Community dissemination of blaCTX-M-dominant extended-spectrum β-lactamase-producing Escherichia coli with widespread multidrug resistance in domestic cats from Ecuador: A One Health molecular epidemiological study.

BACKGROUND AND AIM: Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli represents an increasing One Health threat because of its dissemination among humans, animals, and the environment and its frequent association with multidrug resistance (MDR). Companion animals may serve as reservoirs of clinically important resistant bacteria; however, molecular epidemiological information on ESBL-producing E. coli in domestic cats from Ecuador remains limited. This study aimed to determine the prevalence, antimicrobial susceptibility patterns, β-lactamase gene distribution, and potential risk factors associated with ESBL-producing E. coli carriage in domestic cats from Machala, Ecuador. MATERIALS AND METHODS: A cross-sectional study was conducted from August 2023 to August 2024 involving 199 domestic cats presented to the Veterinary Clinic of the Universidad Técnica de Machala. Rectal swabs were cultured on CHROMagar™ ESBL, and ESBL production was phenotypically confirmed using the double-disk synergy test according to Clinical and Laboratory Standards Institute criteria. Antimicrobial susceptibility testing against 12 agents was performed using the Kirby-Bauer disk diffusion method. Polymerase chain reaction was used to detect , , and . MDR was defined as non-susceptibility to at least one antimicrobial agent in three or more categories. Risk factor associations were evaluated using Pearson's chi-square or Fisher's exact test. RESULTS: ESBL-producing E. coli was detected in 83 of 199 cats, corresponding to a prevalence of 41.7% (95% confidence interval: 35.1-48.7). The gene predominated in 60/83 isolates (72.3%), followed by in 19/83 (22.9%) and in 1/83 (1.2%). At least one targeted gene was detected in 64/83 isolates (77.1%), whereas 19/83 phenotypically positive isolates lacked all three targeted genes. MDR was observed in 74/83 isolates (89.2%). All isolates remained susceptible to imipenem and meropenem, whereas the highest resistance rates were recorded for trimethoprim-sulfamethoxazole, tetracycline, cefepime, levofloxacin, and doxycycline. None of the evaluated risk factors was significantly associated with ESBL gene positivity. CONCLUSION: Domestic cats in Machala showed a high prevalence of -dominant, multidrug-resistant ESBL-producing E. coli. These findings indicate widespread community dissemination and support the inclusion of companion animals in Ecuadorian antimicrobial resistance surveillance and stewardship programs under a coordinated One Health framework.