype 2 is known to cause severe infections (meningitis, endocarditis, and septicemia) in pigs and is considered an emerging zoonotic agent. Antibiotics have long been used in the swine industry for disease treatment/prevention and growth promoters. This pattern of utilization resulted in the spread of antibiotic resistance in S. suis worldwide. Interestingly, pigs may harbor S. suis in their tonsils without developing diseases, while North American strains belonging to the sequence type 28 (ST28) are nonvirulent in animal models. Consequently, the aim of this study was to purify and characterize a bacteriocin produced by a nonvirulent strain of S. suis serotype 2, with a view to a potential therapeutic and preventive application. S. suis 90-1330 belonging to ST28 and previously shown to be nonvirulent in an animal model exhibited antibacterial activity toward all S. suis pathogenic isolates tested. The bacteriocin produced by this strain was purified to homogeneity by cationic exchange and reversed-phase fast protein liquid chromatography. Given its properties (molecular mass of <4 kDa, heat, pH and protease stability, and the presence of modified amino acids), the bacteriocin, named suicin 90-1330, belongs to the lantibiotic class. Using a DNA-binding fluorophore, the bacteriocin was found to possess a membrane permeabilization activity. When tested on other swine pathogens, the suicin showed activity against Staphylococcus hyicus and Staphylococcus aureus, whereas it was inactive against all Gram-negative bacteria tested. Amino acid sequencing of the purified bacteriocin showed homology (90.9% identity) with nisin U produced by Streptococcus uberis. The putative gene cluster involved in suicin production was amplified by PCR and sequence analysis revealed the presence of 11 open reading frames, including the structural gene and those required for the modification of amino acids, export, regulation, and immunity. Further studies will

  9. Suicin 90-1330 from a nonvirulent strain of Streptococcus suis: a nisin-related lantibiotic active on gram-positive swine pathogens.

    PubMed

    LeBel, Geneviève; Vaillancourt, Katy; Frenette, Michel; Gottschalk, Marcelo; Grenier, Daniel

    2014-09-01

    Streptococcus suis serotype 2 is known to cause severe infections (meningitis, endocarditis, and septicemia) in pigs and is considered an emerging zoonotic agent. Antibiotics have long been used in the swine industry for disease treatment/prevention and growth promoters. This pattern of utilization resulted in the spread of antibiotic resistance in S. suis worldwide. Interestingly, pigs may harbor S. suis in their tonsils without developing diseases, while North American strains belonging to the sequence type 28 (ST28) are nonvirulent in animal models. Consequently, the aim of this study was to purify and characterize a bacteriocin produced by a nonvirulent strain of S. suis serotype 2, with a view to a potential therapeutic and preventive application. S. suis 90-1330 belonging to ST28 and previously shown to be nonvirulent in an animal model exhibited antibacterial activity toward all S. suis pathogenic isolates tested. The bacteriocin produced by this strain was purified to homogeneity by cationic exchange and reversed-phase fast protein liquid chromatography. Given its properties (molecular mass of <4 kDa, heat, pH and protease stability, and the presence of modified amino acids), the bacteriocin, named suicin 90-1330, belongs to the lantibiotic class. Using a DNA-binding fluorophore, the bacteriocin was found to possess a membrane permeabilization activity. When tested on other swine pathogens, the suicin showed activity against Staphylococcus hyicus and Staphylococcus aureus, whereas it was inactive against all Gram-negative bacteria tested. Amino acid sequencing of the purified bacteriocin showed homology (90.9% identity) with nisin U produced by Streptococcus uberis. The putative gene cluster involved in suicin production was amplified by PCR and sequence analysis revealed the presence of 11 open reading frames, including the structural gene and those required for the modification of amino acids, export, regulation, and immunity. Further studies will

  10. In vitro antibacterial activity of some plant essential oils

    PubMed Central

    Prabuseenivasan, Seenivasan; Jayakumar, Manickkam; Ignacimuthu, Savarimuthu

    2006-01-01

    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 active essential oils were tested using two fold agar dilution method at concentrations ranging from 0.2 to 25.6 mg/ml. Results: Out of 21 essential oils tested, 19 oils showed antibacterial activity against one or more strains. Cinnamon, clove, geranium, lemon, lime, orange and rosemary oils exhibited significant inhibitory effect. Cinnamon oil showed promising inhibitory activity even at low concentration, whereas aniseed, eucalyptus and camphor oils were least active against the tested bacteria. In general, B. subtilis was the most susceptible. On the other hand, K. pneumoniae exhibited low degree of sensitivity. Conclusion: Majority of the oils showed antibacterial activity against the tested strains. However Cinnamon, clove and lime oils were found to be inhibiting both gram-positive and gram-negative bacteria. Cinnamon oil can be a good source of antibacterial agents. PMID:17134518

  11. Antibacterial activity of Pseudoalteromonas in the coral holobiont.

    PubMed

    Shnit-Orland, Maya; Sivan, Alex; Kushmaro, Ariel

    2012-11-01

    Corals harbor diverse and abundant prokaryotic populations. Bacterial communities residing in the coral mucus layer may be either pathogenic or symbiotic. Some species may produce antibiotics as a method of controlling populations of competing microbial species. The present study characterizes cultivable Pseudoalteromonas sp. isolated from the mucus layer of different coral species from the northern Gulf of Eilat, Red Sea, Israel. Six mucus-associated Pseudoalteromonas spp. obtained from different coral species were screened for antibacterial activity against 23 tester strains. Five of the six Pseudoalteromonas strains demonstrated extracellular antibacterial activity against Gram-positive-but not Gram-negative-tester strains. Active substances secreted into the cell-free supernatant are heat-tolerant and inhibit growth of Bacillus cereus, Staphylococcus aureus, and of ten endogenous Gram-positive marine bacteria isolated from corals. The Pseudoalteromonas spp. isolated from Red sea corals aligned in a phylogenetic tree with previously isolated Pseudoalteromonas spp. of marine origin that demonstrated antimicrobial activity. These results suggest that coral mucus-associated Pseudoalteromonas may play a protective role in the coral holobiont's defense against potential Gram-positive coral pathogens. PMID:22767125

  12. Synthesis and in vitro antibacterial activity of oxazolidine LBM-415 analogs as peptide deformylase inhibitors.

    PubMed

    Yu, Linliang; Zhou, Weicheng; Wang, Zhenyu

    2011-03-01

    The drug resistant bacteria pose a severe threat to human health. The increasing resistance of those pathogens to traditional antibacterial therapy renders the identification of new antibacterial agents with novel antibacterial mechanisms an urgent need. In this study, a series of (2S)-N-substituted-1-[(formyhydroxyamino)methyl]-1-oxohexyl]-2-oxazolidinecarboxamides were designed, synthesized and evaluated for in vitro antibacterial activity. Most of these compounds displayed good activities against Gram-positive organisms comparable to reference agent LBM-415. PMID:21288715

  13. Vancomycin tolerance in Gram-positive cocci.

    PubMed

    Moscoso, Miriam; Domenech, Mirian; García, Ernesto

    2011-12-01

    Vancomycin, a glycopeptide antimicrobial agent, represents the last line of defence against a wide range of multi-resistant Gram-positive pathogens such as enterococci, staphylococci and streptococci. However, vancomycin-resistant enterococci and staphylococci, along with vancomycin-tolerant clinical isolates, are compromising the therapeutic efficacy of vancomycin. It is conceivable that tolerance may emerge during prolonged vancomycin use. It has not been until recently, however, that the molecular basis of this tolerance began to be understood. Superoxide anions might be involved in the bactericidal activity of vancomycin in enterococci, and recent evidence suggests that the stringent response is partly responsible for vancomycin tolerance in Enterococcus faecalis. The mechanism of vancomycin tolerance in Staphylococcus aureus and Streptococcus pneumoniae is sometimes associated with a reduction of autolysin activity. Vancomycin tolerance in S. aureus and S. pneumoniae also appears to be somehow related with the two-component regulatory systems linked to cell envelope stress, although the precise molecular regulatory pathways remain poorly defined. PMID:23761352

  14. A microdomain for protein secretion in Gram-positive bacteria.

    PubMed

    Rosch, Jason; Caparon, Michael

    2004-06-01

    Gram-positive bacteria face unique challenges in generating biologically active conformations for their exported proteins because they lack a dedicated compartment for folding secreted polypeptides. We have discovered that protein secretion by way of the general secretory (Sec) pathway in the important human pathogen Streptococcus pyogenes proceeds through a single microdomain. Unlike other mechanisms for asymmetry involving the Sec pathway, proteins destined for secretion are targeted to a single locus distal to either cell pole that has specialized to contain the Sec translocons. This subcellular organization may represent a paradigm for secretion common to other Gram-positive pathogens with profound implications for pathogenesis. PMID:15178803

  15. Antibacterial and antifungal activities of neocryptolepine, biscryptolepine and cryptoquindoline, alkaloids isolated from Cryptolepis sanguinolenta.

    PubMed

    Cimanga, K; De Bruyne, T; Pieters, L; Totte, J; Tona, L; Kambu, K; Berghe, D V; Vlietinck, A J

    1998-05-01

    From the 80% EtOH extract of Cryptolepis sanguinolenta (Lindl.) Schlechter (Periplocaeae) root bark, a cryptolepine isomer named neocryptolepine, and two dimeric alkaloids named biscryptolepine and cryptoquindoline were isolated. These compounds were tested for their putative antibacterial and antifungal activities. Results have indicated that neocryptolepine showed an antibacterial activity against Gram-positive bacteria (MIC < 100 μg/ml), but was less acive against Gram-negative bacteria. It also inhibited the growth of the yeast C. albicans. Biscryptolepine exhibited only an activity against some Gram-positive bacteria (MIC = 62.5 or 31 μg/ml) while cryptoquindoline did not shown an activity against all selected microorganisms. The antibacterial activity of neocryptolepine and biscryptolepine is bacteriostatic rather than bactericidal. No antifungal activity could be observed for all alkaloids in our test system at the highest test concentration of 100 μg/ml. PMID:23195843

  16. Ethanol production in Gram-positive microbes

    DOEpatents

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

    1996-01-09

    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.

  17. Ethanol production in Gram-positive microbes

    DOEpatents

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

    1999-06-29

    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.

  18. Ethanol production in Gram-positive microbes

    DOEpatents

    Ingram, Lonnie O'Neal; Barbosa-Alleyne, Maria D. F.

    1996-01-01

    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.

  19. Ethanol production in gram-positive microbes

    DOEpatents

    Ingram, Lonnie O'Neal; Barbosa-Alleyne, Maria D. F.

    1999-01-01

    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.

  20. Mechanism of action of recombinant acc-royalisin from royal jelly of Asian honeybee against gram-positive bacteria.

    PubMed

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

    2012-01-01

    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

  1. Antibacterial and antifungal activity of aromatic constituents of essential oils.

    PubMed

    Pattnaik, S; Subramanyam, V R; Bapaji, M; Kole, C R

    1997-01-01

    Five aromatic constituents of essential oils (cineole, citral, geraniol, linalool and menthol) were tested for antimicrobial activity against eighteen bacteria (including Gram-positive cocci and rods, and Gram-negative rods) and twelve fungi (three yeast-like and nine filamentous). In terms of antibacterial activity linalool was the most effective and inhibited seventeen bacteria, followed by cineole, geraniol (each of which inhibited sixteen bacteria), menthol and citral aromatic compounds, which inhibited fifteen and fourteen bacteria, respectively. Against fungi the citral and geraniol oils were the most effective (inhibiting all twelve fungi), followed by linalool (inhibiting ten fungi), cineole and menthol (each of which inhibited seven fungi) compounds. PMID:9218354

  2. Distribution and significance of heterotrophic marine bacteria with antibacterial activity.

    PubMed Central

    Nair, S; Simidu, U

    1987-01-01

    Bacteria with antibacterial activity were isolated from seawater, sediments, phytoplankton, and zooplankton of Suruga, Sagami, and Tokyo Bays and from soft corals and sponges collected from the Taiwan coast. Of the 726 strains isolated, 37 showed antibacterial activity against either Vibrio parahaemolyticus (ATCC 17802) or Staphylococcus aureus (P209). Sediment harbored the lowest number of these forms of bacteria, and those from Tokyo Bay did not show any activity. Attached isolates showed greater activity compared with free-living forms. Relatively high numbers of strains with antibacterial activity were associated with phytoplankton. Among the zooplankton isolates, cladocerans harbored the maximum number of antibacterial strains. Isolates were more inhibitory to gram-positive test cultures. Autoinhibition was observed only among 8% of the isolates. Marine nonproducers were more susceptible. Pseudomonas/Alteromonas species made up 81.0% of isolates, of which 30% were pigmented strains. The absence or reduction in number of bacteria with antibacterial activity in Tokyo Bay is attributed to its eutrophic nature, which may tend to moderate the production of antibacterial compounds. PMID:3435149

  3. New antimicrobial agents as therapy for resistant gram-positive cocci.

    PubMed

    Lentino, J R; Narita, M; Yu, V L

    2008-01-01

    Vancomycin- and methicillin-resistant gram-positive cocci have emerged as an increasingly problematic cause of hospital-acquired infections. We conducted a literature review of newer antibiotics with activity against vancomycin-resistant and methicillin-resistant gram-positive cocci. Quinupristin/dalfopristin, linezolid, daptomycin, and tigecycline have in vitro activity for methicillin-resistant staphylococci and are superior to vancomycin for vancomycin-resistant isolates. Dalbavancin, telavancin, and oritavancin are new glycopeptides that have superior pharmacodynamic properties compared to vancomycin. We review the antibacterial spectrum, clinical indications and contraindications, pharmacologic properties, and adverse events associated with each of these agents. Daptomycin has rapid bactericidal activity for Staphylococcus aureus and is approved for use in bacteremia and right-sided endocarditis. Linezolid is comparable to vancomycin in patients with methicillin-resistant S. aureus (MRSA) pneumonia and has pharmacoeconomic advantages given its oral formulation. Quinupristin/dalfopristin is the drug of choice for vancomycin-resistant Enterococcus faecium infections but has no activity against Enterococcus faecalis. Tigecycline has activity against both enterococcus species and MRSA; it is also active against Enterobacteriaceae and anaerobes which allows for use in intra-abdominal and diabetic foot infections. A review of numerous in vitro and animal model studies shows that interaction between these newer agents and other antistaphylococcal agents for S. aureus are usually indifferent (additive). PMID:17899228

  4. Antibacterial Activity of Essential Oils from Palmarosa, Evening Primrose, Lavender and Tuberose

    PubMed Central

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

    2009-01-01

    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

  5. In vitro antibacterial activity of cefpiramide.

    PubMed Central

    Pfaller, M A; Niles, A C; Murray, P R

    1984-01-01

    A microbroth dilution method was used to measure the MICs of cefpiramide (SM 1652), cefotaxime, moxalactam, ceftazidime, cefoperazone, ceftriaxone, piperacillin, and mezlocillin against 921 isolates of gram-negative (701) and gram-positive (220) bacteria. The activity of cefpiramide was equivalent to those of piperacillin and mezlocillin against members of the family Enterobacteriaceae and gram-positive isolates, including enterococci. Cefpiramide had equivalent or slightly greater activity against Pseudomonas aeruginosa than the other beta-lactam antibiotics tested. PMID:6426381

  6. Synthesis and antibacterial activity of nisin-containing block copolymers.

    PubMed

    Joshi, Pranav R; McGuire, Joseph; Neff, Jennifer A

    2009-10-01

    Nisin, an antibacterial peptide proven to be an effective inhibitor of Gram-positive bacteria, was incorporated into novel block copolymer constructs and tested for retained antibacterial activity. Covalent coupling was achieved by chemical modification of the N-terminal isoleucine to introduce a thiol group. Thiolated-nisin derivatives were then linked to poly[ethylene oxide]-poly[propylene oxide]-poly[ethylene oxide] (PEO-PPO-PEO) triblocks that had been end-activated such that terminal hydroxyl groups of the PEO chains were replaced with pyridyl disulfide moieties. The nisin-containing block copolymers were separated from free nisin by dialysis and showed antimicrobial activity against the Gram-positive indicator strain Pediococcus pentosaceus. The contribution to antimicrobial activity from nisin that was covalently linked was not distinguished from the contribution of nisin that had associated with the PEO-PPO-PEO triblocks through noncovalent interactions. However, nisin that was covalently linked showed activity upon reduction of the disulfide bond and release from the end-activated PEO. PMID:19358262

  7. Antibacterial Activity of DNA-Stabilized Silver Nanoclusters Tuned by Oligonucleotide Sequence.

    PubMed

    Javani, Siamak; Lorca, Romina; Latorre, Alfonso; Flors, Cristina; Cortajarena, Aitziber L; Somoza, Álvaro

    2016-04-27

    Silver nanoclusters (AgNCs) stabilized by DNA are promising materials with tunable fluorescent properties, which have been employed in a plethora of sensing systems. In this report, we explore their antimicrobial properties in Gram-positive and Gram-negative bacteria. After testing 9 oligonucleotides with different sequence and length, we found that the antibacterial activity depends on the sequence of the oligonucleotide employed. The sequences tested yielded fluorescent AgNCs, which can be grouped in blue, yellow, and red emitters. Interestingly, blue emitters yielded poor antibacterial activity, whereas yellow and red emitters afforded an activity similar to silver nitrate. Furthermore, structural studies using circular dichroism indicate the formation of complexes with different stability and structure, which might be one of the factors that modulate their activity. Finally, we prepared a trimeric structure containing the sequence that afforded the best antimicrobial activity, which inhibited the growth of Gram-positive and negative bacteria in the submicromolar range. PMID:27058628

  8. Disulfide-Bond-Forming Pathways in Gram-Positive Bacteria

    PubMed Central

    2015-01-01

    Disulfide bonds are important for the stability and function of many secreted proteins. In Gram-negative bacteria, these linkages are catalyzed by thiol-disulfide oxidoreductases (Dsb) in the periplasm. Protein oxidation has been well studied in these organisms, but it has not fully been explored in Gram-positive bacteria, which lack traditional periplasmic compartments. Recent bioinformatics analyses have suggested that the high-GC-content bacteria (i.e., actinobacteria) rely on disulfide-bond-forming pathways. In support of this, Dsb-like proteins have been identified in Mycobacterium tuberculosis, but their functions are not known. Actinomyces oris and Corynebacterium diphtheriae have recently emerged as models to study disulfide bond formation in actinobacteria. In both organisms, disulfide bonds are catalyzed by the membrane-bound oxidoreductase MdbA. Remarkably, unlike known Dsb proteins, MdbA is important for pathogenesis and growth, which makes it a potential target for new antibacterial drugs. This review will discuss disulfide-bond-forming pathways in bacteria, with a special focus on Gram-positive bacteria. PMID:26644434

  9. Antimicrobial Activities of Methanol, Ethanol and Supercritical CO2 Extracts of Philippine Piper betle L. on Clinical Isolates of Gram Positive and Gram Negative Bacteria with Transferable Multiple Drug Resistance

    PubMed Central

    Valle, Demetrio L.; Cabrera, Esperanza C.; Puzon, Juliana Janet M.; Rivera, Windell L.

