Antimicrobial Prescribing and Laboratory Reported Bacterial Resistance in Companion Animals in Southeastern Brazil

Antimicrobial resistance (AMR) is a major One Health challenge, and Brazilian data integrating veterinary prescribing with local susceptibility profiles remain scarce. This study characterized antimicrobial prescribing by veterinarians and descriptively compared prescribing patterns with regional laboratory-reported resistance profiles in urinary and otic infections in dogs and cats. Questionnaire responses from 109 veterinarians and 1050 bacterial isolates (608 urinary/genitourinary and 442 otic; 18,137 susceptibility results in the source dataset before interpretive exclusions) were analyzed. Only 34/109 (31.2%) veterinarians requested antimicrobial susceptibility testing before therapy, more often specialists than general practitioners (43.2% vs. 23.1%; p = 0.035). General practitioners reported greater use of amoxicillin/clavulanate, enrofloxacin, doxycycline, and amoxicillin/ampicillin (p < 0.05). Higher overall prescribing intensity was associated with more frequent use of doxycycline, neomycin/tobramycin, cefalotin/cephalexin/cefazolin, and macrolides (p ≤ 0.04). Escherichia coli was reported as predominant in urinary samples, and Staphylococcus was reported in otic samples at genus level. Enrofloxacin showed relevant resistance among the main isolates, whereas amoxicillin/clavulanate reported resistance varied by bacterial species (71.4% resistance in Klebsiella pneumoniae and 8.9% in otic S. pseudintermedius). Treatment duration varied widely, particularly for otitis and urinary tract infections. The unlinked datasets identified potential areas for review, including opportunities to expand microbiological diagnostics, reduce empirical use of antimicrobials with relevant resistance, and standardize antimicrobial selection and treatment duration.