Methicillin-resistant Staphylococcus aureus
bacteremia (MRSAB) often persists despite full susceptibility to
vancomycin; therefore, associated factors were assessed. A retrospective cohort analysis of 222 patients with MRSAB treated with
vancomycin was conducted; patients with persistent MRSAB (pMRSAB) were compared to those with nonpersistent
bacteremia (
NPB). Incidence of pMRSAB was 9%. More patients with
vancomycin MIC = 2 mg/L had pMRSAB (16%) compared to patients with
vancomycin MIC <2 mg/L (5%), P = 0.012. SCCmec type and
Panton-Valentine leukocidin production were similar between patients with pMRSAB and
NPB. There was no difference in
vancomycin troughs, time to first dose, or area under the concentration-time curve/MIC between groups. More metastatic complications were observed in pMRSAB 63% versus
NPB 32% (P = 0.005). Multivariate analysis found
endocarditis (odds ratio [OR], 2.3; P = 0.021), complicated MRSAB (OR, 2.6; P = 0.009),
vancomycin MIC = 2 (OR, 2.6; P = 0.009), and
septic shock (OR 2.2 P = 0.031), which were independent predictors of pMRSAB.