In vitro activities of daptomycin (LY146032) and paldimycin (U-70,138F) against anaerobic gram-positive bacteria

The in vitro activities of daptomycin (LY146032), paldimycin (U-70,138F), vancomycin, and penicillin G against 344 clinical isolates of anaerobic gram-positive bacteria were determined by an agar dilution method in calcium-supplemented (50 micrograms/ml) Wilkins-Chalgren medium, using an inoculum of 10(5) CFU. Daptomycin demonstrated excellent activity against a broad range of anaerobic gram-positive cocci and bacilli, including Peptostreptococcus, Eubacterium, Bifidobacterium, Actinomyces, Propionibacterium, and Lactobacillus species and Clostridium difficile. Highly resistant strains (MIC, greater than or equal to 64 micrograms/ml) were encountered sporadically from different genera, but these accounted for only 3% of all isolates tested. Vancomycin showed similar activity but was less active against Lactobacillus species and Peptostreptococcus prevotii. Paldimycin was inactive against most genera of anaerobic gram-positive bacteria. Overall, penicillin G remained the most broadly active agent against these isolates.