Nisin gold nanoparticles assemble as potent antimicrobial agent against Enterococcus faecalis and Staphylococcus aureus clinical isolates

2017 ◽  
Vol 37 ◽  
pp. 20-27 ◽  
Author(s):  
Pradeepa ◽  
K. Udaya Bhat ◽  
S.M. Vidya
Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3195 ◽  
Author(s):  
Yingyu Wang ◽  
Xiaowei Li ◽  
Yang Wang ◽  
Stefan Schwarz ◽  
Jianzhong Shen ◽  
...  

The optrA gene, which confers transferable resistance to oxazolidinones and phenicols, is defined as an ATP-binding cassette (ABC) transporter but lacks transmembrane domains. The resistance mechanism of optrA and whether it involves antibiotic efflux or ribosomal protection remain unclear. In this study, we determined the MIC values of all bacterial strains by broth microdilution, and used ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry to quantitatively determine the intracellular concentrations of linezolid and florfenicol in Enterococcus faecalis and Staphylococcus aureus. Linezolid and florfenicol both accumulated in susceptible strains and optrA-carrying strains of E. faecalis and S. aureus. No significant differences were observed in the patterns of drug accumulation among E. faecalis JH2-2, E. faecalis JH2-2/pAM401, and E. faecalis JH2-2/pAM401+optrA, but also among S. aureus RN4220, S. aureus RN4220/pAM401, and S. aureus RN4220/pAM401+optrA. ANOVA scores also suggested similar accumulation conditions of the two target compounds in susceptible strains and optrA-carrying strains. Based on our findings, the mechanism of optrA-mediated resistance to oxazolidinones and phenicols obviously does not involve active efflux and the OptrA protein does not confer resistance via efflux like other ABC transporters.


1998 ◽  
Vol 42 (3) ◽  
pp. 721-724 ◽  
Author(s):  
Michael J. Rybak ◽  
Diane M. Cappelletty ◽  
Tabitha Moldovan ◽  
Jeffrey R. Aeschlimann ◽  
Glenn W. Kaatz

ABSTRACT The activities of the oxazolidinone antibacterial agents eperezolid (PNU-100592) and linezolid (PNU-100766) were compared with that of vancomycin against clinical isolates of methicillin-susceptible and -resistant Staphylococcus aureus (n = 200), coagulase-negative staphylococci (n = 100), and vancomycin-susceptible and -resistant Enterococcus faecalisand Enterococcus faecium (n = 50). Eperezolid and linezolid demonstrated good in vitro inhibitory activity, regardless of methicillin susceptibility for staphylococci (MIC at which 90% of the isolates are inhibited [MIC90] range, 1 to 4 μg/ml) or vancomycin susceptibility for enterococci (MIC90 range, 1 to 4 μg/ml). In time-kill studies, eperezolid and linezolid were bacteriostatic in action. A postantibiotic effect of 0.8 ± 0.5 h was demonstrated for both eperezolid and linezolid against S. aureus, S. epidermidis, E. faecalis, and E. faecium.


2015 ◽  
Vol 61 (5) ◽  
pp. 351-356 ◽  
Author(s):  
Gabriela María Olmedo ◽  
Mariana Grillo-Puertas ◽  
Luciana Cerioni ◽  
Viviana Andrea Rapisarda ◽  
Sabrina Inés Volentini

Bacterial biofilms are commonly formed on medical devices and food processing surfaces. The antimicrobials used have limited efficacy against the biofilms; therefore, new strategies to prevent and remove these structures are needed. Here, the effectiveness of brief oxidative treatments, based on the combination of sodium hypochlorite (NaClO) and hydrogen peroxide (H2O2) in the presence of copper sulfate (CuSO4),were evaluated against bacterial laboratory strains and clinical isolates, both in planktonic and biofilm states. Simultaneous application of oxidants synergistically inactivated planktonic cells and prevented biofilm formation of laboratory Escherichia coli, Salmonella enterica serovar Typhimurium, Klebsiella pneumoniae, and Staphylococcus aureus strains, as well as clinical isolates of Salmonella enterica subsp. enterica, Klebsiella oxytoca, and uropathogenic E. coli. In addition, preformed biofilms of E. coli C, Salmonella Typhimurium, K. pneumoniae, and Salmonella enterica exposed to treatments were removed by applying 12 mg/L NaClO, 0.1 mmol/L CuSO4, and 350 mmol/L H2O2for 5 min. Klebsiella oxytoca and Staphylococcus aureus required a 5-fold increase in NaClO concentration, and the E. coli clinical isolate remained unremovable unless treatments were applied on biofilms formed within 24 h instead of 48 h. The application of treatments that last a few minutes using oxidizing compounds at low concentrations represents an interesting disinfection strategy against pathogens associated with medical and industrial settings.


2001 ◽  
Vol 42 (4) ◽  
pp. 264-268 ◽  
Author(s):  
Marinella S. Laport ◽  
Angela C.D. de Castro ◽  
Adriana Villardo ◽  
Jose Abelardo C. Lemos ◽  
Maria do Carmo F. Bastos ◽  
...  

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