| As a resident bacterium in humans and animals,Enterococcus faecalis can carry a large number of mobile elements to facilitate the transmission of drug resistance genes,and the reports of death caused by Enterococcus faecalis infection are increasing year by year.Therefore,this study took Enterococcus faecalis isolated from pig farms as the entry point,investigated the drug resistance of12 drugs in 8 major categories by agar dilution method on Enterococcus faecalis isolated from farms in Aksu region,Xinjiang,and detected drug resistance genes by PCR and sequencing,molecular typing was used to classify the genetic relationship,the transmission characteristics of multidrug resistance genes optrA and lsa(E)in Enterococcus faecalis were investigated by combining with splice transfer test,and the drug resistance situation in local pig farming was initially assessed.The results of the trial were as follows.1.A total of 322 strains of Enterococcus faecalis were isolated from 1023 samples from four farms in Aksu area with an isolation rate of 33.7%,of which 44 strains were isolated from pig farm A with an isolation rate of 16.4%,81 strains from pig farm B with an isolation rate of 34.6%,35 strains from pig farm C,with an isolation rate of 28.9% and 162 strains from pig farm D with an isolation rate of 40.6%.2.The drug sensitivity results showed that the resistance rates of Enterococcus faecalis from pig farms in Aksu area to erythromycin,tylosin,tetracycline,doxycycline,gentamicin and vonimycin were above 96%,the resistance rates to linezolid,florfenicol,levofloxacin and enrofloxacin were from 14.3% to 42.6%.And the Enterococcus faecalis of swine origin in this area were all multidrug resistant strains,the main resistance spectrum type was 6 ～ 8 resistances,accounting for more than 80.0%,of which 90.9% was 6 ～ 8 resistances in pig farm A,98.7% was 8～ 10 resistances in pig farm B,80.0% was 6 resistances in pig farm C and 97.6% was 6 ～ 8resistances in pig farm D.3.The results of drug resistance genes showed that the detected macrolide resistance genes were erm B mainly,with a detection rate of 97.8%,tetracycline drug resistance genes were tet(M)and tet(L)mainly,accounting for 100.0% and 91.6% respectively,and the detection rate of detected aminoglycoside drug resistance genes aac(6’)-le-aph(2")-Ia was 71.7%,acylglycoside drug resistance genes were dominated by fex(A)and optrA(which also mediates oxazolidinones)with detection rates of 19.6% and 14.6% respectively,and the detection rate of lsa(E),the gene of truncated lateralisins,was 57.1%.4.The results of genetic relationship results showed that the 31 Enterococcus faecalis strains carrying optrA and lsa(E)or only one of the two genes in Aksu region were divided into 2 clonal groups(CC480 and CC16)and 7 individual ST types(ST32,ST81,ST369,ST532,ST632,ST633 and ST1007).PFGE typing classified them into 19 phenotypes,and the genetic relationship combined with splice transfer test results revealed both clonal transmission and horizontal transfer of optrA and lsa(E)genes in Enterococcus faecalis in Aksu region.The results of high-throughput sequencing indicated that the two successfully spliced strains might also have other resistance phenotypes and resistance genes,and a certain number of plasmids and mobile elements were also present,which further supported the possibility of horizontal transfer of resistance genes.In conclusion,the drug resistance situation of Enterococcus faecalis from pigs in Aksu region is serious and the transmission modes of multidrug resistance genes optrA and lsa(E)carried by Enterococcus faecalis are both clonal transmission and horizontal transfer. |
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