Legionnaires' disease at autopsy.

Sporadic deaths from Legionnaires' disease may escape detection at autopsy. Known epidemiological and clinical features of the disease should arouse suspicion and prompt appropriate bacteriological studies. The pathological findings in Legionnaires' disease are almost entirely confined to the lungs and are not distinct from any other severe bacterial bronchopneumonia. The causative organism, Legionella pneumophila, is difficult to identify on a Gram stain but will stain nonspecifically with the Giemsa, Warthin-Starry, and Dieterle techniques. The direct fluorescent antibody method allows specific identification of Legionella in paraffin-embedded tissue sections.