title: Long-term effects of hospital water network disinfection on Legionella and other waterborne bacteria in an Italian university hospital.
abstract: OBJECTIVE
  Legionella control still remains a critical issue in healthcare settings where the preferred approach to health risk assessment and management is to develop a water safety plan. We report the experience of a university hospital, where a water safety plan has been applied since 2002, and the results obtained with the application of different methods for disinfecting hot water distribution systems in order to provide guidance for the management of water risk.
  
  
  METHODS
  The disinfection procedures included continuous chlorination with chlorine dioxide (0.4-0.6 mg/L in recirculation loops) reinforced by endpoint filtration in critical areas and a water treatment based on monochloramine (2-3 mg/L). Real-time polymerase chain reaction and a new immunoseparation and adenosine triphosphate bioluminescence analysis were applied in environmental monitoring.
  
  
  RESULTS
  After 9 years, the integrated disinfection-filtration strategy significantly reduced positive sites by 55% and the mean count by 78% (P < .05); however, the high costs and the occurrence of a chlorine-tolerant clone belonging to Legionella pneumophila ST269 prompted us to test a new disinfectant. The shift to monochloramine allowed us to eliminate planktonic Legionella and did not require additional endpoint filtration; however, nontuberculous mycobacteria were isolated more frequently as long as the monochloramine concentration was 2 mg/L; their cultivability was never regained by increasing the concentration up to 3 mg/L.
  
  
  CONCLUSIONS
  Any disinfection method needs to be adjusted/fine-tuned in individual hospitals in order to maintain satisfactory results over time, and only a locally adapted evidence-based approach allows assessment of the efficacy and disadvantages of the control measures.
authors: Department of Translational Research, New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy.
authors: Beatrice
authors: B
authors: Casini
authors: Andrea
authors: A
authors: Buzzigoli
authors: Maria Luisa
authors: ML
authors: Cristina
authors: Anna Maria
authors: AM
authors: Spagnolo
authors: Pietro
authors: P
authors: Del Giudice
authors: Silvio
authors: S
authors: Brusaferro
authors: Andrea
authors: A
authors: Poscia
authors: Umberto
authors: U
authors: Moscato
authors: Paola
authors: P
authors: Valentini
authors: Angelo
authors: A
authors: Baggiani
authors: Gaetano
authors: G
authors: Privitera
mesh_terms: D003428:Cross Infection / Q000517:prevention & control*; D004203:Disinfection / Q000379:methods / Q000592:standards; D004784:Environmental Monitoring; D006785:Hospitals, University / Q000592:standards; D006801:Humans; D007558:Italy / Q000453:epidemiology; D007875:Legionella; D007876:Legionellosis / Q000517:prevention & control*; D015397:Program Evaluation; D014871:Water Microbiology / Q000592:standards; D014881:Water Supply / Q000592:standards*