Legionnaires' disease: seek and ye shall find.

Legionella pneumophila is among the top three or four microbial causes of community-acquired pneumonia, yet is often misdiagnosed and inadequately treated. New laboratory tests should simplify the diagnosis. Also, contrary to common perception, the disease is usually spread via aspiration of water from contaminated hot water distribution systems, not from air conditioning systems. The treatment of choice has shifted from erythromycin to the newer macrolides and quinolones. Routine culturing of the hospital water supply is a requisite first step in preventing hospital-acquired Legionnaires' disease.