Summary: The hot water supplies of 11 private healthcare facilities in the city of Bologna, Italy, were
monitored for the presence of Legionella spp. Four samplings were made in each establishment over a period of
one year and in total 121 samples were collected from distribution points situated near the water-boiler and
inside the wards (taps and showers). Legionellae were recovered from all the water supplies in question:
Legionella spp. in 86.8% of samples, L. pneumophila in 82.6% of samples. L. pneumophila was found in all the
water supplies at levels averaging above 104 cfu/L in five health facilities and reaching a maximum
concentration of 107 cfu/L. The only parameter to have affected the presence of legionellae was the water
temperature, which was seen to be inversely correlated to the concentration of Legionella spp. Despite the high
levels of contamination from L. pneumophila, no cases of nosocomial Legionnaires' disease were reported
during the period of the study.