Isolation And Identification, Biological Characteristics Of The Study Of E.coliO157:H7

E. coli (Escherichia coli), commonly known as E. coli, belonging to of Enterobacteriaceae(Enterobacterriaceae) genus Escherichia (Escherichis), the vast majority of warm-blooded animalgut dominant facultative anaerobic sojourn floraunder normal circumstances, the animal’s bodydoes not have the disease-causing ability. Later research found that different pathogenicity ofdifferent serotypes on the body, O157: H7serotype main serotypes of E. coli, and humanhemorrhagic colitis and hemolytic uremic syndrome，asymptomatic carriers of cattle, sheep andother ruminants，Serious threat to the public health and safety。In1982，The first time the bacteriaisolated from stool specimens of patients with diarrhea in USA, Also reported with theconsumption of hamburgers. Since then，Western countries such as the United States, the UnitedKingdom, Canada, Japan and China reported caused by EHEC O157: H7outbreaks and sporadiccases rapid increase。As the O157: H7has low infectious dose, pathogenic strong and seriousclinical symptoms，So that infection has become a global public health problem widespreadconcern。This topic is taken diseased three different parts of the cattle (cattle farm in Anhui province, acattle farm in Heilongjiang and Shandong cattle) Isolation and identification of bacteria, one of themore serious a cattle farm in Heilongjiang，There were more than3000cattle in a cattle farm.,Some calves were borned successively in the end of October2011, After the first stage of calvesborn1to3days, calves began to appear watery diarrhea, survival of calves from1to3months,There were gradual death phenomenon, the necropsy of them presented intestinal mucosa bleeding,renal parenchymalvariability of spleen enlargement, liver and kidney. Diseased dead cattlecollected to laboratory diagnosis, biochemical experiments,susceptibility testing， pathogenicityexperiments and detection of virulence genes.Results: Biochemical results show Glucose, lactose,xylose, mannose, maltose, mycosis sugar, fructose, nitrates, Euonymus alcohol indigo matrix ispositive, Raffinose, sorbitol, VP, sucrose, H2S and citrate as negative The pathogen causing bovineonset as enterohemorrhagic E. coli O157: H7By PCR, To the sensitive nature of the analysis ofE.coli O157: H7isolates using the Kirby-Bauer method,it had a higher sensitivity to gentamicin,card kanamycin and chloramphenicol, etc, It had higher degree of drug resistance to Penicillintetracycline and ampicillin, etc and had moderate degree of drug resistance to ciprofloxacin,streptomycin and rifampicin,etc. It was showed that EHEC O157: H7had a high pathogenicity bypathogenic experimental results. the virulence of test results show that LD50of E.coli O157: H7is7.9×10~7CFU，MLD is5.0×10~6CFU. E.coli O157: H7isolates is detected ofvirulence genes by PCR,which is eaeA, stx1and hly gene co-exist. Of Anhui cattle A1strain) andShandong cattle (S1strain) organisms isolated were identified by PCR colon Escherichia coli, A1strains biochemical results: glucose, lactose, xylose, mannosesugars, maltose, mushroom sugar,fructose, nitrate, sorbitol, Euonymus alcohol, indigo matrix is positive; raffinose, VP, sucrose, H2Sand citrate was negative. Susceptibility test results show: ceftazidime and amikacin, tobramycin,cefoperazone and furans properly because of high sensitivity; but on the erythromycin, cefotaximepalate and the ofloxacin, Lifestyle flat minor resistance; there is a strong resistance tociprofloxacin, chloramphenicol and tetracycline antibiotics. Pathogenic experimental results showthat there is a certain pathogenicity; S1strains biochemical results: glucose, lactose, xylose,mannose, maltose, mushroom sugar, fructose, nitrate, sorbitol, sucrose, Euonymus alcohol indigomatrix is positive; the raffinose, VP, H2S and citrate negative; susceptibility test results showedthat: there is a strong resistance to antibiotics such as chloramphenicol, streptomycin, norfloxacinand erythromycin sex; cefoperazone, amikacin strong sensitivity; degree of resistance toceftazidime and tobramycin; showed no significant sensitivity to nitrofurantoin in mediation;pathogenic the experimental results show that there is a certain pathogenicity...