Bactericidal activity of imipenem compared to erythromycin against intracellular Legionella pneumophila.

Pneumonia is the leading cause of death due to nosocomial infections with mortality ranging from 30 to 70%. Because imipenem has potent in vitro activity against virtually all major causes of nosocomial pneumonia, including P. aeruginosa, S. aureus, members of the family Enterobacteriaceae, and anaerobic organisms, it is used by many physicians as the empirical therapy of choice in severe nosocomial pneumonias. Recognition of Legionella species as nosocomial pathogens has been increasing. The incidence of Legionnaires' disease among patients with nosocomial pneumonia is reported to be as high as 30% (1), but the real prevalence is unknown. Imipenem has bactericidal activity against Legionella in vitro but has not previously been tested for efficacy against intracellular Legionellae.