Identification and biological characteristics analysis of diarrhea E.coli in dairy and meat calves in livestock farms in Northern Hebei
10.16303/j.cnki.1005-4545.2025.04.10
- VernacularTitle:冀北地区养殖场中奶/肉犊牛腹泻性大肠杆菌鉴定及生物学特征分析
- Author:
Zhaoxing ZHANG
1
;
Jianghong HENG
;
Hongwei ZHANG
;
Yanying ZHANG
;
Yan ZHANG
;
Peiguo LI
Author Information
1. 河北旅游职业学院,河北 承德 067000
- Publication Type:Journal Article
- Keywords:
calf;
E.coli;
serotype;
virulence genes;
drug resistance;
LD50
- From:
Chinese Journal of Veterinary Science
2025;45(4):693-698
- CountryChina
- Language:Chinese
-
Abstract:
This study aims to analyze the biological characteristics such as pathogenicity,serotype,virulence genes,and drug resistance of Escherichia coli(E.coli)causing diarrhea in dairy and meat calves in different farms in the Northern Hebei.From 2022 to 2023,120 diseased tissue sam-ples(feces,anal swabs,and livers)of calves(0-2 months old)suffering from diarrhea in the north-ern Hebei region were collected.The detection of viral and parasitic pathogens was negative.Bacte-rial isolation and cultivation,morphological observation,biochemical identification,and PCR meth-ods were used to identify E.coli.Biological characteristics such as pathogenicity,serum typing,vir-ulence genes,and drug resistance were detected using mouse virulence test,glass plate agglutina-tion test,PCR method,and K-B drug sensitivity paper method,and determine the median lethal dose(LD50)of representative strains of dominant serotypes in mice respectively.The results showed that 76 strains of E.coli were isolated,and 56 strains were pathogenic E.coli that could cause varying degrees of death in mice,with mortality rates all above 40％.Among 56 pathogenic E.coli strains,O6 and O152 were the dominant pathogenic serotypes,among which 48 strains(85.7％)were enterotoxic E.coli(ETEC),6 strains(10.7％)were enteropathogenic E.coli(EPEC),and 2 strains(3.6％)were enterohemorrhagic E.coli(EHEC).The detection rates of vir-ulence genes fyuA,irp2,fliC,stx1,stx2,K88,K99,eaeA and ler were over 50％,while the de-tection rates of other types of virulence genes were 3.6％to 37.0％.The resistance rates to nine drugs such as ampicillin,neomycin,and amoxicillin were over 42.9％,and the resistance rates to other drugs were 12.5％to 32.1％,showing multiple drug resistance and at least resistance to three types of antibiotics.The LD50 values of the dominant serotype of representative strains ETO 152 strain and EPO6 were 3.16×104 and 3.22×106 CFU/mL,respectively.This study can provide ref-erence for the prevention and control of E.coli disease in dairy and meat calves in the Northern Hebei region.
