Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada; INRS-Institut Armand-Frappier, Laval, QC, Canada.
Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada.
Water Res. 2015 Mar 15;71:244-56. doi: 10.1016/j.watres.2015.01.006. Epub 2015 Jan 13.
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.
嗜肺军团菌常存在于热水分配系统中，而热控制是医疗机构常用的控制措施。本研究提出了一种基于水温分布特征和管网温度分布的风险评估方法，旨在指导有效的监测策略，并识别高风险区域。在五家医疗机构的热水分配系统的不同部位，监测了控制点（热水器、再循环、典型用水点）的温度和热损失，并利用这些数据开发了一种基于温度的风险评估工具。详细调查显示，水龙头中损坏的回流阀会导致因冷热混合而产生广泛的温度损失。通过培养或 qPCR 检测，热水器中出来的水温始终保持在 60°C 以上且整个管网温度保持在 55°C 以上的系统中，军团菌为阴性。对于不符合这些温度标准的系统，使用温度分布特征和系统特征来识别嗜肺军团菌的风险区域；通过培养和 qPCR 更频繁的微生物检测来确认更高的风险。结果证实，在热水分配系统中保持足够高的温度可以抑制嗜肺军团菌的培养能力。然而，正如 qPCR 检测到嗜肺军团菌的持续存在所表明的那样，风险仍然存在。
