AcrAB-TolC主动外排系统与猪源耐药大肠杆菌多重耐药的相关性

Correlation between AcrAB-TolC active efflux system and multidrug resistance in porcine drug-resistant Escherichia coli

以前期获得的25株猪源耐药大肠杆菌为试验菌株,采用药敏纸片法测定以上分离菌株对氟苯尼考、多西环素、庆大霉素等11种药物的敏感性,并分析其多重耐药表型;采用PCR方法和实时荧光定量PCR方法分别检测25株猪源大肠杆菌中AcrAB-TolC主动外排基因的携带率以及不同耐药数量的多重耐药菌株的外排泵基因arA和acrB的表达量,同时分析其主动外排调控基因marA、soxS、robA和acrR相对表达量的差异,从mRNA水平上探讨外排泵基因表达量和调控因子与大肠杆菌多重耐药性的相关性。结果显示,25株耐药大肠杆菌中acrA、acrB和tolC等3种主动外排基因的携带率分别为68.00%、72.00%和76.00%;acrA、acrB这2种主动外排基因以及调控基因marA和soxS的相对表达量和多重耐药的耐药谱数呈正相关,调控基因acrR的相对表达量和多重耐药的耐药谱数呈负相关;robA调控基因的表达量均低于标准菌株,且与耐药谱数无明显相关性。结果表明,猪源耐药大肠杆菌携带acrA、acrB、tolC等3种基因主动外排基因的携带率较高,且与多重耐药菌株的耐药谱具有相关性;调控因子的表达量亦与多重耐药的耐药谱具有相关性。

The 25strains of pig-resistant E.coli obtained in the previous period were used as test strains,and the sensitivity of the above isolates to 11drugs such as florfenicol,doxycycline and gentamicin was determined by Kirby-Bauer method,and the phenotype of multidrug resistance was analyzed.PCR and real-time quantitative PCR were used to detect the carrying rate of AcrAB-TolC active efflux genes in 25strains of E.coli and the expression of arA and acrBin efflux pumps of multi-drug resistant strains with different drug resistance.At the same time,the differences in the relative expression levels of active efflux regulatory genes marA,soxS,robA and acrR were analyzed.The relationship between efflux pump gene expression and regulatory factors and multidrug resistance of E.coli was investigated from the mRNA level.The expression rates of acrA,acrBand tolCactive efflux genes in 25strains of E.coli were 68.00%,72.00% and 76.00%,respectively;the relative expression levels of acrA and acrB active efflux genes and regulatory genes marA and soxS were positively correlated with the multidrug resistance spectrum,and the relative expression of acrR was negatively correlated with multidrug resistance;the expression level of robAregulatory gene was lower than that of the standard strain,and there was no significant correlation with the drug resistance spectrum.The drug-resistant E.coli has a high carrying rate of acrA,acrB and tolCactive efflux genes,and is associated with the drug resistance spectrum of multi-drug resistant strains.The expression level of regulatory factors is also correlated with the multidrug resistance spectrum.