Nosocomial Legionellosis Associated with Aspiration of Nasogastric Feedings Diluted in Tap Water

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Abstract
Problem: Two cases of nosocomial legionellosis due to Legionella pneumophila serogroup 6 (Lp6) were identified in the intensive care unit. Both patients had a history of aspiration of nasogastric tube feedings, developed pulmonary infiltrates, had positive cultures for Lp6, had serological titer rises to Legionella, were treated, and recovered. Method: Isolates of Lp6 from the potable water system and patients were characterized by DNA restriction enzyme analyses using pulsed-field gel electrophoresis (PFGE). Results: Water samples grew >10⁴ CFU/L of Lp6, and the same PFGE pattern was observed with the patient and water isolates. Potable water was used only for delivering medications and diluting feeding solutions given through the nasogastric tubes of the patients. Heat shock of the hot water system (140° to 16°F or 60° to 70°C, 4 hours) was performed and the temperature was maintained between 131° to 140°F (55° to 60°C). Surveillance over 18 months revealed a reduction in Legionella to 7<10² CFU/L. Conclusion: We speculate that nosocomial Legionella pneumonia occurred due to aspiration of nasogastric tube solutions diluted with tap water. A nursing practice change to use only sterile water to dilute feedings and flush medications for nasogastric administration was instituted. The hot water temperature at the faucet was increased to ≥131°F (≥60°C) to control Legionella. No further nosocomial cases have occurred.