Isolation And Identification Of Chicken Escherichia Coli In The Area Of Shanxi Jinzhong

Escherichia coli is the main pathogenic bacteria which caused colibacillosis.It has complex antigenicity and numerous serotypes which can cause acute sepsis and tissue inflammation in airbag,pericardium,oviduct,peritoneum,joints,intestines,brain,eyes and so on.As the poultry industry grows faster and faster,The disease of poultry Escherichia coli is becoming more and more serious and complicated.At present,the infection rate in China can reach 5%to 30%,and the fatality rate is as high as 90%.30 Escherichia coli of chicken samples were collected from the patient or dead chickens in the area of Jinzhong of shanxi province.Chicken Escherichia coli was isolated from liver and cultured in Maconkey Agar and nutrient agar medium to morphological observation.Purified bacteria also did the biochemical test,serological test and animal experiment.Biochemical test included Sugar fermentation,hydrogen sulfide,methyl red(MR),indole(indole)and urease test.In addition,we extracted the genomic DNA of Chicken Escherichia coli and used the universal primer of 16S rDNA to amplify this gene by PCR.After sequenced,the result was compared with the sequence of Chicken Escherichia coli of GenBank to test the homology.And then,the evolutionary tree was constructed for genetic analysis.The results showed that:Firstly,we isolated eight Escherichia coli strains which accorded with the characteristic of the bacterial colony,Gram Stain and biochemistry.The eight Escherichia coli strains was named PY1?PY7?PY8?JX2?JX3?JX4?JX5?JX6.Secondly,the result of PCR experiment showed that the homology between the reference sequence of Chicken Escherichia coli from GenBank and amplified target of gene was 99%The genetic analysis result showed that JX2 with JX3 and PY7 with PY8 strain and was in one branch,respectively,which indicated that they had a more close genetic relationship.But JX6 and PY1 JX2?JX3 had a far genetic relationship with the branch of JX2 and JX3 strains,respectively.It indicated that JX6 strain and PY1 strain may have a variation.JX5 maked up one branch by itself but it had a close gentic relationship with JX4 strains.Thirdly,identified 6 strains,belonging to 3 serotypers,they were 078(PY1,PY7,JX2),O2(JX4,JX6),O11(PY8)serotypes respectively.But we couldn't make sure the serotyper of JX5.Fourthly,the drug susceptibility test of pathogens showed that isolated strains were most sensitive to cefotaxime sodium,azithromycin,kanamycin,gentamicin;were more sensitive to cefradine and the drugs of quinolones.But the isolated strains were multiple drug resistance.The amount of drug reached at least 4,at most 13.The strains which the quantity of drug resistance had more than 5 accounted for 87.5%.There was no intermediate strain in the isolated bacteria strain.The drug resistance rate of quinolones was 75%,and that of amoxicillin,doxycycline and rifampicin were 100%.Lastly,animal experiment was did by intramuscular injecting bacteria solution such an stock solution,diluted 10 times solution and diluted 100 times solution to ten-day chicken.The result showed that PY1?PY7?PY8 strains were belong to virulent strain,JX and JX3 strains were mesogen strain,and JX4?JX5?JX6 strains were low virulent strain.This study confirmed the main serotyper and sensitive drugs of chicken Escherichia coli in the area of Jinzhong of Shanxi province.It lay a foundation for further studying the disease caused by pathogenicity of Escherichia coli and establishing practical and effective prevention and control measures.