Isolation,Identification,Virulence Genes Detection And Drug Sensitivity Test Of E.coli O157:H7 In Some Areas Of Xinjiang

To study the distribution of E.coli O157:H7 of healthy cattle in some areas of xinjiang,and their characteristics of virulence genes and drug sensitivity to some antibioticsof isolates,and finally to verify effects of immunomagnetic enrichment on the separation of bovine E.coli O157:H7 in practice.1.883 anal swab samples and 48 carcass surface swab samples were randomly collected from 10 farms which located at Yili,bole,Changji and Wujiaqu and Urumqi in Xinjiang.after EC broth enrichment,Immunomagnetic beads,SMAC and MUG were used for screening.Finally above isolates were identified by PCR and biochemical tests.2.The isolated bovine origin E.coli O157:H7 strains were detected by PCR method for Stx1,Stx2,eaeA,Hly,Tccp and other virulence genes.3.To those isolated bovine origin E.coli O157:H7 strains,K-B test was used for sensitive detection of 17 kinds of veterinary clinical commonly used anti gram negative bacillus drugs.4.243 anal swabs,feces,forage,drinking water and carcass swabs were collected from cattle farms in Yili,Changji and Wujiaqu.Immunomagnetic beads and no Immunomagnetic beads method were separately used for enrichment of E.coli O157:H7,then the subsequent steps were carried on for the isolation and identification.Fisher test and McNemar's Test were used for statistical analysis to evaluate the role of immunomagnetic enrichment in the separation of bovine E.coli O157:H7 in practice.Results show:1.There are altogether 16 E.coli O157:H7 strains were isolated from 931 tested samples?Among them 11 from Yili,the isolate rate is 3.93%,5 from Urumqi,the isolate rate is 1.48%,and no E.coli O157:H7 were isolated from Bole,Changji and Wujiaqu.From 883 anal swabs and 48 carcass swabs14 strains and 2 strains of E.coli O157:H7 were detected,The detection rate was 1.59% and 4.17%.2.The carrying rate of Shiga toxin gene of 16 isolated strains was 81.3%.The carrying rates of Stx1,Stx2 and Stx1 and Stx2 were 12%,25% and 43.7%,respectively.The carrying rates of eaeA,Hly and Tccp were 100%,87.5%,and 75%,respectively.3.All of the 16 strains of E.coli O157:H7 isolates were most sensitive to tobramycin,up to 100%.Followed by cefoxitin,cefepime,levofloxacin,aztreonam,ceftazidime,reached 93.8%.The resistance to Maddie was the highest,and the drug resistance rate was 100%.4.8 strains of E.coli O157:H7 were isolated from the 243 samples by immunomagnetic beads.However,only 4 of them were detected in the ordinary method,although the difference was not statistically significant(P?0.05),But,asa result,,the immunomagnetic beads method can improve E.coli O157:H7 detection numberin this study.From the above results,we can draw a conclusion:E.coli O157:H7 is common in healthy cattle in some areas of Xinjiang,but the separation rate is not high;E.coli O157:H7 was detected in beef carcass swabs,and most of the isolates carry a variety of virulence genes.It is speculated that it has strong potential pathogenicity to humans;All 16 isolates were resistant to antibiotics,but the overall level of drug resistance was not high;Although there was no significant difference between the two methods,compared to conventional methods,the immunomagnetic beads method can increased the number of isolates.Therefore,it is recommended to use immunomagnetic beads enrichment method in the development of E.coli O157:H7 pathogen detection..