Legionella Contamination in Hot Water of Italian Hotels

Abstract

A cross-sectional multicenter survey of Italian hotels was conducted to investigate Legionella spp. contamination of hot water. Chemical parameters (hardness, free chlorine concentration, and trace element concentrations), water systems, and building characteristics were evaluated to study risk factors for colonization. The hot water systems of Italian hotels were strongly colonized by Legionella; 75% of the buildings examined and 60% of the water samples were contaminated, mainly at levels of >10 3 CFU liter ؊1 , and Legionella pneumophila was the most frequently isolated species (87%). L. pneumophila serogroup 1 was isolated from 45.8% of the contaminated sites and from 32.5% of the hotels examined. When a multivariate logistic model was used, only hotel age was associated with contamination, but the risk factors differed depending on the contaminating species and serogroup. Soft water with higher chlorine levels and higher temperatures were associated with L. pneumophila serogroup 1 colonization, whereas the opposite was observed for serogroups 2 to 14. In conclusion, Italian hotels, particularly those located in old buildings, represent a major source of risk for Legionnaires' disease due to the high frequency of Legionella contamination, high germ concentration, and major L. pneumophila serogroup 1 colonization. The possible role of chlorine in favoring the survival of Legionella species is discussed.

Risk Factors for Contamination of Hotel Water Distribution Systems by Legionella Species

“…These findings confirm other reports, which indicated a positive association of L. pneumophila with pH (10,11,12). The differences in distribution of species according to water characteristics confirm the hypothesis of (4,5,11). Contamination by Legionella spp.…”

Control of Legionella Contamination and Risk of Corrosion in Hospital Water Networks following Various Disinfection Procedures

“…At sampling, water temperature (digital thermometer), chlorine dioxide (Microquant DPD method; Merck, Darmstadt, Germany), monochloramine (indophenol method; Hach Lange, Milan, Italy), and hydrogen peroxide (RQflex 2 reflectometer; Merck, Darmstadt, Germany) were measured. The samples were returned to the laboratory immediately after collection and analyzed within 24 h as described elsewhere (26).…”

Legionnaires’ disease in Italy: results of the epidemiological surveillance from 2000 to 2011

“…is a ubiquitous intracellular microorganism colonising natural and artificial aquatic environments, which grows at temperatures of 25 to 42°C [1][2]. Presently, a total of 55 species and more than 70 serogroups has been classified [3]; Legionella pneumophila serogroup 1 (Lp1) is the most frequently reported aetiological agent in community-acquired legionellosis, although also other serogroups, especially Lp4 and Lp6, are frequently involved in hospitalacquired cases and outbreaks, as well as other species commonly indicated as Legionella species (L. anisa, L. bozemanii, L. dumoffii, L. longbeachae, L. micdadei) [4][5][6][7][8][9].…”