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Creepy ... MRSA's "MIC creep" to vancomycin portends worse outcomes
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.