Antimicrobial resistance and characterization of ESBL-producing Escherichia coli from poultry and cattle in Isfahan, Iran
摘要
The rise of antimicrobial resistance (AMR), particularly from extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli, poses a global public health threat. This study investigated the prevalence, genetic characteristics, and antimicrobial resistance patterns of ESBL-producing E. coli isolated from free-range poultry and clinically healthy cattle in Isfahan, Iran.
MethodA total of 300 fecal samples were collected between May 2023 to May 2024, including 150 from smallholder poultry farms and 150 from a mix of dairy and beef cattle farms. Twenty privately owned farms (10 poultry and 10 cattle) were randomly selected using a stratified random sampling approach. All animals were clinically assessed by a licensed veterinarian and found to be healthy at the time of sampling. Samples were screened for ESBL production, and antimicrobial susceptibility testing (AST) was performed using the Kirby-Bauer disk diffusion method according to CLSI 2018 guidelines. Phenotypic confirmation of ESBLs was conducted using the double-disk synergy test (DDST). Genotypic analysis targeting blaCTX-M, blaTEM, blaAmpC, mcr-1, qnrS, qnrB, and aac(6’)-Ib-cr genes and Class 1 and 2 integrons was conducted via PCR.
ResultsESBL-producing E. coli was detected in 43.33% of poultry and 36.67% of cattle samples. The most common gene was blaCTX-M (30.77% poultry, 45.45% cattle). Multidrug resistance (MDR) occurred in 53.85% and 54.55% of poultry and cattle isolates, respectively. No statistically significant differences were observed between species (p > 0.05).
ConclusionThe findings underscore the potential zoonotic risk of ESBL- and MDR-producing E. coli from livestock. Strengthened antibiotic stewardship and molecular surveillance in Iranian agriculture are essential.