The circulation of Legionella spp. in different wards of the Azienda Ospedaliero-Universitaria Pisana (a 1605-bed tertiary care teaching hospital, composed of several buildings on two different sites in the city of Pisa) was evaluated by the study of the genetic variability and the chlorine-susceptibility of environmental strains isolated prior to and throughout the application of continuous chlorine dioxide treatment. The application of a quantitative ATP assay to the rapid screening of chlorine-tolerant strains was also assessed. The surveillance-plan adopted allowed to monitor the spread of Legionella spp. in the hospital water distribution system and demonstrated the occurrence of chlorine-tolerant types as well as their persistance despite chlorination. Chlorine-susceptibility remained unchanged over time and was not influenced by long-term exposure to chlorination. In conclusion, chlorine dioxide reduced the mean counts of Legionella spp. and decreased the percentage of positive sites in buildings where effective levels of free chlorine were reached. However, it did not achieve eradication of Legionella spp., leading to the adoption of an integrated disinfection/filtration strategy. In our experience, a water risk-management plan based on proactive measures (clinical and environmental surveillance, maintenance and disinfection-filtration procedures) resulted in the prevention of further cases of nosocomial legionellosis.
Colonizzazione a lungo termine da ceppi cloro-tolleranti di Legionella pneumophila sierogruppo 1 strain Wadsworth della rete idrica di un Ospedale Universitario
CASINI, BEATRICE;BAGGIANI, ANGELO;PRIVITERA, GAETANO PIERPAOLO
2008-01-01
Abstract
The circulation of Legionella spp. in different wards of the Azienda Ospedaliero-Universitaria Pisana (a 1605-bed tertiary care teaching hospital, composed of several buildings on two different sites in the city of Pisa) was evaluated by the study of the genetic variability and the chlorine-susceptibility of environmental strains isolated prior to and throughout the application of continuous chlorine dioxide treatment. The application of a quantitative ATP assay to the rapid screening of chlorine-tolerant strains was also assessed. The surveillance-plan adopted allowed to monitor the spread of Legionella spp. in the hospital water distribution system and demonstrated the occurrence of chlorine-tolerant types as well as their persistance despite chlorination. Chlorine-susceptibility remained unchanged over time and was not influenced by long-term exposure to chlorination. In conclusion, chlorine dioxide reduced the mean counts of Legionella spp. and decreased the percentage of positive sites in buildings where effective levels of free chlorine were reached. However, it did not achieve eradication of Legionella spp., leading to the adoption of an integrated disinfection/filtration strategy. In our experience, a water risk-management plan based on proactive measures (clinical and environmental surveillance, maintenance and disinfection-filtration procedures) resulted in the prevention of further cases of nosocomial legionellosis.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
