| Recently,with the increasing use of antibiotic promotes the emergence of E.coli resistance that brings great challenges to clinical treatment.Due to the increasing prevalence of multidrug-resistant bacteria,especially these bacterias often carried carbapenem resistance genes.Unfortunately,colistin resistance phenomenon was quickly becoming more and more serious.The polymyxin resistance was considered to be caused by chromosome mutation,since plasmid-mediated colistin resistance gene mcr-1 was reported by Chinese scientist firstly,and mcr-1 gene in conjugative plasmid,and may be accompanied by a transfer plasmid and spread and diffusion,plasmid-mediated colistin resistance mcr-1 was becoming a hot research.Comparison and analysis of the local data carrying resistance to antibotic E.coli for pigs in different regions of China at different year in feces.Antimicrobial susceptibility testing of E.coli isolates from four areas including Gudong Province,Henan Province and Liaoning Province,were determined with the broth dilution method following the Clinical Laboratory Standards Institute(CLSI)guideline.The resistance rate of E.coli isolate from all the four areas of ampicillin,tetracycline,doxycycline,florfenicol was more than 70%,the resistance rate of apramycin,gentamicin,ciprofloxacin was between 10% to 30%.But the strains were sensitive to cephalosporins and amikacin.Using the PCR method for screening of colistin resistance gene;the minimum inhibitory concentration(MIC)experiment to determine the antimicrobial resistance by conjugation experiments to determine the drug resistance genes to spread,and the level of mechanism.Results show:From a total of 2780 swine fecal samples were isolated and identified 1992 strains of Escherichia coli including the 764 from the abattoir of Guangdong Province,the 635 from the farm of Guangdong Province,the 271 from the farm of Henan Province,the 322 fromthe abattoir of Liaoning Province,the total isolation rate was 72%.The selection of two different farms in different years of 95 isolates that were mcr-1positive take conjugation experiment,a total of 51 transconjugants were successfully obtained,conjucation rate was 46%,including the 25 conjucations from the farm of Guangdong Province,the congjucaton rate was 46%;the 26 congjucations from the farm of Henan Province,the congjucation rate was 63%.Of 51 conjucations of colisin resisitant Escherichia coli isolates plasimd replicon genotyping,Escherichia coli plasimd replicon common genotypes,the result showed that the 4 kinds of plasimd detected.The result showed that the prevalence of IncX4-plasimd in51 conjucations was 69%(n=35),follow by IncI2-plasimd was 15%(n=8).The result of this study showed the resistance of Escherichia coli strains obtained from four areas of three provinces,in particular,the ampicilin,tetracycline,doxycycline drug resistance were more than 70%.The resistance rate of colistin was the highest in 2015,the lowest in 2017.The detection rate of mcr-1 gene was similar to the resistance rate of colistin.Though the monitouring of different regions in different years of pig resistance to colistin of Escherichia coli in data obtained from three provinces,provide reference date on resistence to polymyxin mcr-1 mechanism.The horizontal transmission of IncHI2 plasmids,as carriers of multiple resistance genes,among E.coli in animals,animal-derived food,and humans,is not only a challenge to animal husbandry industry,but also poses a serious threat to human therapy and public health. |
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