Nosocomial legionnaires’ disease discovered in community hospitals following cultures of the water system: Seek and ye shall find, ,

Background: The reservoir for hospital-acquired legionnaires’ disease is the water distribution system. The Allegheny County (Pa.) Health Department recommended environmental cultures for all health care facilities for the prevention of hospital-acquired Legionella infection including facilities with no known cases of legionnaires’ disease. Methods: Environmental cultures of hot water tanks, faucets, and showerheads were performed in six health care facilities according to health department guidelines. If hot water tanks, faucets, or showerheads yielded Legionella , monitoring with Legionella culture and urinary antigen was performed for all cases of nosocomial pneumonia. Results: Legionella was isolated from the water distribution system in 83% (five of six) of facilities. Three facilities dropped out of the study; two decided to disinfect the water and one had no Legionella in the water system. The other three facilities all discovered cases of legionnaires’ disease during the 1-year study period after introduction of Legionella testing. L. pneumophilia, serogroups 1, 3, and 5, caused 12 cases of hospital-acquired legionnaires’ disease. Positive diagnostic tests included: 10 of 12 (83%) urinary antigen, 6 of 8 (75%) respiratory cultures, and 2 of 5 (40%) serology. Molecular typing confirmed that the source of infection was the water supply in two hospitals. Conclusion: Routine environmental cultures for Legionella in the water distribution system are recommended even if the hospital had not previously recognized cases of hospital-acquired legionnaires’ disease. The Allegheny County Health Department guidelines were inexpensive to implement and resulted in the discovery of cases that would have otherwise been undiagnosed. (AJIC Am J Infect Control 1998;26:8-11)