Legionella contamination in hot water of Italian hotels.
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 > or =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.
Borella
Paola
P
Department of Hygiene and Microbiology, Via Campi, 287, I-41100 Modena, Italy. borella.paola@unimore.it
Montagna
Maria Teresa
MT
Stampi
Serena
S
Stancanelli
Giovanna
G
Romano-Spica
Vincenzo
V
Triassi
Maria
M
Marchesi
Isabella
I
Bargellini
Annalisa
A
Tatò
Daniela
D
Napoli
Christian
C
Zanetti
Franca
F
Leoni
Erica
E
Moro
Matteo
M
Scaltriti
Stefania
S
Ribera D'Alcalà
Gabriella
G
Santarpia
Rosalba
R
Boccia
Stefania
S
D015169:Colony Count, Microbial; D005618:Fresh Water / Q000737:chemistry / Q000382:microbiology*; D006358:Hot Temperature; D007558:Italy; D007875:Legionella / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D016952:Legionella pneumophila / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D012044:Regression Analysis; D012703:Serotyping; D014195:Travel; D014876:Water Pollution; D014881:Water Supply