The impact of pipeline changes and temperature increase in a hospital historically colonised with Legionella

Sci Rep. 2021 Jan 21;11(1):1916. doi: 10.1038/s41598-021-81625-6.


Healthcare-related Legionnaires' disease has a devastating impact on high risk patients, with a case fatality rate of 30-50%. Legionella prevention and control in hospitals is therefore crucial. To control Legionella water colonisation in a hospital setting we evaluated the effect of pipeline improvements and temperature increase, analysing 237 samples over a 2-year period (first year: 129, second year: 108). In the first year, 25.58% of samples were positive for Legionella and 16.67% for amoeba. Assessing the distance of the points analysed from the hot water tank, the most distal points presented higher proportion of Legionella colonisation and lower temperatures (nearest points: 6.4% colonised, and temperature 61.4 °C; most distal points: 50% and temperature 59.1 °C). After the first year, the hot water system was repaired and the temperature stabilised. This led to a dramatic reduction in Legionella colonisation, which was negative in all the samples analysed; however, amoeba colonisation remained stable. This study shows the importance of keeping the temperature stable throughout the circuit, at around 60 °C. Special attention should be paid to the most distal points of the circuit; a fall in temperature at these weak points would favour the colonisation and spread of Legionella, because amoeba (the main Legionella reservoir) are not affected by temperature.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amoeba / pathogenicity
  • Cross Infection
  • Hospitals
  • Humans
  • Legionella / growth & development
  • Legionella / pathogenicity*
  • Legionnaires' Disease / epidemiology
  • Legionnaires' Disease / microbiology*
  • Legionnaires' Disease / prevention & control*
  • Temperature
  • Water Microbiology*
  • Water Supply