Overt vancomycin resistance in MRSA is still unusual, but ID docs are worried about the bug’s rising minimum inhibitory concentrations in some regions, with MICs > 1 mcg/mL associated with worse outcomes. Kullar et al retrospectively looked at Detroit’s Henry Ford Hospital’s 5-year micro data in 320 patients with MRSA bacteremia, reporting a 52% rate of vancomycin treatment failure. Vanco MIC > 1 had an odds ratio of 1.5 for treatment failure. They suggest targeting high troughs of 15-20 mg/mL and/or the more complex pharmacokinetic calculation, the 24-hour-area-under-the-curve-to-MIC (24-hr AUC/MIC) > 421. Clin Infect Dis 2011;52:975-981.
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