title: Bactericidal effect of chlorine on Mycobacterium paratuberculosis in drinking water.
abstract: OBJECTIVE
  One possible route of transmission of Mycobacterium paratuberculosis from cattle to humans is via contaminated water supplies. The aim of this work was to determine whether this organism can survive standard water treatment processes.
  
  
  RESULTS
  Two strains of M. paratuberculosis (bovine strain, NCTC 8578 and human strain Linda, ATCC 43015) were subjected to various chlorine concentrations (0.5, 1.0 and 2.0 microg ml(-1)) for 15 and 30 min. Chlorine test solutions were made up in two types of water, sterile water that had been deionized and subjected to reverse osmosis (DRO) and DRO water containing MgCl(2), CaCl(2), NaHCO(3) and bovine serum albumin (0.3% w/v), the latter to mimic conditions the organism would experience in commercial water treatment operations.
  
  
  CONCLUSIONS
  The data showed that when initial inoculum levels were high (10(6) cfu ml(-1)) neither M. paratuberculosis strain was completely killed at the free chlorine concentrations and contact times applied. Log10 reductions in the range 1.32-2.82 were observed. The greatest log(10) reduction in cell numbers (2.82 and 2.35 for the bovine and human strains, respectively) was observed at the highest chlorine concentration (2 microg ml(-1)) and longest contact time (30 min).
  
  
  CONCLUSIONS
  This work highlights the need for further research into the survival of M. paratuberculosis during water treatment.
authors.affiliation: Department of Food Science (Food Microbiology), Queen's University Belfast, Newforge Lane, Belfast BT9 5PX, Northern Ireland, UK.
authors.forename: L B
authors.initials: LB
authors.lastname: Whan
authors.forename: I R
authors.initials: IR
authors.lastname: Grant
authors.forename: H J
authors.initials: HJ
authors.lastname: Ball
authors.forename: R
authors.initials: R
authors.lastname: Scott
authors.forename: M T
authors.initials: MT
authors.lastname: Rowe
mesh_terms: D002713:Chlorine / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004305:Dose-Response Relationship, Drug; D016927:Mycobacterium avium subsp. paratuberculosis / Q000187:drug effects* / Q000254:growth & development; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D013997:Time Factors; D014871:Water Microbiology; D014881:Water Supply
chemical_list: D012710:Serum Albumin, Bovine; D002713:Chlorine