    2016-01-01

    Piper betle L. has traditionally been used in alternative medicine in different countries for various therapeutic purposes, including as an anti-infective agent. However, studies reported in the literature are mainly on its activities on drug susceptible bacterial strains. This study determined the antimicrobial activities of its ethanol, methanol, and supercritical CO2 extracts on clinical isolates of multiple drug resistant bacteria which have been identified by the Infectious Disease Society of America as among the currently more challenging strains in clinical management. Assay methods included the standard disc diffusion method and the broth microdilution method for the determination of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentrations (MBC) of the extracts for the test microorganisms. This study revealed the bactericidal activities of all the P. betle leaf crude extracts on methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and metallo-β-lactamase-producing Pseudomonas aeruginosa and Acinetobacter baumannii, with minimum bactericidal concentrations that ranged from 19μg/ml to 1250 μg/ml. The extracts proved to be more potent against the Gram positive MRSA and VRE than for the Gram negative test bacteria. VRE isolates were more susceptible to all the extracts than the MRSA isolates. Generally, the ethanol extracts proved to be more potent than the methanol extracts and supercritical CO2 extracts as shown by their lower MICs for both the Gram positive and Gram negative MDRs. MTT cytotoxicity assay showed that the highest concentration (100 μg/ml) of P. betle ethanol extract tested was not toxic to normal human dermal fibroblasts (HDFn). Data from the study firmly established P. betle as an alternative source of anti-infectives against multiple drug resistant bacteria. PMID

  10. Antimicrobial Activities of Methanol, Ethanol and Supercritical CO2 Extracts of Philippine Piper betle L. on Clinical Isolates of Gram Positive and Gram Negative Bacteria with Transferable Multiple Drug Resistance.

    PubMed

    Valle, Demetrio L; Cabrera, Esperanza C; Puzon, Juliana Janet M; Rivera, Windell L

    2016-01-01

    Piper betle L. has traditionally been used in alternative medicine in different countries for various therapeutic purposes, including as an anti-infective agent. However, studies reported in the literature are mainly on its activities on drug susceptible bacterial strains. This study determined the antimicrobial activities of its ethanol, methanol, and supercritical CO2 extracts on clinical isolates of multiple drug resistant bacteria which have been identified by the Infectious Disease Society of America as among the currently more challenging strains in clinical management. Assay methods included the standard disc diffusion method and the broth microdilution method for the determination of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentrations (MBC) of the extracts for the test microorganisms. This study revealed the bactericidal activities of all the P. betle leaf crude extracts on methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and metallo-β-lactamase-producing Pseudomonas aeruginosa and Acinetobacter baumannii, with minimum bactericidal concentrations that ranged from 19μg/ml to 1250 μg/ml. The extracts proved to be more potent against the Gram positive MRSA and VRE than for the Gram negative test bacteria. VRE isolates were more susceptible to all the extracts than the MRSA isolates. Generally, the ethanol extracts proved to be more potent than the methanol extracts and supercritical CO2 extracts as shown by their lower MICs for both the Gram positive and Gram negative MDRs. MTT cytotoxicity assay showed that the highest concentration (100 μg/ml) of P. betle ethanol extract tested was not toxic to normal human dermal fibroblasts (HDFn). Data from the study firmly established P. betle as an alternative source of anti-infectives against multiple drug resistant bacteria. PMID

  11. Synthesis and antibacterial activity of sulfonamides. SAR and DFT studies

    NASA Astrophysics Data System (ADS)

    Boufas, Wahida; Dupont, Nathalie; Berredjem, Malika; Berrezag, Kamel; Becheker, Imène; Berredjem, Hajira; Aouf, Nour-Eddine

    2014-09-01

    A series of substituted sulfonamide derivatives were synthesized from chlorosulfonyl isocyanate (CSI) in tree steps (carbamoylation, sulfamoylation and deprotection). Antibacterial activity in vitro of some newly formed compounds investigated against clinical strains Gram-positive and Gram-negative: Escherichia coli and Staphylococcus aureus applying the method of dilution and minimal inhibition concentration (MIC) methods. These compounds have significant bacteriostatic activity with totalities of bacterial strains used. DFT calculations with B3LYP/6-31G(d) level have been used to analyze the electronic and geometric characteristics deduced for the stable structure of three compounds presenting conjugation between a nitrogen atom N through its lone pair and an aromatic ring next to it. The principal quantum chemical descriptors have been correlated with the antibacterial activity.

  12. Antibacterial activity of LCB01-0062, a novel oxazolidinone.

    PubMed

    Jung, Sung-Ji; Yun, I-Na-Rae; Park, Hee Soo; Lee, Hyun-Hee; Jeong, Ji-Woong; Kim, Yong-Zu; Cho, Young-Lak; Kwak, Jin-Hwan

    2012-12-01

    LCB01-0062, a novel oxazolidinone, has potent antibacterial activity against clinical isolates of Gram-positive bacteria. The in vitro activity of LCB01-0062 was compared with that of linezolid, oxacillin, erythromycin, ciprofloxacin, vancomycin and quinupristin/dalfopristin. Among the tested agents, LCB01-0062 showed the most potent antibacterial activity against meticillin-resistant Staphylococcus aureus, meticillin-resistant coagulase-negative staphylococci and vancomycin-resistant enterococci. LCB01-0062 was 4-8-fold more active than linezolid, the first oxazolidinone drug, against Gram-positive bacteria. The time-kill curves of LCB01-0062 were analysed at concentrations of 0.5×, 1×, 2×, 4× and 8× the minimum inhibitory concentration against S. aureus strains. LCB01-0062 showed bacteriostatic activity during 24 h. LCB01-0062 was also more effective than linezolid against S. aureus in a systemic mouse model of infection. PMID:23058227

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

    PubMed

    Cornaglia, G

    2009-03-01

    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

  14. Draft genome sequence analysis of a Pseudomonas putida W15Oct28 strain with antagonistic activity to Gram-positive and Pseudomonas sp. pathogens.

    PubMed

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

    2014-01-01

    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

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

    PubMed Central

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

    2014-01-01

    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

  16. [New antimicrobials against Gram-positive organisms].

    PubMed

    Montejo, M

    2008-01-01

    Glycopeptides have been the antimicrobials most commonly used for infections by Gram-positive organisms and methicillin resistant S. aureus (MRSA). In recent years, however, glycopeptide resistance and tolerance have become a serious problem. Thus, enterococci highly resistant to vancomycin, vancomycin-intermediate/ resistant S. aureus (VISA), and vancomycin tolerance in S. aureus are found, and increased therapeutic failure and mortality are clinically reported with vancomycin MIC for S. aureus > or = 1.5-2 microg/mL. When faced with these organisms, we therefore need potent bactericidal antimicrobials that may be empirically administered, effective against susceptible and resistant pathogens, easily dosed, with few adverse effects and no significant interaction with other drugs, and that can be administered in an outpatient setting. In bacteremia by methicillin-susceptible S. aureus, use of vancomycin is associated to a greater failure and mortality rate as compared to semisynthetic penicillins. New treatment options for MRSA infections include daptomycin, linezolid, tygecycline, and quinupristin/dalfopristin. New anti-MRSA drugs are also under development, including glycopeptides (dalbavancin, telavancin, and oritavancin), ceftobiprole, and iclaprim. This paper reviews the new antimicrobials against Gram-positive organisms. PMID:18957022

  17. Peptide conversations in Gram-positive bacteria.

    PubMed

    Monnet, Véronique; Juillard, Vincent; Gardan, Rozenn

    2016-05-01

    Within Gram-positive bacteria, the expression of target genes is controlled at the population level via signaling peptides, also known as pheromones. Pheromones control a wide range of functions, including competence, virulence, and others that remain unknown. Until now, their role in bacterial gene regulation has probably been underestimated; indeed, bacteria are able to produce, by ribosomal synthesis or surface protein degradation, an extraordinary variety of peptides which are released outside bacteria and among which, some are pheromones that mediate cell-to-cell communication. The review aims at giving an updated overview of these peptide-dependant communication pathways. More specifically, it follows the whole peptide circuit from the peptide production and secretion in the extracellular medium to its interaction with sensors at bacterial surface or re-import into the bacteria where it plays its regulation role. In recent years, as we have accumulated more knowledge about these systems, it has become apparent that they are more complex than they first appeared. For this reason, more research on peptide-dependant pathways is needed to develop new strategies for controlling functions of interest in Gram-positive bacteria. In particular, such research could lead to alternatives to the use of antibiotics against pathogenic bacteria. In perspective, the review identifies new research questions that emerge in this field and that have to be addressed. PMID:25198780

  18. Influence of metallocene substitution on the antibacterial activity of multivalent peptide conjugates.

    PubMed

    Hoffknecht, Barbara C; Prochnow, Pascal; Bandow, Julia E; Metzler-Nolte, Nils

    2016-07-01

    Peptide dendrimers and derivatisation of peptides with metallocenes showed promising results in the search for new antibacterial agents. The two concepts are combined in this work leading to multivalent, metallocene-containing peptide derivates. These new peptides were synthesised utilising microwave assisted, copper(I) catalyzed alkyne-azide cycloaddition (CuAAC, "click" chemistry). Twelve new peptide conjugates, containing either a ferrocenoyl group or a ruthenocenoyl group on so-called ultrashort (i.e. < 5 amino acids) peptides, and ranging from monovalent to trivalent conjugates, were synthesised and their antibacterial activity was investigated by minimal inhibitory concentration (MIC) assays on five different bacterial strains. The antibacterial activity was compared to the same peptide conjugates without metallocenes. The resulting MIC values showed a significant enhancement of the antibacterial activity of these peptide conjugates against Gram-positive bacteria by the metallocenoyl groups. Additionally, the compounds with two metallocenoyl groups presented the best antibacterial activities overall. PMID:26988572

  19. Activities of Tedizolid and Linezolid Determined by the Reference Broth Microdilution Method against 3,032 Gram-Positive Bacterial Isolates Collected in Asia-Pacific, Eastern Europe, and Latin American Countries in 2014.

    PubMed

    Pfaller, Michael A; Flamm, Robert K; Jones, Ronald N; Farrell, David J; Mendes, Rodrigo E

    2016-09-01

    Tedizolid and linezolid in vitro activities against 3,032 Gram-positive pathogens collected in Asia-Pacific, Eastern European, and Latin American medical centers during 2014 were assessed. The isolates were tested for susceptibility by the current reference broth microdilution methods. Due to concern over the effect of MIC endpoint criteria on the results of testing the oxazolidinones tedizolid and linezolid, MIC endpoint values were read by two methods: (i) reading the MIC at the first well where the trailing began without regard for pinpoint trailing, according to CLSI M07-A10 and M100-S26 document instructions for reading linezolid (i.e., 80% inhibition of growth; these reads were designated tedizolid 80 and linezolid 80), and (ii) at 100% inhibition of growth (designated tedizolid 100 and linezolid 100). All Staphylococcus aureus, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus anginosus group, and Enterococcus faecalis isolates were inhibited at tedizolid 80 and 100 MIC values of 0.25 and 0.5, 0.25 and 0.25, 0.25 and 0.5, 0.12 and 0.25, and 0.5 and 1 μg/ml, respectively. Generally, MIC50 and MIC90 results for tedizolid 80 and linezolid 80 were one doubling dilution lower than those read at 100% inhibition. Tedizolid was 4- to 8-fold more potent than linezolid against all the isolates tested regardless of the MIC endpoint criterion used. Despite the differences in potency, >99.9% of isolates tested in this survey were susceptible to both linezolid and tedizolid using CLSI and EUCAST interpretive criteria. In conclusion, tedizolid demonstrated greater in vitro potency than linezolid against Gram-positive pathogens isolated from patients in medical centers across the Asia-Pacific region, Eastern Europe, and Latin America. PMID:27353270

  20. In vitro antibacterial activity in seed extracts of Manilkara zapota, Anona squamosa, and Tamarindus indica.

    PubMed

    Kothari, Vijay; Seshadri, Sriram

    2010-01-01

    Extracts prepared from seeds of Manilkara zapota, Anona squamosa, and Tamarindus indica were screened for their antibacterial activity by disc diffusion and broth dilution methods. Acetone and methanol extracts of T. indica seeds were found active against both gram-positive and gram-negative organisms. MIC values of potent extracts against susceptible organisms ranged from 53-380 μg/mL. Methanol extract of T. indica and acetone extract of M. zapota seeds were found to be bactericidal. PMID:21031260

  1. Characterization of a Novel Small Molecule That Potentiates β-Lactam Activity against Gram-Positive and Gram-Negative Pathogens

    PubMed Central

    Nair, Dhanalakshmi R.; Monteiro, João M.; Memmi, Guido; Thanassi, Jane; Pucci, Michael; Schwartzman, Joseph; Pinho, Mariana G.

    2015-01-01

    In a loss-of-viability screen using small molecules against methicillin-resistant Staphylococcus aureus (MRSA) strain USA300 with a sub-MIC of a β-lactam, we found a small molecule, designated DNAC-1, which potentiated the effect of oxacillin (i.e., the MIC of oxacillin decreased from 64 to 0.25 μg/ml). Fluorescence microscopy indicated a disruption in the membrane structures within 15 min of exposure to DNAC-1 at 2× MIC. This permeabilization was accompanied by a rapid loss of membrane potential, as monitored by use of the DiOC2 (3,3′-diethyloxacarbocyanine iodide) dye. Macromolecular analysis showed the inhibition of staphylococcal cell wall synthesis by DNAC-1. Transmission electron microscopy of treated MRSA USA300 cells revealed a slightly thicker cell wall, together with mesosome-like projections into the cytosol. The exposure of USA300 cells to DNAC-1 was associated with the mislocalization of FtsZ accompanied by the localization of penicillin-binding protein 2 (PBP2) and PBP4 away from the septum, as well as mild activation of the vraRS-mediated cell wall stress response. However, DNAC-1 does not have any generalized toxicity toward mammalian host cells. DNAC-1 in combination with ceftriaxone is also effective against an assortment of Gram-negative pathogens. Using a murine subcutaneous coinjection model with 108 CFU of USA300 as a challenge inoculum, DNAC-1 alone or DNAC-1 with a sub-MIC of oxacillin resulted in a 6-log reduction in bacterial load and decreased abscess formation compared to the untreated control. We propose that DNAC-1, by exerting a bimodal effect on the cell membrane and cell wall, is a viable candidate in the development of combination therapy against many common bacterial pathogens. PMID:25583731

  2. Antibiotic therapeutic options for infections caused by drug-resistant Gram-positive cocci.

    PubMed

    Banwan, K; Senok, A C; Rotimi, V O

    2009-01-01

    Serious infections caused by Gram-positive bacteria are currently difficult to treat because many of these pathogens are now resistant to standard antimicrobial agents. As a result of the emergence and spread of multidrug-resistant Gram-positive pathogens, new antimicrobial agents are urgently needed for clinical use. In recent years, there has been an increase in the number of drugs that have activity against these Gram-positive pathogens. Daptomycin, tigecycline, linezolid, quinupristin/dalfopristin and dalbavancin are five antimicrobial agents that are useful for the treatment of infections due to drug-resistant Gram-positive cocci. This review focuses on their mechanism of action, pharmacokinetics, spectrum of activity, clinical effectiveness, drug interaction and safety. These antimicrobial agents provide the clinician with additional treatment options among the limited therapies for resistant Gram-positive bacterial infection. PMID:20701863

  3. Synthesis and antibacterial activity of novel levofloxacin derivatives containing a substituted thienylethyl moiety

    PubMed Central

    2012-01-01

    Background and the purpose of the study Piperazinyl quinolones such as ciprofloxacin, ofloxacin and levofloxacin are an important group of quinolone antimicrobials which are widely used in the treatment of various infectious diseases. In the present study, we synthesized a new series of levofloxacin derivatives and evaluated their antibacterial activities. Methods The N-substituted analogs of levofloxacin 6a–j were prepared by nucleophilic reaction of N-desmethyl levofloxacin 11 with thienylethyl bromide derivatives 8 or 9. All target compounds were tested using conventional agar dilution method in comparison to levofloxacin and N-desmethyl levofloxacin and their MIC values were determined against a panel of Gram-positive and Gram-negative bacteria. Results All compounds showed significant antibacterial activities against Gram-positive bacteria (MIC = 0.04-6.25 μg/mL); however, the activity against Gram-negative bacteria was lower (MIC = 1.56–100 μg/mL). As is evident from the data, oxime derivatives 6e, 6h and 6i are superior in inhibiting the growth of Gram-positive bacteria (MIC = 0.04–0.19 μg/mL), and their activities were found to be 5–25 times better than N-desmethyl levofloxacin 11 and equal or better than levofloxacin 4. Conclusion We have designed and synthesized novel quinolone derivatives bearing functionalized thienylethyl moiety on the piperazine ring of levofloxacin. The results of antibacterial screening against Gram-positive and Gram-negative bacteria revealed that the introduction of functionalized thienylethyl moiety on the piperazine ring of levofloxacin can improve the activity against Gram-positive bacteria. Gram-positive bacteria are responsible for a wide range of infectious diseases, and rising resistance in this group is causing increasing concern. Thus, this study introduces structural features of levofloxacin scaffold for development of new candidates in the field of anti-Gram positive chemotherapy PMID:23351676

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

    PubMed Central

    2011-01-01

    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

  5. Probing interaction of gram-positive and gram-negative bacterial cells with ZnO nanorods.

    PubMed

    Jain, Aanchal; Bhargava, Richa; Poddar, Pankaj

    2013-04-01

    In the present work, the physiological effects of the ZnO nanorods on the Gram positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Aerobacter aerogenes) bacterial cells have been studied. The analysis of bacterial growth curves for various concentrations of ZnO nanorods indicates that Gram positive and Gram negative bacterial cells show inhibition at concentrations of ~64 and ~256 μg/mL respectively. The marked difference in susceptibility towards nanorods was also validated by spread plate and disk diffusion methods. In addition, the scanning electron micrographs show a clear damage to the cells via changed morphology of the cells from rod to coccoid etc. The confocal optical microscopy images of these cells also demonstrate the reduction in live cell count in the presence of ZnO nanorods. These, results clearly indicate that the antibacterial activity of ZnO nanorods is higher towards Gram positive bacterium than Gram negative bacterium which indicates that the structure of the cell wall might play a major role in the interaction with nanostructured materials and shows high sensitivity to the particle concentration. PMID:23827568

  6. Sonochemical coating of silver nanoparticles on textile fabrics (nylon, polyester and cotton) and their antibacterial activity

    NASA Astrophysics Data System (ADS)

    Perelshtein, Ilana; Applerot, Guy; Perkas, Nina; Guibert, Geoffrey; Mikhailov, Serguei; Gedanken, Aharon

    2008-06-01

    Silver nanoparticles were synthesized and deposited on different types of fabrics using ultrasound irradiation. The structure of silver-fabric composites was studied by physico-chemical methods. The mechanism of the strong adhesion of silver nanoparticles to the fibers is discussed. The excellent antibacterial activity of the Ag-fabric composite against Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive) cultures was demonstrated.

  7. Binuclear mercury(II) complexes of sulfonium ylides: Synthesis, structural characterization and anti-bacterial activity

    NASA Astrophysics Data System (ADS)

    Sabounchei, Seyyed Javad; Bagherjeri, Fateme Akhlaghi; Boskovic, Colette; Gable, Robert W.; Karamian, Roya; Asadbegy, Mostafa

    2013-02-01

    Reaction of α-keto stabilized sulfonium ylides (Me)2SCHC(O)C6H4R (R = p-Me (a); p-Cl (b)) with HgX2 (X = Cl, Br and I) in equimolar ratios using methanol as solvent leads to binuclear products of the type [HgX2(ylide)]2 (X = Cl (1), Br (2) and I (3)). Single crystal X-ray diffraction analysis reveals the presence of unexpected asymmetric halide-bridged dinuclear structures for 1a and 2b. Characterization of the compounds by IR, 1H- and 13C NMR spectroscopy confirmed coordination of the ylide to the metal through the carbon atom. In addition, the antibacterial effects of DMSO-solutions of the complexes were investigated by the disc diffusion method against three Gram positive and three negative bacteria. All complexes represent antibacterial activity against these bacteria with high levels of inhibitory potency exhibited against the Gram-positive species.

