2024-2025年河北省犊牛源腹泻大肠杆菌流行病学调查OA

To investigate the epidemiological characteristics of Escherichia coli(E.coli)associated with calf diarrhea in Hebei Province,a total of 240 fecal samples from diarrheic calves were collected between 2024 and 2025 for E.coli isolation and identification.The isolates were analyzed for virulence genes,antimicrobial susceptibility,antimicrobial resistance genes,and biofilm-forming ability,along with phylogenetic group classification and multilocus sequence typing(MLST).The results showed that 214 E.coli isolates were recovered,with an isolation rate of 89.17%.The predominant virulence genes were crl(100%),fliC(92.99%),and ompA(87.85%),while tsh,afa,and traB were not detected.Phylogenetic analysis revealed that most isolates belonged to groups B1(54.21%)and A(33.18%).Antimicrobial susceptibility testing indicated high resistance rates to streptomycin(65.89%)and ciprofloxacin(50.47%),with 51.40%of isolates showing multidrug resistance,and 24.77%resistant to more than 10 antibiotics.The most frequently detected antimicrobial resistance genes were tetracycline resistance gene tet(A)(31.78%),β-lactam resistance gene blaTEM(28.97%),and sulfonamide resistance gene sul2(28.97%).Biofilm-forming ability assays showed that 60.75%of isolates were capable of forming biofilms,and all B2 group strains exhibited biofilm-forming ability.MLST analysis of 40 multidrug resistance isolates identified 38 distinct sequence type(ST),including 15 novel ST,with ST20 and ST1140 as the predominant types.This study provides a theoretical basis for developing targeted prevention and control strategies for calf diarrhea caused by E.coli in dairy and beef cattle farms in Hebei Province.