A Microbiological Indicator of Multidrug Resistance in Feline Urinary Tract Infections: Antimicrobial Resistance Patterns in Cats in Portugal.

Antimicrobial resistance (AMR) is an increasing concern in veterinary medicine and may compromise empirical treatment of feline urinary tract infections (UTIs). This retrospective observational study evaluated antimicrobial resistance patterns and their association with multidrug resistance (MDR) in bacterial isolates obtained from urine cultures of cats presented to a feline referral practice in Lisbon, Portugal, between January 2023 and December 2025. A total of 174 cats with positive urine cultures were included, yielding 178 bacterial isolates. Escherichia coli was the most frequent pathogen (57.30%), followed by Enterococcus spp. (16.98%) and Staphylococcus spp. (14.61%). Antimicrobial resistance was detected in 107/178 isolates (60.11%), and 76/178 (42.70%) were classified as multidrug-resistant. Extended-spectrum beta-lactamase-producing Escherichia coli and methicillin-resistant Staphylococcus strains were also identified. Resistance to penicillins and fluoroquinolones was significantly associated with MDR (p < 0.001). These findings highlight the high burden of antimicrobial resistance in feline urinary isolates in this clinical setting and support routine urine culture and susceptibility testing to guide therapeutic decision-making, particularly in recurrent, complicated, or high-risk cases.