Legionnaires' disease associated with habitual drinking of hot spring water.

A 57-year-old man presented with pneumonia, respiratory distress, and myelodysplastic syndrome. A diagnosis of Legionnaires' disease due to Legionella pneumophila (L. pneumophila) was established. The patient had long been drinking tap water via a conduit from a hot spring resource, from which L. pneumophila was also isolated. Both the patient's strain and the water strain of L. pneumophila were identified as serogroup 1, and the genetic relatedness between the two strains as seen by pulsed-field gel electrophoresis was 87%. The patient was successfully treated with erythromycin, fluoroquinolone, and rifampicin. This case raises an important issue on public health represented by legionellosis in Japan.