Outcomes with daptomycin in the treatment of Staphylococcus aureus infections with a range of vancomycin MICs

Abstract

Objectives: Recent recommendations by the Infectious Diseases Society of America for the treatment of Staphylococcus aureus suggest the use of alternative agents when vancomycin MIC values are ≥2 mg/L. This study examines the outcome of patients treated with daptomycin for S. aureus infections with documented vancomycin MICs. Patients and methods: All patients with skin, bacteraemia and endocarditis infections due to S. aureus with vancomycin MIC values in CORE 2005-08, a retrospective, multicentre, observational registry, were studied. The outcome (cure, improved, failure or non-evaluable) was the investigator assessment at the end of daptomycin therapy. Success was defined as cure or improved. Results: Five hundred and forty-seven clinically evaluable patients were identified with discrete vancomycin MIC values [MIC<2 mg/L: 451 (82%); MIC ≥2 mg/L: 96 (18%)]. The vancomycin MIC groups were well matched for patient characteristics, types of infections, first-line daptomycin use (19%) and prior vancomycin use (58%). Clinical success was reported in 94% of patients. No differences were detected in the daptomycin success rate by the vancomycin MIC group overall or by the infection type. A multivariate logistic regression also failed to identify vancomycin MIC as a predictor of daptomycin failure. Adverse event (AE) rates were not different when analysed by MIC group; both groups had ~17% of patients with one AE. Conclusions: In this diverse population, daptomycin was associated with similar outcomes for patients, regardless of whether the vancomycin MIC was categorized as <2 or ≥2 mg/L. Further studies are warranted. © The Author 2010.