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Activity of Vancomycin, Ceftaroline, and Mupirocin Against Staphylococcus aureus from a 2011 National Surveillance Study in the United States.
Antimicrob Agents Chemother. 2013 Nov 18;
Authors: Richter SS, Diekema DJ, Heilmann KP, Dohrn CL, Crispell EK, Riahi F, McDanel JS, Satola SW, Doern GV
Abstract
Forty-two medical centers from throughout the United States participating in a longitudinal surveillance program were asked to submit 100 consecutive Staphylococcus aureus isolates during July-December 2011. Susceptibility testing using CLSI broth microdilution and mecA detection by PCR analysis was performed on the 4,131 isolates collected. The Etest GRD (Glycopeptide Resistance Detection, bioMérieux) and brain heart infusion agar containing 4 μg/ml vancomycin (BHIV) were used to screen methicillin-resistant S. aureus (MRSA) isolates for heterogeneous intermediate-level resistance to vancomycin (hVISA). Isolates with positive hVISA screen results were confirmed by population analysis profiling-area under the curve (PAP-AUC) analysis. The genetic relatedness of hVISA, ceftaroline nonsusceptible or high-level (HL) mupirocin resistant MRSA isolates was assessed by pulsed-field gel electrophoresis (PFGE). Among 2093 MRSA isolates, the hVISA screen results were positive with 47 isolates by Etest GRD and 30 isolates by BHIV agar screen. Twenty-five of the GRD or BHIV screen positive isolates were confirmed as hVISA by PAP-AUC testing. Results of the current study were compared to results obtained from prior surveillance performed in 2009. The prevalence of hVISA among MRSA was higher in 2011 compared with 2009 (1.2% vs. 0.4%, P=0.003), especially for isolates with vancomycin MICs of 2 (45.4% vs. 14.3%, P=0.01). The overall rate of ceftaroline susceptibility in the current study was 99.4% (one hVISA isolate had an intermediate ceftaroline MIC). HL mupirocin resistance increased from 2.2% in 2009 to 3.2% in 2011 (P=0.006). Although overall rates of hVISA and HL mupirocin resistance are low, they have increased since 2009.
PMID: 24247138 [PubMed - as supplied by publisher]