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 of ten resistant to most antibiotics. The emergence of enterococci with reduce d susceptibility to vancomycin has created an urgent need for novel antibio tics 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 staphylococc i, streptococci and enterococci tested. A combination of LY333328 and cipro floxacin was additive for 50% of Enterococcus faecium strains resistant to both vancomycin and ciprofloxacin, and for 100% of vancomycin-susceptible a nd either ciprofloxacin-susceptible or -resistant strains.