In vitro activity of LY333328 (oritavancin) against Gram-positive aerobic cocci and synergy with ciprofloxacin against enterococci.

Gram-positive cocci are a major cause of nosocomial bacteraemias and are often resistant to most antibiotics. The emergence of enterococci with reduced susceptibility to vancomycin has created an urgent need for novel antibiotics to combat infections associated with these bacteria. In this study the in vitro activity of LY333328 (oritavancin), a semi-synthetic glycopeptide, was evaluated. LY333328 was effective against all strains of staphylococci, streptococci and enterococci tested. A combination of LY333328 and ciprofloxacin was additive for 50% of Enterococcus faecium strains resistant to both vancomycin and ciprofloxacin, and for 100% of vancomycin-susceptible and either ciprofloxacin-susceptible or -resistant strains.