Efficacy of ciprofloxacin in treatment and prophylaxis of experimental Staphylococcus aureus endocarditis caused by a cloxacillin-tolerant strain and its non-tolerant variant

The efficacy of ciprofloxacin in treatment and prophylaxis of Staphylococcus aureus endocarditis in rats infected with a strain tolerant to the standard anti-staphylococcal antibiotics cloxacillin, vancomycin and teicoplanin was compared with its non-tolerant variant. After 5 days of treatment with ciprofloxacin 30 mg/kg subcutaneously every 8 h bacterial densities in vegetations from animals infected with the tolerant and the non-tolerant strain were similar. Resistance to ciprofloxacin did not emerge in either strain of S. aureus during treatment. In prophylaxis experiments a single dose of ciprofloxacin (30 mg/kg) administered 30 min before bacterial challenge afforded almost full protection for both the tolerant and the non-tolerant strain