  8. Synthesis, SAR and antibacterial activity of hybrid chloro, dichloro-phenylthiazolyl-s-triazines

    PubMed Central

    Gahtori, Prashant; Ghosh, Surajit Kumar; Singh, Brijesh; Singh, Udaya Pratap; Bhat, Hans Raj; Uppal, Archana

    2011-01-01

    A series of hybrid novel chloro (1a–9a) and dichloro (10b–18b) phenylthiazolyl-s-triazine were synthesized and subsequently subjected to their antibacterial activity against three gram positive viz. Lactobacillus casei (NCIM-2651); Bacillus cereus (NCIM-2458); Staphylococcus aureus (NCIM-2120) and three gram negative viz Salmonella typhimurium (NCIM-2501); Escherichia coli (NCIM-2065); Klebsiella aerogenes (NCIM-2098). The SAR studies around the lead compound revealed that introduction of electron withdrawing groups and amino (–NH–) and mercapto (–S–) linker bridge seemed more promising towards antibacterial activity. Moreover, the virtual Molinspiration screenings are in compliance with Ghose’s rule. PMID:23960775

  9. Antibacterial, Antifungal and antioxidant activities of some medicinal plants.

    PubMed

    Wazir, Asma; Mehjabeen, -; Jahan, Noor; Sherwani, Sikander Khan; Ahmad, Mansoor

    2014-11-01

    The purpose of this study was to evaluate the antibacterial, antifungal and antioxidant activities of medicinal plants. The antibacterial activity of methanolic extracts of three medicinal plants (Swertia chirata, Terminalia bellerica and Zanthoxylum armatum) were tested against Gentamicin (standard drug) on eleven gram positive and seventeen gram negative bacteria by agar well method. It was revealed that seven-gram negative and six gram positive bacterial species were inhibited by these plant extracts. Minimum inhibitory concentrations (MIC) of the extracts were determined by broth micro-dilution method. The significant MIC value of Swertia chirata was 20mg/ml against Serratia marcesens, Zanthoxylum armatum was 10 mg/ml against Aeromonas hydrophila and Terminali bellerica was 20mg/ml against Acinetobacter baumanii as well as Serratia marcesens. Antifungal screening was done for methanolic extracts of these plants by agar well method with the 6 saprophytic, 5 dermatophytic and 6 yeasts. In this case Griseofulvin was used as a standard. All saprophytes and dermatophytes were showed resistance by these plants extracts except Microsporum canis, which was inhibited by Z. armatum and S. chirata extracts. The significant MIC value of Zanthoxylum armatum was 10mg/ml against Microsporum canis and Swertia chirata was 10mg/ml against Candida tropicalis. The anti-oxidant study was performed by DPPH free radical scavenging assay using ascorbic acid as a reference standard. Significant antioxidant activities were observed by Swertia chirata and Zanthoxylum armatum at concentration 200μg/ml was 70% DPPH scavenging activity (EC50=937.5μg/ml) while Terminalia bellerica showed 55.6% DPPH scavenging activity (EC50=100μg/ml). This study has shown that these plants could provide potent antibacterial compounds and may possible preventive agents in ROS related ailments. PMID:26045377

  10. [Epidemiology of the infection by resistant Gram-positive microorganisms].

    PubMed

    Cercenado, E

    2016-09-01

    Resistance among Gram-positive microorganisms to classical and new antimicrobials is a therapeutic threat. In Spain, methicillin resistance among Staphylococcus aureus (25-30%) and coagulase-negative staphylococci (50-60%) seems to have stabilized in the last decade. Among enterococci, vancomycin resistance is less than 5%. Both linezolid and daptomycin, in general, show good activity against these microorganisms. However, the resistance rates of Staphylococcus epidermidis to linezolid (20.9%), and of Enterococcus faecium to daptomycin (10.5%) in isolates from intensive care units are a worrying. PMID:27608305

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

    NASA Astrophysics Data System (ADS)

    Guo, Yanyan; Rogelj, Snezna; Zhang, Peng

    2010-02-01

    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.

  12. Antibacterial Activity of Myristica fragrans against Oral Pathogens

    PubMed Central

    Shafiei, Zaleha; Shuhairi, Nadia Najwa; Md Fazly Shah Yap, Nordiyana; Harry Sibungkil, Carrie-Anne; Latip, Jalifah

    2012-01-01

    Myristica fragrans Houtt is mostly cultivated for spices in Penang Island, Malaysia. The ethyl acetate and ethanol extracts of flesh, mace and seed of Myristica fragrans was evaluated the bactericidal potential against three Gram-positive cariogenic bacteria (Streptococcus mutans ATCC 25175, Streptococcus mitis ATCC 6249, and Streptococcus salivarius ATCC 13419) and three Gram-negative periodontopathic bacteria (Aggregatibacter actinomycetemcomitans ATCC 29522, Porphyromonas gingivalis ATCC 33277, and Fusobacterium nucleatum ATCC 25586). Antibacterial activities of the extracts was determined by twofold serial microdilution, with minimum inhibitory concentrations (MIC) ranging from 1.25 to 640 mg/mL and 0.075 to 40 mg/mL. The minimum bactericidal concentration (MBC) was obtained by subculturing method. Among all extracts tested, ethyl acetate extract of flesh has the highest significant inhibitory effects against Gram-positive and Gram-negative bacteria with mean MIC value ranging from 0.625 to 1.25 ± 0.00 (SD) mg/mL; P = 0.017) and highest bactericidal effects at mean MBC value ranging from 0.625 mg/mL to 20 ± 0.00 (SD) mg/mL. While for seed and mace of Myristica fragrans, their ethanol extracts exhibited good antibacterial activity against both groups of test pathogens compared to its ethyl acetate extracts. All of the extracts of Myristica fragrans did not show any antibacterial activities against Fusobacterium nucleatum ATCC 25586. Thus, our study showed the potential effect of ethyl acetate and ethanol extracts from flesh, seed and mace of Myristica fragrans to be new natural agent that can be incorporated in oral care products. PMID:23049613

  13. Fabrication of silver-coated cobalt ferrite nanocomposite and the study of its antibacterial activity

    NASA Astrophysics Data System (ADS)

    Kooti, M.; Saiahi, S.; Motamedi, H.

    2013-05-01

    A new silver coated cobalt ferrite nanocomposite, Ag@CoFe2O4, was prepared by a two-step procedure. In the first step, cobalt ferrite nanoparticles were synthesized by a combustion method using glycine as a fuel. This ferrite was then coated with nanosilver via chemical reduction of Ag+ solution. The as-synthesized Ag@CoFe2O4 was characterized by X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The antibacterial activity of this composite was investigated against some Gram-positive and Gram-negative bacteria and compared with those of silver nanoparticles and some standard antibacterial drugs.

  14. Synthesis and In-vitro Antibacterial Activities of Acetylanthracene and Acetylphenanthrene Derivatives of Some Fluoroquinolones

    PubMed Central

    Shamsa, Fazel; Foroumadi, Alireza; Shamsa, Hashim; Samadi, Nasrin; Faramarzi, Mohammad Ali; Shafiee, Abbas

    2011-01-01

    Novel analogues of N-piperazinyl fluoroquinolones were prepared and evaluated against a panel of Gram-positive and Gram-negative bacteria, to study the effect of introducing bulky anthracene and phenanthrene moieties on the antibacterial effects of norfloxacin, ciprofloxacin and gatifloxacin. Although most of the novel synthesized compounds had lower antibacterial effects, some derivatives showed better activity in comparison with mother drugs based on molar concentration; for example, the 3-acetyl phenanthrene analogue of norfloxacin was more effective than E. coli and K. pneumonia. PMID:24250347

  15. 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

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

    2014-01-01

    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 μg/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 β-lactamase (ESBL)-producing and non-ESBL-producing E. coli and Klebsiella pneumoniae, with 90% of the isolates inhibited by an MIC of ≤1 μg/ml. The MIC50 and MIC90 values for plazomicin against Pseudomonas aeruginosa were 4 μg/ml and 16 μg/ml, respectively, compared with 4 μg/ml and 8 μg/ml, respectively, for amikacin. Plazomicin had an MIC50 of 8 μg/ml and an MIC90 of 32 μg/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 μg/ml and 1 μg/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

  16. Report: Studies on antibacterial activity of some traditional medicinal plants used in folk medicine.

    PubMed

    Israr, Fozia; Hassan, Fouzia; Naqvi, Baqir Shyum; Azhar, Iqbal; Jabeen, Sabahat; Hasan, S M Farid

    2012-07-01

    Ethanolic extracts of eight medicinal plants commonly used in folk medicine were tested for their antibacterial activity against four Gram positive strains (Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis and, Streptococcus pneumoniae) and six Gram negative strains (Escherichia coli, Proteus vulgaris, Proteus mirabilis. Salmonella typhi para A, Salmonella typhi para B and Shigella dysenteriae) that were obtained from different pathological laboratories located in Karachi, Pakistan. Disc diffusion method was used to analyze antibacterial activity. Out of eight, five medicinal plants showed antibacterial activity against two or more than two microbial species. The most effective antimicrobial plant found to be Punica granatum followed by Curcuma zedoaria Rosc, Grewia asiatica L and Carissa carandas L, Curcuma caesia Roxb respectively. From these results, it is evident that medicinal plants could be used as a potential source of new antibacterial agents. PMID:22713958

  17. Antibacterial and Cytotoxic Activity of Compounds Isolated from Flourensia oolepis

    PubMed Central

    Joray, Mariana Belén; Trucco, Lucas Daniel; González, María Laura; Napal, Georgina Natalia Díaz; Palacios, Sara María; Bocco, José Luis; Carpinella, María Cecilia

    2015-01-01

    The antibacterial and cytotoxic effects of metabolites isolated from an antibacterial extract of Flourensia oolepis were evaluated. Bioguided fractionation led to five flavonoids, identified as 2′,4′-dihydroxychalcone (1), isoliquiritigenin (2), pinocembrin (3), 7-hydroxyflavanone (4), and 7,4′-dihydroxy-3′-methoxyflavanone (5). Compound 1 showed the highest antibacterial effect, with minimum inhibitory concentration (MIC) values ranging from 31 to 62 and 62 to 250 μg/mL, against Gram-positive and Gram-negative bacteria, respectively. On further assays, the cytotoxic effect of compounds 1–5 was determined by MTT assay on acute lymphoblastic leukemia (ALL) and chronic myeloid leukemia (CML) cell lines including their multidrug resistant (MDR) phenotypes. Compound 1 induced a remarkable cytotoxic activity toward ALL cells (IC50 = 6.6–9.9 μM) and a lower effect against CML cells (IC50 = 27.5–30.0 μM). Flow cytometry was used to analyze cell cycle distribution and cell death by PI-labeled cells and by Annexin V/PI staining, respectively. Upon treatment, 1 induced cell cycle arrest in the G2/M phase accompanied by a strong induction of apoptosis. These results describe for the first time the antibacterial metabolites of F. oolepis extract, with 1 being the most effective. This chalcone also emerges as a selective cytotoxic agent against sensitive and resistant leukemic cells, highlighting its potential as a lead compound. PMID:26819623

  18. Antibacterial and Cytotoxic Activity of Compounds Isolated from Flourensia oolepis.

    PubMed

    Joray, Mariana Belén; Trucco, Lucas Daniel; González, María Laura; Napal, Georgina Natalia Díaz; Palacios, Sara María; Bocco, José Luis; Carpinella, María Cecilia

    2015-01-01

    The antibacterial and cytotoxic effects of metabolites isolated from an antibacterial extract of Flourensia oolepis were evaluated. Bioguided fractionation led to five flavonoids, identified as 2',4'-dihydroxychalcone (1), isoliquiritigenin (2), pinocembrin (3), 7-hydroxyflavanone (4), and 7,4'-dihydroxy-3'-methoxyflavanone (5). Compound 1 showed the highest antibacterial effect, with minimum inhibitory concentration (MIC) values ranging from 31 to 62 and 62 to 250 μg/mL, against Gram-positive and Gram-negative bacteria, respectively. On further assays, the cytotoxic effect of compounds 1-5 was determined by MTT assay on acute lymphoblastic leukemia (ALL) and chronic myeloid leukemia (CML) cell lines including their multidrug resistant (MDR) phenotypes. Compound 1 induced a remarkable cytotoxic activity toward ALL cells (IC50 = 6.6-9.9 μM) and a lower effect against CML cells (IC50 = 27.5-30.0 μM). Flow cytometry was used to analyze cell cycle distribution and cell death by PI-labeled cells and by Annexin V/PI staining, respectively. Upon treatment, 1 induced cell cycle arrest in the G2/M phase accompanied by a strong induction of apoptosis. These results describe for the first time the antibacterial metabolites of F. oolepis extract, with 1 being the most effective. This chalcone also emerges as a selective cytotoxic agent against sensitive and resistant leukemic cells, highlighting its potential as a lead compound. PMID:26819623

  19. Synthesis, structure and in vitro antibacterial activities of new hybrid disinfectants quaternary ammonium compounds: pyridinium and quinolinium stilbene benzenesulfonates.

    PubMed

    Chanawanno, Kullapa; Chantrapromma, Suchada; Anantapong, Theerasak; Kanjana-Opas, Akkharawit; Fun, Hoong-Kun

    2010-09-01

    The series of pyridinium (1-10) and quinolinium (11-20) stilbene benzenesulfonates have been synthesized and their structures were investigated by UV-vis, FT-IR and (1)H NMR spectroscopy. In addition, compound 5 was also determined by single crystal X-ray diffraction technique. The antibacterial activity of the synthesized compounds against both gram-positive and gram-negative bacteria has been determined. The quinolinium derivatives exhibited two very potent characteristic activities, namely, (i) specific activity to Methicillin-Resistant Staphylococcus aureus and (ii) with broad band spectrum activity. Compounds 11, 13 and 14 are the most active showing broad spectrum antibacterial activity against gram-positive (Methicillin-Resistant S. aureus, S. aureus, Bacillus subtilis, Vancomycin-Resistant Enterococcus faecalis and E. faecalis) and gram-negative bacterium (Shigella sonnei). The MICs of these compounds were found to be better than that of Benzalkonium chloride (BZK), the commercially used disinfectant. PMID:20619939

  20. Evaluation of Parmotrema reticulatum Taylor for Antibacterial and Antiinflammatory Activities.

    PubMed

    Jain, A P; Bhandarkar, S; Rai, G; Yadav, A K; Lodhi, S

    2016-01-01

    Lichens produce variety of secondary metabolites including depsides, depsidones and dibenzofurans having multifunctional activity in response to external environmental condition. Present study provides evidence for in vitro antibacterial and in vivo antiinflammatory activity of acetone and ethanol extracts of Parmotrema reticulatum. In vitro antibacterial activity was investigated against gram positive and gram negative bacteria. Cotton pellet-induced granuloma, xylene-induced ear swelling, carragennan-induced edema, histamine-induced and carboxymethylcellulose sodium-induced leukocyte emigration in mice models were used to quantify the antiinflammatory activity. Acetone and ethanol extracts were showed antibacterial activity against Bacillus subtilis (minimal inhibitory concentration: 100 and 150 μg/ml) and Staphylococcus aureus (minimal inhibitory concentration: 100 and 200 μg/ml), Escherichia coli (minimal inhibitory concentration: 200 and 250 μg/ml), and Pseudomonasa eruginosa (minimal inhibitory concentration: 200 and 300 μg/ml). Acetone extract was inhibited edema significantly at 200 mg/kg with xylene, cotton pellet, carragennan and histamine induced edema in vivo models. Ethanol extract was found effective at dose of 300 mg/kg with all in vivo antiinflammatory models. The results showed significant (P<0.01) antiinflammatory effects at 200 and 300 mg/kg dose of acetone and ethanol extracts, respectively, which can be concluded that significant activity may be due to presence of flavanoids in ethanol extract and usnic acid in acetone extract. PMID:27168687

  1. Antibacterial and antitumour activities of some plants grown in Turkey

    PubMed Central

    Usta, Canan; Yildirim, Arzu Birinci; Turker, Arzu Ucar

    2014-01-01

    Screening of antibacterial and antitumour activities of 33 different extracts prepared with three types of solvents (water, ethanol and methanol) was conducted. The extracts were obtained from 11 different plant species grown in Turkey: Eryngium campestre L., Alchemilla mollis (Buser) Rothm., Dorycnium pentaphyllum Scop., Coronilla varia L., Onobrychis oxyodonta Boiss., Fritillaria pontica Wahlenb., Asarum europaeum L., Rhinanthus angustifolius C. C. Gmelin, Doronicum orientale Hoffm., Campanula glomerata L. and Campanula olympica Boiss. Antibacterial activity against six bacteria was evaluated: Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pyogenes, Staphylococcus aureus and Staphylococcus epidermidis by using disc diffusion and well diffusion methods. S. aureus and S. epidermidis were most sensitive to the methanolic extract from A. europaeum. S. pyogenes was vulnerable to all used extracts of D. orientale. In addition, ethanolic or methanolic extracts of E. campestre, A. mollis, D. pentaphyllum, C. varia, R. angustifolius, C. glomerata and C. olympica displayed strong antibacterial activity against at least one of the tested gram-negative bacteria. The methanolic extract from R. angustifolius showed a broad-spectrum activity against both gram-positive and gram-negative bacteria. Antitumour activity was evaluated with Agrobacterium-tumefaciens-induced potato disc tumour assay. Best antitumour activity was obtained with the aqueous extract from A. europaeum and methanolic extract from E. campestre (100% and 86% tumour inhibition, respectively). PMID:26740759

  2. Evaluation of Parmotrema reticulatum Taylor for Antibacterial and Antiinflammatory Activities

    PubMed Central

    Jain, A. P.; Bhandarkar, S.; Rai, G.; Yadav, A. K.; Lodhi, S.

