In vitro activity of the combination of trovafloxacin and other antibiotics against enterococci.

The activities of trovafloxacin and ciprofloxacin against 38 strains of non-beta-lactamase-producing enterococci, resistant to ampicillin, 34 strains susceptible to ampicillin, and 3 vancomycin-resistant enterococci were studied. Trovafloxacin was more active than ciprofloxacin against all the enterococci studied. The ampicillin-resistant strains were more susceptible than the ampicillin-susceptible strains to both agents. The effect of combining trovafloxacin with gentamicin, ampicillin-sulbactam, novobiocin, rifampin, teicoplanin, and vancomycin was determined for 17 strains by the checkerboard method. An additive effect by inhibition was seen with all antibiotics studied. The results by killing varied with the different agents studied. Gentamicin, ampicillin-sulbactam, and novobiocin produced an additive killing effect with trovafloxacin. Reduced killing was seen when rifampin, vancomycin, or teicoplanin were added to trovafloxacin.