Early Use of Daptomycin Versus Vancomycin for Methicillin-Resistant Staphylococcus aureus Bacteremia With Vancomycin Minimum Inhibitory Concentration >1 mg/L: A Matched Cohort Study

Background. Recent reports have described decreased effectiveness with vancomycin treatment for methicillin-resistant Staphylococcus aureus bacteremia (MRSAB) when the vancomycin minimum inhibitory concentration (MIC) is >1 µg/mL. Methods. This matched, retrospective cohort study compared the clinical effectiveness of daptomycin with that of vancomycin for the treatment of MRSAB with vancomycin MICs >1 µg/mL. The primary outcome was clinical failure, defined as a composite of 30-day mortality or bacteremia persisting for ≥ 7d ays. Results. One hundred seventy patients were matched 1:1 with respect to the antimicrobial administered. In the daptomycin group, all patients received 1 µg/mL. Treatment with daptomycin resulted in significantly improved outcomes, including decreased 30-day mortality and persistent bacteremia. These results support the practice of switching early from vancomycin to daptomycin for the treatment of MRSAB when the vancomycin MIC is >1 µg/mL.