Oritavancin Activity against Staphylococcus aureus Causing Invasive Infections in U. S. and European Hospitals: a 5-Year International Surveillance Program

In this study, oritavancin had modal MIC, MIC50, and MIC90 values of 0.03, 0.03, and 0.06 mu g/ml, respectively, against Staphylococcus aureus. Similar results (MIC50/90, 0.03/0.06 mu g/ml) were observed against methicillin-resistant and -susceptible isolates and those demonstrating multidrug-resistant (MDR) and non-MDR phenotypes. When oritavancin (MIC50/90, 0.06/0.12 mg/ml) was tested against S. aureus with elevated MIC values for daptomycin (i.e., 1 to 4 mg/ml) and vancomycin (i.e., 2 mg/ml), it showed MIC results 2-fold higher than those for the more susceptible vancomycin or daptomycin counterparts (MIC50/90, 0.03/0.06 mg/ml), yet it inhibited these isolates at <= 0.25 mg/ml.