Cefovecin selects for higher-level and more persistent antimicrobial resistance among gastrointestinal Escherichia coli in some cats compared to amoxicillin-clavulanic acid in an observational longitudinal study.

OBJECTIVE: This observational study compared the development and persistence of antimicrobial resistance (AMR) in feline microbiota following treatment with cefovecin or amoxicillin-clavulanic acid. METHODS: Cats treated with cefovecin or amoxicillin-clavulanic acid, at the attending veterinarian's discretion, were recruited from multiple sources between December 2022 and May 2024. Fecal samples were collected on the first day of treatment and 1, 2, 3, 4, 8, and 12 weeks afterward. Samples were cultured for Escherichia coli, Kirby-Bauer disk diffusion was performed, and isolates with decreased cefovecin susceptibility were enumerated. Samples were tested for AMR genes with a targeted deep amplicon sequencing panel. The proportions of nonsusceptible isolates were compared across time and treatments. RESULTS: 9 cats treated with cefovecin and 10 cats treated with amoxicillin-clavulanic acid were included. Both groups developed ampicillin-resistant E coli, which persisted longer in the cefovecin group. There were significantly greater odds of recovering E coli not susceptible to amoxicillin-clavulanic acid (OR, 72; 95% CI, 5.4 to 980), ceftriaxone (OR, 930; 95% CI, 81 to 11,000), and cefoxitin (OR, 46, 95% CI, 1.7 to 1,200) in the cefovecin group, driven by 1 cefovecin-treated cat shedding resistant E coli for weeks 1 through 4. CONCLUSIONS: A minority of cats may shed E coli resistant to β-lactams following cefovecin treatment, and the risk of AMR is likely lower after amoxicillin-clavulanic acid treatment. CLINICAL RELEVANCE: Since cats are commonly treated with cefovecin, some treated cats shedding high-level β-lactam-resistant E coli may pose a threat to feline and human health. Using amoxicillin-clavulanic acid instead may minimize resistance.