Abstract
The widespread use of antimicrobials in poultry production exerts selective pressure for the emergence of resistant bacteria, yet molecular data on resistance determinants in Escherichia coli from commercial farms in Central Asia remain scarce. This study aimed to characterize antimicrobial resistance genes and mobile genetic elements in E. coli isolates from a layer poultry farm in the West Kazakhstan region. A total of 100 samples (cloacal swabs, fresh feces, internal organs, and wild pigeons) were collected. E. coli was isolated using selective media and confirmed by qPCR targeting the uidA gene. Forty isolates were confirmed, of which ten (25%) carried at least one resistance gene as determined by a panel of 57 primer sets. All ten isolates carrying antimicrobial resistance-associated genes (100%) harbored determinants associated with multidrug resistance. The most frequently detected genes were blaTEM (80%), aadA17 (90%), and intI1-a-marko (80%). A high prevalence of qacEΔ1 (80%) was also observed. At least one class 1 integron-associated gene was detected in all resistant isolates and those carrying both integron variants harbored the highest numbers of resistance genes (14–19). Resistance gene profiles in pigeon isolates mirrored those from poultry, suggesting wild birds as potential vectors. The correlation between detected resistance genes and farm antimicrobial use (enrofloxacin, trimethoprim/sulfonamide combinations) indicates strong selective pressure. These findings suggest that poultry farms may serve as environments supporting the persistence and dissemination of antimicrobial resistance-associated genes in E. coli and underscore the need for enhanced biosecurity and antimicrobial stewardship within a One Health framework.