Massive diarrhea in Legionella micdadei pneumonitis.

Mild diarrhea of poorly documented volume is common early in the course of Legionella infection. We report massive diarrhea of 1.8 to 3 liters per day in a patient with pneumonia in whom Legionella micdadei was isolated from pleural fluid and infection was confirmed serologically. The large volume of diarrhea, not previously associated with Legionella infection, remained unexplained despite clinical evaluation and postmortem study of the gastrointestinal tract. This case expands the clinical spectrum of Legionnaires' disease to include massive diarrhea, which in our patient constituted the chief complaint.