Acute and chronic Legionnaires' disease and co-existent tuberculosis: a trial of erythromycin.

To assess the prevalence of Legionnaires' disease, 115 patients with 'difficult-to-treat' chest infections were screened for Legionnella pneumophila. The results were positive in 10 (37%) of 27 patients with pulmonary tuberculosis, 15 (22%) of 68 with a recent onset acute respiratory infection, and 7 (35%) of 20 patients with history of a chronic respiratory infection. These 32 patients were enrolled in an open therapeutic trial of erythromycin. Less severe cases (17 of 32) received erythromycin stearate orally (500 mg 4-times daily) for up to 28 days, while severe cases were treated for the first few days with intravenous erythromycin lactobionate (4 g/day). Weekly chest X-ray examinations revealed prompt resolution. Most patients had no signs and symptoms detectable after 7 days, and none persisted up to 28 days. There were no therapeutic failures and microbiological tests on Day 28 were negative for Legionella pneumophila. It is suggested that the possibility of co-existing legionellosis should be considered in all patients with difficult to treat acute and chronic chest infections, particularly in developing countries where tuberculosis is very common, and treatment instituted or supplemented with erythromycin as the drug of choice.