Oritavancin Activity against Vancomycin-Susceptible and Vancomycin-Resistant Enterococci with Molecularly Characterized Glycopeptide Resistance Genes Recovered from Bacteremic Patients, 2009-2010

Abstract

ABSTRACTOritavancin exhibited potent activity against vancomycin-susceptible (MIC50and MIC90, 0.015/0.03 μg/ml) andvanB-carryingE. faecalisisolates (MIC50and MIC90, 0.015 and 0.015 μg/ml). Higher (16- to 32-fold) MIC50s and MIC90s forvanA-harboringE. faecaliswere noted (MIC50and MIC90, 0.25 and 0.5 μg/ml), although oritavancin inhibited all strains at ≤0.5 μg/ml. Vancomycin-susceptible andvanB-carryingE. faeciumstrains (MIC50and MIC90, ≤0.008 and ≤0.008 μg/ml for both) were very susceptible to oritavancin, as were VanA-producing isolates (MIC50and MIC90, 0.03 and 0.06 μg/ml). Oritavancin exhibited goodin vitropotency against this collection of organisms, including vancomycin-resistant enterococci.