Analysis Of Antimicrobial Resistance Of Escherichia Coli From Retail Livestock And Chicken Meat In Urumqi

To investigate antibiotic resistance and drug resistant genes of Escherichia coli from retail livestock and chicken meat in Urumqi,Xinjiang,and to preliminarily explore the horizontal transmission rule of drug-resistant genes,so as to provides a basis for the prevention and control of bacterial drug resistance of meat products.E.coli were isolated from retail livestock and chicken meat samples(n=353)in different regional fresh nineteen supermarkets in seven districts of Urumqi,including chicken(n=90),pork(n=90),beef(n=84)and mutton(n=89).Those isolates were screened and isolated by Mc Conkey medium and CHROMagar^TMOrientation,and identified by specific 16S r DNA.The phylogenetic groups of the isolates were analyzed using multiplex PCR,resistance of isolates were determined by K-B disk diffusion method,and corresponding resistant genes were amplified by PCR and sequenced.The plasmid replicon typing and integrons of bla⁺_CTX-M isolates were detected by multiplex PCR,and completed conjugation experiments of bla⁺_CTX-M isolates by the filter method;analyze the homology among the bla⁺_CTX-M isolates by PFGE typing method.A total of 252 strains were isolated from 353 meat samples.The results of the phylogenetic group analysis showed a domination by groups A(79.4%),followed by B1(12.3%).The resistance phenotypes test shows that 40.5%of the 252 isolates were multidrug-resistant,mainly with triple resistance.Multi-drug resistance rate of pork source isolates(62.3%,43/69)>mutton source(35.3%,24/68)>chiken source(33.3%,20/60)>beef source(27.2%,15/55).Those strains were highly resistant to tetracycline(49.6%),ampicillin(41.6%)and sulfamethoxazole/trimethoprim(30.9%),but were low resistant to amikacin(1.9%),polymyxin B(0.8%),ampicilillin-sulbactam(0.4%).The detection of drug resistance genes tet A,bla _TEM,cml A,aad A1,aac,sul1 and bla _CTX-M were 90.4%,32.1%,31.3%,27.4%,14.5%,12.8%and 12.8%,respectively,whereas tet A,tet B,and tet G were not detected.Nine plasmids out of 18 bla⁺_CTX-M isolates were successfully typed,including five with Inc I1 type plasmids,three with Inc FIB type plasmids and one with Inc Y type plasmids,and 83.3%of the isolates carried class I integrons,with no class II integrons detected.Conjugation experiments show that 18 bla⁺_CTX-M could transfer bla _CTX-Minto the E.coli J53.Twelve PFGE patterns were found in 18 bla⁺_CTX-ME.coli strains,indicated that the homology between different livestock and chicken meat source strains is relatively distant.Bla⁺_CTX-M strains spread mainly by horizontal transmission and individual clonal spread.The contamination of E.coli was serious in Urumqi's commercial livestock and chicken meat,bla⁺_CTX-M E.coli strains were spread horizontally and vertically during the production and processing chain of livestock and chicken meat.The pollution of meat products during the slaughtering,processing and sales process should be prevented and controlled.