Isolation And Identification Of Duck E.coli And Screening Of Sensitive Drugs In Benxi Region

Duck Escherichia coli infection is a partial or systemic infection of an individual duck with pathogenic Escherichia coli.In the process of large-scale duck feeding,losses caused by the death of Escherichia coli infection are relatively common.The pathological characteristics of Escherichia coli disease in ducks are diverse,the clinical symptoms are complex,and the drug resistance of pathogenic bacteria is greatly different,which has been troubling the development of poultry breeding industry.In recent years,with the gradual formation of large-scale aquaculture,major diseases such as avian influenza and Newcastle disease have been effectively controlled,and the etiology of Escherichia coli shows an obvious upward trend due to its poor attention and low prevention and treatment effect.The duck breeding industry in Benxi area of liaoning province is developing rapidly.The study on the characteristics and drug resistance of duck Escherichia coli strains in this area has important guiding significance for the effective prevention and treatment of duck Escherichia coli disease.In this study,12 duck farms in 5 districts and counties of Benxi city were aseptically collected samples of duck liver suspected to have died of Escherichia coli in ducks for isolation and identification.A total of 24 strains of E.coli were identified by observation of colony morphology and biochemical tests.Among the 24 strains of duck-derived Escherichia coli,except one strain could not be stereotyped,the remaining 23 strains were divided into 9serotypes,among which O₁₅ and O₃₅ were dominant serotypes,and O₁₁₉ was the first serotype detected.These serotypes were detected in 12 farms in Benxi city.The results of pathogenicity test showed that high pathogenicity escherichia coli isolates had strong pathogenicity.Seven strains of highly pathogenic escherichia coli were isolated and distributed uniformly in all duck farms in benxi area.O15 and O35 are the dominant serotypes of duck-derived escherichia coli in benxi area,which were detected in all county farms.The results showed that the isolates of duck Escherichia coli were completely resistant to erythromycin and ampicillin.The drug resistance rate of doxycycline and norfloxacin was58.33%to 62.50%.The drug resistance rate to kanamycin,cefotaxime and ciprofloxacin was41.67%to 50.00%.The drug resistance rate of gentamicin and amikacin was 33.33%to37.50%.The drug resistance rate of fosfomycin is the lowest,only 16.67%.It is suggested that fosfomycin can be used for the treatment of Escherichia coli disease in ducks in benxi area.The cross protection test found that there was no cross protection between O₁₅ and O₃₅ in benxi area.However,in the investigation,the immune effect of single vaccine was not ideal,and it was recommended to use O₁₅ and O₃₅ polyvalent vaccines for protection.