Antimicrobial susceptibility of bacteria isolated from canine and feline urinary tract samples in New Zealand

To describe the bacterial species isolated from canine and feline urinary tract samples submitted to veterinary laboratories in New Zealand and document the susceptibility of these isolates to commonly used antimicrobials. Antimicrobial susceptibility data from canine and feline urinary tract samples were retrospectively extracted from results collected as part of a national antimicrobial resistance (AMR) surveillance programme from the three main commercial veterinary laboratory groups in New Zealand. The data was collected between May 2022 and September 2023. Antimicrobial susceptibility data were reported for 2,208 bacterial isolates from canine urinary tract samples and 1,284 bacterial isolates from feline urinary tract samples during the study period. The most common bacteria detected in canine samples were <i>Escherichia coli</i> (45.7%), <i>Staphylococcus intermedius</i> group (16.9%), <i>Proteus mirabilis</i> (15.8%) and <i>Streptococcus</i> spp. (5.3%). In feline samples, <i>E. coli</i> was most common (66.7%), followed by <i>Enterococcus</i> spp. (15%), <i>Staphylococcus</i> spp. (9.7%) and <i>P. mirabilis</i> (3.7%). Resistance to cephalothin was common amongst Enterobacteriaceae in both dogs and cats, with only 51.3% of canine <i>E. coli</i> and 62.2% of feline <i>E.coli</i> susceptible to this antibiotic. Susceptibility of canine <i>E. coli</i> was higher for amoxicillin-clavulanic acid (amoxi-clav; 84.2%), tetracycline (87.3%), trimethoprim-sulfamethoxazole (TMS; 93.7%) and enrofloxacin (95.9%). Feline <i>E. coli</i> were similarly susceptible to amoxi-clav (86%), tetracycline (89.5%), TMS (95.4%) and enrofloxacin (96.6%). Multiple drug resistance (MDR), defined as resistance to three or more antimicrobial classes, was detected in 8.4% of canine <i>E. coli</i> and 6.9% of feline <i>E. coli</i>. MDR was also common in canine <i>Enterococcus</i> spp. (9.5%), with many isolates resistant to enrofloxacin (64.9%) and tetracycline (28.6%). Feline enterococci were commonly resistant to enrofloxacin (64.7%) and tetracycline (37.4%). Most canine and feline <i>Enterococcus</i> spp. were susceptible to amoxi-clav (95.2% and 98.9%, respectively). In both dogs and cats, <i>Staphylococcus</i> spp. displayed high susceptibility to enrofloxacin (99.5% and 98.4% respectively), amoxi-clav (93.5% and 96%), cephalothin (93.7% and 95.1%) and TMS (90.7% and 97.6%). Methicillin resistance was detected in 4.9% of canine <i>Staph. intermedius</i> group. Compared to many other countries, the incidence of AMR is relatively low in bacteria isolated from feline and canine urinary tract samples in New Zealand. However, there has been an apparent increase in resistance in canine isolates since last studied. This highlights the importance of regular monitoring for AMR and the value of susceptibility testing for informing both individual case management and local prescribing practices.