Predicing vancomycin failure in MRSA bacteremia
Death, long hospital stays, and treatment failures are more likely when vancomycin is used for MRSA bacteremia with minimum inhibitory concentrations (MIC) > 1 mcg/mL. Lubin et al propose a clinical prediction rule to predict relative vancomycin resistance, based on a retrospective analysis of 272 patients with MRSA bacteremia at Tufts. Oversimplifying slightly: Having less than two risk factors (age > 50; prior receipt of vanco; prior MRSA bacteremia; chronic liver disease, or a nontunneled venous catheter) had a 91% negative predictive value for having an MRSA strain with MIC > 1 (relative vancomycin resistance). Having 2 or more factors had a positive predictive value of only 30%, though. There was no prospective validation cohort. Clin Infect Dis 2011;52:997-1002.