Nosocomial Legionella pneumonia in a population of head and neck cancer patients.

A prospective study of nosocomial pneumonia following major head and neck surgery was conducted when it was recognized that Legionella contaminated the hospital water supply. Legionella pneumonia had not previously been diagnosed in our hospital. Every head and neck patient with nosocomial pneumonia had specialized tests performed. During the 18-month study period, 29% of patients with nosocomial pneumonia (7 of 27) had evidence of legionellosis. The sero-group of the infecting Legionella was the same as the Legionella in the water supply. Legionella was seen exclusively in patients with clinically evident aspiration. Legionella pneumonia was not demonstrated in patients undergoing laryngectomy. We conclude that specialized testing must be employed to avoid delay in diagnosis and failure to administer specific antibiotic therapy. Legionellosis may be underdiagnosed in hospitalized patients.