Review of azithromycin activity against Legionella spp

Azithromycin is about as active against Legionella spp. in vitro as is erythromycin, with modal MICs approximately 0.5 to 0.125 microgram/ml, depending on the method used. In contrast, azithromycin is much more active against intracellular L. pneumophila than is erythromycin. In a guinea pig model of Legionnaires' disease, azithromycin is much more active than is erythromycin or clarithromycin. Despite the paucity of reports of treatment of Legionnaires' disease with azithromycin, it is likely to be as or more effective than erythromycin.