A semisynthetic glycopeptide antibiotic; inhibits the growth of Gram-positive bacteria in vitro, including S. pneumoniae, S. pyogenes, vancomycin-sensitive Enterococcus species, and various methicillin-resistant staphylococci (MIC50s = 0.03, ≤0.002, 0.13, and 0.03-0.13 mg/L, respectively); increases survival in mouse models of infection with S. aureus and S. pneumoniae (ED50s = 0.08 and 0.56 mg/kg, respectively)