title: Characterisation of extended-spectrum β-lactamase and AmpC β-lactamase-producing Enterobacteriaceae isolated from companion animals in New Zealand.
abstract: OBJECTIVE
  To assess the occurrence of, and characterise, extended-spectrum β-lactamase (ESBL) and AmpC β-lactamase (AmpC)-producing Enterobacteriaceae isolated by veterinary diagnostic laboratories from infection sites in companion animals in New Zealand.
  
  
  METHODS
  Selected Enterobacteriaceae isolates were submitted by seven New Zealand veterinary diagnostic laboratories. They were isolated from infection sites in companion animals between June 2012 and June 2013, and were resistant to amoxicillin-clavulanic acid, fluoroquinolones, or any combination of two or more antimicrobials. Based on disk diffusion test results, the isolates were phenotypically categorised according to production of ESBL and AmpC. Genes for ESBL and AmpC production were amplified by PCR and sequenced. Escherichia coli isolates were also typed by multilocus sequence typing.
  
  
  RESULTS
  A total of 115 isolates matching the inclusion criteria were obtained from the participating laboratories, of which 74 (64%) originated from dogs and 29 (25%) from cats. Seven bacterial species were identified, of which E. coli was the most common (87/115, 76%). Of the 115 isolates, 10 (9%) expressed the ESBL phenotype, 43 (37%) the AmpC phenotype, and seven (6%) both ESBL and AmpC phenotypes. Of the 60 ESBL and AmpC-producing isolates, 36 (60%) were E. coli. Amongst these isolates, 27/60 (45%) were classified as multidrug resistant, compared with 15/55 (27%) non-ESBL or AmpC-producing isolates (p<0.01). Ninety five isolates were resistant to amoxicillin-clavulanic acid and 58 (61%) of these were ESBL or AmpC-producing. The predominant ESBL genes were blaCTX-M-14and blaCTX-M-15, and the dominant plasmid-encoded AmpC gene was blaCMY-2. Thirty-eight E. coli multilocus sequence types (ST) were identified, and the most prevalent were ST12 (12/89, 13%), ST131 (6/89, 7%) and ST648 (6/89, 7%). ESBL and AmpC-producing isolates accounted for 35/1,082 (3.2%) of the Enterobacteriaceae isolated by one laboratory network over the study period.
  
  
  CONCLUSIONS
  ESBL and AmpC-producing Enterobacteriaceae were associated with clinical infections in companion animals in New Zealand, and were often multidrug resistant. In this study, these organisms accounted for <5% of all Enterobacteriaceae isolated from infection sites by one laboratory network, but their prevalence among isolates resistant to amoxicillin-clavulanic acid was 61%. Therefore routine secondary testing for ESBL and AmpC production by Enterobacteriaceae that are resistant to amoxicillin-clavulanic acid in primary testing could improve the accuracy of definitive antimicrobial therapy in companion animals in New Zealand.
authors.affiliation: a Institute of Veterinary Animal and Biomedical Sciences , Massey University , Private Bag 11222, Palmerston North 4442 , New Zealand.
authors.forename: A
authors.initials: A
authors.lastname: Karkaba
authors.affiliation: a Institute of Veterinary Animal and Biomedical Sciences , Massey University , Private Bag 11222, Palmerston North 4442 , New Zealand.
authors.forename: A
authors.initials: A
authors.lastname: Grinberg
authors.affiliation: a Institute of Veterinary Animal and Biomedical Sciences , Massey University , Private Bag 11222, Palmerston North 4442 , New Zealand.
authors.forename: J
authors.initials: J
authors.lastname: Benschop
authors.affiliation: b mEpiLab, Hopkirk Research Institute, Institute of Veterinary Animal and Biomedical Sciences , Massey University , Palmerston North 4442 , New Zealand.
authors.forename: E
authors.initials: E
authors.lastname: Pleydell
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000453:epidemiology / Q000382:microbiology*; D002415:Cats; D004283:Dog Diseases / Q000453:epidemiology / Q000382:microbiology*; D004285:Dogs; D024901:Drug Resistance, Multiple, Bacterial; D004755:Enterobacteriaceae / Q000145:classification / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D009520:New Zealand / Q000453:epidemiology; D057805:Pets; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D001618:beta-Lactamases
keywords: AmpC; Antimicrobial resistance; ESBL; Enterobacteriaceae; Escherichia coli; MLST; multidrug resistance