Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2014

Fluoroquinolone-Resistant Extraintestinal Pathogenic Escherichia coli (ExPEC) from Australian Canines: A Reservoir of Human-Associated Clonal Lineages  (#26)

David Wakeham 1 2 , Si Yu Guo 2 3 , Huub J M Brouwers 3 , Rowland N Cobbold 2 , Sam Abraham 1 , Joanne L Platell 4 , James R Johnson 5 , Toni A Chapman 3 , David M Gordon 6 , Vanessa R Barrs 7 , Darren J Trott 1
  1. School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy, SA, Australia
  2. School of Veterinary Science, University of Queensland, Gatton, QLD, Australia
  3. Elizabeth Macarthur Agricultural Institute, Menangle, NSW, Australia
  4. Biosecurity Sciences Laboratory, Department of Agriculture and Fisheries, Brisbane, QLD, Australia
  5. VA Medical Centre, Minneapolis, MN, U.S.A
  6. School of Biology, The Australian National University, Acton, ACT, Australia
  7. University Veterinary Teaching Hospital Faculty of Veterinary Science, The University of Sydney, Camperdown, NSW, Australia

Fluoroquinolone-resistant extraintestinal pathogenic Escherichia coli (FQ-R ExPEC) assigned previously to phylogenetic group D were recently isolated from Australian dogs. This study aimed to better define the role of canine faeces as a reservoir of ExPEC clonal lineages of public health significance and their potential as canine pathogens. Sixty-seven fluoroquinolone-resistant E. coli isolates obtained from either the faeces of hospitalised dogs (n = 28) or canine extraintestinal infections (n = 39) were characterised and compared. Phylogenetic group was reassigned using the new Clermont multiplex PCR method and isolates underwent random amplified polymorphic DNA (RAPD) analysis, virulence genotyping, resistance phenotyping/genotyping, screening for human-associated ExPEC O-types, and multi-locus sequence typing. Canine faeces were identified to contain several sequence types (STs) also associated with clinical extraintestinal infections. These included ST354 (phylogroup F; 62.7%; 26 clinical, 16 faecal), ST420 (phylogroup B2, 1.5% 1 clinical); O1-ST38 (phylogroup D; 19.4%; 4 clinical, 9 faecal), O15:K52:H1-ST393 (phylogroup D; 4.5%; 1 clinical, 2 faecal), and O15:K1-ST130 (phylogroup D; 1.5%, 1 clinical isolate), O7-ST457 (phylogroup F; 3.0%; 1 clinical, 1 faecal) and O1-ST648 (phylogroup F; 3.0%; 2 clinical). RAPD profile-based analysis indicated three major clusters and 11 sub-clusters, whilst most ST-specific sub-clusters contained only faecal or clinical isolates, three (corresponding with ST354, ST393, and ST457) contained closely related, intermingled isolates from each source. All faecal isolates and 97% of clinical isolates exhibited a multidrug-resistant phenotype (MDR: resistant ≥ 3 antimicrobial classes) suggesting fluoroquinolone resistance as an indicator of MDR status. Median resistance scores did not differ significantly by source (median 4: P > 0.10). Genes encoding CTX-M and AmpC β-lactamases were identified in isolates from five of the seven STs.  Overall, canine faeces are a large, previously overlooked reservoir of FQ-R-ExPEC clonal lineages, suggesting frequent zooanthroponotic transmission of FQ-R ExPEC between humans and dogs, possibly within both veterinary hospital and household environments.