A survey of methods used to detect nosocomial legionellosis among participants in the National Nosocomial, Infections Surveillance System

OBJECTIVE: To help define the scope of nosocomial legionnaire's disease (LD ) and to assess use of recommended diagnostic methods and transmission cont rol practices. METHODS: We surveyed 253 hospitals participating in the National Nosocomial Infections Surveillance (NNIS) System. The anonymous survey included quest ions about episodes of nosocomial LD, environmental sampling practices, mai ntenance of hospital water systems, and diagnostic techniques. RESULTS: Of 192 hospitals that responded, 29% reported at least one episode of nosocomial LD from 1990 through 1996, and 61% of these reported at leas t two episodes. Of 79 hospitals with transplant programs, 42% reported noso comial LD, compared with 20% of hospitals without transplant programs. Envi ronmental sampling had been conducted by 55% of hospitals, including 79% of those reporting nosocomial LD. Legionella were isolated in 34% that sample d potable water and 19% that sampled cooling system reservoirs. Supplementa l potable-water decontamination systems were installed in 20% of hospitals. Only 19% routinely performed testing for legionellosis among patients at h igh risk for nosocomial LD. CONCLUSIONS: Nosocomial LD is relatively common among NNIS hospitals, espec ially those performing organ transplants. Environmental sampling for Legion ella is a common practice among NNIS hospitals, and Legionella often are is olated from sampled hospital cooling towers and hospital potable-water syst ems. Hospitals have responded to suspected nosocomial LD infection with a v ariety of water sampling and control strategies; some have not attempted to sample or decontaminate water systems despite identified transmission (Inf ect Control Hosp Epidemiol 1999;20:412-416).