Antimicrobial activity and spectrum of Ly146032, a lipopeptide antibiotic, including susceptibility testing recommendations

Abstract

LY146032, a new lipopeptide, was found to have a spectrum of gram-positive antimicrobial activity that includes activity against staphylococci (methicillin susceptible and resistant), beta-hemolytic Streptococcus spp., pneumococci, viridans group Streptococcus spp., anaerobic gram-positive cocci, Clostridium spp., and enterococci. The new lipopeptide was generally bactericidal and showed more rapid killing of Listeria spp. (MIC, 1 to 2 μg/ml) and staphylococci than either vancomycin or teicoplanin. The 30-μg disk was preferred to the 15-μg disk on the basis of the preliminary interpretive criteria for susceptibility which indicated zone diameters of ≥16 mm for susceptible strains (MIC, ≤2.0 μg/ml) and ≤12 mm for resistant strains (MIC, ≥8.0 μg/ml). These criteria are valid pending the testing of additional gram-positive strains which have LY146032 MICs of ≥8 μg/ml.