Identification & Classification And Main Virulence Genes Analysis Of Escherichia Coli. Isolated From Calf Diarrhea In Ningxia Province

In order to effectively deal with the calf diarrheal diseases, this research is mainly about the predominant serotypes and virulence genes of Escherichia coli. distribution in Ningxia. There are 32 samples of dead calf tissue we have collected at the period of 2015.3-2015.12. And 118 samples of dead calves in which the heart, liver, spleen, lung, kidney and intestinal lymph node tissue are involved, another 86 samples are the fecal of diarrhea calf, all of these samples involve 118 calves with diarrhea. Finally, we have got 114 isolated E. coli. by biochemical identification method and 16S rDNA identification method, which has 52 tissue samples and 62 fecal samples.34 kinds of O antigen serotypes of E. coli. were used to be identified, the results show:O26,O138, O126, O51, O92, O107, O68, O86, O35, O13, O55, O8, O142, O91, O137, O144, O153, O18, O20, O101, O158, O22, O93, O148, O117, O109, O9, O15, O53 total of 29 serotypes in 86 strains of E.coli. isolates were identified, the detection rate is 75.43%; in addition, O10, O112, O7, O128, O43 were undetected. The predominant serotypes are O26 (6/114), O126 (5/114), O18 (9/114), O35 (4/114), O158 (8/114), O101 (6/114), O107 (5/114), O9 (5/114) involve 48 strains isolated E.coli. which account for 42.11% in 114 isolates, accounting for 55.81% in 86 strains of e.coli. isolates.These E.coli. isolates included 37 tissue samples and 49 fecal samples, the serotypes of another 28 strains E.coli. were unidentified.By consulting relevant literature, six kinds of virulence genes were selected to detect the 48 strains’ predominant stereotypes. They are fimh, afa, eae, ehly, ipah and f41.Test results show:32 strains of E.coli. which contain fimh genes account for 66.67% in 48 strains; 8 strains which contain afa virulence gene account for 16.67% in 48 strains; 5 strains which contain eae virulence gene account for 10.41% in 48 strains; 2 isolates of E. coli. strains which contain both fimh and afa genes; the other three virulence genes were undetected.A part of the product-related genes were analysed, the results show:the similarity of gene’s sequence between the Measured gene sequence and the shown of GenBank is 98%-100%.