Abstract

Antimicrobial resistance (AMR) in Escherichia coli poses a global public health threat, yet companion animals such as dogs remain underrepresented in surveillance efforts. This study investigated risk factors associated with E. coli resistance to amoxicillin-clavulanic acid, ceftazidime, and enrofloxacin in 263 healthy dogs from urban and rural veterinary clinics in Chile. Fecal samples were collected from dogs that had not received antibiotics in the preceding four weeks, and E. coli isolates growing on antimicrobial-impregnated selective agar were tested using VITEK2, following Clinical and Laboratory Standards Institute guidelines. A structured questionnaire captured demographic, clinical, and environmental data, and logistic regression was used to identify significant associations. Resistance rates were 13.3% for amoxicillin-clavulanic acid, 5.98% for ceftazidime, and 18.3% for enrofloxacin. Dogs purchased from pet stores had 6.04-fold higher odds of ceftazidime resistance compared to adopted dogs (95% CI: 1.88-21.32, p = 0.003). Prior hospitalization increased the risk of enrofloxacin resistance (OR = 4.24, p < 0.001), while cohabitation with healthcare workers reduced the risk of resistance to both enrofloxacin (OR = 0.17, p < 0.001) and amoxicillin-clavulanic acid (OR = 0.32, p = 0.008). Notably, occasional contact with free-roaming animals also exhibited a protective effect (OR = 0.32, p = 0.011). These results underscore the need for AMR surveillance in companion animals, improved antimicrobial stewardship, and the adoption of a One Health approach to effectively address AMR across species.