Evaluation of ciprofloxacin alone and in combination with other antibiotics in a murine model of thigh muscle infection.

The therapeutic efficacies of ciprofloxacin and some comparative drugs were evaluated in a model of thigh muscle infection in neutropenic mice. Ciprofloxacin was found to be highly effective against all gram-negative and gram-positive bacteria tested. Combinations of ciprofloxacin and either gentamicin or beta-lactam antibiotics exhibited additive or slightly synergistic effects against the Enterobacteriaceae and gram-positive isolates. Azlocillin was found to increase significantly the efficacy of ciprofloxacin against Pseudomonas aeruginosa. Antagonistic interactions with vancomycin, which impaired the bactericidal activity of ciprofloxacin against Streptococcus faecalis, were observed only in vitro but not in vivo, whereas erythromycin also slightly reduced the therapeutic efficacy of ciprofloxacin in vivo.