title: Detection and characterization of pCT-like plasmid vectors for blaCTX-M-14 in Escherichia coli isolates from humans, turkeys and cattle in England and Wales.
abstract: OBJECTIVE
  To detect and characterize Escherichia coli strains and pCT-like plasmids implicated in the dissemination of the CTX-M-14 gene in animals and humans, in England and Wales.
  
  
  METHODS
  UK CTX-M-14-producing E. coli (n=70) from cattle (n=33), turkeys (n=9), sheep (n=2) and humans (n=26) were screened using multiplex PCR for the detection of a previously characterized plasmid, pCT. Isolates found to be carrying two or more pCT genetic markers were further analysed using PFGE. Their antimicrobial-resistance genes and virulence genes were also determined. These plasmids were transferred to Salmonella enterica serotype Typhimurium 26R and further examined for incompatibility type, genetic environment of the bla(CTX-M-14) gene, size, restriction fragment length polymorphism (RFLP) and nikB sequence.
  
  
  RESULTS
  The 25 E. coli isolates carrying pCT genetic markers generated 19 different PFGE profiles, and 23 isolates had different virulence and antimicrobial-resistance gene patterns. One isolate from cattle was a verotoxigenic E. coli ('VTEC'); the rest were commensal or extra-intestinal pathogenic E. coli. pCT-like plasmids with similar molecular characteristics (size, replicon type, RFLP pattern, pCT markers and genetic environment of the bla(CTX-M-14) gene) were detected in 21/25 of the field isolates, which comprised those from cattle (n=9), turkeys (n=8) and humans (n=4). All pCT-like plasmids were conjugative, and most were IncK (n=21) and had the same local genetic environment flanking the bla(CTX-M-14) gene (n=23). RFLP analysis demonstrated ≥ 75% similarity among most plasmids (n=22).
  
  
  CONCLUSIONS
  pCT-like plasmids were common vectors for horizontal dissemination of 30% of the bla(CTX-M-14) genes to different E. coli isolates from humans, cattle and turkeys.
authors.affiliation: Department of Bacteriology, Animal Health and Veterinary Laboratories Agency, Addlestone, UK. m.stokes@vla.defra.gsi.gov.uk
authors.forename: M O
authors.initials: MO
authors.lastname: Stokes
authors.forename: J L
authors.initials: JL
authors.lastname: Cottell
authors.forename: L J V
authors.initials: LJ
authors.lastname: Piddock
authors.forename: G
authors.initials: G
authors.lastname: Wu
authors.forename: M
authors.initials: M
authors.lastname: Wootton
authors.forename: D J
authors.initials: DJ
authors.lastname: Mevius
authors.forename: L P
authors.initials: LP
authors.lastname: Randall
authors.forename: C J
authors.initials: CJ
authors.lastname: Teale
authors.forename: M D
authors.initials: MD
authors.lastname: Fielder
authors.forename: N G
authors.initials: NG
authors.lastname: Coldham
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004739:England; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology* / Q000662:veterinary*; D006801:Humans; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011201:Poultry Diseases / Q000382:microbiology*; D014422:Turkeys; D006113:United Kingdom; D037521:Virulence Factors / Q000235:genetics; D014852:Wales; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial; D037521:Virulence Factors; C456080:beta-lactamase CTX-M-14; D001618:beta-Lactamases