Fluoroquinolone-resistant extraintestinal pathogenic Escherichia coli, including O25b-ST131, isolated from faeces of hospitalized dogs in an Australian veterinary referral centre.

Objective: To determine rates of carriage of fluoroquinolone-resistant Escherichia coli and extraintestinal pathogenic E. coli (ExPEC) among dogs in a specialist referral hospital and to examine the population structure of the isolates.

Methods: Fluoroquinolone-resistant faecal E. coli isolates (n = 232, from 23 of 123 dogs) recovered from hospitalized dogs in a veterinary referral centre in Sydney, Australia, over 140 days in 2009 were characterized by phylogenetic grouping, virulence genotyping and random amplified polymorphic DNA (RAPD) analysis.

Results: The RAPD dendrogram for representative isolates showed one group B2-associated cluster and three group D-associated clusters; each contained isolates with closely related ExPEC-associated virulence profiles. All group B2 faecal isolates represented the O25b-ST131 clonal group and were closely related to recent canine extraintestinal ST131 clinical isolates from the east coast of Australia by RAPD analysis.

Conclusions: Hospitalized dogs may carry fluoroquinolone-resistant ExPEC in their faeces, including those representing O25b-ST131.