| With the deve lopment of modern breeding,antimicrobial use(AMU) is bec oming essential to food animal production. Ant imicrobials are used to treat and preve nt disease, enhanc e feed efficiency and promote the growth of animals. Antimic r obial s have been be nefic ial to animal husbandry and veterinary medic ine, but ma ny bacterial specie s have e volved to become resistant under pre ssure of these antimic robials. The drug-resi stant bacteria are making it more difficult to successfully treat infections. However, as the serious abuse of antibiotics in the li vestock and poultry, Esc herichia coli strai ns from swine are becoming increas ingly resistant to most antibiotics. Li ves tock animals might act as a res ervoir for resistant bac teria, which can be transferred to humans e ithe r thr ough environmental routes or through the food chain. the re i s a need t o monitor antimicrobial use( AMU) and antimicrobial r esis tance(AMR) in livestock indus tries.In order to investigate the antimicrobial resistance of Escherichia coli from s wi ne, a total of275 Es cheri chia coli isolates were collect ed from 318 swine sampl es in Jilin Provi nce, including samples from healthy live pigs, piglets suffered from diarrhea and pork from make t.Susceptibility of 275 isolates to fifteen antimicrobial a gents was tested. The phylogenetic background was det erminated by mult iple x PCR. The results indicated t hat 176 of 275 isolates were multiple resistant, meani ng that 64% of the E. coli strains were r esis tant to more t han 3kinds of antimicrobial age nts. All of the isolates were sensit ive t o meropenem and polymyxin B.In addi tion, the drug-resistant rates to quinolones, tetracycline, chloramphenic ol, sulfanilami de,and β--lactam antibiot ics of the E. c oli isola tes from diarrhea piglets are rema r kbly higher than thos e from healthy swi ne and por k. The major ity of i solates bel onged to phylogenetic group A and B1, whi ch are of non-pathogeni c. The pr oportion of group A and group B2 of E. coli strains from diarrhe ic pi glet s is remarkably higer than those from heal thy swine.According to the detec tion of resistance genes with Escherichia coli fr om swine of high resistance r ate, the molecular genetic bas is and molecul ar epidemiol ogy wer e explored. Three kinds of ESBLs genes, CTX-M,TEM and SHV of β-lactamase encoding genes and six kinds of TET genes, tet(A),tet( B),te t(C),tet( D),tet(M) and t et(W) were investigate d by PCR. 116 E.coli isolates carrie d the bl aTEM-2 gene. bla CTX-M ge ne is predominant. tet( A), tet(B), t et(C)and tet(M) were detected wit h the rates of 64%, 22%( 1/55), 1% and 5%, r espect ivel y.tet(A)/tet(B) i s predominant.In order to investigate the role of conjugative plasmid i n the spread of antibiotic res istancein mul ti-drug resistant Escherichia coli, 50 swine Escherichia coli i solates carrying mult i-drug resistance were selected for conj ugal tr ansfe r assays. The donors and transconj ugants against 12 different antimi crobial agents were tested by means of Kirby-Baue r disc agar diffusion. The multiplex PCR wa s used to determinat e plasmid replicon typing. Among 50 donor isolates of Escherichia coli, a total of 18 donor i solates was conjugated success fully. The conjugation rate was 36%. Most of plasmids in the 18 tra nsconjugant s belonged to FI B. The result re veals that conjugative plasmids play a ma jor role in the spread of bacteri al drug-resistance. Thi s investigation aquire the epidemiol ogical bac kgr ound and basic data of drug resistance of E. coli from swi ne and study the horizontal spread of multi-drug resistance. It could give some directions to clinical me dication and drug resistanc e surveillance. |
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