title: Heterogeneity in chlorine susceptibility for Legionella pneumophila released from Acanthamoeba and Hartmannella.
abstract: OBJECTIVE
  To assess chlorine susceptibility of Legionella pneumophila grown from two amoebic hosts, Acanthamoeba castellanii and Hartmannella vermiformis.
  
  
  RESULTS
  After being released from amoebae, Leg. pneumophila were chlorinated at 2 and 5 mg l(-1) for 5 min-24 h. Bacterial culturability and cytoplasmic membrane deterioration were quantified by culture assay on BCYEalpha agar and BacLight stains coupled with a fluorescent microscope, respectively. Chlorination reduced the culturability of Leg. pneumophila by 2.93-4.59 log CFU ml(-1) and damaged cellular membrane by 53.8-99.2%. Moreover, cells released from H. vermiformis exhibited significantly lower degrees in culturability reduction (P = 0.0008) and membrane deterioration (P < 0.0001) when compared with those from A. castellanii. The amoebic genus is the most significant parameter affecting cytoplasmic membrane integrity of chlorinated Legionella (P < 0.0001), followed by free chlorine concentration (P = 0.042).
  
  
  CONCLUSIONS
  Legionella pneumophila replicated from H. vermiformis possess greater chlorine resistance than the cells from A. castellanii.
  
  
  CONCLUSIONS
  This study shows the heterogeneity of amoebae-grown Leg. pneumophila in chlorine susceptibility, which should be considered in the control of legionellae proliferation, particularly in the systems where H. vermiformis is dominant, e.g. hot water plumbing.
authors.affiliation: Institute of Environmental Health, College of Public Health, National Taiwan University, Taipei, Taiwan, Republic of China. chingwenchang@ntu.edu.tw
authors.forename: C-W
authors.initials: CW
authors.lastname: Chang
authors.forename: C-H
authors.initials: CH
authors.lastname: Kao
authors.forename: Y-F
authors.initials: YF
authors.lastname: Liu
mesh_terms: D000048:Acanthamoeba / Q000382:microbiology*; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects; D002713:Chlorine / Q000032:analysis / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004202:Disinfectants / Q000494:pharmacology*; D006249:Hartmannella / Q000382:microbiology*; D016952:Legionella pneumophila / Q000187:drug effects* / Q000254:growth & development
chemical_list: D004202:Disinfectants; D002713:Chlorine