Antimicrobial activity of daptomycin tested against clinical strains of indicated species isolated in North American medical centers (2003).

Daptomycin is a cyclic lipopeptide approved for use by the US Food and Drug Administration (FDA) for the treatment of complicated skin and skin structure infections caused by Staphylococcus aureus, groups A and B beta-hemolytic streptococci, and vancomycin-susceptible Enterococcus faecalis. We evaluated the daptomycin spectrum against these pathogens by testing 2759 clinical strains consecutively collected in more than 30 hospitals located across the United States and Canada. The isolates were susceptibility tested against daptomycin and many comparators by the reference broth microdilution method. Daptomycin was very active against indicated species with the highest MIC results being 1, 2, and 0.5 microg/mL for S. aureus, E. faecalis, and beta-hemolytic streptococci, respectively. All isolates tested were considered susceptible to daptomycin, according to Clinical and Laboratory Standards Institute and FDA breakpoints, and daptomycin was the most potent (lowest MIC90) among selected antimicrobials commonly used to treat Gram-positive infections. Resistance to oxacillin or vancomycin did not influence daptomycin activity against S. aureus or E. faecalis.