title: A 17-month evaluation of a chlorine dioxide water treatment system to control Legionella species in a hospital water supply.
abstract: OBJECTIVE
  To assess the safety and efficacy of a chlorine dioxide water treatment system in controlling Legionella in a hospital water supply.
  
  
  METHODS
  For 17 months following installation of the system, we performed regular water cultures throughout the building, assessed chlorine dioxide and chlorite levels, and monitored metal corrosion.
  
  
  RESULTS
  Sites that grew Legionella species decreased from 41% at baseline to 4% (P = .001). L. anisa was the only species recovered and it was found in samples of both hot and cold water. Levels of chlorine dioxide and chlorite were below Environmental Protection Agency (EPA) limits for these chemicals in potable water. Further, enhanced carbon filtration effectively removed the chemicals, even at chlorine dioxide levels of more than twice what was used to treat the water. After 9 months, corrosion of copper test strips exposed to the chlorine dioxide was not higher than that of control strips. During the evaluation period, there were no cases of nosocomial Legionella in the building with the system, whereas there was one case in another building.
  
  
  CONCLUSIONS
  Our results indicate that operation of a chlorine dioxide system effectively removed Legionella species from a hospital water supply. Furthermore, we found that the system was safe, as levels of chlorine dioxide and chlorite were below EPA limits. The system did not appear to cause increased corrosion of copper pipes. Our results indicate that chlorine dioxide may hold promise as a solution to the problem of Legionella contamination of hospital water supplies.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Hospital Epidemiology and Infection Control, Johns Hopkins Medical Institutions, Baltimore, Maryland, 21287, USA.
authors.forename: Arjun
authors.initials: A
authors.lastname: Srinivasan
authors.forename: Gregory
authors.initials: G
authors.lastname: Bova
authors.forename: Tracy
authors.initials: T
authors.lastname: Ross
authors.forename: Karen
authors.initials: K
authors.lastname: Mackie
authors.forename: Nicholas
authors.initials: N
authors.lastname: Paquette
authors.forename: William
authors.initials: W
authors.lastname: Merz
authors.forename: Trish M
authors.initials: TM
authors.lastname: Perl
mesh_terms: D000046:Academic Medical Centers; D015142:Baltimore / Q000453:epidemiology; D018893:Bronchoalveolar Lavage; D017606:Chlorine Compounds / Q000032:analysis / Q000592:standards; D003343:Corrosion; D003428:Cross Infection / Q000382:microbiology / Q000517:prevention & control* / Q000635:transmission; D004203:Disinfection / Q000379:methods* / Q000592:standards; D006801:Humans; D016952:Legionella pneumophila / Q000302:isolation & purification / Q000472:pathogenicity; D007877:Legionnaires' Disease / Q000175:diagnosis / Q000517:prevention & control* / Q000635:transmission; D008284:Maintenance and Engineering, Hospital / Q000379:methods*; D010087:Oxides / Q000032:analysis / Q000592:standards; D018571:Sentinel Surveillance; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods* / Q000592:standards; D014881:Water Supply / Q000032:analysis
chemical_list: D017606:Chlorine Compounds; D010087:Oxides; C025109:chlorine dioxide