title: Presence of CTX gene cluster in environmental non-O1/O139 Vibrio cholerae and its potential clinical significance.
abstract: OBJECTIVE
  The aim of this study was to understand the epidemiological linkage of clinical and environmental isolates of Vibrio cholerae and to determine their genotypes and virulence genes content.
  
  
  METHODS
  A total of 60 V. cholerae strains obtained from clinical specimens (n = 40) and surface waters (n = 20) were subjected to genotyping using PFGE and determination of their virulence-associated gene clusters.
  
  
  RESULTS
  PCR analysis showed the presence of chromosomally located hly and RTX genetic elements in 100% and 90% of the environmental isolates, respectively. The phage-mediated genetic elements such as CTX, TLC and VPI were detected in 5% of the environmental isolates suggesting that the environmental isolates cannot acquire certain mobile gene clusters. A total of 4 and 18 pulsotypes were obtained among the clinical and environmental V. cholerae isolates, respectively. Non-pathogenic environmentally isolated V. cholerae constituted a distinct cluster with one single non-O1, non-O139 strain (EP6) carrying the virulence genes similar to the epidemic strains. This may suggest the possible potential of conversion of non-pathogenic to a pathogenic environmental strain.
  
  
  CONCLUSIONS
  The emergence of a single environmental isolate in our study containing the pathogenicity genes amongst the diverse non-pathogenic environmental isolates needs to be further studied in the context of V. cholerae pathogenicity sero-coversion.
authors.affiliation: Department of Bacteriology, Pasteur Institute of Iran, Tehran, Iran.
authors.forename: B
authors.initials: B
authors.lastname: Bakhshi
authors.forename: H
authors.initials: H
authors.lastname: Mohammadi-Barzelighi
authors.forename: A
authors.initials: A
authors.lastname: Sharifnia
authors.forename: A
authors.initials: A
authors.lastname: Dashtbani-Roozbehani
authors.forename: M
authors.initials: M
authors.lastname: Rahbar
authors.forename: M R
authors.initials: MR
authors.lastname: Pourshafie
mesh_terms: D002771:Cholera / Q000382:microbiology*; D002772:Cholera Toxin / Q000235:genetics*; D004783:Environmental Microbiology; D006801:Humans; D005810:Multigene Family; D016133:Polymerase Chain Reaction; D014734:Vibrio cholerae / Q000235:genetics* / Q000302:isolation & purification; D037521:Virulence Factors / Q000235:genetics
chemical_list: D037521:Virulence Factors; D002772:Cholera Toxin