Risk of Hospital-Acquired Legionnaires' Disease in Cities Using Monochloramine Versus Other Water Disinfectants

Abstract

Objective:To measure the association between the disinfection of municipal drinking water with monochloramine and the occurrence of hospital-acquired legionnaires' disease (LD).Setting:One hundred sixty-six U.S. hospitals.Design:Survey of 459 members of the Society for Healthcare Epidemiology of America (SHEA) for hospital features; endemic- and outbreak-related, hospital-acquired LD; the source of the hospital water supply; and the methods of disinfection used by the hospitals and municipal water treatment plants.Results:SHEA members representing 166 (36%) of 459 hospitals responded; 33 (20%) reported one or more episodes of hospital-acquired LD during the period from 1994 to 1998 and 23 (14%) reported an outbreak of hospital-acquired LD during the period from 1989 to 1998. Hospitals with an occurrence of hospital-acquired LD had a higher census (median, 319 vs 221;P= .03), more acute care beds (median, 500 vs 376;P= .04), and more intensive care unit beds (median, 42 vs 24;P= .009) than did other hospitals. They were also more likely to have a transplant service (74% vs 42%;P= .001) and to perform surveillance for hospital-acquired disease (92% vs 61%;P= .001). After adjustment for the presence of a transplant program and surveillance for legionnaires' disease, hospitals supplied with drinking water disinfected with monochloramine by municipal plants were less likely to have sporadic cases or outbreaks of hospital-acquired LD (odds ratio, 0.20; 95% confidence interval, 0.07 to 0.56) than were other hospitals.Conclusion:Water disinfection with monochloramine by municipal water treatment plants significantly reduces the risk of hospital-acquired LD.

Introduction of Monochloramine into a Municipal Water System: Impact on Colonization of Buildings by Legionella spp

“…Instead, we observed a dramatic and statistically significant reduction in the proportion of sites colonized. Finally, these findings are supported by previous work documenting that MC reduces the risk of Legionella colonization in hospitals (11) and the risk of outbreaks of nosocomial Legionnnaires' disease (13).…”

“…The risk of colonization of individual buildings has been associated with the age of the building, the complexity of the water system, and the type of hot water heater used (1). On the basis of the results of previous in vitro experiments (7,8) and studies indicating that hospitals supplied with MC-treated water were less likely to have sporadic cases and outbreaks of LD (11,13), we hypothesized that changing the residual disinfectant of a municipal water system from CL to MC might result in decreased Legionella colonization of building water systems across the community. To test this hypothesis, we obtained water samples for culture from buildings served by a municipal water system before and after the system switched from CL to MC.…”

The role of water in healthcare-associated infections

“…[32]. Of note, monochloramine use in municipal water has been shown to reduce Legionella infection risk in hospitals [33, 34]. …”

Point-of-care controls for nosocomial legionellosis combined with chlorine dioxide potable water decontamination: a two-year survey at a Welsh teaching hospital

“…A variety of methods have been attempted for the eradication of legionella from water systems with mixed success. 11 These methods include silver-copper ionization, 12-14 chlorine dioxide, 15 monochloramine 16,17 and ultraviolet light, 18 and have involved the expenditure of significant sums of money. The engineering measures with chlorine dioxide that have been instituted in both the hot and cold water systems at this hospital are costing in excess of £25 000 per annum with only minimal effects on the presence of the organism in the water system.…”