title: Occurrence and characteristics of extended-spectrum-β-lactamase- and AmpC-producing clinical isolates derived from companion animals and horses.
abstract: OBJECTIVE
  To investigate the occurrence and characteristics of extended-spectrum β-lactamase (ESBL)- and AmpC-producing Enterobacteriaceae isolates in clinical samples of companion animals and horses and compare the results with ESBL/AmpC-producing isolates described in humans.
  
  
  METHODS
  Between October 2007 and August 2009, 2700 Enterobacteriaceae derived from clinical infections in companion animals and horses were collected. Isolates displaying inhibition zones of ≤ 25 mm for ceftiofur and/or cefquinome by disc diffusion were included. ESBL/AmpC production was confirmed by combination disc tests. The presence of resistance genes was identified by microarray, PCR and sequencing, Escherichia coli genotypes by multilocus sequence typing and antimicrobial susceptibility by broth microdilution.
  
  
  RESULTS
  Sixty-five isolates from dogs (n = 38), cats (n = 14), horses (n = 12) and a turtle were included. Six Enterobacteriaceae species were observed, mostly derived from urinary tract infections (n = 32). All except 10 isolates tested resistant to cefotaxime and ceftazidime by broth microdilution using clinical breakpoints. ESBL/AmpC genes observed were bla(CTX-M-1, -2, -9, -14, -15,) bla(TEM-52), bla(CMY-2) and bla(CMY-)(39). bla(CTX-M-1) was predominant (n = 17). bla(CTX-M-9) occurred in combination with qnrA1 in 3 of the 11 Enterobacter cloacae isolates. Twenty-eight different E. coli sequence types (STs) were found. E. coli carrying bla(CTX-M-1) belonged to 13 STs of which 3 were previously described in Dutch poultry and patients.
  
  
  CONCLUSIONS
  This is the first study among a large collection of Dutch companion animals and horses characterizing ESBL/AmpC-producing isolates. A similarity in resistance genes and E. coli STs among these isolates and isolates from Dutch poultry and humans may suggest exchange of resistance between different reservoirs.
authors.affiliation: Department of Bacteriology and TSEs, Central Veterinary Institute of Wageningen UR, PO Box 65, 8200 AB Lelystad, The Netherlands. cindy.dierikx@wur.nl
authors.forename: C M
authors.initials: CM
authors.lastname: Dierikx
authors.forename: E
authors.initials: E
authors.lastname: van Duijkeren
authors.forename: A H W
authors.initials: AH
authors.lastname: Schoormans
authors.forename: A
authors.initials: A
authors.lastname: van Essen-Zandbergen
authors.forename: K
authors.initials: K
authors.lastname: Veldman
authors.forename: A
authors.initials: A
authors.lastname: Kant
authors.forename: X W
authors.initials: XW
authors.lastname: Huijsdens
authors.forename: K
authors.initials: K
authors.lastname: van der Zwaluw
authors.forename: J A
authors.initials: JA
authors.lastname: Wagenaar
authors.forename: D J
authors.initials: DJ
authors.lastname: Mevius
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000382:microbiology*; D002415:Cats; D016000:Cluster Analysis; D004283:Dog Diseases / Q000382:microbiology*; D004285:Dogs; D004755:Enterobacteriaceae / Q000201:enzymology* / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000382:microbiology / Q000662:veterinary*; D005838:Genotype; D006734:Horse Diseases / Q000382:microbiology*; D006736:Horses; D046228:Microarray Analysis; D008826:Microbial Sensitivity Tests / Q000379:methods; D058885:Multilocus Sequence Typing; D009426:Netherlands; D057805:Pets; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014552:Urinary Tract Infections / Q000382:microbiology / Q000662:veterinary*; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D001618:beta-Lactamases