Temperature as a determining factor in the occurrence of Legionella sp. bacteria in hot water systems in hospitals and social welfare homes.

Introduction And Objective: Water in installations in hospitals and social welfare homes (SWHs) should meet the requirements of the Directive of the European Parliament and of the Council on the quality of water intended for human consumption and national regulations issued on its basis. At present, 60 species of bacteria of the genus Legionella sp. are known (of which 30 are considered as pathogenic for humans), and more than 80 serologic groups. The aim of the study was determination of the effect of temperature on contamination of hot water systems with Legionella sp. bacteria in buildings of hospitals and SWHs in the Kielce Province, Poland, based on measurement of the temperature of domestic hot water during the period 2014-2018.

Material And Methods: 631 results of temperature measurements and examinations of the quality of hot water were analyzed for the presence of the occurrence of Legionella sp. bacteria, conducted in 30 buildings of hospitals and 32 buildings of social welfare homes.

Results: From among 581 samples, only 8.95% (n=52) had a temperature of ≥55°C. The mean temperature of water in the installations of buildings, calculated based on measurements carried out while collecting samples for the study, was 46°C in 2014, and up to 47°C in 2018. The allowable limit of bacteria was exceeded in 13.04% (n=69) of the samples at the temperature < 55°C, and in 3.85% (n=2) of the samples in which the temperature was higher or equal to 55°C.

Conclusions: Water temperature ≥55°C significantly reduced the occurrence of excessive contamination of samples with Legionella sp. bacteria. Proper temperature of domestic water in water systems in hospitals and SWHs is indispensable for the provision of health safety of the patients.