Antimicrobial resistance and genomic characteristics of bovine Escherichia coli from five northern provinces of China

Escherichia coli ( E. coli ) from food-producing animals serves as an important reservoir of antibiotic resistance genes (ARGs). To investigate the baseline genomic and antimicrobial resistance (AMR) profiles of bovine-associated E. coli from northern China, 143 fecal samples were collected across five provinces for analysis. A total of 112 E. coli isolates were recovered from 143 bovine fecal samples, with isolation rates ranging from 60 to 100%. Disk diffusion testing revealed high resistance to ampicillin (81.25%), cefotaxime (75.89%), and tetracycline (75.89%), and 68.75% of isolates were multidrug-resistant. Whole-genome sequencing of 112 isolates identified 47 multi-locus sequence types (notably ST69, ST1431, ST10, and ST58) and 63 serotypes. Closely related isolates across distant provinces suggested the presence of genetically related bovine-associated lineages across regions. A total of 74 ARG subtypes were detected, predominantly belonging to the aminoglycoside and beta-lactam resistance classes. Notably, the ARGs arr-3 , floR , mdf(A) , qnrS1, and tet (A) exhibited differences in distribution among provinces ( p < 0.05), indicating variation in resistance gene profiles across sampling locations. Overall genotype–phenotype concordance was observed, although agreement varied among ARG classes. Virulence profiling revealed a predominance of adherence-related genes, especially fimH and entA-D , while only three isolates were classified as classical diarrheagenic E. coli based on virulence markers. Forty-one plasmid replicon types were identified, with IncFIB and IncHI2 being the most frequent and broadly distributed. The number of detected plasmid replicon types was positively associated with the number of ARGs and VFGs. This study provides foundational genomic insights into bovine-associated E. coli from northern China and highlights the potential contribution of plasmids to ARG carriage and resistance profiles. These findings support the need for sustained genomic surveillance within a One Health framework.