The Hospital Tap Water System as a Source of Nosocomial Legionella Infections for Staff Members and Patients

Abstract

The number of nosocomial infections due to Legionella pneumophila is probably underestimated in many countries. The aim of the present study was to estimate the risk of legionellosis due to L. pneumophila sg 1 and sg 2-14 for patients and hospitals staff members from the water system in a Polish hospital. Samples were taken from hospital tap water systems before and after thermal disinfection (80°C) when a reduction in Legionella positive samples of 91-40% was found. L. pneumophila sg 1 was only detected in water samples taken before disinfection. Simultaneously, serum samples from staff members were collected and examined by micro-agglutination tests using antigens prepared from type strains of L. pneumophila 10 serogroups and four strains of L. pneumophila sg 2-14 isolated from the hospital water system. The level of antibodies to L. pneumophila sg 1 was insignificant. However a high (≥256) titre of antibodies was found to some type L. pneumophila as well as to environmental L. pneumophila strains. The results of this study show a possible risk to hospital staff members' from infection by Legionella other than L. pneumophila sg 1. It was demonstrated that the high number of legionellae in water distribution systems can be successfully reduced by heat treatment.