Legionella pneumonia due to exposure to 24-hour bath water contaminated by Legionella pneumophila serogroup-5

A 79-year-old man was admitted to hospital from his nursing home for treatment of pneumonia, but died 7 days after admission. Legionella pneumonia was diagnosed after isolation of Legionella pneumophila serogroup-5 from sputum culture. The environment of the nursing home was investigated; only water specimens from the 24-hour bath were positive by culture for Legionella pneumophila serogroup-5. Subsequent analysis by pulsed-field gel electrophoresis revealed an identical pattern in isolates from both sputum culture and 24 hour bath water culture. Among 123 inpatients and staff of the nursing home, 17 were found to be seropositive for Legionella pneumophila serogroup-5.