A comparison of the efficacy of azithromycin and clarithromycin in oral therapy of experimental airborne Legionnaires' disease

Abstract

The activities of two new macrolides, azithromycin and clarithromycin, were compared in an aerosol-infected guinea-pig model of legionnaires' disease. The results of this study indicate that a low oral dose of azithromycin (3.6 mg/kg) administered once daily gives 100% survival in Legionella pneumophila-infected animals. An eight-fold higher dose of clarithromycin (28.8 mg/kg) given twice-daily was required to achieve the same effect. Similarly, azithromycin was more effective than clarithromycin in preventing pyrexia and in reducing numbers of bacteria and lesions in the lung.