Isolation，identification，and drug resistance analysis of pathogenic Escherichia coli causing diarrhea in Hu sheep

doi:10.16178/j.issn.0528-9017.20240802

Abstract

Abstract:

In order to analyze the infection status，virulence gene profiles，and antimicrobial resistance of pathogenic Escherichia coli in diarrhea sheep from a Hu sheep farm，this study conducted bacterial isolation and identification，virulence gene detection and drug susceptibility testing on anal swab samples collected from the affected flock. The results showed that 59 strains of intestinal E. coli were isolated from 80 samples.Among these，44 strains were enteropathogenic E. coli（EPEC），accounting for 74.58% of the isolates；9 strains were enterotoxigenic E. coli（ETEC），accounting for 15.25%；4 strains were Shiga toxin-producing E. coli（STEC），accounting for 6.78%；2 strains were ETEC/STEC hybrids，accounting for 3.39%. Antimicrobial susceptibility testing of 38 randomly selected pathogenic strains revealed resistance rates to 21 commonly used antibiotics ranging from 7.89% to 100.00%. Resistance to penicillin and erythromycin was the most severe，with both reaching 100.00%. In contrast，the strains were relatively susceptible to ceftiofur and florfenicol，with resistance rates of 7.89% and 13.16%，respectively. A total of 18 strains were classified as multidrug-resistant，accounting for 47.37%. In conclusion，EPEC was the predominant pathogenic E. coli associated with clinical diarrhea in sheep from this farm，and the isolates exhibited widespread and strong antimicrobial resistance. The findings of this study provide a scientific basis for developing rational medication and disease control strategies for the farm and lay a foundation for the scientific diagnosis and targeted treatment of bacterial diarrhea in Hu sheep.

Key words: Hu sheep, enteropathogenic Escherichia coli, isolation and identification, antimicrobial resistance

CLC Number:

S852.61

FEI Zhonghua, JIANG Xiaoli, WU Fei, CHEN Yijie, YE Shiyi, LI Junxing. Isolation，identification，and drug resistance analysis of pathogenic Escherichia coli causing diarrhea in Hu sheep[J]. Journal of Zhejiang Agricultural Sciences, 2026, 67(2): 481-487.

Figures/Tables 8

Fig. 1 Colony morphology of the isolated bacteria on blood agar and MacConkey agar medium

Fig. 2 Gram-staining microscopy of the isolated bacteria

Fig. 3 Verification electrophoretogram of east1-positive strains

Fig. 4 Verification electrophoretogram of stx1-positive strains

Fig. 5 Verification electrophoretogram of eaeA-positive strains

Fig. 6 Detection rate of bacterial strains with different virulence gene patterns

Fig. 7 Antibiotic resistance profile of the 38 E. coli strains

Fig. 8 Distribution of isolates by number of antibiotic classes resisted

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