Limitations of the study. The study was based on a retrospective analysis of hot water test results. Identification of Legionella bacteria at species level was not performed. In addition, the study covered only a limited number of facilities located in one province.
Introduction and objective:
The occurrence of bacteria of the genus Legionella sp. in hot water supply systems in buildings is a real threat to human health, especially for patients in hospitals and residents of nursing homes. The aim of the study was determination of the degree of colonization of hot water systems in hospitals and nursing homes in the Świętokrzyskie Province in south-east Poland.

Material and methods:
Between 2014 – 2018, samples were collected from hot water systems in 30 hospitals and 32 nursing homes in order to determine the degree of contamination. 631 samples collected of the bacteria Legionella sp were analyzed.

Excessive contamination (≥ 100CFU/100 ml) with the bacteria Legionella sp. was detected in 12.12% (n=71) of samples. Contamination was significantly more frequently detected in samples from hot water systems in nursing homes, compared to hospitals (16.48% vs. 10.37%). Above-standard contamination of hot water systems with Legionella sp. bacteria occurred in 34.43% of the facilities, and was more frequent in hospitals (41.38%) than in the nursing homes (28.13%). In 21.3% of the facilities, contamination was detected many times during the study period.

Excessive contamination of hot water systems with Legionella sp. bacteria in the examined facilities was a common phenomenon. The presence of the pathogen in the installations of these facilities may constitute a considerable health hazard for patients and residents.

Project financed under the program the Minister of Education and Science called “Regional Initiative of Excellence” in the years 2019-2023, project no. 024/RID/2018/19, amount of financing 11 999 000,00 PLN
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