Itaru Nakamura1, Junko Amemura-Maekawa2, Fumiaki Kura3, Takehito Kobayashi4, Akihiro Sato5, Hidehiro Watanabe6, Tetsuya Matsumoto7. 1. Department of Infection Prevention and Control, Tokyo Medical University Hospital, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan. Electronic address: task300@tokyo-med.ac.jp. 2. Department of Bacteriology I, National Institute of Infectious Diseases, 1-23-1, Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan. Electronic address: jmaekawa@nih.go.jp. 3. Department of Bacteriology I, National Institute of Infectious Diseases, 1-23-1, Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan; Division of Biosafety Control and Research, National Institute of Infectious Diseases, 1-23-1, Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan. Electronic address: fkura@nih.go.jp. 4. Department of Infection Prevention and Control, Tokyo Medical University Hospital, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan. Electronic address: t_koba@tokyo-med.ac.jp. 5. Department of Infection Prevention and Control, Tokyo Medical University Hospital, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan. Electronic address: a-sato@tokyo-med.ac.jp. 6. Department of Infection Prevention and Control, Tokyo Medical University Hospital, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan. Electronic address: hw-nabe4@tokyo-med.ac.jp. 7. Department of Medicine, International University of Health and Welfare Narita, 4-3, Kouzunomori, Narita-shi, Chiba, 162-8640, Japan. Electronic address: tetsu@sc4.so-net.ne.jp.
Abstract
OBJECTIVE: The feasibility of the decontamination procedure for Legionella pneumophila of water systems in healthcare facilities varies by water purification and disinfection methods in each country. We evaluated the efficacy of feasible decontamination strategies in Japan. METHODS: This study was conducted at Tokyo Medical University Hospital (1015 beds) between 2015 and 2018. Samples from the water system and cooling tower were cultured periodically. Hyper-chlorination of cool tap water (>0.2 ppm), increases in the temperature of hot water (>55 °C), and flushing were used as decontamination strategies. The case of healthcare-associated legionellosis was surveyed. Environmental and clinical isolates were genotyped. RESULTS: 1439 environmental samples were collected; 19 (1.3%) samples tested positive for L. pneumophila from water faucets of patient rooms, toilets, waste rooms, and water sourced from wells. Genotyping of 12 isolates confirmed that the same strains were present in eight environmental isolates and two isolates from patients over three years. Although the environmental contamination of the water system was persistent, the number of positive locations of hospital environments gradually decreased; eight in 2015, four in 2016, three in 2017, and four in 2018, respectively. CONCLUSIONS: Monitoring contamination, hyper-chlorination, controlling temperature, and flushing were effective as a Legionella decontamination strategy.
OBJECTIVE: The feasibility of the decontamination procedure for Legionella pneumophila of water systems in healthcare facilities varies by water purification and disinfection methods in each country. We evaluated the efficacy of feasible decontamination strategies in Japan. METHODS: This study was conducted at Tokyo Medical University Hospital (1015 beds) between 2015 and 2018. Samples from the water system and cooling tower were cultured periodically. Hyper-chlorination of cool tap water (>0.2 ppm), increases in the temperature of hot water (>55 °C), and flushing were used as decontamination strategies. The case of healthcare-associated legionellosis was surveyed. Environmental and clinical isolates were genotyped. RESULTS: 1439 environmental samples were collected; 19 (1.3%) samples tested positive for L. pneumophila from water faucets of patient rooms, toilets, waste rooms, and water sourced from wells. Genotyping of 12 isolates confirmed that the same strains were present in eight environmental isolates and two isolates from patients over three years. Although the environmental contamination of the water system was persistent, the number of positive locations of hospital environments gradually decreased; eight in 2015, four in 2016, three in 2017, and four in 2018, respectively. CONCLUSIONS: Monitoring contamination, hyper-chlorination, controlling temperature, and flushing were effective as a Legionella decontamination strategy.
Authors: Matthias Unterberg; Tim Rahmel; Thomas Kissinger; Christian Petermichl; Michael Bosmanns; Martin Niebius; Christina Schulze; Hans-Peter Jochum; Nina Parohl; Michael Adamzik; Hartmuth Nowak Journal: J Prev Med Hyg Date: 2021-09-15