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Controlling Legionella pneumophila in Showerheads: Combination of Remedial Intervention and Preventative Flushing

Shock chlorination and remedial flushing are suggested to address Legionella pneumophila (Lp) contamination in buildings or during their (re)commissioning. However, data on general microbial measurements (adenosine tri-phosphate [ATP], total cell counts [TCC]), and the abundance of Lp are lacking to...

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Autores principales: Grimard-Conea, Marianne, Prévost, Michèle
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10301046/
https://www.ncbi.nlm.nih.gov/pubmed/37374862
http://dx.doi.org/10.3390/microorganisms11061361
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author Grimard-Conea, Marianne
Prévost, Michèle
author_facet Grimard-Conea, Marianne
Prévost, Michèle
author_sort Grimard-Conea, Marianne
collection PubMed
description Shock chlorination and remedial flushing are suggested to address Legionella pneumophila (Lp) contamination in buildings or during their (re)commissioning. However, data on general microbial measurements (adenosine tri-phosphate [ATP], total cell counts [TCC]), and the abundance of Lp are lacking to support their temporary implementation with variable water demands. In this study, the weekly short-term (3-week) impact of shock chlorination (20–25 mg/L free chlorine, 16 h) or remedial flushing (5-min flush) combined with distinct flushing regimes (daily, weekly, stagnant) was investigated in duplicates of showerheads in two shower systems. Results showed that the combination of stagnation and shock chlorination prompted biomass regrowth, with ATP and TCC in the first draws reaching large regrowth factors of 4.31–7.07-fold and 3.51–5.68-fold, respectively, from baseline values. Contrastingly, remedial flushing followed by stagnation generally resulted in complete or larger regrowth in Lp culturability and gene copies (gc). Irrespective of the intervention, daily flushed showerheads resulted in significantly (p < 0.05) lower ATP and TCC, as well as lower Lp concentrations than weekly flushes, in general. Nonetheless, Lp persisted at concentrations ranging from 11 to 223 as the most probable number per liter (MPN/L) and in the same order of magnitude (10(3)–10(4) gc/L) than baseline values after remedial flushing, despite daily/weekly flushing, unlike shock chlorination which suppressed Lp culturability (down 3-log) for two weeks and gene copies by 1-log. This study provides insights on the most optimal short-term combination of remedial and preventative strategies that can be considered pending the implementation of suitable engineering controls or building-wide treatment.
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spelling pubmed-103010462023-06-29 Controlling Legionella pneumophila in Showerheads: Combination of Remedial Intervention and Preventative Flushing Grimard-Conea, Marianne Prévost, Michèle Microorganisms Article Shock chlorination and remedial flushing are suggested to address Legionella pneumophila (Lp) contamination in buildings or during their (re)commissioning. However, data on general microbial measurements (adenosine tri-phosphate [ATP], total cell counts [TCC]), and the abundance of Lp are lacking to support their temporary implementation with variable water demands. In this study, the weekly short-term (3-week) impact of shock chlorination (20–25 mg/L free chlorine, 16 h) or remedial flushing (5-min flush) combined with distinct flushing regimes (daily, weekly, stagnant) was investigated in duplicates of showerheads in two shower systems. Results showed that the combination of stagnation and shock chlorination prompted biomass regrowth, with ATP and TCC in the first draws reaching large regrowth factors of 4.31–7.07-fold and 3.51–5.68-fold, respectively, from baseline values. Contrastingly, remedial flushing followed by stagnation generally resulted in complete or larger regrowth in Lp culturability and gene copies (gc). Irrespective of the intervention, daily flushed showerheads resulted in significantly (p < 0.05) lower ATP and TCC, as well as lower Lp concentrations than weekly flushes, in general. Nonetheless, Lp persisted at concentrations ranging from 11 to 223 as the most probable number per liter (MPN/L) and in the same order of magnitude (10(3)–10(4) gc/L) than baseline values after remedial flushing, despite daily/weekly flushing, unlike shock chlorination which suppressed Lp culturability (down 3-log) for two weeks and gene copies by 1-log. This study provides insights on the most optimal short-term combination of remedial and preventative strategies that can be considered pending the implementation of suitable engineering controls or building-wide treatment. MDPI 2023-05-23 /pmc/articles/PMC10301046/ /pubmed/37374862 http://dx.doi.org/10.3390/microorganisms11061361 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Grimard-Conea, Marianne
Prévost, Michèle
Controlling Legionella pneumophila in Showerheads: Combination of Remedial Intervention and Preventative Flushing
title Controlling Legionella pneumophila in Showerheads: Combination of Remedial Intervention and Preventative Flushing
title_full Controlling Legionella pneumophila in Showerheads: Combination of Remedial Intervention and Preventative Flushing
title_fullStr Controlling Legionella pneumophila in Showerheads: Combination of Remedial Intervention and Preventative Flushing
title_full_unstemmed Controlling Legionella pneumophila in Showerheads: Combination of Remedial Intervention and Preventative Flushing
title_short Controlling Legionella pneumophila in Showerheads: Combination of Remedial Intervention and Preventative Flushing
title_sort controlling legionella pneumophila in showerheads: combination of remedial intervention and preventative flushing
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10301046/
https://www.ncbi.nlm.nih.gov/pubmed/37374862
http://dx.doi.org/10.3390/microorganisms11061361
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