The WHO Guideline for Legionella and the Prevention of Legionellosis advocate that a water safety plan has to be established in the health care settings for the water risk management. Elements of the risk management plan are active surveillance for infections caused by waterborne pathogens, standard operating procedures for sanitization, maintenance and operation of water systems, and scheduled controls on water samples collected from significant environmental sources. This paper describes the results of a five-year monitoring programme applied to the water-distribution system of the University Hospital of Pisa (Italy) to evaluate the efficacy of an integrated water safety plan in controlling Legionella spp. colonization of the potable water system. Moreover, the impact of the safety plan on the ecology of Legionella in the water network was evaluated by studying the genetic variability of the strains isolated prior to and throughout the application of continuous chlorine-dioxide treatment. After 45 months of water hyperchlorination, Legionella spp. was still present but the positive supply points were reduced by 53%, the samples exceeding 103 CFU/L were cut down by 44% and the mean counts showed a decrease of 95%. The majority of the isolates belonged to Legionella pneumophila serogroup 1 (160/161: 99%). Molecular typing, carried out on 63 isolates (39% of the positive samples) selected on space and temporal criteria, indicated the circulation and the persistence in the hospital environment of three prevalent clones of L. pneumophila Wadsworth. Two clones were predominant and pre-existing sanitation, the other was isolated only after three years of water treatment. Despite the ineffectiveness of chlorine dioxide in eradicating L. pneumophila, the risk management plan adopted was effective in preventing any further case of nosocomial legionellosis.
Applicazione di un piano integrato di gestione del rischio idrico da Legionella in un’Azienda Ospedaliera Universitaria e verifica dell’efficacia a lungo termine delle misure di controllo
CASINI, BEATRICE;BAGGIANI, ANGELO;PRIVITERA, GAETANO PIERPAOLO
2007-01-01
Abstract
The WHO Guideline for Legionella and the Prevention of Legionellosis advocate that a water safety plan has to be established in the health care settings for the water risk management. Elements of the risk management plan are active surveillance for infections caused by waterborne pathogens, standard operating procedures for sanitization, maintenance and operation of water systems, and scheduled controls on water samples collected from significant environmental sources. This paper describes the results of a five-year monitoring programme applied to the water-distribution system of the University Hospital of Pisa (Italy) to evaluate the efficacy of an integrated water safety plan in controlling Legionella spp. colonization of the potable water system. Moreover, the impact of the safety plan on the ecology of Legionella in the water network was evaluated by studying the genetic variability of the strains isolated prior to and throughout the application of continuous chlorine-dioxide treatment. After 45 months of water hyperchlorination, Legionella spp. was still present but the positive supply points were reduced by 53%, the samples exceeding 103 CFU/L were cut down by 44% and the mean counts showed a decrease of 95%. The majority of the isolates belonged to Legionella pneumophila serogroup 1 (160/161: 99%). Molecular typing, carried out on 63 isolates (39% of the positive samples) selected on space and temporal criteria, indicated the circulation and the persistence in the hospital environment of three prevalent clones of L. pneumophila Wadsworth. Two clones were predominant and pre-existing sanitation, the other was isolated only after three years of water treatment. Despite the ineffectiveness of chlorine dioxide in eradicating L. pneumophila, the risk management plan adopted was effective in preventing any further case of nosocomial legionellosis.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
