Comparative in vitro activity of LY146032 (daptomycin), a new lipopeptide antimicrobial.

The in vitro activity of LY146032, a new cyclic lipopeptide antibiotic, was compared with those of vancomycin, teicoplanin, and either oxacillin or ampicillin by determining agar dilution MIC values for 304 clinical gram-positive isolates. LY146032 had superior in vitro activity against oxacillin-resistant staphylococci when compared to vancomycin or teicoplanin. Against oxacillin-sensitive staphylococci, group JK-diphtheroids, streptococci, Listeria monocytogenes and Clostridium difficile, LY146032 was equally or less active than vancomycin, teicoplanin, or the penicillins tested. When tested by macrobroth dilution MIC/MBC, LY146032 showed good bactericidal activity against all organisms with the exception of Clostridium difficile.