Daptomycin activity against uncommonly isolated streptococcal and other gram-positive species groups

A total of 1,356 clinical isolates were tested against daptomycin by broth microdilution methods. Daptomycin was active against seven groups of viridans group streptococci (MIC50 and MIC90 values ranging from ≤0.06 and ≤0.06 μg/ml [Streptococcus bovis and Streptococcus dysgalactiae] to 0.5 and 1 μg/ml [Streptococcus mitis, Streptococcus oralis, and Streptococcus parasanguinis], respectively), beta-hemolytic streptococci serogroups C, F, and G (MIC50 and MIC90, ≤0.06 to 0.25 and 0.12 to 0.25 μg/ml, respectively), Corynebacterium spp. (MIC50 and MIC90, ≤0.06 and 0.12 μg/ml, respectively), and Micrococcus spp. (MIC50 and MIC90, ≤0.06 and 0.25 μg/ml, respectively). Listeria monocytogenes exhibited higher daptomycin MICs (MIC50 and MIC90, 2 and 4 μg/ml, respectively) than other tested organisms.