Isolation And Identification Of E.coli From Diarrhea Calves And Its Partial Biological Characteristics In Parts Of Xinjiang

Enterotoxigenic Escerichia coli(ETEC) is a species of Pathogenic bacteria and can cause diarrhea in Humanity and animals, especially in young animals,such as newborn calves,piglets, lambs. It have happened newborn calf diarrhea in six large-scale cattle farms from four areas of Shihezi,Shawan,Aksu,Bole in Xinjiang successively from March to June in 2015,The incidence of newborn calves diarrhea is 40%-60% and the mortality rate of death is 50%-70%,the diarrhea has lead to death of thousands of calves, it’s a kind of serious economic losses for these farms,On the basis of epidemiological, clinical examination and dissection Collecting death calves’ lymphonodi mesosteniales and other samples from this six large-scale cattle farms,by experimentation of Isolation and identification, detection of pili gene and enterotoxigenic gene with PCR, hemolysis test, pathogenicity test of mice and drug sensitivity test to determine the relevance of six large-scale cattle farms with E.coli, The following is the result of the experiments:(1)Collected death calves’ mesenteric lymph nodes, livers, intestinal contents and other diseased samples due to diarrhea for 60 in total from four areas’ six large-scale cattle farms in the southern and northern of Xin jiang, 53 isolates are obtained from 60 samples and its cultural characteristics and biochemical tests are conform to the characteristic of E.coli. Making 53 isolates inoculated on plate of 5% sheep blood respectively,the results showned that 53 isolates were β-hemolytic, It is evident that E. Coli is the reason cause diarrhea of calves come from these six cattle farms.(2)Using the method of O antigen agglutination test to detect the serotypes of this six large-scale cattle farms,Ten of them are identified,including eight kinds of serotypes, they are O101,O7,O11,O20, O30,O44, O1,O76.Serotypes are different in different regional.(3)Using the method of multiplex PCR to detect Adhesin genes and enterotoxin genes,the results showed 49 isolated strains carrying K99 fimbriae gene、F41 fimbriae gene and Sta Enterotoxin gene,the positive rate is 92.5%. The majority of isolates carrying K99, F41 and Sta virulence factor are enterotoxigenic Escherichia colis.(4)The result of drug sensitive test experiments shows that drug tolerance of E.coli is different in different regions and different Antibiotics, most isolated strains are resistant to ampicillin, amoxicillin, amoxicillin/clavulanate,cephalothin,cefradine,gentamicin,ciprofloxacin and insensitivity to amikacin, Cefoxitin.(5)Using the method of intraperitoneal injection to mice, 10 representative strains come from different regions Infected mice and all of them were killed at 12 ~ 36 h,9 of them can cause death within 12 h, 10 healthy control group of mice are alive.Dissecting death mice and obtaining livers within a sterile environment,through Isolation and Identification of bacteria, E.coli are received from death mice and proving isolates have strong pathogenicity.In conclusion,the E.coli of carrying K99 fimbriae gene、F41 fimbriae gene and Sta Enterotoxin gene are one of the main reason that caused diarrhea of calves. This study initially revealed the prevalence of drug resistance and virulence genes of Bovine E.col in parts of Xin Jiang and provided a scientific reference of drug prevention and immunization for the area.