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

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