Frequency and antimicrobial susceptibility profiles of bacterial species isolated from canine and feline urine samples in Sydney, Australia, 2012-2021.

Bacterial urinary tract infections are frequently diagnosed in veterinary practice and often treated empirically. Recommended treatment differs for sporadic versus recurrent infections. Antimicrobial selection is ideally informed by local antibiograms; however, this data is currently unavailable for dogs and cats in Sydney, Australia's largest city by population. The objectives of this retrospective study were to: i) identify the proportions of bacterial species in positive cultures from canine and feline urine samples submitted between 2012 and 2021 to a veterinary diagnostic laboratory in Sydney, Australia, ii) describe and compare antimicrobial susceptibility profiles between isolates from sporadic and recurrent positive cultures and iii) develop local antibiograms to facilitate evidence-based decisions around empiric therapy. A total of 1506 positive urine cultures were obtained from 567 dogs and 471 cats. The most frequently isolated bacteria were Escherichia coli (58 %), Enterococcus spp. (17 %), Staphylococcus spp. (13.4 %) and Proteus spp. (9 %). Eighty-three percent of bacterial isolates were susceptible to at least one first-line empirical choice (amoxicillin and/or trimethoprim-sulfonamide). E. coli had the highest percentage of multidrug-resistant isolates from animals with sporadic (32 %) and recurrent positive cultures (40 %). Susceptibility of E. coli to amoxicillin increased from 47 % in 2012 to 55 % in 2021. Susceptibility of S. pseudintermedius to amoxicillin-clavulanic acid and oxacillin decreased from 100 % in 2012 to 54 % in 2021.Twenty-two percent of S. pseudintermedius isolates were methicillin-resistant. Compared to reports from other locations, our findings suggest that amoxicillin may be less effective as a first-line choice for treating canine and feline UTI in Sydney.