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Legionella Colonization in Hospital Water Distribution Systems
1)Department of Microbiology, Kanagawa Prefectural Institute of Public Health, 2)Department of Bacteriology 1, National Institute of Infectious Diseases, 3)Department of Parasitology, National Institute of Infectious Diseases
Hitomi OHYA1), Miyuki SUZUKI1), Tomoka MASAOKA1), Naoki NAKAJIMA1), Ichiro FURUKAWA1), Junko AMEMURA-MAEKAWA2), Fumiaki KURA2), Shinji IZUMIYAMA3) & Toshiro KUROKI1)
(Received November 7, 2017)
(Accepted June 15, 2018)
Key words: Legionella, colonization, water supply system, hospital

Nosocomial legionellosis has been reported to be associated with Legionella colonization of hospital water supply systems. Legionella colonization of the water supply system should be investigated to prevent the infection. This study aimed to determine the level of Legionella colonization in water supply systems in three hospitals in Kanagawa, Japan with Legionella DNA detection and culture methods. Water samples were collected from taps and showers, and swab samples were collected by swabbing the inside of taps and showerheads. Legionella culture was positive in 26.7%, 37.5% and 66.7% of the water samples, and in 0%, 14.3% and 7.7% of the swab samples from water supply systems of the three hospitals, respectively. Legionella DNA was found in 6.7%, 93.8% and 60.0% of the water samples, and in 0%, 7.1%, and 0% of the swab samples, respectively. Legionella pneumophila SG1, SG5, and SG6, Legionella feeleii SG1, and Legionella sp. L-29 were isolated from the water supply systems. Among the parameters analyzed, residual chlorine concentrations showed an inverse relationship with Legionella colonization in the water supply system according to a multivariate logistic regression analysis. This study suggests that hospital water supply systems are highly contaminated with Legionella spp. Control measures for preventing Legionella colonization should be implemented in hospital water supply systems.

[ Kansenshogaku Zasshi 92: 678-685, 2018 ]

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