Potable Water as a Cause of Sporadic Cases of Community-Acquired Legionnaires' Disease

Stout, Janet E.; Yu, Victor L.; Muraca, Paul W.; Joly, J; Troup, Nancy; Tompkins, Lucy S.

doi:10.1056/nejm199201163260302

Cited by 128 publications

(68 citation statements)

References 28 publications

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“…Inhalation of aerosols or microaspiration of contaminated water has been recognized as a source of legionellosis (227). After the initial description of an outbreak of severe respiratory disease occurring in Pennsylvania, which showed that person-to-person transmission was unlikely (77), subsequent reports of Legionella infections were repeatedly associated with contaminated water in both communityacquired (165,229) and nosocomial (30,90,140,142,176) settings. The ecology of L. pneumophila was extensively studied and confirmed empirical observations of its predilection for growth in hot water tanks and its localization in sediment (228).…”

Section: Legionellaceaementioning

confidence: 99%

Microorganisms Resistant to Free-Living Amoebae

2004

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Free-living amoebae feed on bacteria, fungi, and algae. However, some microorganisms have evolved to become resistant to these protists. These amoeba-resistant microorganisms include established pathogens, such as Cryptococcus neoformans, Legionella spp., Chlamydophila pneumoniae, Mycobacterium avium, Listeria monocytogenes, Pseudomonas aeruginosa, and Francisella tularensis, and emerging pathogens, such as Bosea spp., Simkania negevensis, Parachlamydia acanthamoebae, and Legionella-like amoebal pathogens. Some of these amoeba-resistant bacteria (ARB) are lytic for their amoebal host, while others are considered endosymbionts, since a stable host-parasite ratio is maintained. Free-living amoebae represent an important reservoir of ARB and may, while encysted, protect the internalized bacteria from chlorine and other biocides. Free-living amoebae may act as a Trojan horse, bringing hidden ARB within the human “Troy,” and may produce vesicles filled with ARB, increasing their transmission potential. Free-living amoebae may also play a role in the selection of virulence traits and in adaptation to survival in macrophages. Thus, intra-amoebal growth was found to enhance virulence, and similar mechanisms seem to be implicated in the survival of ARB in response to both amoebae and macrophages. Moreover, free-living amoebae represent a useful tool for the culture of some intracellular bacteria and new bacterial species that might be potential emerging pathogens

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Section: Legionellaceaementioning

confidence: 99%

Microorganisms Resistant to Free-Living Amoebae

2004

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“…Potable water supplies that harbour L. pneumophila are an important source of communityacquired Legionnaires' disease (Stout et al, 1992a), and most cases of community-acquired legionellosis probably result from the presence of Legionella bacteria in the water distribution systems (Bernander and Kallings, 1998). In a Canadian study, 6.2% of water samples from single-family residences were found to be positive for legionellae compared with 25% for multiple-dwelling apartments (Marrie et al, 1994).…”

Section: Environmental Sources Of Legionellosismentioning

confidence: 99%

Legionella: from environmental habitats to disease pathology, detection and control

Atlas

1999

Environmental Microbiology

213

148

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Studies on Legionella show a continuum from environment to human disease. Legionellosis is caused by Legionella species acquired from environmental sources, principally water sources such as cooling towers, where Legionella grows intracellularly in protozoa within biofilms. Aquatic biofilms, which are widespread not only in nature, but also in medical and dental devices, are ecological niches in which Legionella survives and proliferates and the ultimate sources to which outbreaks of legionellosis can be traced. Invasion and intracellular replication of L. pneumophila within protozoa in the environment play a major role in the transmission of Legionnaires' disease. Protozoa provide the habitats for the environmental survival and reproduction of Legionella species. L. pneumophila proliferates intracellularly in various species of protozoa within vacuoles studded with ribosomes, as it also does within macrophages. Growth within protozoa enhances the environmental survival capability and the pathogenicity (virulence) of Legionella. The growth requirements of Legionella, the ability of Legionella to enter a viable non‐culturable state, the association of Legionella with protozoa and the occurrence of Legionella within biofilms complicates the detection of Legionella and epidemiological investigations of legionellosis. Polymerase chain reaction (PCR) methods have been developed for the molecular detection of Legionella and used in environmental and epidemiological studies. Various physical and chemical disinfection methods have been developed to eliminate Legionella from environmental sources, but gaining control of Legionella in environmental waters, where they are protected from disinfection by growing within protozoa and biofilms, remains a challenge, and one that must be overcome in order to eliminate sporadic outbreaks of legionellosis.

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“…6 Acquisition of legionnaires' disease usually occurs following the aspiration or inhalation of aerosols from contaminated potable water or cooling towers. [7][8][9][10][11][12][13][14] Most hospital-acquired outbreaks of legionnaires' disease have been associated with the contamination of hospital drinking water with Legionella species. 15 Efforts to prevent hospital-acquired legionnaires' disease have focused on increasing the temperature of hot water and the supplemental chlorination of drinking water.…”

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

Heffelfinger

Kool²,

Fridkin³

et al. 2003

Infect. Control Hosp. Epidemiol.

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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.

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Potable Water as a Cause of Sporadic Cases of Community-Acquired Legionnaires' Disease

Abstract: Potable-water supplies that harbor L. pneumophila are an important source of community-acquired legionnaires' disease. Future studies should include attempts to identify the environmental sources of this infection.

Cited by 128 publications

References 28 publications

Microorganisms Resistant to Free-Living Amoebae

Microorganisms Resistant to Free-Living Amoebae

Legionella: from environmental habitats to disease pathology, detection and control

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

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