Study On Epidemiology And The Correlation Analysis Between Resistance Phenotype And Resistance Genes Of E. Coli Strains From Ducks In Sichuan

To investigate epidemiology of the colibacillosis in ducks and resistance of E. coli strains in Sichuan, in this study, E. coli strains were isolated from scaled duck farms in7areas in Sichuan and the serotype and pathogenicity were identified. PCR method was established to detect E. coli strains. The E. coli strains used for the correlation analysis between resistance phenotype and resistance genes. The results are showed as follows:The epidemic situation of pathogenic E. coli strains from ducks in Sichuan In this study bacteria cultivation and biochemical test was performed to isolate and identify208E. coli strains from ducks with suspected duck colibacillosis. E. coli could be detected in most of duck farm, including62strains from Pengzhou,46strains from Meishan,39strains from Xinjin,21strains from Mianyang,19strains from Deyang,13strains from Qionglai,8strains from Dujiangyan.110E. coli strains were pathogenic strains (52.9%,110/208) by the pathogenicity test. The results showed that pathogenic E. coli strains from ducks were widely distributed in Sichuan.The distribution of serotype of E. coli strains from ducks in Sichuan Serotype identification was used for identify208E. coli strains and169E. coli strains (81.3%,169/208) were identified which belong to25kinds of E, coli O serotypes. The dominant serotype of these strains was O3, O26, O76, O81O100abd O127. There are differences of dominant serotypes in different areas. The results showed that the complexity and regionally of E. coli serotypes.11serotypes E.coli were pathogenic strains, and O76and O127were the main popular pathogenic serotypes of E. coli strains in Sichuan by the pathogenicity test.39E. coli strains were not E. coli O groups, and13E. coli strains were pathogenic strains, foreshow the appearance of the new pathogenic E. coli serotypes.PCR method of E. coli strains from ducks was established and clinical application According to the E. coli housekeeping gene phoA, PCR primers were designed to establish PCR method has specificity and sensitivity. The result of sequencing showed that the similarity of the amplified fragment and phoA gene sequence was high (96%).208E. coli strains from ducks were detected by PCR method, and high positive rate (100%). This method was suitable for rapid detection of E. coli in a large number of samples in clinical.The resistance detection and resistance spectrum analysis of E. coli strains from ducks in Sichuan208E. coli strains show different resistance and sensitivity to36species of common antibiotics. The bacteriostasis of IPM (100%) was the best, followed by TZP (98.6%), AMK (95.6%), FEP (92.7%), and CAZ (92.3%). PG and OX was the highest resistance that the resistance rate was100%, followed by TC (95.7%), AMX (87.5%), and DOX (78.4%). The isolated208strains includes25kinds of drug resistance spectrum that it shows multi-drug resistance, more than seven-resistant strains accounted for93.3%of the isolates. The multi-drug resistance of strains in Dujiangyan and Xinjin were the most serious, and the strains resistant to26antibiotics. The resistance rate of PG and OX were high (100%) in different areas. The isolates were not resistance to IPM and TZP which the resistant rates were0%. Strains of different serotypes have multiple resistances. The strains of0142resistance to8～12antibiotics (100%); The strains of O149resistance to13～17antibiotics (100%); The strains of O131resistance to18～22antibiotics (100%); The strains of093resistance to23～28antibiotics (100%); The strains of O1(57.1%)、O2(88.9%)、O3(70.6%)、 O26(78.6%)、O76(64.3%)、O81(73.7%)、O100(64.7%)、O117(100%)、O127(87.5%) and158(100%) resistance to8～17antibiotics.Analysis of resistance gene and resistant phenotype of E. coli strains from ducks in Sichuan187E. coli strains has resistance gene (89.9%,187/208) by PCR to detect resistance gene of208E. coli strains. The detection rate of tetA (79.8%) was the highest, followed by dhps (55.8%), aph(3’)-Ⅱa (32.2%), parC (31.3%), aadA2(24.0%), aadAl (22.1%). The result showed that the popular resistance gene of E. coli strains from ducks in Sichuan were tetA, dhps, parC, aph(3’)-Ⅱa, aadA2, and aadAl. The isolates were detected multiple drug resistance gene, mainly more than3kinds of resistance gene and account for85.6%(178/208) of the isolates. Resistance genes of21E. coli strains (10.1%,21/208) were not detected, and maybe have other resistance genes. The coincidence rate between resistance gene and resistant phenotype was high, among them, AMK with aadAl gene and TOB with aadA2gene were the highest (100%).