Antimicrobial resistance profiles of bacterial pathogens from feline urinary tract infections in Rio de Janeiro, Brazil

This study characterized the bacterial epidemiology and antimicrobial resistance profiles of 448 isolates recovered from feline urine cultures in Rio de Janeiro, Brazil, between 2020 and 2024. Antimicrobial susceptibility was assessed by disk diffusion and interpreted according to CLSI VET01S and Brazilian Committee on Antimicrobial Susceptibility Testing (BrCAST) breakpoints. Escherichia coli was the predominant pathogen (45.1%), followed by Proteus spp. (16.3%) and Klebsiella spp. (12.5%). Resistance to antimicrobials recommended as first-line options by the ISCAID guidelines was frequent among E. coli isolates, including trimethoprim-sulfamethoxazole (57.2%), cephalexin (52.5%), and amoxicillin-clavulanate (43.9%). Veterinary fluoroquinolones showed moderate resistance (enrofloxacin 28.5%, marbofloxacin 20.9%), while nitrofurantoin resistance reached 37.7%. Third-generation cephalosporins and carbapenems retained the highest activity (ceftazidime 13.2%; meropenem 0%). Multidrug resistance (MDR) was observed in 55.8% of all isolates, with the highest prevalence in Proteus spp. (79.5%) and E. coli (57.9%). Resistance to third-generation cephalosporins was detected in 22.8% of E. coli isolates, and carbapenem resistance was detected in 5 isolates from different species. These findings indicate that resistance to first-line agents is common in feline uropathogens in this setting and support the routine use of urine culture and antibiotic susceptibility testing to guide antimicrobial therapy.