Role of hot water temperature and water system use on Legionella control in a tertiary hospital: An 8-year longitudinal study

Laura Gavaldà, Marian Garcia-Nuñez, Sara Quero, Carmen Gutierrez-Milla, Miquel Sabrià

Research output: Contribution to journalArticleResearch

11 Citations (Scopus)

Abstract

© 2018 Elsevier Ltd Although measures to minimize Legionella colonization in sanitary hot water installations are well established, there is little evidence of their long-term effectiveness in hospital buildings. During an 8-year period, hot water in a large hospital building was sampled monthly in areas with suitable dimensioning and recirculation and in areas with dead legs and low-use taps. In the former areas, the percentage of Legionella-negative samples was 83.2% when the temperature was ≥55%, 64.9% when between 50.1 °C and 54.0 °C, and 51.6% when ≤50 °C (p for trend <0.001). In the highest temperature group, no samples with ≥103 cfu/L were observed. In poorly designed areas, only 44.7% of samples were negative, and 28.9% presented ≥103 cfu/L although reaching 55 °C. In these areas, multivariate analysis showed that if hot water supplies were not used daily, the risk of Legionella colonization was greater than two-fold (odds ratio: 2.84; 95% confidence interval: 1.26–6.41), and the risk of finding Legionella concentrations ≥103 cfu/L was more than three-fold (odds ratio: 3.18; 95% confidence interval: 1.36–7.46), regardless the temperature. These findings indicate that the effectiveness of maintaining sanitary hot water at a minimum temperature of 55 °C is significantly better than that at 50 °C for the environmental control of Legionella but only in installations with suitable dimensioning and recirculation. In installations that do not meet these conditions, high temperatures alone result in insufficient control.
Original languageEnglish
Pages (from-to)460-466
JournalWater Research
Volume149
DOIs
Publication statusPublished - 1 Feb 2019

Keywords

  • Control measures
  • Hospital water network
  • Legionella
  • Outlets flushing
  • Water temperature

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