Epidemiological Investigation And Genetic Correlation Analysis Of Escherichia Coli From Three Fur Animals In Zhucheng

Escherichia coli can cause colibacillosis in animals and humans.It widely exists in the intestines of animals and people.It is not only a resident intestinal bacterium,but also a conditional pathogen.Some special serotypes or immune deficiency caused by other non-infectious conditions and infectious pathogens can lead to the infection of animals and people.In order to study the epidemiology of Escherichia coli in minks,foxes and minks and the genetic correlation among the isolated strains,182 fecal samples were collected from three farms in Zhucheng in August 2017,of which 78 were collected from mink farms,97 from fox farms and 7 from mink farms.After sample collection and treatment,E.coli was isolated and identified by means of enrichment,selective medium culture and 16 S rRNA identification.Thirty-one pathogenic serotypes were detected by agglutination test with kits,14 commonly used antibiotics were detected by disk agar diffusion(K-B method),and DNA was extracted to detect the presence of 24 resistance genes and a class of integrons;Multilocus sequence typing(MLST)was performed on bacteria,and traceability analysis and genetic evolution of strains of coliform bacteria were carried out.Thus,the epidemic situation of E.coli in three farms in the region was clarified.After isolation and identification,95 of 182 samples contained E.coli,the positive rate was 52.20%(95/182).Seventeen strains were identified as pathogenic serotypes by agglutination test,including 10 different types,of which the detection rate of O104:H4 was23.53%(4/17).The results of drug sensitivity test showed that 95 strains of E.coli showed different resistance to 14 antibiotics,the highest resistance to ampicillin was 91.58%(87/95),and the sensitivity to cefoxitin was 1.05%(1/95).Fifteen drug-resistant genes were detected,among which the quinolone-resistant gene qnrS was the highest,the detection rate was66.32%(63/95).31 strains of E.coli were detected to carry class I integrons,the detection rate was 32.63%.The class I integron detection results showed that there were seven drug-resistant gene cassettes in the strains.The most gene cassettes were dfrA27+aadA2+qnrA(17/31).The isolates carrying integrons had multiple resistance.Thestrain ratio of the drug was 93.55%.The number of SAS software showed that there was a significant difference between the existence of drug-resistant genes and the resistance of Escherichia coli to these antibiotics(P < 0.05),which was related to the existence of a specific drug-resistant gene.After analyzing 95 ST sequences,55 different ST genotypes were obtained,of which the ST46 genotype was the most,accounting for 11.57%(11/95)of the total,and no new allele genotype was found.The largest clone group with seven clones(CC1~CC7)was CC6,and the closest genetic evolution relationship between ST10 and ST218,ST48,ST215,ST744,ST43,ST1634,ST656 and ST716 was not found in the isolates composed of ST10 and ST218,ST48,ST215,ST744,ST1634,ST656 and ST716.The homologous strains tend to come from the same species;among them,ST189,ST10 and ST46 are the clonal ancestors of corresponding clone groups CC5,CC6 and CC7 respectively;pathogenic serotypes are dispersed in the genetic evolution tree,and have no correlation with the genetic relationship between strains and ST type;there is no correlation in the composition of drug resistance spectrum;most of the same clone groups are similar in evolutionary branches,and some strains are different.Far away,such as st4147 and st189,may be related to the difference of seven housekeeping gene sequences of different strains;isolates with closer evolutionary branches are related to the carrying of drug resistance spectrum.This study completed the epidemic characteristics of Escherichia coli,the distribution of pathogenic serotypes,and the resistance to common antibiotics,as well as drug resistance genes and integration,which were carried from leeches,foxes,and scorpions in three fur-source farms in Zhucheng area.It interprets the distribution characteristics,drug resistance,epidemic characteristics and genetic evolution of E.coli in this region,and developed effective preventive measures against the possible outbreak of E.coli disease in fur animals.