title: Temperature diagnostic to identify high risk areas and optimize Legionella pneumophila surveillance in hot water distribution systems.
abstract: Legionella pneumophila is frequently detected in hot water distribution systems and thermal control is a common measure implemented by health care facilities. A risk assessment based on water temperature profiling and temperature distribution within the network is proposed, to guide effective monitoring strategies and allow the identification of high risk areas. Temperature and heat loss at control points (water heater, recirculation, representative points-of-use) were monitored in various sections of five health care facilities hot water distribution systems and results used to develop a temperature-based risk assessment tool. Detailed investigations show that defective return valves in faucets can cause widespread temperature losses because of hot and cold water mixing. Systems in which water temperature coming out of the water heaters was kept consistently above 60 °C and maintained above 55 °C across the network were negative for Legionella by culture or qPCR. For systems not meeting these temperature criteria, risk areas for L. pneumophila were identified using temperature profiling and system's characterization; higher risk was confirmed by more frequent microbiological detection by culture and qPCR. Results confirmed that maintaining sufficiently high temperatures within hot water distribution systems suppressed L. pneumophila culturability. However, the risk remains as shown by the persistence of L. pneumophila by qPCR.
authors.affiliation: Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada; INRS-Institut Armand-Frappier, Laval, QC, Canada. Electronic address: emilie.bedard@polymtl.ca.
authors.forename: Emilie
authors.initials: E
authors.lastname: Bédard
authors.affiliation: Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Fey
authors.affiliation: Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada.
authors.forename: Dominique
authors.initials: D
authors.lastname: Charron
authors.affiliation: INRS-Institut Armand-Frappier, Laval, QC, Canada.
authors.forename: Cindy
authors.initials: C
authors.lastname: Lalancette
authors.affiliation: Centre d'expertise en analyse environnementale du Québec, Québec, QC, Canada.
authors.forename: Philippe
authors.initials: P
authors.lastname: Cantin
authors.affiliation: Department of Medical Microbiology and Infectious Diseases, Centre Hospitalier Régional de Rimouski, Rimouski, QC, Canada.
authors.forename: Patrick
authors.initials: P
authors.lastname: Dolcé
authors.affiliation: Department of Microbiology and Immunology (Infection Control), CHU Ste-Justine, Université de Montréal, Montréal, QC, Canada.
authors.forename: Céline
authors.initials: C
authors.lastname: Laferrière
authors.affiliation: INRS-Institut Armand-Frappier, Laval, QC, Canada.
authors.forename: Eric
authors.initials: E
authors.lastname: Déziel
authors.affiliation: Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada.
authors.forename: Michèle
authors.initials: M
authors.lastname: Prévost
mesh_terms: D004203:Disinfection / Q000379:methods; D006358:Hot Temperature; D016952:Legionella pneumophila / Q000302:isolation & purification*; D007877:Legionnaires' Disease / Q000517:prevention & control*; D008284:Maintenance and Engineering, Hospital; D012498:Sanitary Engineering; D014871:Water Microbiology; D014881:Water Supply
keywords: Culturability; Legionella pneumophila; Premise plumbing; Temperature profile; Thermal control; Viable but not culturable (VBNC)