Failure of ciprofloxacin to eradicate brucellosis in experimental animals.

Ciprofloxacin is a quinolone that penetrates well intracellularly. It was shown to be active against Brucella melitensis in vitro. In this study, ciprofloxacin and tetracycline were used to treat B. melitensis and B. abortus infections in mice. The drugs were given for 7, 14, 21 and 28 days. Tetracycline reduced spleen and liver weight and splenic bacterial counts and eliminated the infection in 70% of mice treated for 3 or 4 weeks. Ciprofloxacin, on the other hand, did not affect liver or spleen weight or bacterial counts after 3-4 weeks of therapy. It failed to eradicate the organism from any of the mice treated. It is concluded that ciprofloxacin is probably not suitable for the treatment of brucellosis.