Identification And Drug Susceptibility Test Of Pathogenic Escherichia Coli Isolated From Laying Hens And Preparation Of Its Multivalent Inactivated Vaccine

Chicken colibacillosis is kind of disease infected by some serotype Escherichia coli, characterized by omphalitis, hematosepsis, salpingitis, synovitis, granuloma, vitelline peritonitis and ophthalmia etc. With the development of intensive culture and extension of farming output, chicken colibacillosis has been a kind of important infectious diseases, more and more serious, causing enormous economic loss. Effectively prevention and control of chicken colibacillosis is critical for development of chicken farm , more importantly, proper use of antibiotic is main preventive and control measures.Through the sterile acquisition of 40 fresh liver from suspected Colibacillosis in avian of two chicken farms in Xi'an and Tongchuan City for the separation and identification of bacteria, and according to the form of bacteria, cultivating chanracter smearing, staining microscopy, biochemical tests and animal pathogenicity tests,the experiment finaly selected out 21 strains of the endemic avian pathogenic Escherichia coli (E.coli).and examined the antibiotics sensitivity of the strains isolated from the two farms to 20 kinds commonly used antibiotics.the results show that 12 strains E.coli of chicken farm in Tongchuan are obviously resistance to Doxycycline, Amoxicillin, Ampicillin, Pioneerâ… , Pioneerâ…£and Pioneerâ…¥, and are highly sensitive to Norfloxacin, Nitrofurantoin, Ofloxacin and Ciprofloxacin. 9 Strains E.coli of chicken farm in Xi'an are obviously resistance to Streptomycin, Kanamycin, Doxycycline, Amoxicillin and Ampicillin, and are highly sensitive to Hartridge bacteria, Norfloxacin, Ofloxacin, Amikacin, Ciprofloxacin and Tetracycline.21 strains isolated Escherichia coli was send to China institute of veterinary drug control for identification of serotype, obtaining 3 serotype as O78, O1 and O2 6 respectively. Multivalent inactivated vaccine was prepared with obtained 3 kind of serotype Escherichia coli, testing its safety and protection, the results show that no adverse reaction was observed and protective rate was absolute. Field experiment was tested in Xi'an and Tongchuan city, immunizing adult chicken with 0.5 mL dose, results show that no adverse reaction was observed, after immunization, mortality of control decreased from 2.9% and 2.6% to 1.2% and 1.1% respectively. Finally the results above show that the vaccine prepared in the study was able to protect chicken flock effectively.