English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Methicillin-resistant Staphylococcus aureus (MRSA) isolates that are susceptible to vancomycin but are tolerant to its killing effect may present a potential challenge for effective treatment. This study compared the microbiologic characteristics of clinical vancomycin-tolerant (VT-MRSA) and vancomycin-susceptible (VS-MRSA) strains using phenotypic and gene regulation studies. MRSA isolates collected from vancomycin-treated patients with bacteremia over a 5-year period were analyzed for vancomycin, daptomycin, and telavancin susceptibility, as well as accessory gene regulator (agr) group and function. Vancomycin tolerance was defined by a minimum bactericidal concentration (MBC)/minimum inhibitor concentration (MIC) ratio of ≥32 mg/liter. VT-MRSA isolates were compared to VS-MRSA isolates for differences in antimicrobial susceptibility, time-kill activity, and gene expression of key cell envelope response genes vraSR, dltA, and mprF. All 115 isolates evaluated were susceptible to vancomycin, daptomycin, and telavancin. Seven isolates (6%) were VT-MRSA. agr group II was more prevalent in isolates with vancomycin MBC/MIC ratios of ≥8. In time-kill analyses, VT-MRSA had reduced vancomycin killing, but daptomycin and telavancin activities were maintained. Significantly greater gene expression was observed in VT-MRSA after 72 h of subinhibitory antibiotic exposures. Vancomycin most notably increased vraSR expression (P = 0.002 versus VS-MRSA strains). Daptomycin and telavancin increased expression of all genes studied, most significantly mprF expression (P &lt; 0.001). Longer durations of antibiotic exposure (72 h versus 24 h) resulted in substantial increases in gene expression in VT-MRSA. Although the clinical impact of VT-MRSA is not fully recognized, these data suggest that VT-MRSA strains, while still susceptible, have altered gene regulation to adapt to the antimicrobial effects of glyco- and lipopeptides that may emerge during prolonged durations of exposure.

antimicrobial agents and chemotherapy

Vancomycin Tolerance in Methicillin-Resistant Staphylococcus aureus: Influence of Vancomycin, Daptomycin, and Telavancin on Differential Resistance Gene Expression