title: Evaluation of a new monochloramine generation system for controlling Legionella in building hot water systems.
abstract: OBJECTIVE
  To evaluate the efficacy of a new monochloramine generation system for control of Legionella in a hospital hot water distribution system.
  
  
  METHODS
  A 495-bed tertiary care hospital in Pittsburgh, Pennsylvania. The hospital has 12 floors covering approximately 78,000 m(2).
  
  
  METHODS
  The hospital hot water system was monitored for a total of 29 months, including a 5-month baseline sampling period prior to installation of the monochloramine system and 24 months of surveillance after system installation (postdisinfection period). Water samples were collected for microbiological analysis (Legionella species, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Acinetobacter species, nitrifying bacteria, heterotrophic plate count [HPC] bacteria, and nontuberculous mycobacteria). Chemical parameters monitored during the investigation included monochloramine, chlorine (free and total), nitrate, nitrite, total ammonia, copper, silver, lead, and pH.
  
  
  RESULTS
  A significant reduction in Legionella distal site positivity was observed between the pre- and postdisinfection periods, with positivity decreasing from an average of 53% (baseline) to an average of 9% after monochloramine application (P<0.5]). Although geometric mean HPC concentrations decreased by approximately 2 log colony-forming units per milliliter during monochloramine treatment, we did not observe significant changes in other microbial populations.
  
  
  CONCLUSIONS
  This is the first evaluation in the United States of a commercially available monochloramine system installed on a hospital hot water system for Legionella disinfection, and it demonstrated a significant reduction in Legionella colonization. Significant increases in microbial populations or other negative effects previously associated with monochloramine use in large municipal cold water systems were not observed.
authors.affiliation: Special Pathogens Laboratory, Pittsburgh, Pennsylvania.
authors.forename: Scott
authors.initials: S
authors.lastname: Duda
authors.forename: Sheena
authors.initials: S
authors.lastname: Kandiah
authors.forename: Janet E
authors.initials: JE
authors.lastname: Stout
authors.forename: Julianne L
authors.initials: JL
authors.lastname: Baron
authors.forename: Mohamed
authors.initials: M
authors.lastname: Yassin
authors.forename: Marie
authors.initials: M
authors.lastname: Fabrizio
authors.forename: Juliet
authors.initials: J
authors.lastname: Ferrelli
authors.forename: Rahman
authors.initials: R
authors.lastname: Hariri
authors.forename: Marilyn M
authors.initials: MM
authors.lastname: Wagener
authors.forename: John
authors.initials: J
authors.lastname: Goepfert
authors.forename: James
authors.initials: J
authors.lastname: Bond
authors.forename: Joseph
authors.initials: J
authors.lastname: Hannigan
authors.forename: Denzil
authors.initials: D
authors.lastname: Rogers
mesh_terms: D000150:Acinetobacter / Q000187:drug effects / Q000254:growth & development; D002700:Chloramines / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods*; D006358:Hot Temperature; D006801:Humans; D007875:Legionella / Q000187:drug effects* / Q000254:growth & development; D007877:Legionnaires' Disease / Q000517:prevention & control; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development; D020615:Stenotrophomonas maltophilia / Q000187:drug effects / Q000254:growth & development; D062606:Tertiary Care Centers; D014867:Water / Q000737:chemistry; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*
chemical_list: D002700:Chloramines; D004202:Disinfectants; D014867:Water; C030816:chloramine