    2016-01-01

    Lichens produce variety of secondary metabolites including depsides, depsidones and dibenzofurans having multifunctional activity in response to external environmental condition. Present study provides evidence for in vitro antibacterial and in vivo antiinflammatory activity of acetone and ethanol extracts of Parmotrema reticulatum. In vitro antibacterial activity was investigated against gram positive and gram negative bacteria. Cotton pellet-induced granuloma, xylene-induced ear swelling, carragennan-induced edema, histamine-induced and carboxymethylcellulose sodium-induced leukocyte emigration in mice models were used to quantify the antiinflammatory activity. Acetone and ethanol extracts were showed antibacterial activity against Bacillus subtilis (minimal inhibitory concentration: 100 and 150 μg/ml) and Staphylococcus aureus (minimal inhibitory concentration: 100 and 200 μg/ml), Escherichia coli (minimal inhibitory concentration: 200 and 250 μg/ml), and Pseudomonasa eruginosa (minimal inhibitory concentration: 200 and 300 μg/ml). Acetone extract was inhibited edema significantly at 200 mg/kg with xylene, cotton pellet, carragennan and histamine induced edema in vivo models. Ethanol extract was found effective at dose of 300 mg/kg with all in vivo antiinflammatory models. The results showed significant (P<0.01) antiinflammatory effects at 200 and 300 mg/kg dose of acetone and ethanol extracts, respectively, which can be concluded that significant activity may be due to presence of flavanoids in ethanol extract and usnic acid in acetone extract. PMID:27168687

  3. Antioxidative, antibrowning and antibacterial activities of sixteen floral honeys.

    PubMed

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

    2011-09-01

    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

  4. Acquired inducible antimicrobial resistance in Gram-positive bacteria

    PubMed Central

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

    2012-01-01

    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 β-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

  5. Antimicrobial Diterpenes from Azorella Species Against Gram-Positive Bacteria.

    PubMed

    Donoso, Viviana; Bacho, Mitchell; Núiñez, Solange; Rovirosa, Juana; San-Martin, Aurelio; Leiva, Sergio

    2015-11-01

    The present study was aimed at evaluating the antibacterial activity of mulinane and azorellane diterpenes isolated from the Andean plants Azorella compacta and A. trifoliolata and semisynthetic derivatives against reference and multidrug-resistant strains. The results revealed that the semisynthetic compound 7-acetoxy-mulin-9,12-diene (5) exhibited antibacterial activity against reference and multidrug-resistant strains of Staphylococcus aureus and moderate antimycobacterial activity against Mycobacterium smegmatis ATCC 14468. PMID:26749825

  6. Antibacterial activity of antibacterial cutting boards in household kitchens.

    PubMed

    Kounosu, Masayuki; Kaneko, Seiichi

    2007-12-01

    We examined antibacterial cutting boards with antibacterial activity values of either "2" or "4" in compliance with the JIS Z 2801 standard, and compared their findings with those of cutting boards with no antibacterial activity. These cutting boards were used in ten different households, and we measured changes in the viable cell counts of several types of bacteria with the drop plate method. We also identified the detected bacterial flora and measured the minimum antimicrobial concentrations of several commonly used antibacterial agents against the kinds of bacteria identified to determine the expected antibacterial activity of the respective agents. Cutting boards with activity values of both "2" and "4" proved to be antibacterial in actual use, although no correlation between the viable cell counts and the antibacterial activity values was observed. In the kitchen environment, large quantities of Pseudomonas, Flavobacterium, Micrococcus, and Bacillus were detected, and it was confirmed that common antibacterial agents used in many antibacterial products are effective against these bacterial species. In addition, we measured the minimum antimicrobial concentrations of the agents against lactobacillus, a typical good bacterium, and discovered that this bacterium is less sensitive to these antibacterial agents compared to more common bacteria. PMID:18198718

  7. Microcins from Enterobacteria: On the Edge Between Gram-Positive Bacteriocins and Colicins

    NASA Astrophysics Data System (ADS)

    Rebuffat, Sylvie

    Most bacteria and archaea produce gene-encoded antimicrobial peptides/proteins called bacteriocins, which are secreted by the producing bacteria to compete against other microorganisms in a given niche. They are considered important mediators of intra- and interspecies interactions and therefore a factor in ­maintaining the microbial diversity and stability. They are ribosomally synthesized, and most of them are produced as inactive precursor proteins, which in some cases are further enzymatically modified. Bacteriocins generally exert potent antibacterial activities directed against bacterial species closely related to the producing bacteria. Bacteriocins are abundant and diverse in Gram-negative and Gram-positive bacteria. This chapter focuses on colicins and microcins from enterobacteria (mainly Escherichia coli) and on bacteriocins from lactic acid bacteria (LAB). Microcins are the lower-molecular-mass bacteriocins produced by Gram-negative bacteria with a repertoire of only 14 representatives. They form a very restricted family of bacteriocins, compared to the huge family of LAB bacteriocins that is constituted of several hundreds of peptides, with which microcins share common characteristics. Nevertheless, microcins also show similarities, particularly in their uptake mechanisms, with the higher-molecular-mass colicins, also produced by E. coli strains. On the edge between LAB bacteriocins and colicins, microcins appear to combine highly efficient strategies developed by both Gram-positive and Gram-negative bacteria at different levels, including uptake, translocation, killing of target cells, and immunity of the producing bacteria, making them important actors of bacterial competitions and fascinating models for novel concepts toward antimicrobial strategies and against resistance mechanisms.

  8. Synthesis and antibacterial activity of of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Maliszewska, I.; Sadowski, Z.

    2009-01-01

    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.

  9. In Vitro Study to Evaluate Antibacterial and Non-haemolytic Activities of Four Iranian Medicinal Plants

    PubMed Central

    Sepahi, S; Ghorani-Azam, A; Sepahi, S; Asoodeh, A; Rostami, S

    2014-01-01

    Objective: Aqueous extracts of four medicinal plants including Ferula gummosa, Echinophora orientalis, Nasturtium microphyllum and Verbascum thapsus were used to determine their antibacterial activities and minimum inhibitory concentration (MIC). The aim of this study was to assess antibacterial activity of extracts of four medicinal plants against a Gram-positive and a Gram-negative bacteria (Staphylococcus aureus PTCC1431, and Escherichia coli HP101BA 7601c). Methods: Radial diffusion assay was used to assess the antibacterial activity of extracted samples. Haemolysis assay was also used to examine their nontoxic effects on human red blood cells. Results: This study showed that all the mentioned plants have satisfactory antibacterial effects against both Gram-positive and Gram-negative bacteria. Minimum inhibitory concentration values of these samples were less than 750 μg/mL. In addition, no significant haemolytic activity was observed at their MIC values. Conclusion: The results of this study showed that all these studied plants have good potential for further studies for drug discovery. PMID:25429470

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-01-01

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

  12. Antibacterial Activity of Ti3C2Tx MXene.

    PubMed

    Rasool, Kashif; Helal, Mohamed; Ali, Adnan; Ren, Chang E; Gogotsi, Yury; Mahmoud, Khaled A

    2016-03-22

    MXenes are a family of atomically thin, two-dimensional (2D) transition metal carbides and carbonitrides with many attractive properties. Two-dimensional Ti3C2Tx (MXene) has been recently explored for applications in water desalination/purification membranes. A major success indicator for any water treatment membrane is the resistance to biofouling. To validate this and to understand better the health and environmental impacts of the new 2D carbides, we investigated the antibacterial properties of single- and few-layer Ti3C2Tx MXene flakes in colloidal solution. The antibacterial properties of Ti3C2Tx were tested against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) by using bacterial growth curves based on optical densities (OD) and colonies growth on agar nutritive plates. Ti3C2Tx shows a higher antibacterial efficiency toward both Gram-negative E. coli and Gram-positive B. subtilis compared with graphene oxide (GO), which has been widely reported as an antibacterial agent. Concentration dependent antibacterial activity was observed and more than 98% bacterial cell viability loss was found at 200 μg/mL Ti3C2Tx for both bacterial cells within 4 h of exposure, as confirmed by colony forming unit (CFU) and regrowth curve. Antibacterial mechanism investigation by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) coupled with lactate dehydrogenase (LDH) release assay indicated the damage to the cell membrane, which resulted in release of cytoplasmic materials from the bacterial cells. Reactive oxygen species (ROS) dependent and independent stress induction by Ti3C2Tx was investigated in two separate abiotic assays. MXenes are expected to be resistant to biofouling and offer bactericidal properties. PMID:26909865

  13. Screening for fractions of Oxytropis falcata Bunge with antibacterial activity.

    PubMed

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

    2009-01-01

    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

  14. Glass bead transformation method for gram-positive bacteria

    PubMed Central

    Rattanachaikunsopon, Pongsak; Phumkhachorn, Parichat

    2009-01-01

    A simple, inexpensive and reproducible transformation method was developed for Gram-positive bacteria. It was based on agitation of bacterial protoplasts with glass beads in the presence of DNA and polyethylene glycol. By using this method, introduction of pGK12 into protoplasts of several strains of Gram-positive bacteria was achieved. PMID:24031442

  15. Methods for targetted mutagenesis in gram-positive bacteria

    SciTech Connect

    Yang, Yunfeng

    2014-05-27

    The present invention provides a method of targeted mutagenesis in Gram-positive bacteria. In particular, the present invention provides a method that effectively integrates a suicide integrative vector into a target gene in the chromosome of a Gram-positive bacterium, resulting in inactivation of the target gene.

  16. Synthesis and in vitro antibacterial activity of 7-(3-alkoxyimino-4-amino-4-methylpiperidin-1-yl) fluoroquinolone derivatives.

    PubMed

    Wang, Ju-Xian; Zhang, Yi-Bin; Liu, Ming-Liang; Wang, Bo; Chai, Yun; Li, Su-Jie; Guo, Hui-Yuan

    2011-06-01

    A series of novel 7-(3-alkoxyimino-4-amino-4-methylpiperidin-1-yl)fluoroquinolone derivatives were designed, synthesized and evaluated for their in vitro antibacterial activity and cytotoxicity. All of the target compounds have potent antibacterial activity against the tested Gram-positive and Gram-negative strains, and exhibit good potency in inhibiting the growth of Staphylococcus aureus including MRSA, Staphylococcus epidermidis including MRSE and Streptococcus pneumoniae (MICs: 0.125-4 μg/mL). Compound 22, with the best activity against Gram-positive strains, is 4-16 fold more potent than gemifloxacin, gatifloxacin and levofloxacin against Enterococcus faecalis, and 16- and 4-fold more potent than levofloxacin against S. epidermidis 09-6 and S. pneumoniae 08-4, respectively. PMID:21481984

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

    PubMed

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

    2013-01-01

    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

  18. Chemical composition and antibacterial activity of the essential oil of Espeletia nana.

    PubMed

    Peña, Alexis; Rojas, Luis; Aparicio, Rosa; Alarcón, Libia; Baptista, José Gregorio; Velasco, Judith; Carmona, Juan; Usubillaga, Alfredo

    2012-05-01

    The essential oil of the leaves of Espeletia nana Cuatrec., obtained by hydrodistillation, was analyzed by GC-MS, which allowed the identification of 24 components, which made up 99.9% of the oil. The most abundant compounds were a-pinene (38.1%), beta-pinene (17.2%), myrcene (15.0%), spathulenol (4.2%), bicyclogermacrene (4.0%), a-zingiberene (4.0%), and gamma-himachalene (3.7%). Antibacterial activity was tested against Gram-positive and Gram-negative bacteria using the agar disk diffusion method. Activity was observed only against Gram-positive bacteria. MIC values were determined for Staphylococcus aureus ATCC 25923 (200 microg/mL) and Enterococcusfaecalis ATCC 29212 (600 microg/mL). PMID:22799102

  19. Synthesis, characterization and antibacterial activities of some new ferrocene-containing penems.

    PubMed

    Long, Bohua; He, Chunlian; Yang, Yingbin; Xiang, Jiannan

    2010-03-01

    The synthesis and structure-activity relationships of a series of new penems bearing ferrocenyl group attached to the C-2 position of the penem nucleus were described. The beta-lactanic derivatives obtained had been characterized as sodium salts, through (1)H NMR and IR, as well as through element analysis. Their in vitro antibacterial activities against both Gram-positive including meticillin-resistant Staphylococcus aureus (MRSA) and Gram-negative bacteria were tested. Most of the penems exhibited superior or equivalent efficacy of antibacterial activity as well as high stability to renal dehydropeptidase-I (DHP-I) compared with faropenem. In particular, the compound 14h having a heterocyclic group showed the most potent antibacterial activity. PMID:20053481

  20. New antimicrobial approaches to gram positive respiratory infections.

    PubMed

    Liapikou, Adamantia; Cilloniz, Catia; Mensa, Josep; Torres, Antonio

    2015-06-01

    Nowadays, we face growing resistance among gram-positive and gram-negative pathogens that cause respiratory infection in the hospital and in the community. The spread of penicillin- and macrolide-resistant pneumococci, Community-acquired methicillin-resistant staphylococcus aureus (Ca-MRSA), the emergence of glycopeptide-resistant staphylococci underline the need for underline the need for therapeutic alternatives. A number of new therapeutic agents, with activity against the above Gram (+) respiratory pathogens, as ceftaroline, ceftopibrole, telavancin, tedizolid have become available, either in clinical trials or have been approved for clinical use. Especially, the development of new oral antibiotics, as nemonaxacin, omadacyclin, cethromycin and solithromycin will give a solution to the lack of oral drugs for outpatient treatment. In the future the clinician needs to optimize the use of old and new antibiotics to treat gram (+) respiratory serious infections. PMID:24878422

  1. Microwave-assisted synthesis of CdO-ZnO nanocomposite and its antibacterial activity against human pathogens

    NASA Astrophysics Data System (ADS)

    Karthik, K.; Dhanuskodi, S.; Gobinath, C.; Sivaramakrishnan, S.

    2015-03-01

    CdO-ZnO nanocomposite was prepared by microwave-assisted method and characterized by X-ray crystallography (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). It exhibits hexagonal cubic structure with an average crystallite size of 27 nm. From the UV-Vis spectra, the bandgap is estimated as 2.92 eV. The fluorescence spectrum shows a near band edge emission at 422 nm. In addition the antibacterial activity of CdO-ZnO nanocomposite was carried out in-vitro against two kinds of bacteria: gram negative bacteria (G -ve) i.e. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and gram positive bacteria (G +ve): Staphylococcus aureus, Proteus vulgaris and Bacillus spp. This study indicates the zone of inhibition of 40 mm has high antibacterial activity towards the gram positive bacterium S. aureus.

  2. Microwave-assisted synthesis of CdO-ZnO nanocomposite and its antibacterial activity against human pathogens.

    PubMed

    Karthik, K; Dhanuskodi, S; Gobinath, C; Sivaramakrishnan, S

    2015-03-15

    CdO-ZnO nanocomposite was prepared by microwave-assisted method and characterized by X-ray crystallography (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). It exhibits hexagonal cubic structure with an average crystallite size of 27 nm. From the UV-Vis spectra, the bandgap is estimated as 2.92 eV. The fluorescence spectrum shows a near band edge emission at 422 nm. In addition the antibacterial activity of CdO-ZnO nanocomposite was carried out in-vitro against two kinds of bacteria: gram negative bacteria (G -ve) i.e. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and gram positive bacteria (G +ve): Staphylococcus aureus, Proteus vulgaris and Bacillus spp. This study indicates the zone of inhibition of 40 mm has high antibacterial activity towards the gram positive bacterium S. aureus. PMID:25546491

  3. In vitro antibacterial activity of ME1207, a new oral cephalosporin.

    PubMed

    Miyazaki, S; Miyazaki, Y; Tsuji, A; Nishida, M; Goto, S

    1991-08-01

    ME1207 is the prodrug of ME1206. Its in vitro antibacterial activity was compared with that of cefteram, cefpodoxime, cefixime, and cefaclor against various clinical isolates. ME1206 was more active than the other cephems tested against staphylococci, streptococci, Morganella morganii, Pseudomonas cepacia, and Flavobacterium meningosepticum and had the most potent activity against Haemophilus influenzae and Neiserria gonorrhoeae. The drug also showed a wide spectrum of activity against other gram-positive and gram-negative bacteria, except methicillin-resistant Staphylococcus aureus, Enterococcus faecalis, Citrobacter freundii, Pseudomonas aeruginosa, Xanthomonas maltophilia, and Alcaligenes xylosoxydans. PMID:1929344

  4. Orally active carbapenem antibiotics I. Antibacterial and pharmacokinetic potential of 2-phenyl and 2-thienylcarbapenems.

    PubMed

    Sunagawa, Makoto; Ueda, Yutaka; Okada, Shin-Ichiro; Watanabe, Shoji; Hashizuka, Takahiko; Hori, Seiji; Sasaki, Akira; Eriguchi, Yoshiro; Kanazawa, Katsunori

    2005-12-01

    In order to design orally active carbapenem antibiotics effective against beta-lactam-resistant pathogens, such as penicillin-resistant Streptococcus pneumoniae (PRSP) and beta-lactamase non-producing ampicillin-resistant Haemophilus influenzae (BLNAR), a series of novel 2-phenylcarbapenems and some 2-thienyl derivatives were synthesized and tested for antibacterial activities. These compounds were highly active against PRSP, BLNAR, and major Gram-positive and Gram-negative bacteria that cause community-acquired infections. Their pivaloyloxymethylester-type prodrug exhibited good oral absorption in mice, suggesting that this series of carbapenems were promising as a prototype of novel orally active beta-lactams. PMID:16506696

  5. Unveiling the Mode of Action of Two Antibacterial Tanshinone Derivatives

    PubMed Central

    Wang, Dongdong; Zhang, Wuxia; Wang, Tingting; Li, Na; Mu, Haibo; Zhang, Jiwen; Duan, Jinyou

    2015-01-01

    In this study, 2-(N-pyrrolidine-alkyl) tanshinones bearing pyrrolidine groups were synthesized and the antibacterial mechanism was explored. These derivatives selectively elicited antibacterial activity against Gram-positive bacteria. Moreover, their antibacterial activities were time-, concentration-dependent and persistent. It appeared that Fenton-mediated hydroxyl radicals were involved, and the disruption of cell membranes was observed. This study indicates that 2-(N-pyrrolidine-alkyl) tanshinones might be potential candidates as antibacterial agents. PMID:26263982

  6. Unveiling the Mode of Action of Two Antibacterial Tanshinone Derivatives.

    PubMed

    Wang, Dongdong; Zhang, Wuxia; Wang, Tingting; Li, Na; Mu, Haibo; Zhang, Jiwen; Duan, Jinyou

    2015-01-01

    In this study, 2-(N-pyrrolidine-alkyl) tanshinones bearing pyrrolidine groups were synthesized and the antibacterial mechanism was explored. These derivatives selectively elicited antibacterial activity against Gram-positive bacteria. Moreover, their antibacterial activities were time-, concentration-dependent and persistent. It appeared that Fenton-mediated hydroxyl radicals were involved, and the disruption of cell membranes was observed. This study indicates that 2-(N-pyrrolidine-alkyl) tanshinones might be potential candidates as antibacterial agents. PMID:26263982

  7. [Antimicrobial susceptibility of clinical isolates of aerobic Gram-positive cocci and anaerobic bacteria in 2006].

    PubMed

    Yamaguchi, Takahiro; Yoshida, Isamu; Itoh, Yoshihisa; Tachibana, Mineji; Takahashi, Choichiro; Kaku, Mitsuo; Kanemitsu, Keiji; Okada, Masahiko; Horikawa, Yoshinori; Shiotani, Joji; Kino, Hiroyoshi; Ono, Yuka; Baba, Hisashi; Matsuo, Shuji; Asari, Seishi; Toyokawa, Masahiro; Matsuoka, Kimiko; Kusano, Nobuchika; Nose, Motoko; Murase, Mitsuharu; Miyamoto, Hitoshi; Saikawa, Tetsunori; Hiramatsu, Kazufumi; Kohno, Shigeru; Yanagihara, Katsunori; Yamane, Nobuhisa; Nakasone, Isamu; Maki, Hideki; Yamano, Yoshinori

    2010-12-01

    The activity of antibacterial agents against aerobic Gram-positive cocci (26 species, 1022 strains) and anaerobic bacteria (23 species, 184 strains) isolated from clinical specimens in 2006 at 16 clinical facilities in Japan were studied using either broth microdilution or agar dilution method. The ratio of methicillin-resistant strains among Staphylococcus aureus and Staphylococcus epidermidis was 53.0% and 65.8%, suggesting that resistant strains were isolated at high frequency. Vancomycin (VCM) and quinupristin/dalfopristin (QPR/DPR) had good antibacterial activity against methicillin-resistant S. aureus and methicillin-resistant S. epidermidis, with MIC90s of < or = 2 micrcog/mL. The ratio of penicillin (PC) intermediate and resistant strains classified by mutations of PC-binding proteins among Streptococcus pneumoniae was 87.6%. Ceftriaxone, cefpirome, cefepime, carbapenem antibiotics, VCM, teicoplanin, linezolid(LZD) and QPR/DPR had MIC90s of < or = 1 microg/mL against PC-intermediate and resistant S. pneumoniae strains. Against all strains of Enterococcus faecalis and Enterococcus faecium, the MICs of VCM and TEIC were under 2 microg/mL, and no resistant strain was detected, suggesting that these agents had excellent activities against these species. 10.9% of E. faecalis strains or 3.5% of E. faecium strains showed intermediate or resistant to LZD. 24.4% of E. faecium strains showed intermediate or resistant to QPR/DPR. Against all strains of Clostridium difficile, the MIC of VCM were under 1 microg/mL, suggesting that VCM had excellent activity against C. difficile. Carbapenems showed good activity against Peptococcaceae, Bacteroides spp., and Prevotella spp. However since several strains of Bacteroides fragilis showed resistant to carbapenems and the susceptibility of this species should be well-focused in the future. PMID:21425596

  8. [Antimicrobial susceptibility of clinical isolates of aerobic gram-positive cocci and anaerobic bacteria in 2008].

