Legionnaires' disease: unusual clinical and laboratory features.

During a nosocomial epidemic of Legionnaires' disease, clinical and laboratory observations led to the recognition of remarkable aspects in six patients. Features included two episodes of disease, dual or sequential infections with Legionella pneumophila and other pathogens; transient deafness with erythromycin therapy, and Legionnaires' disease with a pleural effusion but no pulmonary infiltrate. Expectorated sputum culture yielded two serogroups of L. pneumophila in one patient. Cultures of transtracheal and endotracheal aspirates and of blood led to the diagnosis, permitted evaluation of confounding potential pathogens, and confirmed Legionnaires' disease in the absence of seroconversion. Although many manifestations of Legionnaires' disease were quite typical in this outbreak, these additional unusual features expand the spectrum and illustrate the value of rapid diagnostic methods.