Studies on ciprofloxacin therapy of experimental Legionnaires' disease.

The concentration of ciprofloxacin in the serum and tissues of normal guinea-pigs was monitored after intramuscular and oral administration. Significant concentrations were attained in the kidneys, but higher doses were required before serum and lung concentrations became measurable. Ciprofloxacin, given parenterally, prevented pyrexia and death of guinea-pigs infected by aerosols of Legionella pneumophila. Although it markedly reduced the number of bacteria in the lungs, it did not prevent the development of pulmonary lesions. Ciprofloxacin administered orally was not so effective in preventing death, although pyrexia was prevented and numbers of bacteria in the lungs of guinea-pigs were reduced. The low minimum inhibitory and bactericidal concentrations of ciprofloxacin against L. pneumophila together with the in vivo results observed suggest that this antibiotic could be of value in the treatment of human beings suffering from Legionnaires' disease.