Isolation And Identification,Analysis Of Pathogenicity And Drug Resistance Of APEC In Some Regions Of Anhui Province

Avian pathogenic Escherichia coli(APEC)is one of the major bacterial pathogens that threaten the development of the poultry industry.Studies have shown that avian pathogenic Escherichia coli is a repository of virulence and drug resistance genes of human extrapathogenic Escherichia coli(ExPEC),and poultry food contaminated with it may be the main source of ExPEC spread across hosts.Therefore,research on the pathogenicity and drug resistance of APEC critical are currently the hot topics.In this study,APEC isolation,identification,pathogenicity,and drug resistance analysis were carried out in some areas of Anhui Province,to provided data reference for APEC epidemic situation,prevention and control in Anhui Province and its epidemiology in the future..The specific research content is as follows:1.Separation and identification of APEC in parts of AnhuiIsolated and identified 72 strains of avian Escherichia coli from cases with clinical symptoms of Escherichia coli by means of culture isolation,biochemical identification and16 sRNA.Of the 72 isolates,14 strains were isolated from feces and intestines and 58 from tissues of external organs.2.Pathogenicity analysis of APECSerological typing,phylogenetic typing,pathogenicity testing,and virulence gene detection were carried out on the 72 isolates to assess pathogenicity of the strains.The phylogenetic genotyping and pathogenicity test results showed that in Anhui Province,in the regional isolates,the B2 group was the dominant phylogenetic group.All 72 strains were APEC,with 58 strains being middle and high pathogenic strains;PCR results showed that the isolates carried a variable number of virulent genes;mat,fimC,ibeB,yijP,ompA,iss,iucD,iroN,and chuA with positive rates exceeding 50%.There was a significant difference in the distribution of aatA,iucD,and cva/cvi genes in extra-intestinal APEC and intestinal APEC isolates.Other virulent genes showed no significant difference in the detection rate of related genes.3.Analysis of drug resistance of APECAnalysis of drug resistance of APEC,revealed all 72 isolates to be ampicillin resistant,but sensitive to polymyxin B and haloperidol,reaching 100 % and 98.6%,respectively of which phenotype multidrug resistant rate of 3-7 heavy drug accounted for 68.1%(49/72).The PCR of resistance gene results showed that the detection rate of Escherichia coliresistant genes was basically the same,and polymyxin,chloramphenicol,and quinolones were accorded with phenotypic resistance.These findings provide new insights into the existence and distribution of virulence-related genes in APEC isolates that will be critical to future APEC epidemiological studies.