Plasmid DNA Analysis, Drug Sensitivity Test And Patterns Of Clinical Isolates Avian Escherichia Coli

The characterization of culture, morphology and biochemistry, antibiotic sensitivity, the patterns of outer membrane protein and plasmid DNA analysis of avian Escherichia coli isolates from chicken breeding farms in Baoding, Qin Huangdao and Beijing areas are investigated in this study. Thirty-eight strains avian Escherichia coli isolates are determined by biochemical test. Among 38 Escherichia coli strains, serotypes of 33 strains are determined. Six kinds of O serogroups, belonging to O₂, O₁₈, O₉₃, O₇₆, O₇₈ and O₈₈ respectively are discovered and 5 strains Escherichia coli are non-typed. Serotyping demonstrates that O₁₈(34.21%), O₇₆(15.79%), O₈₈(19.42%) serogroups are predominant in 6 serogroups. There are multitudinous serotypes, complicated distribution, and large district variety on avian Escherichia coli. Identification of O serotype is in order to focus on prevention and control of avian colibacillosis. Furthermore, the results of the antibiotics sensitivity test of 38 isolates to 24 kinds antibiotics show that all isolates have presented antibiotic resistance disparately as well as multi-resistance. All isolates are sensitive to Cephalosporins antibiotics and Aminoglycosides antibiotics such as Amikacin, Cefazolin, Cefradine, Cefoperazone, and Ceftriaxone. Thirty-eight isolates are extremely resistant to Penicillins antibiotics, Lincomycins antibiotics, Tetracyclines antibiotics and Macrolides antibiotics such as Midecamycine, Lincomycin, Carbenicillin, Tetracycline, Amoxicillin and so on. Antibiotics sensitivity test provides guidance for antibiotic application and scientific foundation from poultry farms. In addition, using supersonic lysis and Sarkosyl extract outer membrane protein (Omp) patterns of 38 strains Escherichia coli are analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Three different Omp patterns are identified with these 38 strains, Of which, O₇₈, O₈₈, O₂, O₁₈, O₉₃, O₇₆ appear Omp-1 pattern, O₇₆ appear Omp- â…¡ pattern, O₉₃, O₇₈, O₈₈, O₂ appear Omp-â…¢ pattern. The results indicate that different serotype strains have the same Omp patterns, and the same serotype strains may have different Omp patterns. The means of O serotype patterns could not reflect genetic relativity among strains completely. Finally, the plamid DNA of 38 strains Escherichia coli is extracted by the method of Kado-Lia and analysed by agarose gel electrophoresis. Plasmids are found in all the strains. Plasmid profile typing obtained 23 plasmid patterns. The comparison of plasminds among strains demonstratesthat the strains derived from the same source exhibite the identical or similar profiles and those from different sources demonstrate the distinct profiles or the similar profiles once in a while. The plasmids of 38 strains Escherichia coli cleaved with Hindlll and EcoR I further prove this result. Plasmid DNA profiles analysis offer scientific reference to molecular epidemiology investigation of avian colibacillosis.