    PubMed

    Yoshida, Isamu; Yamaguchi, Takahiro; Kudo, Reiko; Fuji, Rieko; Takahashi, Choichiro; Oota, Reiko; Kaku, Mitsuo; Kunishima, Hiroyuki; Okada, Masahiko; Horikawa, Yoshinori; Shiotani, Joji; Kino, Hiroyoshi; Ono, Yuka; Fujita, Shinichi; Matsuo, Shuji; Kono, Hisashi; Asari, Seishi; Toyokawa, Masahiro; Kusano, Nobuchika; Nose, Motoko; Horii, Toshinobu; Tanimoto, Ayako; Miyamoto, Hitoshi; Saikawa, Tetsunori; Hiramatsu, Kazufumi; Kohno, Shigeru; Yanagihara, Katsunori; Yamane, Nobuhisa; Nakasone, Isamu; Maki, Hideki; Yamano, Yoshinori

    2012-02-01

    The activity of antibacterial agents against aerobic Gram-positive cocci (25 genus or species, 1029 strains) and anaerobic bacteria (21 genus or species, 187 strains) isolated from clinical specimens in 2008 at 16 clinical facilities in Japan were studied using either broth microdilution or agar dilution method. The ratio of methicillin-resistant strains among Staphylococcus aureus and Staphylococcus epidermidis was 59.6% and 81.2%, suggesting that resistant strains were isolated at high frequency. Vancomycin (VCM), linezolid (LZD) and quinupristin/dalfopristin (QPR/DPR) had good antibacterial activity against methicillin-resistant S. aureus and methicillin-resistant S. epidermidis, with MIC90s of < or = 2 microg/mL. The ratio of penicillin (PC) intermediate and resistant strains classified by mutations of PC-binding proteins among Streptococcus pneumoniae was 92.0% that was highest among our previous reports. Cefpirome, carbapenems, VCM, teicoplanin (TEIC), LZD and QPR/DPR had MIC90s of < or = 1 microg/mL against PC-intermediate and resistant S. pneumoniae strains. Against all strains of Enterococcus faecalis and Enterococcus faecium, the MICs of VCM and TEIC were under 2 microg/mL, and no resistant strain was detected, suggesting that these agents had excellent activities against these species. 15.9% of E. faecalis strains and 1.2% of E. faecium strains showed intermediate to LZD. 17.1% of E. faecium strains showed intermediate or resistant to QPR/DPR. Against all strains of Clostridium difficile, the MIC of VCM was under 1 microg/mL, suggesting that VCM had excellent activity. Carbapenems showed good activity against Clostridiales, Bacteroides spp., and Prevotella spp., but one strain of Bacteroides fragilis showed resistant to carbapenems. And so, the susceptibility of this species should be well-focused in the future at detecting continuously. PMID:22808693

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

    PubMed

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

    2014-09-01

    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

  10. Plants used in Guatemala for the treatment of respiratory diseases. 1. Screening of 68 plants against gram-positive bacteria.

    PubMed

    Caceres, A; Alvarez, A V; Ovando, A E; Samayoa, B E

    1991-02-01

    Respiratory ailments are important causes of morbidity and mortality in developing countries. Ethnobotanical surveys and literature reviews conducted in Guatemala during 1986-88 showed that 234 plants from 75 families, most of them of American origin, have been used for the treatment of respiratory ailments. Three Gram-positive bacteria causing respiratory infections (Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus pyogenes) were used to screen 68 of the most commonly used plants for activity. Twenty-eight of these (41.2%) inhibited the growth of one or more of the bacteria tested. Staphylococcus aureus was inhibited by 18 of the plant extracts, while 7 extracts were effective against Streptococcus pyogenes. Plants of American origin which exhibited antibacterial activity were: Gnaphalium viscosum, Lippia alba, Lippia dulcis, Physalis philadelphica, Satureja brownei, Solanum nigrescens and Tagetes lucida. These preliminary in vitro results provide scientific basis for the use of these plants against bacterial respiratory infections. PMID:2023428

  11. Human Defensin 5 Disulfide Array Mutants: Disulfide Bond Deletion Attenuates Antibacterial Activity Against Staphylococcus aureus

    PubMed Central

    Wanniarachchi, Yoshitha A.; Kaczmarek, Piotr; Wan, Andrea; Nolan, Elizabeth M.

    2011-01-01

    Human α-defensin 5 (HD5, HD5ox to specify the oxidized and disulfide linked form) is a 32-residue cysteine-rich host-defense peptide, expressed and released by small intestinal Paneth cells, that exhibits antibacterial activity against a number of Gram-negative and –positive bacterial strains. To ascertain the contributions of its disulfide array to structure, antimicrobial activity, and proteolytic stability, a series of HD5 double mutant peptides where pairs of cysteine residues corresponding to native disulfide linkages (Cys3—Cys31, Cys5—Cys20, Cys10—Cys30) were mutated to Ser or Ala residues were overexpressed in E. coli, purified and characterized. A hexa mutant peptide, HD5[Serhexa], where all six native Cys residues are replaced by Ser residues was also evaluated. Removal of a single native S—S linkage influences oxidative folding and regioisomerization, antibacterial activity, Gram-negative bacterial membrane permeabilization, and proteolytic stability. Whereas the majority of the HD5 mutant peptides show low-micromolar activity against Gram-negative E. coli ATCC 25922 in colony counting assays, the wild-type disulfide array is essential for low-micromolar activity against Gram-positive S. aureus ATCC 25923. Removal of a single disulfide bond attenuates the activity observed for HD5ox against this Gram-positive bacterial strain. This observation supports the notion that the HD5ox mechanism of antibacterial action differs for Gram-negative and Gram-positive species (Wei, G.; de Leeuw, E., Pazgier, M., Yuan, W., Zou, G., Wang, J., Ericksen, B., Lu, W.-Y.; Lehrer, R. I.; Lu, W. (2009) J. Biol. Chem. 284, 29180-29192), and that the native disulfide array is a requirement for its activity against S. aureus. PMID:21861459

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

    PubMed

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

    2008-01-01

    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

  13. Antibacterial Activity of Pseudonocardia sp. JB05, a Rare Salty Soil Actinomycete against Staphylococcus aureus

    PubMed Central

    Jafari, Nesa; Behroozi, Reza; Farajzadeh, Davoud; Farsi, Mohammad; Akbari-Noghabi, Kambiz

    2014-01-01

    Staphylococcus aureus is a Gram-positive bacterium that causes many harmful and life-threatening diseases. Some strains of this bacterium are resistant to available antibiotics. This study was designed to evaluate the ability of indigenous actinomycetes to produce antibacterial compounds against S. aureus and characterize the structure of the resultant antibacterial compounds. Therefore, a slightly modified agar well diffusion method was used to determine the antibacterial activity of actinomycete isolates against the test microorganisms. The bacterial extracts with antibacterial activity were fractionated by silica gel and G-25 sephadex column chromatography. Also, the active fractions were analyzed by thin layer chromatography. Finally, the partial structure of the resultant antibacterial compound was characterized by Fourier transform infrared spectroscopy. One of the isolates, which had a broad spectrum and high antibacterial activity, was designated as Pseudonocardia sp. JB05, based on the results of biochemical and 16S rDNA gene sequence analysis. Minimum inhibitory concentration for this bacterium was 40 AU mL−1 against S. aureus. The antibacterial activity of this bacterium was stable after autoclaving, 10% SDS, boiling, and proteinase K. Thin layer chromatography, using anthrone reagent, showed the presence of carbohydrates in the purified antibacterial compound. Finally, FT-IR spectrum of the active compound illustrated hydroxyl groups, hydrocarbon skeleton, and double bond of polygenic compounds in its structure. To the best of our knowledge, this is the first report describing the efficient antibacterial activity by a local strain of Pseudonocardia. The results presented in this work, although at the initial stage in bioactive product characterization, will possibly contribute toward the Pseudonocardia scale-up for the production and identification of the antibacterial compounds. PMID:25202705

  14. Antibacterial activities and phytochemical analysis of Cassia fistula (Linn.) leaf

    PubMed Central

    Panda, Sujogya K.; Padhi, L. P.; Mohanty, G.

    2011-01-01

    Cassia fistula Linn. which belongs to family Leguminosae is a medium-sized tree and its different parts are used in ayurvedic medicine as well as home remedies for common ailments. Sequential extraction was carried out using solvents viz. petroleum ether, chloroform, ethanol, methanol and water from leaf of the plant were investigated for preliminary phytochemical and antibacterial property. Results of the study showed that all the extracts had good inhibitory activity against Gram-positive test organism. Although all five extracts showed promising antibacterial activity against test bacterial species, yet maximum activity was observed in ethanol extract. The minimum inhibitory concentration ranged in between 94 to 1 500 μg/ml. Evaluation of phytochemicals such as alkaloids, flavonoids, carbohydrates, glycosides, protein and amino acids, saponins, and triterpenoids revealed the presence of most of constituents in polar extracts (ethanol, methanol, and aqueous) compared with nonpolar extracts (petroleum ether and chloroform). Furthermore, the ethanol extract was subjected to TLC bioautography and time-kill study against Staphylococcus epidermidis. All the findings exhibit that the leaf extracts have broad-spectrum activity and suggest its possible use in treatment of infectious diseases. PMID:22171295

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

    PubMed Central

    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

    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

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

    PubMed

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

    2005-10-31

    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

  17. Clinical update on linezolid in the treatment of Gram-positive bacterial infections

    PubMed Central

    Ager, Sally; Gould, Kate

    2012-01-01

    Gram-positive pathogens are a significant cause of morbidity and mortality in both community and health care settings. Glycopeptides have traditionally been the antibiotics of choice for multiresistant Gram-positive pathogens but there are problems with their use, including the emergence of glycopeptide-resistant strains, tissue penetration, and achieving and monitoring adequate serum levels. Newer antibiotics such as linezolid, a synthetic oxazolidinone, are available for the treatment of resistant Gram-positive bacteria. Linezolid is active against a wide range of Gram-positive bacteria and has been generally available for the treatment of Gram-positive infections since 2000. There are potential problems with linezolid use, including its bacteriostatic action and the relatively high incidence of reported adverse effects, particularly with long-term use. Long-term use may also be complicated by the development of resistance. However, linezolid has been shown to be clinically useful in the treatment of several serious infections where traditionally bacteriocidal agents have been required and many of its adverse effects are reversible on cessation. It has also been shown to be a cost-effective treatment option in several studies, with its high oral bioavailability allowing an early change from intravenous to oral formulations with consequent earlier patient discharge and lower inpatient costs. PMID:22787406

  18. Chemical composition and antibacterial activity of the essential oil of Ruilopezia bracteosa.

    PubMed

    Alarcón, Libia; Peña, Alexis; Velascd, Judith; Baptista, José Gregorio; Rojas, Luis; Aparicio, Rosa; Usubillaga, Alfredo

    2015-04-01

    The essential oil from the leaves ofRuilopezia bracteosa was obtained by hydrodistillation, and analyzed by GC-MS. Eighteen components, which made up 99.6% of the oil were identified, the most abundant being β-myrcene (34.2%), α-pinene (24.3%), 7-epi-α-selinene (9.1%), β-pinene (8.5%) and 6,9-guaiadiene (4.4%). Antibacterial activity was tested against Gram-positive and Gram-negative bacteria using broth microdilution and disk agar diffusion methods. MIC values found presented significant differences between both methods, which may be due to diffusion factors. PMID:25973502

  19. Antimicrobial activity of isopteropodine.

    PubMed

    García, Rubén; Cayunao, Cesia; Bocic, Ronny; Backhouse, Nadine; Delporte, Carle; Zaldivar, Mercedes; Erazo, Silvia

    2005-01-01

    Bioassay-directed fractionation for the determination of antimicrobial activity of Uncaria tomentosa, has led to the isolation of isopteropodine (0.3%), a known Uncaria pentacyclic oxindol alkaloid that exhibited antibacterial activity against Gram positive bacteria. PMID:16042336

  20. The acetylproteome of Gram-positive model bacterium Bacillus subtilis.

    PubMed

    Kim, Dooil; Yu, Byung Jo; Kim, Jung Ae; Lee, Yong-Jik; Choi, Soo-Geun; Kang, Sunghyun; Pan, Jae-Gu

    2013-05-01

    N(ε) -lysine acetylation, a reversible and highly regulated PTM, has been shown to occur in the model Gram-negative bacteria Escherichia coli and Salmonella enterica. Here, we extend this acetylproteome analysis to Bacillus subtilis, a model Gram-positive bacterium. Through anti-acetyllysine antibody-based immunoseparation of acetylpeptides followed by nano-HPLC/MS/MS analysis, we identified 332 unique lysine-acetylated sites on 185 proteins. These proteins are mainly involved in cellular housekeeping functions such as central metabolism and protein synthesis. Fifity-nine of the lysine-acetylated proteins showed homology with lysine-acetylated proteins previously identified in E. coli, suggesting that acetylated proteins are more conserved. Notably, acetylation was found at or near the active sites predicted by Prosite signature, including SdhA, RocA, Kbl, YwjH, and YfmT, indicating that lysine acetylation may affect their activities. In 2-amino-3-ketobutyrate CoA ligase Kbl, a class II aminotransferase, a lysine residue involved in pyridoxal phosphate attachment was found to be acetylated. This data set provides evidence for the generality of lysine acetylation in eubacteria and opens opportunities to explore the consequences of acetylation modification on the molecular physiology of B. subtilis. PMID:23468065

  1. Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites.

    PubMed

    Song, Cunfeng; Chang, Ying; Cheng, Ling; Xu, Yiting; Chen, Xiaoling; Zhang, Long; Zhong, Lina; Dai, Lizong

    2014-03-01

    A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. These nanocomposites are considered to have potential application in antibacterial coatings on biomedical devices to reduce nosocomial infection rates. PMID:24433897

  2. Pharmacologic options for CNS infections caused by resistant Gram-positive organisms.

    PubMed

    Peppard, William J; Johnston, Carolyn J; Urmanski, Angela M

    2008-02-01

    Infectious disease continues to evolve, presenting new and challenging clinical situations for practitioners. Specific to device-related and neurosurgical-related CNS infections, Gram-positive organisms are of growing concern. Current Infection Disease Society of America guidelines for the treatment of CNS infections offer little direction after conventional therapy, consisting of vancomycin, has failed or the patient has demonstrated intolerance. A review of literature evaluating alternative therapies, specifically linezolid, quinupristin/dalfopristin, daptomycin and tigecycline, will be presented. Interpretations of these data are offered followed by a brief presentation of future therapies, including ortavancin, telavancin, dalbavancin, ceftobiprole and iclaprim, all of which possess potent Gram-positive activity. PMID:18251666

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

    PubMed

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

    2014-01-01

    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

  4. Antibacterial Activity of Mother Tinctures of Cholistan Desert Plants in Pakistan

    PubMed Central

    Ahmad, M.; Ghafoor, Nazia; Aamir, M. N.

    2012-01-01

    The mother tinctures of desert were screened for antibacterial activity against bacterial strains of Gram-positive and Gram-negative bacteria. Mother tinctures were prepared by maceration process and antibacterial activity of different plants was evaluated and compared by measuring their zones of inhibition. The results indicated that Boerrhavia diffusa mother tincture had excellent activity only against Escherichia coli. Mother tincture of Chorozophora plicata showed highly effective results against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa whereas Echinops echinatus mother tincture showed highly effectiveness only against Salmonella typhi. Heliotropium europaeum mother tincture exhibited highly effective results against Bacillus subtilis in all concentrations. Tamrix aphylla presented maximum activity only against Bacillus subtilis in all three concentrations. Among the selected species Heliotropium europaeum, Chorozophora plicata and Tamrix aphylla were more effective plants against many microorganisms. However, Boerrhavia diffusa and Echinops echinatus were less effective plants against tested pathogenic bacteria. PMID:23716878

  5. Antibacterial activity of mother tinctures of cholistan desert plants in pakistan.

    PubMed

    Ahmad, M; Ghafoor, Nazia; Aamir, M N

    2012-09-01

    The mother tinctures of desert were screened for antibacterial activity against bacterial strains of Gram-positive and Gram-negative bacteria. Mother tinctures were prepared by maceration process and antibacterial activity of different plants was evaluated and compared by measuring their zones of inhibition. The results indicated that Boerrhavia diffusa mother tincture had excellent activity only against Escherichia coli. Mother tincture of Chorozophora plicata showed highly effective results against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa whereas Echinops echinatus mother tincture showed highly effectiveness only against Salmonella typhi. Heliotropium europaeum mother tincture exhibited highly effective results against Bacillus subtilis in all concentrations. Tamrix aphylla presented maximum activity only against Bacillus subtilis in all three concentrations. Among the selected species Heliotropium europaeum, Chorozophora plicata and Tamrix aphylla were more effective plants against many microorganisms. However, Boerrhavia diffusa and Echinops echinatus were less effective plants against tested pathogenic bacteria. PMID:23716878

  6. Multidrug efflux pumps of Gram-positive bacteria.

    PubMed

    Schindler, Bryan D; Kaatz, Glenn W

    2016-07-01

    Gram-positive organisms are responsible for some of the most serious of human infections. Resistance to front-line antimicrobial agents can complicate otherwise curative therapy. These organisms possess multiple drug resistance mechanisms, with drug efflux being a significant contributing factor. Efflux proteins belonging to all five transporter families are involved, and frequently can transport multiple structurally unrelated compounds resulting in a multidrug resistance (MDR) phenotype. In addition to clinically relevant antimicrobial agents, MDR efflux proteins can transport environmental biocides and disinfectants which may allow persistence in the healthcare environment and subsequent acquisition by patients or staff. Intensive research on MDR efflux proteins and the regulation of expression of their genes is ongoing, providing some insight into the mechanisms of multidrug recognition and transport. Inhibitors of many of these proteins have been identified, including drugs currently being used for other indications. Structural modifications guided by structure-activity studies have resulted in the identification of potent compounds. However, lack of broad-spectrum pump inhibition combined with potential toxicity has hampered progress. Further work is required to gain a detailed understanding of the multidrug recognition process, followed by application of this knowledge in the design of safer and more highly potent inhibitors. PMID:27449594

  7. Photodynamic inactivation of Gram-positive bacteria employing natural resources.

    PubMed

    Mamone, L; Di Venosa, G; Gándara, L; Sáenz, D; Vallecorsa, P; Schickinger, S; Rossetti, M V; Batlle, A; Buzzola, F; Casas, A

    2014-04-01

    The aim of this paper was to investigate a collection of plant extracts from Argentina as a source of new natural photosensitizers (PS) to be used in Photodynamic Inactivation (PDI) of bacteria. A collection of plants were screened for phototoxicity upon the Gram-positive species Staphylococcus epidermidis. Three extracts turned out to be photoactive: Solanum verbascifolium flower, Tecoma stans flower and Cissus verticillata root. Upon exposure to a light dose of 55J/cm(2), they induced 4, 2 and 3logs decrease in bacterial survival, respectively. Photochemical characterisation of S. verbascifolium extract was carried out. PDI reaction was dependent mainly on singlet oxygen and to a lesser extent, on hydroxyl radicals, through type II and I reactions. Photodegradation experiments revealed that the active principle of the extract was not particularly photolabile. It is noticeable that S. verbascifolium -PDI was more efficient under sunlight as compared to artificial light (total eradication vs. 4 logs decrease upon 120min of sunlight). The balance between oxidant and antioxidant compounds is likely to be masking or unmasking potential PS of plant extracts, but employing the crude extract, the level of photoactivity of S. verbascifolium is similar to some artificial PS upon exposure to sunlight, demonstrating that natural resources can be employed in PDI of bacteria. PMID:24705374

