Antibiotic therapy of experimental airborne Legionnaires' disease

The efficacy of erythromycin, gentamicin and rifampicin has been compared in the treatment of experimental airborne Legionnaires' disease in guinea-pigs. Evaluation was based on survival of animals after 1LD50 or 10LD50 infection, on numbers of Legionella pneumophila in the lungs and on the extent of histopathological lesions. All three drugs were effective in increasing survival in 1LD50 infections, but only rifampicin gave any protection against 10LD50 infection. Rifampicin was the most effective agent in eliminating viable L. pneumophila from the lungs and also in preventing pulmonary lesions.