| Objective:To isolate and identify E.coli O157:H7 from different animal sources in Xinjiang,study its biological characteristics and epidemic transmission law,provide scientific basis for the evaluation of E.coli O157:H7 pollution in various regions of Xinjiang,and provide reference for controlling the transmission of E.coli O157:H7 from different animals,so as to ensure the healthy development of animal husbandry from the source.Methods:（1）Samples of different animals（feces,anal swabs and carcass swabs）were collected from different regions of Xinjiang.They were enriched with EC broth,enriched with immunomagnetic beads,and then selectively cultured with CT-SMAC and MUG.Finally,rfb E and fli C genes were detected by PCR;（2）The virulence genes such as stx1,stx2,eae A,Tccp and Hly were detected by PCR;（3）The sensitivity of the isolates was detected by K-B method,and 13 drug resistance genes were detected by PCR;（4）Pulsed field gel electrophoresis（PFGE）and whole genome sequencing（WGS）were used to explore the genetic correlation between strains.Results:（1）From 7149 samples of different animals collected from 12 regions of Xinjiang,38 strains of E.coli O157:H7 were isolated.The isolation rates of cattle,sheep,camel,donkey and human were 0.3%（13/3788）,0.5%（5/966）,1.0%（17/1792）,2.4%（1/42）and 0.4%（2/561）respectively;The separation rates of E.coli O157:H7 in Urumqi,Ili,Hami,Aksu,Karamay,Turpan,Altay and Kezhou were 0.3%（9/3618）,2.0%（7/358）,1.1%（4/381）,0.3%（1/295）,3.0%（1/34）,2.4%（4/167）,0.8%（11/1381）and4.4%（1/23）,respectively.（2）Five virulence genes（stx1,stx2,eae A,Tccp and Hly）were detected by PCR;The pathogenicity was detected by mouse challenge test.（3）22 strains were resistant to 2～15 antibiotics,21strains（52.6%）were resistant to piperacillin,and one strain（2.6%）was resistant to polymyxin B;Ten drug resistance genes were detected:bla CTX-M,bla CTX-M-1,bla TEM,bla SHV,tet G,tet E,aac,aad A1,sul1 and cml A1.bla CTX-M-2,bla CTX-M-9and tet A were not detected.（4）PFGE results showed that 38 strains of E.coli O157:H7were divided into 16 different clusters,including 9 strains in one cluster,4 strains in three clusters and 2strains in three clusters;There are 3 strains in one cluster;The other clusters were 1 strain.Among them,one human strain,one bovine strain and one camel strain E.coli O157:H7 are in the same cluster.74 drug resistance genes and 273 virulence genes were annotated by whole genome sequencing.Conclusion:Xinjiang cattle,sheep,camels,donkeys and people carry E.coli O157:H7,and the detection rate of camels,donkeys and people is relatively high;The isolates generally carried 1～5 virulence genes,and there was no death in the challenge test,indicating that the pathogenicity of the isolates to mice was not strong;E.coli O157:H7 from different animal sources has multiple drug resistance.10 drug resistance genes were detected,and the drug resistance to piperacillin is the most serious.The results of PFGE and WGS showed that the homology of E.coli O157:H7 from different animal sources in different regions was very high,and the strain may spread across species and regions. |
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