Recurrent infection due to Legionella pneumophila in a patient with AIDS.

We report a patient with AIDS who presented with community-acquired cavitary Legionella pneumophila pneumonia. The patient recovered after an extended course of treatment with macrolide antibiotics. He returned to the hospital 4 months later with a febrile illness. Chest radiograms appeared normal. Cultures of blood yielded L. pneumophila. The isolate from blood was indistinguishable from the isolate from sputum taken during the first infection, as shown by restriction-endonuclease analysis and pulsed-field gel electrophoresis. These data suggest that the second infection represented reactivation of a persistent focus of infection that was not apparent when the patient had pneumonia.