Summary
Legionnaires' disease, more formally known as legionellosis, is a relatively common form of severe pneumonia caused by Legionella, a genus of waterborne bacteria. Legionellosisis acquired by inhalation of legionellae from contaminated environmental sources. Legionella pneumophila serogroup 1 is responsible for more than 80% of cases in most countries. More than 1500 cases were reported in France in 2005. The initial diagnosis is based on tests for urinary antigens. The mortality rate for legionellosis depends on the promptness of appropriate antibiotic therapy. Macrolides (erythromycin or intravenous azithromycin, which is preferred over erythromycin for its improved pharmacodynamic properties) and fluoroquinolones (levofloxacin) are the antibiotics of choice for severe legionellosis. *Authors: Dr S Jarraud and Prof. J Etienne (February 2007)*.