  8. Denitrification in Gram-positive bacteria: an underexplored trait.

    PubMed

    Verbaendert, Ines; De Vos, Paul; Boon, Nico; Heylen, Kim

    2011-01-01

    Denitrifying organisms are essential in removing fixed nitrogen pollutants from ecosystems (e.g. sewage sludge). They can be detrimental (e.g. for agricultural soil) and can also produce the greenhouse gas N2O (nitrous oxide). Therefore a more comprehensive understanding of this process has become increasingly important regarding its global environmental impact. Even though bacterial genome sequencing projects may reveal new data, to date the denitrification abilities and features in Gram-positive bacteria are still poorly studied and understood. The present review evaluates current knowledge on the denitrification trait in Gram-positive bacteria and addresses the likely existence of unknown denitrification genes. In addition, current molecular tools to study denitrification gene diversity in pure cultures and environmental samples seem to be highly biased, and additional novel approaches for the detection of denitrifying (Gram-positive) bacteria appear to be crucial in re-assessing the real diversity of denitrifiers. PMID:21265783

  9. Is the use o f Gunnera perpensa extracts in endometritis related to antibacterial activity?

    PubMed

    McGaw, L J; Gehring, R; Katsoulis, L; Eloff, J N

    2005-06-01

    Rhizome extracts of Gunnera perpensa are used in traditional remedies in South Africa to treat endometritis both in humans and animals. An investigation was undertaken to determine whether this plant possesses antibacterial activity, which may explain its efficacy. Gunnera perpensa rhizome extracts were prepared serially with solvents of increasing polarity and tested for antibacterial activity. Test bacteria included the Gram-positive Enterococcus faecalis and Staphylococcus aureus and the Gram-negative Escherichia coli and Pseudomonas aeruginosa. A moderate to weak level of antibacterial activity in most of the extracts resulted, with the best minimal inhibitory concentration (MIC) value of 2.61 mg ml(-1) shown by the acetone extract against S. aureus. The extracts were also submitted to the brine shrimp assay to detect possible toxic or pharmacological effects. All the extracts were lethal to the brine shrimp larvae at a concentration of 5 mg ml(-1). The acetone extract was extremely toxic at 1 mg ml(-1), with some toxicity evident at 0.1 mg ml(-1). The remainder of the extracts generally displayed little activity at concentrations lower than 5 mg ml(-1). In summary, the results indicate that although the extracts demonstrated a level of pharmacological activity, the relatively weak antibacterial activity is unlikely to justify the use of G. perpensa rhizomes in the traditional treatment of endometritis. Rather, the slightly antibacterial nature of the rhizomes may contribute to an additive effect, along with their known uterotonic activity, to the overall efficacy of the preparation. PMID:16137130

  10. Antibacterial Activity of a Novel Peptide-Modified Lysin Against Acinetobacter baumannii and Pseudomonas aeruginosa

    PubMed Central

    Yang, Hang; Wang, Mengyue; Yu, Junping; Wei, Hongping

    2015-01-01

    The global emergence of multidrug-resistant (MDR) bacteria is a growing threat to public health worldwide. Natural bacteriophage lysins are promising alternatives in the treatment of infections caused by Gram-positive pathogens, but not Gram-negative ones, like Acinetobacter baumannii and Pseudomonas aeruginosa, due to the barriers posed by their outer membranes. Recently, modifying a natural lysin with an antimicrobial peptide was found able to break the barriers, and to kill Gram-negative pathogens. Herein, a new peptide-modified lysin (PlyA) was constructed by fusing the cecropin A peptide residues 1–8 (KWKLFKKI) with the OBPgp279 lysin and its antibacterial activity was studied. PlyA showed good and broad antibacterial activities against logarithmic phase A. baumannii and P. aeruginosa, but much reduced activities against the cells in stationary phase. Addition of outer membrane permeabilizers (EDTA and citric acid) could enhance the antibacterial activity of PlyA against stationary phase cells. Finally, no antibacterial activity of PlyA could be observed in some bio-matrices, such as culture media, milk, and sera. In conclusion, we reported here a novel peptide-modified lysin with significant antibacterial activity against both logarithmic (without OMPs) and stationary phase (with OMPs) A. baumannii and P. aeruginosa cells in buffer, but further optimization is needed to achieve broad activity in diverse bio-matrices. PMID:26733995

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

    PubMed

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

    2014-03-01

    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

  12. Facile Preparation of Ag/NiO Composite Nanosheets and Their Antibacterial Activity

    NASA Astrophysics Data System (ADS)

    Shi, Cui-E.; Pan, Lu; Wang, Cheng-Run; He, Yi; Wu, Yong-Feng; Xue, Sai-Sai

    2016-01-01

    Sheet-like precursors of NiO and Ag/NiO with different Ag contents were synthesized by a facile and easily controlled hydrothermal method. The NiO and Ag/NiO composite nanosheets were prepared by calcination of the corresponding precursors at 400°C for 3 h. The as-synthesized samples were characterized by thermogravimetric analysis, x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The antibacterial activity of NiO and Ag/NiO composites to several gram-positive and gram-negative bacteria was examined. Results showed that NiO nanosheets hardly exhibited antibacterial activity; however, Ag/NiO composites displayed higher activity even with low Ag content.

  13. Antibacterial and EGFR-tyrosine kinase inhibitory activities of polyhydroxylated xanthones from Garcinia succifolia.

    PubMed

    Duangsrisai, Susawat; Choowongkomon, Kiattawee; Bessa, Lucinda J; Costa, Paulo M; Amat, Nurmuhammat; Kijjoa, Anake

    2014-01-01

    Chemical investigation of the methanol extract of the wood of Garcinia succifolia Kurz (Clusiaceae) led to the isolation of 1,5-dihydroxyxanthone (1), 1,7-dihydroxyxanthone (2), 1,3,7-trihydroxyxanthone (3), 1,5,6-trihydroxyxanthone (4), 1,6,7-trihydroxyxanthone (5), and 1,3,6,7-tetrahydroxyxanthone (6). All of the isolated xanthones were evaluated for their antibacterial activity against bacterial reference strains, two Gram-positive (Staphylococcus aureus ATTC 25923, Bacillus subtillis ATCC 6633) and two Gram-negative (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853), and environmental drug-resistant isolates (S. aureus B1, Enteroccoccus faecalis W1, and E. coli G1), as well as for their epidermal growth factor receptor (EGFR) of tyrosine kinase inhibitory activity. Only 1,5,6-trihydroxy-(4), 1,6,7-trihydroxy-(5), and 1,3,6,7-tetrahydroxyxanthones (6) exhibited antibacterial activity against Gram-positive bacteria, however none was active against vancomycin-resistant E. faecalis. Additionally, 1,7-dihydroxyxanthone (2) showed synergism with oxacillin, but not with ampicillin. On the other hand, only 1,5-dihydroxyxanthone (1) and 1,7-dihydroxyxanthone (2) were found to exhibit the EGFR-tyrosine kinase inhibitory activity, with IC50 values of 90.34 and 223 nM, respectively. PMID:25460314

  14. Antibacterial activity of baking soda.

    PubMed

    Drake, D

    1996-01-01

    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

  15. Antibacterial activity of baking soda.

    PubMed

    Drake, D

    1997-01-01

    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

  16. Unusual coiled gram-positive anaerobe isolated from a gutter wall abscess.

    PubMed Central

    Pollock, H M; Rintala, L

    1977-01-01

    A gram-positive, nonsporing coiled rod was visible on Gram stain and isolated in pure culture from 20 ml of pus. This organism differs from previously described species in that it produces only acetic acid from glucose metabolism, hydrolyzes esculin, and has less fermentative activity in carbohydrates. Images PMID:145446

  17. Phenolic Content, Antioxidant Activity, Antibacterial Activity and Phytochemical Composition of Garcinia lancifolia.

    PubMed

    Policegoudra, R S; Saikia, S; Das, J; Chattopadhyay, P; Singh, L; Veer, V

    2012-05-01

    Garcinia lancifolia (Clusiaceae) is an unexplored medicinal plant used as stomachic, diuretic and its fruit is used to cure dysentery and diarrhoea. The acidic fruits are used to prepare juice, pickle and curries. The phytochemical analysis of different extracts of G. lancifolia leaf, stem and fruit revealed the presence of tannins, saponins, flavonoids, terpenoids, alkaloids and cardiac glycosides. The high phenolic content was observed in the methanol extract of leaf followed by methanol extract of stem and dichloromethane extract of leaf. The G. lancifolia fruit juice exhibited high antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Micrococcus luteus, Streptococcus mutans, Bacillus mycoides and Bacillus subtilis. The methanol extract of fruit pulp was also very effective against Gram-positive bacteria when compared with Gram-negative bacteria. The radical scavenging activity of 1,1-diphenyl-2-picrylhydrazyl was highest in fruit juice followed by methanol extract of leaf and stem. All extracts showed concentration-dependent increase in the antioxidant activity. PMID:23439879

  18. Novel antimicrobial peptides that inhibit gram positive bacterial exotoxin synthesis.

    PubMed

    Merriman, Joseph A; Nemeth, Kimberly A; Schlievert, Patrick M

    2014-01-01

    Gram-positive bacteria, such as Staphylococcus aureus, cause serious human illnesses through combinations of surface virulence factors and secretion of exotoxins. Our prior studies using the protein synthesis inhibitor clindamycin and signal transduction inhibitors glycerol monolaurate and α-globin and β-globin chains of hemoglobin indicate that their abilities to inhibit exotoxin production by S. aureus are separable from abilities to inhibit growth of the organism. Additionally, our previous studies suggest that inhibition of exotoxin production, in absence of ability to kill S. aureus and normal flora lactobacilli, will prevent colonization by pathogenic S. aureus, while not interfering with lactobacilli colonization. These disparate activities may be important in development of novel anti-infective agents that do not alter normal flora. We initiated studies to explore the exotoxin-synthesis-inhibition activity of hemoglobin peptides further to develop potential agents to prevent S. aureus infections. We tested synthesized α-globin chain peptides, synthetic variants of α-globin chain peptides, and two human defensins for ability to inhibit exotoxin production without significantly inhibiting S. aureus growth. All of these peptides were weakly or not inhibitory to bacterial growth. However, the peptides were inhibitory to exotoxin production with increasing activity dependent on increasing numbers of positively-charged amino acids. Additionally, the peptides could be immobilized on agarose beads or have amino acid sequences scrambled and still retain exotoxin-synthesis-inhibition. The peptides are not toxic to human vaginal epithelial cells and do not inhibit growth of normal flora L. crispatus. These peptides may interfere with plasma membrane signal transduction in S. aureus due to their positive charges. PMID:24748386

  19. Diversity of pigmented Gram-positive bacteria associated with marine macroalgae from Antarctica.

    PubMed

    Leiva, Sergio; Alvarado, Pamela; Huang, Ying; Wang, Jian; Garrido, Ignacio

    2015-12-01

    Little is known about the diversity and roles of Gram-positive and pigmented bacteria in Antarctic environments, especially those associated with marine macroorganisms. This work is the first study about the diversity and antimicrobial activity of culturable pigmented Gram-positive bacteria associated with marine Antarctic macroalgae. A total of 31 pigmented Gram-positive strains were isolated from the surface of six species of macroalgae collected in the King George Island, South Shetland Islands. On the basis of 16S rRNA gene sequence similarities ≥99%, 18 phylotypes were defined, which were clustered into 11 genera of Actinobacteria (Agrococcus, Arthrobacter, Brachybacterium, Citricoccus, Kocuria, Labedella, Microbacterium, Micrococcus, Rhodococcus, Salinibacterium and Sanguibacter) and one genus of the Firmicutes (Staphylococcus). It was found that five isolates displayed antimicrobial activity against a set of macroalgae-associated bacteria. The active isolates were phylogenetically related to Agrococcus baldri, Brachybacterium rhamnosum, Citricoccus zhacaiensis and Kocuria palustris. The results indicate that a diverse community of pigmented Gram-positive bacteria is associated with Antartic macroalgae and suggest its potential as a promising source of antimicrobial and pigmented natural compounds. PMID:26507390

  20. Protein secretion and surface display in Gram-positive bacteria

    PubMed Central

    Schneewind, Olaf; Missiakas, Dominique M.

    2012-01-01

    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

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

    PubMed

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

    2013-10-01

    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

  2. Decoction, infusion and hydroalcoholic extract of cultivated thyme: antioxidant and antibacterial activities, and phenolic characterisation.

    PubMed

    Martins, Natália; Barros, Lillian; Santos-Buelga, Celestino; Silva, Sónia; Henriques, Mariana; Ferreira, Isabel C F R

    2015-01-15

    Bioactivity of thyme has been described, but mostly related to its essential oils, while studies with aqueous extracts are scarce. Herein, the antioxidant and antibacterial properties of decoction, infusion and hydroalcoholic extract, as also their phenolic compounds, were evaluated and compared. Decoction showed the highest concentration of phenolic compounds (either phenolic acids or flavonoids), followed by infusion and hydroalcoholic extract. In general, the samples were effective against gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) and gram-negative (Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, Enterococcus aerogenes, Proteus vulgaris and Enterobacter sakazakii) bacteria, with decoction presenting the most pronounced effect. This sample also displayed the highest radical scavenging activity and reducing power. Data obtained support the idea that compounds with strong antioxidant and antibacterial activities are also water-soluble. Furthermore, the use of thyme infusion and decoction, by both internal and external use, at recommended doses, is safe and no adverse reactions have been described. PMID:25148969

  3. Evidence of Antibacterial Activities in Peptide Fractions Originating from Snow Crab (Chionoecetes opilio) By-Products.

    PubMed

    Beaulieu, Lucie; Thibodeau, Jacinthe; Desbiens, Michel; Saint-Louis, Richard; Zatylny-Gaudin, Céline; Thibault, Sharon

    2010-10-01

    Antibacterial peptide fractions generated via proteolytic processing of snow crab by-products exhibited activity against Gram-negative and Gram-positive bacteria. Among the bacterial strains tested, peptide fractions demonstrated inhibitory activity against the Gram-negative bacteria such as Aeromonas caviae, Aeromonas hydrophila, Campylobacter jejuni, Listonella anguillarum, Morganella morganii, Shewanella putrefasciens, Vibrio parahaemolyticus and Vibrio vulnificus and against a few Gram-positive bacteria such as Listeria monocytogenes, Staphylococcus epidermidis and Streptococcus agalactiae. The principal bioactive peptide fraction was comprised mainly of proteins and minerals (74.3 and 15.5%, respectively). Lipids were not detected. The amino acid content revealed that arginine (4.6%), glutamic acid (5.3%) and tyrosine (4.8%) residues were represented in the highest composition in the antibacterial peptide fraction. The optimal inhibitory activity was observed at alkaline pH. The V. vulnificus strain, most sensitive to the peptide fraction, was used to develop purification methods. The most promising chromatography resins selected for purification, in order to isolate peptides of interest and to carry out their detailed biochemical characterization, were the SP-Sepharose™ Fast Flow cation exchanger and the Phenyl Sepharose™ High Performance hydrophobic interaction media. The partially purified antibacterial peptide fraction was analyzed for minimum inhibitory concentration (MIC) determination, and the value obtained was 25 μg ml(-1). Following mass spectrometry analysis, the active peptide fraction seems to be a complex of molecules comprised of several amino acids and other organic compounds. In addition, copper was the main metal found in the active peptide fraction. Results indicate the production of antibacterial molecules from crustacean by-products that support further applications for high-value bioproducts in several areas such as food and health

  4. Indirect conductimetric assay of antibacterial activities.

    PubMed

    Sawai, J; Doi, R; Maekawa, Y; Yoshikawa, T; Kojima, H

    2002-11-01

    The applicability of indirect conductimetric assays for evaluation of antibacterial activity was examined. The minimal inhibitory concentration (MIC) obtained by the indirect method was consistent with that by the direct conductimetric assay and the turbidity method. The indirect assay allows use of growth media, which cannot be used in the direct conductimetric assay, making it possible to evaluate the antibacterial activity of insoluble or slightly soluble materials with high turbidity, such as antibacterial ceramic powders. PMID:12407467

  5. Optical control of antibacterial activity

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    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.

  6. Bioinspired synthesis of polydopamine/Ag nanocomposite particles with antibacterial activities.

    PubMed

    Wu, Chengjiao; Zhang, Guoxing; Xia, Tian; Li, Zhenni; Zhao, Kai; Deng, Ziwei; Guo, Dingzong; Peng, Bo

    2015-10-01

    Mussel-inspired chemistry (polydopamine) offers great opportunities to develop inexpensive and efficient process for many types of materials with complex shapes and functions in a mild and friendly environment. This paper describes a facile, yet green approach to synthesize polydopamine/silver (PDA/Ag) nanocomposite particles with a combination use of polydopamine chemistry and electroless metallization of Ag. In this approach, monodisperse spherical polydopamine particles are first synthesized by the oxidation and self-polymerization of dopamine (monomer) in an alkaline water-ethanol solution at room temperature, which are served as the active templates for secondary reactions due to the abundant catechol and amine groups on the surface. Subsequently, the silver precursor-[Ag(NH3)2](+) ions introduced are easily absorbed onto the surface of the PDA particles, and are immediately in situ reduced to metallic Ag nanoparticles with the help of these active catechol and amine groups. During the preparation, no additional reductants, toxic reagents and intricate instruments are needed. These as-synthesized PDA/Ag nanocomposite particles are ideal candidates for antibacterial application because they do not show significant cytotoxicity against HEK293T human embryonic kidney cells in the in vitro cytotoxicity assay, whereas demonstrate enhanced antibacterial abilities against Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus (Gram-positive bacteria) in the antibacterial assays. Owing to their excellent cytocompatibilities and antibacterial activities, these PDA/Ag nanocomposite particles can be considered as the promising antibacterial materials for future biomedical applications. PMID:26117750

  7. Antibacterial, antifungal and cytotoxic activities of amblyone isolated from Amorphophallus campanulatus

    PubMed Central

    Khan, Alam; Rahman, Moizur; Islam, M.S.

    2008-01-01

    Objective: To assess the in vitro antibacterial, antifungal and cytotoxic activities of amblyone, a triterpenoid isolated from Amorphophallus campanulatus (Roxb). Methods: Disc diffusion technique was used for in vitro antibacterial and antifungal screening. Cytotoxicity was determined against brine shrimp nauplii. In addition, minimum inhibitory concentration (MIC) was determined using serial dilution technique to determine the antibacterial potency. Results: Large zones of inhibition were observed in disc diffusion antibacterial screening against four Gram-positive bacteria (Bacillus subtilis, Bacillus megaterium, Staphylococcus aureus and Streptococcus pyogenes) and six Gram-negative bacteria (Escherichia coli, Shigella dysenteriae, Shigella sonnei, Shigella flexneri, Pseudomonas aeruginosa and Salmonella typhi). The MIC values against these bacteria ranged from 8 to 64 μg/ml. In antifungal screening, the compound showed small zones of inhibition against Aspergillus flavus, Aspergillus niger and Rhizopus aryzae. Candida albicans was resistant against the compound. In the cytotoxicity determination, LC50 of the compound against brine shrimp nauplii was 13.25 μg/ml. Conclusions: These results suggest that the compound has good antibacterial activity against the tested bacteria, moderate cytotoxicity against brine shrimp nauplii and insignificant antifungal activity against the tested fungi. PMID:21264161

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

    PubMed Central

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

    2010-01-01

    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

  9. Antibacterial activity of some Artemisia species extract.

    PubMed

    Poiată, Antonia; Tuchiluş, Cristina; Ivănescu, Bianca; Ionescu, A; Lazăr, M I

    2009-01-01

    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

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

    PubMed

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

    2014-01-01

    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

  11. Evaluation of diffusion and dilution methods to determine the antibacterial activity of plant extracts.

    PubMed

    Klancnik, Anja; Piskernik, Sasa; Jersek, Barbara; Mozina, Sonja Smole

    2010-05-01

    The aim of this study was to evaluate diffusion and dilution methods for determining the antibacterial activity of plant extracts and their mixtures. Several methods for measurement of the minimal inhibitory concentration (MIC) of a plant extract are available, but there is no standard procedure as there is for antibiotics. We tested different plant extracts, their mixtures and phenolic acids on selected gram-positive (Staphylococcus aureus, Bacillus cereus, and Listeria monocytogenes) and gram-negative bacteria (Escherichia coli O157:H7, Salmonella Infantis, Campylobacter jejuni, Campylobacter coli) with the disk diffusion, agar dilution, broth microdilution and macrodilution methods. The disk diffusion method was appropriate only as a preliminary screening test prior to quantitative MIC determination with dilution methods. A comparison of the results for MIC obtained by agar dilution and broth microdilution was possible only for gram-positive bacteria, and indicated the latter as the most accurate way of assessing the antimicrobial effect. The microdilution method with TTC (2,3,5-triphenyl tetrazolium chloride) or INT (2-p-iodophenyl-3-p-nitrophenyl-5-phenyl tetrazolium chloride) to indicate the viability of aerobic bacteria was found to be the best alternative approach, while only ATP determination was appropriate for microaerophilic Campylobacter spp. Using survival curves the kinetics of bacterial inactivation on plant extract exposure was followed for 24h and in this way the MIC values determined by the microdilution method were confirmed as the concentrations of extracts that inhibited bacterial growth. We suggest evaluation of the antibacterial activity of plant extracts using the broth microdilution method as a fast screening method for MIC determination and the macrodilution method at selected MIC values to confirm bacterial inactivation. Campylobacter spp. showed a similar sensitivity to plant extracts as the tested gram-positive bacteria, but S

  12. Assessment of Tamarindus indica Extracts for Antibacterial Activity

    PubMed Central

    Nwodo, Uchechukwu U.; Obiiyeke, Grace E.; Chigor, Vincent N.; Okoh, Anthony I.

