Assessment of monitoring approaches to control Legionella pneumophila within a complex cooling tower system.

Autor: Trigui H; Polytechnique Montréal, Civil, Geological and Mining Engineering Dpt., P.O. Box 6079, Succ. Centre-ville, Montréal H3C 3A7, Québec, Canada., Matthews S; Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue H9X 3V9, Québec, Canada., Bedard E; Polytechnique Montréal, Civil, Geological and Mining Engineering Dpt., P.O. Box 6079, Succ. Centre-ville, Montréal H3C 3A7, Québec, Canada., Charron D; Polytechnique Montréal, Civil, Geological and Mining Engineering Dpt., P.O. Box 6079, Succ. Centre-ville, Montréal H3C 3A7, Québec, Canada. Electronic address: dominique-2.charron@polymtl.ca., Chea S; Direction de l'épuration des eaux usées, Service de l'eau, Ville de Montréal, Montréal H1C 1V3, Québec, Canada., Fleury C; Direction de l'épuration des eaux usées, Service de l'eau, Ville de Montréal, Montréal H1C 1V3, Québec, Canada., Maldonado JFG; Polytechnique Montréal, Civil, Geological and Mining Engineering Dpt., P.O. Box 6079, Succ. Centre-ville, Montréal H3C 3A7, Québec, Canada., Rivard M; Polytechnique Montréal, Civil, Geological and Mining Engineering Dpt., P.O. Box 6079, Succ. Centre-ville, Montréal H3C 3A7, Québec, Canada., Faucher SP; Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue H9X 3V9, Québec, Canada., Prévost M; Polytechnique Montréal, Civil, Geological and Mining Engineering Dpt., P.O. Box 6079, Succ. Centre-ville, Montréal H3C 3A7, Québec, Canada.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2024 Nov 10; Vol. 950, pp. 175136. Date of Electronic Publication: 2024 Jul 30.
DOI: 10.1016/j.scitotenv.2024.175136
Abstrakt: Precise and rapid methods are needed to improve monitoring approaches of L. pneumophila (Lp) in cooling towers (CTs) to allow timely operational adjustments and prevent outbreaks. The performance of liquid culture (ASTM D8429-21) and an online qPCR device were first compared to conventional filter plate culture (ISO 11731-2017), qPCR and semi-automated qPCR at three spiked concentrations of Lp (serogroup 1) validated by flow cytometry (total/viable cell count). The most accurate was qPCR, followed by liquid culture, online and semi-automated qPCR, and lastly, by a significant margin, filter plate culture. An industrial CT system was monitored using liquid and direct plate culture by the facility, qPCR and online qPCR. Direct plate and liquid culture results agreed at regulatory sampling point, supporting the use of the faster liquid culture for monitoring culturable Lp. During initial operation, qPCR and online qPCR results were within one log of culture at the primary pump before deviating after first cleaning. Other points revealed high spatial variability of Lp. The secondary pumps and chiller had the most positivity and highest concentrations by both qPCR and liquid culture compared to the basin and infeed tank. Altogether, this suggests that results from monthly compliance sampling at a single location with plate culture are not representative of Lp risks in this CT due to the high temporal and spatial variability. The primary pump, rather than the CT basin, should be designated for sampling, as it is representative of the health risk. An annual multi point survey of the system should be conducted to identify and target Lp hot spots. Generally, a combination of liquid culture for compliance and frequent qPCR for process control provides a more agile and robust monitoring scheme than plate culture alone, enabling early treatment adjustments, due to lower limit of detection (LOD) and turnover time.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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