title: Biocidal efficacy of monochloramine against planktonic and biofilm-associated Naegleria fowleri cells.
abstract: OBJECTIVE
  Free-living amoebae (FLA) in aqueous systems are a problem for water network managers and health authorities because some are pathogenic, such as Naegleria fowleri, and they have also been reported to operate as reservoirs and vectors of several pathogenic bacteria. Therefore, to better control the occurrence of such amoebae, we evaluate the efficacy of monochloramine against planktonic forms (trophozoites and cysts) and also biofilm-associated cells of N. fowleri as FLA are often associated with biofilms.
  
  
  RESULTS
  From a freshwater biofilm growing in a pilot reactor and inoculated with N. fowleri, we obtained Ct values ranging from 4 to 17 mg Cl2 min l(-1) at 25°C and pH 8·2 on both planktonic and biofilm associated cells. In addition, the inactivation pattern of biofilm associated was intermediate between those of trophozoïtes and cysts.
  
  
  CONCLUSIONS
  The monochloramine efficiency varies with the life stage of N. fowleri (trophozoïte, cyst, and biofilm-associated). The sensitivity to disinfectant of amoeba, that is, trophozoïtes and cysts, in the biofilm life stage is as high as that of their planktonic cyst form.
  
  
  CONCLUSIONS
  This study gives Ct values for cysts and biofilm-associated N. fowleri. This may impact on water treatment strategies against amoebae and should be considered when controlling N. fowleri in man-made water systems such as cooling towers or hot water systems.
authors.affiliation: EDF Recherche et Développement, Laboratoire National d'Hydraulique et Environnement, Chatou Cedex, France; Université de Lorraine, LCPME, UMR 7564 CNRS - UL, Institut Jean Barriol, Villers-lès-Nancy, France; CNRS, LCPME, UMR 7564 CNRS - UL, Villers-lès-Nancy, France.
authors.forename: S
authors.initials: S
authors.lastname: Goudot
authors.forename: P
authors.initials: P
authors.lastname: Herbelin
authors.forename: L
authors.initials: L
authors.lastname: Mathieu
authors.forename: S
authors.initials: S
authors.lastname: Soreau
authors.forename: S
authors.initials: S
authors.lastname: Banas
authors.forename: F P A
authors.initials: FP
authors.lastname: Jorand
mesh_terms: D018441:Biofilms / Q000187:drug effects*; D002700:Chloramines / Q000494:pharmacology*; D004202:Disinfectants / Q000494:pharmacology*; D005618:Fresh Water / Q000469:parasitology; D016848:Naegleria fowleri / Q000187:drug effects* / Q000254:growth & development; D010933:Plankton / Q000187:drug effects*; D053058:Trophozoites / Q000187:drug effects
chemical_list: D002700:Chloramines; D004202:Disinfectants; C030816:chloramine
keywords: Ct value; Free-living amoeba; Naegleria fowleri; freshwater biofilm; monochloramine