Legionella contamination in hot water systems of hospitals, nursing homes, hotels, factories and spas in Tuscany-Italy

Following the report of many cases of Legionnaires’ disease associated with accommodation facilitiessuch as hotels, spas, workplaces, hospitals and nursing homes, we verified if Legionella pneumophila andLegionella spp. were present in some of those structures in Tuscany, in order to estimate the species andserogroups in circulation. Legionella pneumophila serogroup 1 (30.9%) was the most frequently isolatedspecies along with serogroups 3 (16.1%) and 6 (13.3%); these three serogroups are identified, in literature,as those most responsible for Legionnaires’ disease (LD). Studying all analyzed structures, we found someparts of the water system where Legionella concentration was higher than 103 CFU/L, indicated, in Italy, asthe maximum admitted concentration value above which a decontamination treatment is necessary whenone or more cases of healthcare-acquired Legionnaires’ disease are observed. Moreover disinfection isrecommended in any case when counts exceed 10 4CFU/L.Consequently, in order to prevent cases of Legionnaires’ disease, a continuous surveillance of the watersystems of all accommodation facilities is necessary, with particular attention to hospitals and nursinghomes where immunocompromised patients lodge, so as to promptly estimate the presence of thepathogen and consequently plan the most suitable intervention activities. We concluded that, in anystructure, a continuous surveillance and disinfecting treatment of water systems is necessary. Moreover,after any disinfection treatment the temperature of the hot water flowing in the system must be necessarilymaintained near 51°C in order to minimize the probability of recontamination from Legionella and limit therisk of LD in consumers.