Study Of Isolation,Identification And Drug Resistance Of Pathogenic Escherichia Coli From Chicken In Hebei

The degree of drug resistance of pathogenic E.coli is becoming more and more serious.Has posed a great threat to livestock and poultry production safety and human health and public health.The problem of pathogenic E.coli resistance and transmission is of great concern worldwide.Escherichia coli was isolated from the liver of diseased chickens in Hebei province.The isolates were identified by biochemical test and 16S r RNA gene sequencing.The drug sensitivity was determined by K-B method,and the serotype and virulence gene were detected by PCR.Plasmid mediated quinolone resistance(PMQR),Extended-spectrum beta-lactamases genes and integron integrase genes were detected.Escherichia coli were classified according to phylogenetic group classification and multi-locus sequence typing(MLST).Escherichia coli were classified according to phylogenetic group classification and multi-locus sequence typing(MLST).The aim of this study was to elucidate the epidemiological characteristics of pathogenic and drug-resistant Escherichia coli from chickens in Hebei.To provide the basis for the formulation of the corresponding prevention and control strategy.The results are as follows:1.The 56 strains of Escherichia coli were divided into 8 types,and B4 was the main type.There were 11 serotypes,with O₇₈,O₂,O₁₅₇ and O₁ accounting for 26.79%,23.21%,17.86%and 14.29%,respectively.2.There were 26 strains of enteric pathogenic Escherichia coli,including EHEC(76.92%),EAEC(15.38%)and ETEC(7.69%).At the same time,15 virulence genes of Escherichia coli were detected,and the carrying rates of fim C and Omp A were100%.The detection rates of aat A,yij P,irp2,mat and iss were 98.21%,98.21%,96.43%and 92.86%,respectively.The genes associated with iro N transport,such as iro N,fyu A,iuc D and irp2,were above 80%.3.The drug resistance rate of 45 strains of Escherichia coli to fluoroquinolones was 58.93%?80.36%.Which the ratio of carry qnr S,qnr B and aac(6?)-Ib-cr gene were82.22%,4.44%and 4.44%.41 strains showed multiple drug resistance to third-generation cephalosporins,mainly carrying bla _CTX-M-9,bla _CTX-M-1,bla _CTX-M-8,bla CTX-M-25,bla OXA,bla SHV and bla TEM.The bla CTX-M-9 is mainly dominated by bla _CTX-M-65(n=10)subgenes.The detection rate of bla _CTX-M-55(n=15)was the highest in bla _CTX-M-1 group.These strains are all type I integral box.4.The 56 Escherichia coli strains were divided into 22 ST types,and ST88(n=7),ST85(n=6)and ST243(n=6)were the dominant types.ST1199,ST1200,ST1201,ST1202,ST1203,STN1,STN2 and STN3 are the new ST type.There were 4phylogenetic groups,including 24 strains(42.86%)belonging to group D,14 strains(25%)belonging to group B2 and 12 strains(21.43%)belonging to group B1.The other6 strains(10.71%)belonged to group A.There were 19 ST types in 41 strains of PMQR Escherichia coli.The 36 strains with plasmid carrying bla _CTX-M contained 16 ST types,and the dominant types were ST85(n=6)and ST243(n=6).The number of isolates was higher in group D,followed by group B2.In conclusion,chicken-derived Escherichia coli in Hebei region had a variety of serotypes and virulence factors,and generally carried qnr S and bla _CTX-M drug resistance genes,and bla _CTX-M-55,bla _CTX-M-65,bla _CTX-M-14 were the dominant drug resistance gene subtypes in the latter.The results of this study provide data support for the effective prevention and control of pathogenic E.coli in chickens in Hebei.Six novel ST types were detected in MLST typing,which provided data support for the effective prevention and control of pathogenic E.coli from chickens in Hebei.