Characterization Of The Resistance And Resistance Gene In Escherichia Coli Isolates From Fox

Fox has important economic value in China's breeding industry.Because of the widespread use of antibiotics,bacteria have become more and more resistant,and the spectrum of bacterial resistance has also broadened.Integrons,as a genetic gene,can influence the drug resistance of bacteria by acquiring the surrounding drug-resistant gene cassettes,and can make drug resistance widely spread in the same or different bacteria.The dates can provide reference for the use of various antimicrobial agents in fox,and explore the prevalence of E.coli in fox farms,so as to provide basis for fox and proper use of antimicrobial agents to the guidance of science and technology.In this study,490 fecal samples were collected from healthy foxes in 10 different farms in Northeast China,and E.coli was isolated and identified.The results showed that 376 strains of E.coli were identified and the isolation rate was 76.73%.The drug resistance of E.coli isolated from foxes to 15 kinds of antibiotics was determined according to the drug sensitive disk method recommended by CLSI.The results showed that the drug resistance of ampicillin and tetracycline were higher than 80%.The multi-drug resistant rate of E.coli from fox was 87.88%.The sensitivity to imipenem and amikacin was 86.97%and 83.94%respectively.Molecular epidemiological investigation and analysis of the integron gene cassette system were carried out on the isolated E.coli.Plasmid binding transfer experiment was used to explore the transfer of resistance.The results showed that the detection rates of integrase int?1 and int?2 were 62.77%and 13.56%,respectively,and int?3 was not detected.The detection rate of class 1 integron was 57.20%,which only 29.66%of integrons carried gene cassettes.Class 2 integrons were not detected.Sequence analysis showed that there were 10 gene cassettes with six arrangement patterns,followed by dfrA5,aadA22,dfrA27-aadA2,dfrA1-aadA1,dfrA17-aadA5 and dfrA12-orfF-aadA2.The conjugation transfer experiments were carried out on 70 fox-derived E.coli strains,23 strains successfully transferred the resistant plasmids into the recipient E.coliNK5449.In this study,resistant genes were detected by PCR.The results showed when we aligned the mutation profiles of quinolones from E.coli,Glu16?Gly?Leu55?Pro?Arg68?His?Ser83?Leu?Asn108?Asp and Asn186?Ser in gyrA,Gln441?Pro?Pro445?Leu?Asn 452?Ser and Met461?Ile in gyrB,only Ser58?Ile in parC,Ser458?Ala and Gln479?Arg in parE were detected.The detection rate of TEM gene was the 97.11%.The detection rates of parE?gyrB?parC?OXA?qnrS?aphA 1?gyrA?oqxB and CTX-M were 86.17%.79.79%,72.34%,70.48%,67.82%,64.89%,56.38%,51.33%and 50%,respectively.In this study,we analyzed the drug resistance,integron gene box structure and drug resistance genes of E.coli isolated from foxes in Northeast China,Therefore,the study of integron gene box of Escherichia coli from fox is conducive to the prevention and control of drug resistance of E.coli from fox.Through its epidemiological investigation,we have a more comprehensive control of bacterial resistance.