    2011-01-01

    Ethanolic and aqueous (hot and cold) extracts of the fruit pulp, stem bark and leaves of Tamarindus indica were evaluated for antibacterial activity, in vitro, against 13 Gram negative and 5 Gram positive bacterial strains using agar well diffusion and macro broth dilution techniques, simultaneously. The fruit pulp extracts exhibited a wide spectrum of activity; the cold water extract against 95.5% of the test bacterial strains; and the hot water and ethanolic extracts against 90.9% and 86.4%, respectively. In contrast the cold water extract of the leaves and stem bark, each was active against 16.7%; while the ethanolic extract of each was active against 75% of the test strains. The minimum inhibitory concentrations (MIC) ranged from 7.81 mg/mL against Bacillus subtilis ATCC 6051 to 31.25 mg/mL against Escherichia coli ATCC 11775; and the minimum bactericidal concentration (MBC) ranged from 125 mg/mL against Pseudomonas aeruginosa ATCC 10145 to 250 mg/mL against Bacillus subtilis ATCC 6051. PMID:22072893

  13. Assessment of Tamarindus indica extracts for antibacterial activity.

    PubMed

    Nwodo, Uchechukwu U; Obiiyeke, Grace E; Chigor, Vincent N; Okoh, Anthony I

    2011-01-01

    Ethanolic and aqueous (hot and cold) extracts of the fruit pulp, stem bark and leaves of Tamarindus indica were evaluated for antibacterial activity, in vitro, against 13 Gram negative and 5 Gram positive bacterial strains using agar well diffusion and macro broth dilution techniques, simultaneously. The fruit pulp extracts exhibited a wide spectrum of activity; the cold water extract against 95.5% of the test bacterial strains; and the hot water and ethanolic extracts against 90.9% and 86.4%, respectively. In contrast the cold water extract of the leaves and stem bark, each was active against 16.7%; while the ethanolic extract of each was active against 75% of the test strains. The minimum inhibitory concentrations (MIC) ranged from 7.81 mg/mL against Bacillus subtilis ATCC 6051 to 31.25 mg/mL against Escherichia coli ATCC 11775; and the minimum bactericidal concentration (MBC) ranged from 125 mg/mL against Pseudomonas aeruginosa ATCC 10145 to 250 mg/mL against Bacillus subtilis ATCC 6051. PMID:22072893

  14. Synthesis and anti-bacterial activity of some heterocyclic chalcone derivatives bearing thiofuran, furan, and quinoline moieties.

    PubMed

    Zheng, Chang-Ji; Jiang, Sheng-Ming; Chen, Zhen-Hua; Ye, Bai-Jun; Piao, Hu-Ri

    2011-10-01

    36 Novel heterocyclic chalcone derivatives were synthesized and tested for their anti-bacterial activity. Some compounds presented good anti-microbial activities against Gram-positive bacteria (including the multidrug-resistant clinical isolates). This class of compounds presented high potency against Streptococcus mutans, among which the derivatives F2 with an MIC of 2 µg/mL was as active as the standard drug (norfloxacin) and less active than oxacillin. All the compounds did not inhibit the growth of Gram-negative bacteria (Escherichia coli CCARM 1924 or Escherichia coli CCARM 1356) at 64 µg/mL. PMID:21887800

  15. Synthesis and anti-bacterial activities of a bis-chalcone derived from thiophene and its bis-cyclized products.

    PubMed

    Asiri, Abdullah M; Khan, Salman A

    2011-01-01

    A chalcone was prepared by the reaction of terephthalaldehyde with 3-acetyl-2,5-dimethylthiophene. Treatment of this chalcone with thiosemicarbazide/phenyl hydrazine/guanidine hydrochloride/thiourea afforded the corresponding pyrazoline, pyrazole, and pyrimidine in good yields. All the new compounds have been characterized by IR, 1H-NMR, 13C-NMR, GC-MS and elemental analyses. The anti-bacterial activity of these compounds were first tested in vitro by the disk 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 the pyrazoline derivative is better at inhibiting growth of both types of bacteria (gram-positive and gram-negative) compared to chloramphenicol. PMID:21228758

  16. Daptomycin: a novel lipopeptide antibiotic against Gram-positive pathogens

    PubMed Central

    Beiras-Fernandez, Andres; Vogt, Ferdinand; Sodian, Ralf; Weis, Florian

    2010-01-01

    The aim of this review is to summarize the historical background of drug resistance of Gram-positive pathogens as well as to describe in detail the novel lipopeptide antibiotic daptomycin. Pharmacological and pharmacokinetic aspects are reviewed and the current clinical use of daptomycin is presented. Daptomycin seems to be a reliable drug in the treatment of complicated skin and skin structure infections, infective right-sided endocarditis, and bacteremia caused by Gram-positive agents. Its unique mechanism of action and its low resistance profile, together with its rapid bactericidal action make it a favorable alternative to vancomycin in multi-drug resistant cocci. The role of daptomycin in the treatment of prosthetic material infections, osteomyelitis, and urogenital infections needs to be evaluated in randomized clinical trials. PMID:21694898

  17. Cyclic diguanylate signaling in Gram-positive bacteria.

    PubMed

    Purcell, Erin B; Tamayo, Rita

    2016-09-01

    The nucleotide second messenger 3'-5' cyclic diguanylate monophosphate (c-di-GMP) is a central regulator of the transition between motile and non-motile lifestyles in bacteria, favoring sessility. Most research investigating the functions of c-di-GMP has focused on Gram-negative species, especially pathogens. Recent work in Gram-positive species has revealed that c-di-GMP plays similar roles in Gram-positives, though the precise targets and mechanisms of regulation may differ. The majority of bacterial life exists in a surface-associated state, with motility allowing bacteria to disseminate and colonize new environments. c-di-GMP signaling regulates flagellum biosynthesis and production of adherence factors and appears to be a primary mechanism by which bacteria sense and respond to surfaces. Ultimately, c-di-GMP influences the ability of a bacterium to alter its transcriptional program, physiology and behavior upon surface contact. This review discusses how bacteria are able to sense a surface via flagella and type IV pili, and the role of c-di-GMP in regulating the response to surfaces, with emphasis on studies of Gram-positive bacteria. PMID:27354347

  18. Full Spectrum Visible LED Light Activated Antibacterial System Realized by Optimized Cu2O Crystals.

    PubMed

    Shi, Xiaotong; Xue, Chaowen; Fang, Fang; Song, Xiangwei; Yu, Fen; Liu, Miaoxing; Wei, Zhipeng; Fang, Xuan; Zhao, Dongxu; Xin, Hongbo; Wang, Xiaolei

    2016-04-01

    Assisted by three-dimensional printing technology, we proposed and demonstrated a full spectrum visible light activated antibacterial system by using a combination of 500 nm sized Cu2O crystals and light-emitting diode (LED) lamps. Further improved antibacterial ratios were achieved, for the first time, with pure Cu2O for both Gram-positive bacteria and Gram-negative bacteria among all of the six different color LED lamps. For practical antibacterial applications, we revealed that the nonwoven fabric could act as excellent carrier for Cu2O crystals and provide impressive antibacterial performance. Furthermore, integrated with our self-developed app, the poly(ethylene terephthalate) film loaded with Cu2O crystals also showed significant antibacterial property, thus making it possible to be applied in field of touch screen. The present research not only provided a healthier alternative to traditional ultraviolet-based sterilization but also opened an auto-response manner to decrease the rate of microbial contamination on billions of touch screen devices. PMID:26978589

  19. Novel antibacterial polypeptide produced by Lactobacillus paracasei strain NRRL B-50314

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study reports the production and characterization of a novel antibacterial polypeptide, designated as laparaxin, which is secreted by Lactobacillus paracasei NRRL B-50314. The crude laparaxin has antibacterial activity against a range of Gram-positive bacteria including the following: lactic a...

  20. Novel antibacterial polypeptide laparaxin produced by Lactobacillus paracasei strain NRRL B-50314 via fermentation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study reports the production and characterization of a novel antibacterial polypeptide, designated laparaxin, which is secreted by Lactobacillus paracasei NRRL B-50314. Crude laparaxin has antibacterial activity against a wide variety of Gram-positive bacteria, including: lactic acid bacteria ...

  1. Enhanced antibacterial activity of copper/copper oxide nanowires prepared by pulsed laser ablation in water medium

    NASA Astrophysics Data System (ADS)

    Swarnkar, R. K.; Pandey, J. K.; Soumya, K. K.; Dwivedi, P.; Sundaram, S.; Prasad, Sanjay; Gopal, R.

    2016-07-01

    Copper/copper oxide nanowires (NWs) are well known for its antibacterial activity against various pathogens. In the present study, we have shown the enhanced antibacterial activity of the NWs against gram-negative bacterial strains ( Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi) and gram-positive bacterial strains ( Bacillus subtilis and Staphylococcus aureus). The increase in the activity is because of the shape and size of the colloidal NWs which were prepared at room temperature in a one-step process by pulsed laser ablation of copper metal target. The purity, shape and size of the colloidal NWs were well characterized by UV-visible absorption spectroscopy and transmission electron microscopy (TEM). The NWs were of diameters in the range of 15-30 nm and lengths ranging from 200 to 600 nm. The dose-dependent antibacterial activity of these NWs was found to be more effective against gram-negative bacteria compared to gram-positive bacteria. As gram-negative bacteria have thinner layer of cell wall made up of peptidoglycan possibly which makes them more susceptible to Cu/Cu2O NWs, Cu/Cu2O NWs can be a potent candidate to be used as bactericidal or as growth inhibitor.

  2. In vitro antibacterial activity of SM-1652, a new broad-spectrum cephalosporin with antipseudomonal activity.

    PubMed Central

    Fukasawa, M; Noguchi, H; Okuda, T; Komatsu, T; Yano, K

    1983-01-01

    SM-1652 (sodium 7-[D(-)-alpha-(4-hydroxy-6-methylpyridine-3-carboxamido)-alpha-(4-hydroxyphenyl)acetamido]-3-[(1-methyl-1H-tetrazol-5-yl) thiomethyl]-3-cephem-4-carboxylate) is a new semisynthetic cephalosporin derivative with a broad spectrum of antibacterial activity. Its in vitro activity against gram-positive bacteria was comparable to that of cefazolin. SM-1652 exceeded cefazolin in potency and broadness of antibacterial activity against such Enterobacteriaceae as indole-positive Proteus spp., Enterobacter cloacae, and Serratia marcescens. A remarkable feature of the spectrum of SM-1652 is its high activity against Pseudomonadaceae. Against 200 clinical isolates of Pseudomonas aeruginosa, SM-1652 was significantly more active than cefoperazone, cefotaxime, and sulbenicillin and as active as cefsulodin. The activities of SM-1652 against Pseudomonas maltophilia and Pseudomonas cepacia were superior to those of cefoperazone, cefotaxime, cefsulodin, sulbenicillin, and gentamicin. SM-1652 was relatively stable to hydrolysis with plasmid-mediated penicillinases and cephalosporinases produced by gram-negative bacteria. PMID:6601470

  3. Phenolic contents, antioxidant and antibacterial activities of Hymenocardia acida.

    PubMed

    Sofidiya, Margaret O; Odukoya, Olukemi A; Afolayan, Anthony J; Familoni, Oluwole B

    2009-01-01

    This study investigates the antioxidant and antibacterial activities of aqueous and methanolic extracts from Hymenocardia acida Tul. (Hymenocardiaceae). The inhibition values of the extracts and quercetin were found to be very close, with no significant differences at a concentration of 0.05 mg mL(-1) in their ability to inhibit 1,1-diphenyl-2-picrylhydrazyl (DPPH). Total proanthocyanidins for both water and methanol extracts were 20.2 +/- 0.01 and 30.6 +/- 0.51 mg g(-1) (catechin equivalent) while the total phenol contents were 20.0 +/- 0.52 and 35.6 +/- 1.42 mg mL(-1) (tannic acid equivalent), respectively. Positive correlations R(2) = 0.85, R(2) = 0.94, R(2) = 0.97 for DPPH, reducing power and 2'-azino-bis(3-ethylbenzo thiazoline)6-sulphonic acid (ABTS). Linear regression analysis also produced a high correlation coefficient with total proanthocyanidins (DPPH, R(2) = 0.69; ABTS, R(2) = 0.94). H. acida extracts showed low antibacterial activity (minimum inhibitory concentration (MIC) value >or=5.0 mg mL(-1)) against gram negative bacteria but significantly (MIC value gram positive strains tested. Qualitative TLC of the extract was positive for flavonoids, phenols, steroids and triterpenoids. The results of this study support the use of H. acida in traditional Nigerian medicine and show that the alcoholic extract of the leaves can be used as an easily accessible source of natural antioxidant and can be of assistance in some dermatological problems. PMID:19173124

  4. Di-N-Methylation of Anti-Gram-Positive Aminoglycoside-Derived Membrane Disruptors Improves Antimicrobial Potency and Broadens Spectrum to Gram-Negative Bacteria.

    PubMed

    Benhamou, Raphael I; Shaul, Pazit; Herzog, Ido M; Fridman, Micha

    2015-11-01

    The effect of di-N-methylation of bacterial membrane disruptors derived from aminoglycosides (AGs) on antimicrobial activity is reported. Di-N-methylation of cationic amphiphiles derived from several diversely structured AGs resulted in a significant increase in hydrophobicity compared to the parent compounds that improved their interactions with membrane lipids. The modification led to an enhancement in antibacterial activity and a broader antimicrobial spectrum. While the parent compounds were either modestly active or inactive against Gram-negative pathogens, the corresponding di-N-methylated compounds were potent against the tested Gram-negative as well as Gram-positive bacterial strains. The reported modification offers a robust strategy for the development of broad-spectrum membrane-disrupting antibiotics for topical use. PMID:26418734

  5. Oritavancin: a potential weapon in the battle against serious Gram-positive pathogens.

    PubMed

    Crandon, Jared; Nicolau, David P

    2008-06-01

    Oritavancin is a lipoglycopeptide antibiotic with activity against aerobic and anaerobic Gram-positive bacteria. Oritavancin separates itself from other glycopeptides through its potent in vitro activity against resistant isolates of Staphylococcus aureus, Enterococcus spp. and Streptococcus spp. Oritavancin possesses a long half-life that should allow, at maximum, once-daily dosing. Currently, oritavancin has completed two Phase III trials and one Phase II trial for the treatment of complicated skin and skin structure infections, and two Phase II trials for the treatment of Gram-positive bacteremia. In all instances, oritavancin displayed favorable outcomes and was noninferior to comparator agents (vancomycin followed by oral cephalexin) when a comparison was made. Further studies are necessary to fully characterize dose and clinical role. PMID:18505390

  6. Antibacterial and leishmanicidal activities of temporin-SHd, a 17-residue long membrane-damaging peptide.

    PubMed

    Abbassi, Feten; Raja, Zahid; Oury, Bruno; Gazanion, Elodie; Piesse, Christophe; Sereno, Denis; Nicolas, Pierre; Foulon, Thierry; Ladram, Ali

    2013-02-01

    Temporins are a family of short antimicrobial peptides (8-17 residues) that mostly show potent activity against Gram-positive bacteria. Herein, we demonstrate that temporin-SHd, a 17-residue peptide with a net charge of +2 (FLPAALAGIGGILGKLF(amide)), expressed a broad spectrum of antimicrobial activity. This peptide displayed potent antibacterial activities against Gram-negative and Gram-positive bacteria, including multi-drug resistant Staphylococcus aureus strains, as well as antiparasitic activity against promastigote and the intracellular stage (amastigote) of Leishmania infantum, at concentration not toxic for the macrophages. Temporin-SHd that is structured in a non-amphipathic α-helix in anionic membrane-mimetic environments, strongly and selectively perturbs anionic bilayer membranes by interacting with the polar head groups and acyl region of the phospholipids, with formation of regions of two coexisting phases: one phase rich in peptide and the other lipid-rich. The disruption of lipid packing within the bilayer may lead to the formation of transient pores and membrane permeation/disruption once a threshold peptide accumulation is reached. To our knowledge, Temporin-SHd represents the first known 17-residue long temporin expressing such broad spectrum of antimicrobial activity including members of the trypanosomatidae family. Additionally, since only a few shorter members (13 residues) of the temporin family are known to display antileishmanial activity (temporins-TA, -TB and -SHa), SHd is an interesting tool to analyze the antiparasitic mechanism of action of temporins. PMID:23116712

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

    PubMed Central

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

    1998-01-01

    The in vitro and in vivo antibacterial activities of S-4661, a new 1β-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 μg/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 μg/ml. Against imipenem-resistant Pseudomonas aeruginosa, S-4661 was the most active among test agents (MIC90, 8 μg/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

  8. Evaluation of the antibacterial and antibiofilm activities of novel CRAMP-vancomycin conjugates with diverse linkers.

    PubMed

    Mishra, Nigam M; Briers, Yves; Lamberigts, Chris; Steenackers, Hans; Robijns, Stijn; Landuyt, Bart; Vanderleyden, Jos; Schoofs, Liliane; Lavigne, Rob; Luyten, Walter; Van der Eycken, Erik V

    2015-07-21

    We report the design, synthesis and antibacterial activity analysis of conjugates of vancomycin and cathelicidin-related antimicrobial peptides (CRAMP). Vancomycin inhibits the nascent peptidoglycan synthesis and is highly active against Gram-positive bacteria, whereas Gram-negative bacteria are generally insensitive due to a protective outer membrane. CRAMP is known to translocate across the Gram-negative outer membrane by a self-promoted uptake mechanism. Vancomycin-CRAMP conjugates were synthesized using click chemistry with diverse hydrophilic and hydrophobic linkers, with CRAMP functioning as a carrier peptide for the transfer of vancomycin through the outer membrane. Small hydrophobic linkers with an aromatic group result in the most active conjugates against planktonic Gram-negative bacteria, while maintaining the high activity of vancomycin against Gram-positive bacteria. These conjugates thus show a broad-spectrum activity, which is absent in CRAMP or vancomycin alone, and which is strongly improved compared to an equimolar mixture of CRAMP and vancomycin. In addition, these conjugates also show a strong inhibitory activity against S. Typhimurium biofilm formation. PMID:26068402

