Decreasing prevalence of isolates with vancomycin heteroresistance and vancomycin minimum inhibitory concentrations ≥2 mg/L in methicillin-resistant Staphylococcus aureus over 11 years: potential impact of vancomycin treatment guidelines.
We evaluated vancomycin MIC (V-MIC) and the prevalence of intermediately susceptible (VISA) and heteroresistant (hVISA) isolates trends in methicillin-resistant Staphylococcus aureus bacteremia among 720 adults (≥ 18 years) inpatients over 4 study periods (2002-2003, 2005-2006, 2008-2009, and 2010-2012). V-MIC (Etest) and the prevalence of hVISA and VISA (determined by population analysis profile-area under the curve) were stratified according to the study period. Mean vancomycin MIC was 1.78 ± 0.39, 1.81 ± 0.47, 1.68 ± 0.26, and 1.54 ± 0.28 mg/L in 2002-2003, 2005-2006, 2008-2009, and 2010-2012, respectively (P < 0.0001). We noted a steadily decreasing prevalence of isolates with V-MIC ≥ 2 mg/L (50.0%, 45.2%, 35.4%, and 18.7%; P < 0.0001) and hVISA (9.7%, 6.6%, 3.0%, and 2.1%; P=0.0003). VISA prevalence remained low (0-2%). These changes coincided with steadily increasing vancomycin trough levels (9.9 ± 7.8, 11.1 ± 8.4, 16.6 ± 7.8, and 19.7 ± 5.9 mg/L in 2002-2003, 2005-2006, 2008-2009, and 2010-2012, respectively; P < 0.0001). These changes imply that adherence to vancomycin treatment guidelines may suppress the development of less susceptible isolates.
['Khatib|Riad|R|', 'Sharma|Mamta|M|', 'Johnson|Leonard B|LB|', 'Riederer|Kathleen|K|', 'Shemes|Stephen|S|', 'Szpunar|Susan|S|']
D000293:Adolescent D000328:Adult D000368:Aged D000369:Aged, 80 and over D000900:Anti-Bacterial Agents D016470:Bacteremia D004361:Drug Tolerance D004363:Drug Utilization D005260:Female D006801:Humans D008297:Male D055624:Methicillin-Resistant Staphylococcus aureus D008826:Microbial Sensitivity Tests D008875:Middle Aged D015995:Prevalence D012189:Retrospective Studies D013203:Staphylococcal Infections D014640:Vancomycin D055815:Young Adult
Vancomycin Heteroresistance Staphylococcus aureus Bacteremia