Drug Resistance And Resistance Transmission Mechanism Of Escherichia Coli In Central And South China

The drug resistance,distribution and transmission mechanism of genes for Escherichia coli from 7 provinces in Henan,Hubei,Jiangxi,Shaanxi,Hunan,Shanxi and Anhui were studied.The Escherichia coli isolated from chickens collected from the above provinces was identified and the sensitivity of the isolates was tested by micro broth dilution method.The strains were typed with ERIC-PCR,and PCR was used to detect β-lactams,tetracycline,aminoglycosides,quinoxalines,florfenicol,sulfonamides,enrofloxacin,and polymyxin resistant genes bla TEM,flo R,tet related genes,bla CTX related genes,oqx A,oqx B,mcr-1.The mechanism of drug resistance transmission of some drugs was also studied.192 strains of Escherichia coli from chicken were isolated and identified.Escherichia coli is highly resistant to common antibiotics and carries multiple resistance genes.The resistance rates for amoxicillin,cefotifuroxime,cephaloxime,fluphenicol,gentamicin,amikacin,doxycycline,doxycycline,polycolistin,sulfonamides,enoxacin,quinolol,and dysentery were 99.48%,72.92%,54.69%,69.27%,44.27%,20.31%,92.19%,63.54%,32.29%,78.65%,79.69%,16.15%,6.25% espectively.The results of ERIC-PCR molecular typing showed that there were 8 different types for target bands,belonging to 12 different types when the genetic similarity was 75%;when the genetic similarity was 80%,it belongs to 15 different types;when the genetic similarity was 85% and greater than 85%,it belonged to 26 different types.The detection rates of bla TEM,flo R,tet A,tet B,tet C,tet D,tet M,mcr-1,bla CTX-M-1,bla CTX-M-9,bla CTX-M-U,oqx A,oqx B,bla OXA-1,bla OXA-2,bla OXA-10,rmt A,rmt B,rmt C,rmt D,aac-(6’)-Ib,qep A,Sul1,Sul2 and Sul3 were 100%,75.52%,83.33%,50%,17.71%,64.06%,7.29%,38.02%,56.77%,50%,100%,94.79%,81.77%,59.38%,31.25%,3.65%,6.25%,17.71%,6.77%,2.08%,2.08%,2.08%,6.77%,2.08%,54.17%、8.33%、95.83%、96.88% and 17.71% respectively.Conjugation test showed that the heritability of resistance genes in Escherichia coli from chickens was spread horizontally.The subtypes of bla TEM in β-lactam resistant genes main are bla TEM-1 and bla TEM-181.The subtypes of bla CTX-M gene main were bla CTX-M-14,bla CTX-M-15,bla CTX-M-55 and bla CTX-M-65,and bla CTX-M-3,bla CTX-M-27 and bla CTX-M-90 were exist.In the genetic environment of bla CTX-M-1 and bla CTX-M-9,ISEcp1 was detected in the upstream,but the downstream of bla CTX-M-1 was dominated by orf477,and the downstream of bla CTX-M-9 was dominated by IS903.In this experiment,a more complete tet M gene environment was obtained.This environment was more complex,including IS26,tnp A 1,orf13,Gamma Delta,tnp X and tnp R downstream of tet M.In the conjugation test,the conjugation rates of tetracycline,aminoglycosides and polymyxin resistant strains were not high,14.29%,28.57% and 20%,respectively.tet A、tet B、tet C、tet D、tet M、bla TEM、flo R、mcr-1、bla CTX-M-U、bla CTX-M-9、bla CTX-M-1、bla OXA-2、oqx A、oqx B、rmt B、rmt E、rmt H、arm A、Sul1、Sul2、Sul3、bla NDM and other genes could be transferred with the transfer of plasmids in the conjugation test.These genes may be located on mobile plasmids.