  9. The Antibacterial Activity of Cassia fistula Organic Extracts

    PubMed Central

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

    2014-01-01

    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

  10. Improvement of antibacterial activity of some sulfa drugs through linkage to certain phthalazin-1(2H)-one scaffolds.

    PubMed

    Ibrahim, Hany S; Eldehna, Wagdy M; Abdel-Aziz, Hatem A; Elaasser, Mahmoud M; Abdel-Aziz, Marwa M

    2014-10-01

    RAB1 5 is a lead antibacterial agent in which trimethoprim is linked to phthalazine moiety. Similarly, our strategy in this research depends on the interconnection between some sulfa drugs and certain phthalazin-1(2H)-one scaffolds in an attempt to enhance their antibacterial activity. This approach was achieved through the combination of 4-substituted phthalazin-1(2H)-ones 9a, b or 14a, b with sulfanilamide 1a, sulfathiazole 1b or sulfadiazine 1c through amide linkers 6a, b to produce the target compounds 10a-d and 15a-e, respectively. The antibacterial activity of the newly synthesized compounds showed that all tested compounds have antibacterial activity higher than that of their reference sulfa drugs 1a-c. Compound 10c represented the highest antibacterial activity against Gram-positive bacteria Streptococcus pneumonia and Staphylococcus aureus with MIC = 0.39 μmol/mL. Moreover, compound 10d displayed excellent antibacterial activity against Gram-negative bacteria Escherichia coli and Salmonella typhimurium with MIC = 0.39 and 0.78 μmol/mL, respectively. PMID:25113876

  11. Pilins in gram-positive bacteria: A structural perspective.

    PubMed

    Krishnan, Vengadesan

    2015-07-01

    Pilins or fimbrilins are a class of proteins found in bacterial surface pilus, a hair-like surface appendage. Both the Gram-negative and -positive bacteria produce pilins to assemble pili on their cell-surface for different purposes including adherence, twitching motility, conjugation, immunomodulation, biofilm formation, and electron transfer. Immunogenic properties of the pilins make them attractive vaccine candidates. The polymerized pilins play a key role in the initiation of host adhesion, which is a critical step for bacterial colonization and infection. Because of their key role in adhesion and exposure on the cell surface, targeting the pilins-mediated adhesion (anti-adhesion therapy) is also seen as a promising alternative approach for preventing and treating bacterial infections, one that may overcome their ever-increasing repertoires of resistance mechanisms. Individual pilins interact with each other non-covalently to assemble the pilus fiber with the help of associated proteins like chaperones and Usher in Gram-negative bacteria. In contrast, the pilins in Gram-positive bacteria often connect with each other covalently, with the help of sortases. Certain unique structural features present on the pilins distinguish them from one another across different bacterial strains, and these dictate their cellular targets and functions. While the structure of pilins has been extensively studied in Gram-negative pathogenic bacteria, the pilins in Gram-positive pathogenic bacteria have been in only during the last decade. Recently, the discovery of pilins in non-pathogenic bacteria, such as Lactobacillus rhamnosus GG, has received great attention, though traditionally the attention was on pathogenic bacteria. This review summarizes and discusses the current structural knowledge of pilins in Gram-positive bacteria with emphasis on those pilins which are sortase substrates. PMID:26178080

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

    PubMed Central

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

    2014-01-01

    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

  13. Synthetic Teichoic Acid Conjugate Vaccine against Nosocomial Gram-Positive Bacteria

    PubMed Central

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

    2014-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    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.

  15. Antibacterial activities of Groebke-Blackburn-Bienaymé derived imidazo[1,2-a]pyridin-3-amines

    PubMed Central

    Shukla, Nikunj M.; Salunke, Deepak B.; Yoo, Euna; Mutz, Cole A.; Balakrishna, Rajalakshmi; David, Sunil A.

    2012-01-01

    We sought to explore the imidazo[1,2-a]pyridin-3-amines for TLR7 (or 8)-modulatory activities. This chemotype, readily accessed via the Groebke-Blackburn-Bienaymé multi-component reaction, resulted in compounds that were TLR7/8-inactive, but exhibited bacteriostatic activity against Gram-positive bacteria, including methicillin-resistant S. aureus (MRSA). To investigate the mechanism of antibacterial activity of this new chemotype, a resistant strain of S. aureus was generated by serially passaging the organism in escalating doses of the most active analogue. A comparison of minimum inhibitory concentrations (MICs) of known bacteriostatic agents in wild-type and resistant strains indicates a novel mechanism of action. Structure-activity relationship studies have led to the identification of positions on the scaffold for additional structural modifications that should allow for the introduction of probes designed to examine cognate binding partners and molecular targets, while not significantly compromising antibacterial potency. PMID:22925449

  16. Synthesis of new chalcone derivatives containing a rhodanine-3-acetic acid moiety with potential anti-bacterial activity.

    PubMed

    Chen, Zhen-Hua; Zheng, Chang-Ji; Sun, Liang-Peng; Piao, Hu-Ri

    2010-12-01

    With an intention to synergize the anti-bacterial activity of chalcones and rhodanine-3-acetic acid, several hybrid compounds possessing chalcone and rhodanine-3-acetic acid moieties were synthesized and tested for their anti-bacterial activity. Some compounds presented great anti-microbial activities against Gram-positive bacteria (including the multidrug-resistant clinical isolates). This class of compounds presented high potency against Staphylococcus aureus, among which the derivatives 5k with a MIC of 2 μg/mL was as active as the standard drug (norfloxacin) and less active than oxacillin. Compounds 5a-s did not inhibit the growth of Gram-negative bacteria Escherichia coli CCARM 1924 or E. coli CCARM 1356 at 64 μg/mL. PMID:20889240

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

    PubMed Central

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

    2012-01-01

    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 μg/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

  18. Type IV Pili in Gram-Positive Bacteria

    PubMed Central

    Craig, Lisa

    2013-01-01

    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

  19. Antibacterial activities of fluorescent nano assembled triphenylamine phosphonium ionic liquids.

    PubMed

    Brunel, Frédéric; Lautard, Christelle; Garzino, Frédéric; Giorgio, Suzanne; Raimundo, Jean M; Bolla, Jean M; Camplo, Michel

    2016-08-01

    Staphylococcus aureus, a Gram positive coccal bacterium is a major cause of nosocomial infection. We report the synthesis of new triphenylamine phosphonium ionic liquids which are able to self-assemble into multiwall nanoassemblies and to reveal a strong bactericidal activity (MIC=0.5mg/L) for Gram positive bacteria (including resistant strains) comparable to that of standard antibiotics. Time kill, metabolism and fluorescence confocal microscopy studies show a quasi-instantaneously penetration of the nanoassemblies inside the bacteria resulting of a rapid blocking (30min) of their proliferation. As confirmed by rezasurin reduction monitoring, these compounds strongly affect the bacterial metabolism and a Gram positive versus Gram negative selectivity is clearly observed. These fluorescent phosphonium ionic liquid might constitute a useful tool for both translocation studies and to tackle infectious diseases related to the field of implantology. PMID:27287371

  20. Potential enhancement of antibacterial activity of graphene oxide-silver nanocomposite by introducing C2 carbon chain linkage

    NASA Astrophysics Data System (ADS)

    Yun, Hyosuk; Ahmed, Mohammad Shamsuddin; Lee, Kyungmi; Jeon, Seungwon; Lee, Chul Won

    2016-01-01

    Various carbon chain linkages were introduced during the process of synthesizing silver-nanoparticles (AgNPs)-decorated graphene nanocomposites [referred to as GO-Cx-Ag where, HS-(CH2)x-SH = Cx and x = 0, 2, or 4] to evaluate antibacterial properties. The nano-structures of GO-Cx-Ag were characterized using TEM and XPS, revealing that GO-C2-Ag comprises well-dispersed and smaller AgNPs anchored onto the surface of graphene sheets than the GO-C0-Ag and GO-C4-Ag. The antibacterial activities of those nanocomposites were assessed using paper-disk diffusion and minimal inhibitory concentration (MIC) methods against Gram-negative and Gram-positive bacteria. The results showed that carbon chain linkers enhanced the antibacterial activity against Gram-negative Salmonella typhimurium and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. In particular, GO-C2-Ag showed higher antibacterial activity than GO-C0-Ag and GO-C4-Ag due to nearly eight times higher reactive oxygen species (ROS) formation which determined by fluorescence-based ROS detection experiment. Also, LC-inductively coupled plasma mass spectrometer (LC-ICP-MS) demonstrated that the Ag release from GO-Cx-Ag was insignificant (0.03%). However, the higher ROS formation from GO-C2-Ag was facilitated by higher dispersion, smaller size, and well attachment of AgNPs with AgO species onto graphene sheets. These results suggest that the medium length carbon chain linkers in between Ag and GO can be utilized to improve antibacterial activity.

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

    PubMed

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

    2006-09-19

    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 microg/ml. The antibacterial activity of the oils was expressed as MICs (minimum inhibitory concentrations) and MBCs (minimum bactericidal concentrations). At a concentration between 3.9 and 250 microg/ml the oils showed a significant antibacterial effect against both Gram-negative and Gram-positive bacteria. In particular the ATCC strains Pseudomonas aeruginosa (MIC=3.9 microg/ml and 7.8 for flowerheads and leaves, respectively), Proteus mirabilis (MIC=15.6 and 7.8 microg/ml), Salmonella typhi (MIC=7.8 microg/ml) and Proteus vulgaris (MIC=15.6 microg/ml) were the most inhibited. Only Pseudomonas aeruginosa showed MBC at a concentration between 62.6 and 125 microg/ml. The antioxidant activity of the essential oils was evaluated by two cell free colorimetric methods: ABTS and DMPD; leaf oil is more active (4.29 +/- 0.02 trolox equivalents and 4.53 +/- 0.67 ascorbic acid equivalents by ABTS and DMPD, respectively). Finally the antioxidant activity of the essential oils was also evaluated by their effects on human whole blood leukocytes (WB) and on isolated polymorphonucleate (PMN) chemiluminescence. Comparing the effects of the oils from leaves and flowerheads on both PMN and WB chemiluminescence emission, we found no significant differences. Essential oils showed a dose-dependent and linear inhibitory activity on isolated PMN as well as on WB CL emission when PMA-stimulated. On the contrary, the inhibitory activity on resting cells was nonlinear. Our data represent an answer to the continual demand for new antibiotics and antioxidants for the continuous emergence of antibiotic

  2. Molecular cloning, recombinant expression and antibacterial activity analysis of hepcidin from Simensis crocodile (Crocodylus siamensis).

    PubMed

    Hao, Juan; Li, Yan-Wei; Xie, Ming-Quan; Li, An-Xing

    2012-01-01

    Hepcidin, a cysteine-rich cationic antibacterial peptide, plays an important role in human defense against pathogen infection. However, its role in reptile immune response and whether it is involved in antibacterial immune have not yet been proven. In order to study the antibacterial activity of Crocodylus siamensis hepcidin (Cshepc), a common reptile which lives in topic region of Southeast Asia, a cDNA sequence of Cshepc was cloned, which included an open reading frame (ORF) of 300 bp encoding a 99 amino acid preprohepcidin. Cshepc has eight cysteines formed four conserved disulfide bridges, similarly to that of human's. Sequence analysis showed that Cshepc mature peptide was more conserved than that of preprohepcidin. Tissue expression analysis indicated that Cshepc transcripts were highly expressed in the liver, muscle and heart of C. siamensis. Recombinant expressed hepcidin could significantly inhibit the growth of the Gram-negative bacteria Escherichia coli and Aeromonas sobria as well as the Gram-positive bacterium Staphylococcus aureus, and Bacillus subtilis in vitro, suggesting that Cshepc, like human hepcidin could play a role in the antibacterial function in hosts innate immune response. PMID:22967859

  3. In Vitro antibacterial and in Vivo cytotoxic activities of Grewia paniculata

    PubMed Central

    Nasrin, Mahmuda; Dash, Pritesh Ranjan; Ali, Mohammad Shawkat

    2015-01-01

    Objectives: Grewia paniculata (Family: Malvaceae) has been used to treat inflammation, respiratory disorders and fever. It is additionally employed for other health conditions including colds, diarrhea and as an insecticide in Bangladesh. The aim of the present study was to investigate the antibacterial and cytotoxic activities of different extracts of Grewia paniculata. Materials and Methods: The antibacterial activity was evaluated against both gram negative and gram positive bacteria using disc diffusion method by determination of the diameter of zone of inhibition. Cytotoxic activity was performed by brine shrimp (Artemia salina) lethality bioassay. Results: In disc diffusion method, all the natural products (400 μg/disc) showed moderate to potent activity against all the tested bacteria. The ethanol extract of bark (EEB) and ethanol fraction of bark (EFB) (400 μg/disc) exhibited highest activity against Shigella dysenteriae with a zone of inhibition of 23±1.63 mm and 23±1.77 mm respectively. In the brine shrimp lethality bioassay all the extracts showed moderate cytotoxic activity when compared with the standard drug vincristin sulphate. For example, LC50 value of the ethanol fraction of bark (EFB) was 3.01 μg/ml while the LC50 of vincristine sulphate was 0.52 μg/ml. Conclusions: The results suggest that all the natural products possess potent antibacterial and moderate cytotoxic. PMID:25949950

  4. Essential oil analysis and antibacterial activity of Rosmarinus tournefortii from Algeria.

    PubMed

    Bendeddouche, Mansouria Souria; Benhassaini, Hachemi; Hazem, Zouaoui; Romane, Abderrahmane

    2011-10-01

    The volatile compounds obtained by hydrodistillation of the aerial parts of Rosmarinus tournefortii De Noé. growing wild in the occidental region of Algeria were analyzed by GC/MS. Thirty-six compounds were characterized representing 95.6% of the essential oil, with camphor (37.6%), 1,8-cineole (10.0%), p-cymene-7-ol (7.8%), and borneol (5.4%) as the major components. The antimicrobial activity was evaluated against three pathogenic bacteria: Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus). The minimum inhibitory concentration (MIC; mg/mL) was determined by sub-culture on Muller Hinton agar plates. The essential oil exhibited strong antibacterial activity against E. coli and P. aeruginosa, and was also active against Staphylococcus aureus. PMID:22164796

  5. Antibacterial and anticoagulant activities of coumarins isolated from the flowers of Magydaris tomentosa.

    PubMed

    Rosselli, Sergio; Maggio, Antonella; Bellone, Gabriella; Formisano, Carmen; Basile, Adriana; Cicala, Carla; Alfieri, Alessio; Mascolo, Nicola; Bruno, Maurizio

    2007-02-01

    The phytochemical investigation of the acetone and methanol extracts of the flowers of Magydaris tomentosa (Desf.) DC afforded six known coumarins as well as (+)-meranzin hydrate (7), not previously reported as a natural product. The antibacterial activity of umbelliprenin (1), osthol (2), imperatorin (3), citropten (4) and (+)-meranzin hydrate (7) was tested against Gram-positive and Gram-negative bacteria. All coumarins (1-7) isolated in this study inhibited growth of all bacterial strains tested (MIC between 16 and 256 microg/mL), the most active being imperatorin (3) (MICs between 32 and 128 microg/mL) and citropten (4) (MICs between 16 and 256 microg/mL). The anticoagulant activity of compounds 1-4 and 7 was also evaluated. PMID:17128388

  6. Future trends in the treatment of serious Gram-positive infections.

    PubMed

    Metzger, Rosemarie; Bonatti, Hugo; Sawyer, Robert

    2009-01-01

    Gram-positive organisms are the most common bacterial pathogens that cause diseases in humans, with streptococci and staphylococci occurring most frequently. Immunization has been extremely successful in eradicating some Gram-positive infections, such as diphtheria and tetanus, and relatively successful for pneumococci. Staphylococcus aureus vaccines are under investigation. In terms of antimicrobial susceptibility, some Gram-positive organisms have remained sensitive to most antimicrobials, whereas others, including staphylococci, pneumococci and enterococci, have developed clinically relevant resistance. Extensive exposure to antimicrobials in the hospital setting has caused the spread of clones mainly in the hospital environment, yet multiresistance is now also found in community-acquired diseases. Community-acquired methicillin-resistant S. aureus (CA-MRSA) and resistant pneumococci are the most important examples, but even viridans streptococci are becoming resistant to some antibiotics. Moreover, MRSA and vancomycin-resistant enterococci (VRE) are found in pets and farm animals. Because of these concerns, new antimicrobials have been developed during the past decade, including quinupristin/dalfopristin, linezolid, tigecycline, daptomycin and dalbavancin. Also under investigation are beta-lactams, streptogramins and quinolones with activity against MRSA, penicillin-resistant pneumococci and VRE. Finally, infection-control measures, including the identification of carriers of multiresistant organisms and appropriate isolation, must continue to be implemented. PMID:19271030

  7. Rational design of berberine-based FtsZ inhibitors with broad-spectrum antibacterial activity.

    PubMed

    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

    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

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

    PubMed Central

    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

    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

  9. [Recombinant expression and antibacterial activity of i-type lysozyme from sea cucumber Stichopus japonicus].

    PubMed

    Wang, Xiuxia; Cong, Lina; Wang, Dan; Yang, Xijian; Zhu, Beiwei

    2009-02-01

    The cDNA of an i type lysozyme was cloned from Stichopus japonicus (named as SjLys). The DNA fragment of the mature SjLys was subcloned into expression vector of pET-32a (+) to construct the recombinant plasmid of pET32a (+)-SjLys. The recombinant plasmid was then transformed into Escherichia coli BL21 (DE3) pLysS and induced by isopropylthio-beta-D-galactoside (IPTG). The recombinant protein expressed as inclusion bodies was denatured, partially purified and refolded to be an active form. The bacteriolytic activity of recombinant protein purified by the metal-chelating was 19.2 U/mg. The antibacterial activity of the purified recombinant SjLys (rSjLys) was analyzed. The rSjLys protein displayed inhibitive effect on the growth of the tested Gram-positive and Gram-negative bacteria. In particular, rSjLys had a strong inhibitive activity on Vibrio parahaemolyticus and Pseudomonas aeruginosa, both the most common pathogenic bacteria in the marine animals. The heat-treated rSjLys exhibited more potent activities against all tested bacteria. These results indicated that the S. japonicus lysozyme was the enzyme with combined enzymatic (glycosidase) and non-enzymatic antibacterial action, and it had a wide antibacterial spectrum. Therefore, it is suggested that the S. japonicus lysozyme should be one of the important molecules against pathogens in the innate immunity of sea cucumbers. PMID:19459322

  10. Antibacterial Activity of Alkaloid Fractions from Berberis microphylla G. Forst and Study of Synergism with Ampicillin and Cephalothin.

    PubMed

    Manosalva, Loreto; Mutis, Ana; Urzúa, Alejandro; Fajardo, Victor; Quiroz, Andrés

    2016-01-01

    Berberis microphylla is a native plant that grows in Patagonia and is commonly used by aboriginal ethnic groups in traditional medicine as an antiseptic for different diseases. The present study evaluated the antibacterial and synergistic activity of alkaloid extracts of B. microphylla leaves, stems and roots used either individually or in combination with antibiotics against Gram-positive and Gram-negative bacteria. The in vitro antibacterial activities of leaf, stem and root alkaloid extracts had significant activity only against Gram-positive bacteria. Disc diffusion tests demonstrated that the root extract showed similar activity against B. cereus and S. epidermidis compared to commercial antibiotics, namely ampicillin and cephalothin, and pure berberine, the principal component of the alkaloid extracts, was found to be active only against S. aureus and S. epidermidis with similar activity to that of the root extract. The minimum inhibitory concentrations (MICs) of the alkaloid extracts ranged from 333 to 83 μg/mL, whereas minimum bactericidal concentrations (MBCs) varied from 717 to 167 μg/mL. In addition, synergistic or indifferent effects between the alkaloid extracts and antibiotics against bacterial strains were confirmed. PMID:26760994