Epidemiologic determinants of antimicrobial resistance in feline urinary Escherichia coli in the United States (2018-2024).

Lower urinary tract infections are less common in cats than in dogs, with Escherichia coli being the predominant bacterial pathogen responsible for these infections. Although antimicrobial therapy is used for optimal treatment, repeated or prolonged exposure may increase the risk of antimicrobial resistance (AMR). This study examined risk factors for AMR in urinary E. coli isolates from cats across the United States, focusing on prior positive cultures and other host, socioeconomic, and geographic factors, using multilevel logistic regression models, accounting for clustering at the patient, county, and state levels. From 2018 to 2024, antimicrobial susceptibility testing (AST) was performed on 138,695 clinical urinary E. coli isolates from 122,048 cats. The log-odds of antimicrobial non-susceptibility (ANS) increased linearly with the number of positive cultures in the preceding six months. After adjustment, isolates from cats in non-metropolitan counties had higher odds of non-susceptibility for most antimicrobials, compared with those from metropolitan counties. Every 1% rise in the annual county-level percentage of cats with positive culture and AST was associated with a 1-3% lower odds of ANS (p < 0.001). Additionally, isolates from cats in states with 1500-1999 housing units per veterinarian had higher odds of non-susceptibility across all antimicrobialscompared with those in states with 500-999 housing units per veterinarian, except fluoroquinolones. Patient-level factors, particularly recent repeated positive cultures, play a dominant role in AMR in feline urinary E. coli, likely reflecting the cumulative impact of long-standing resistant infections or antimicrobial exposure. Other findings may reflect differences in access to veterinary care or diagnostic testing, or differences in test submission patterns.