Austrian study finds zoonotic Escherichia coli strains dominate pet urinary infections but remain largely susceptible to antibiotics

Research from Austria reveals that urinary tract infections in cats and dogs are primarily caused by familiar zoonotic E. coli strains, most still susceptible to antibiotics, underscoring the importance of integrated surveillance.

A new Austrian study suggests that urinary tract infections in cats and dogs remain dominated by a familiar and potentially zoonotic strain of Escherichia coli, but that most isolates are still susceptible to standard antibiotics.

Researchers examining 51 haemolytic E. coli isolates from routine diagnostic samples between 2017 and 2023 found that 50 belonged to phylogenetic group B2, a lineage long associated with extraintestinal pathogenic E. coli. All isolates carried the fimH adhesin and hlyA haemolysin genes, and nearly all also carried cnf1, reinforcing their classification as ExPEC. The team identified 34 clonal types, indicating substantial diversity, although one lineage, CH103-9, was the most common.

Resistance was uncommon. Forty-five isolates were susceptible to every drug tested, while four were multidrug-resistant. One isolate stood out: an ESBL-producing B2-O25b-ST131 strain, carrying blaCTX-M-15 and showing ciprofloxacin resistance, a profile more often linked with high-risk human infections.

The findings echo earlier work from Europe and South America showing that B2 UPEC strains dominate companion animal urinary infections. The authors say the overlap with human-associated clones underlines the need for One Health surveillance in pets, even where resistance remains relatively rare.

References: Büttner, S., J. Spergser, O. Makarova, et al. 2026. “ Characterisation of Haemolytic Uropathogenic Escherichia coli Isolated From Dogs and Cats.” Veterinary Medicine and Science 12, no. 5: e71200. https://doi.org/10.1002/vms3.71200