大肠埃希菌对碳青霉烯类抗生素的耐药机制研究

Resistance mechanism of Escherichia coli to carbapenems

目的研究中国大肠埃希菌对碳青霉烯类抗菌药物的主要耐药机制。方法测定38株耐碳青霉烯类大肠埃希菌(CRECO)的最低抑菌浓度(MIC);mCIM和eCIM法检测菌株的碳青霉烯酶;外排泵抑制试验检测菌株的外排泵表达;对碳青霉烯酶基因和外排泵基因扩增测序。结果共29株菌产碳青霉烯酶;携带blaNDM-1、blaNDM-5、blaNDM-7、blaIMP和blaKPC-2基因的菌株分别为10,15,1,1和2株;28株菌外排泵抑制试验阳性,所有菌株都携带acra/acrb基因。结论大肠埃希菌对碳青霉烯类抗生素主要的耐药机制为产碳青霉烯酶和外排泵。blaNDM-1和blaNDM-5为主要碳青霉烯酶基因。主要外排泵为AcrAB-TolC三联转运系统。

Objective To investigate the main resistance mechanism of Escherichia coli.Methods The minimal inhibitory concentrations(MIC)of 38 strains of carbapenem resistant Escherichia coli were determined;carbapenemase-producing Escherichia coli was detected by the mCIM and eCIM;The existence of efflux mechanism and efflux pump genes of all strains were detected by the efflux pump inhibition test and PCR amplification.Results There are 29 carbapenemase producing strains were detected,in which,15 and 10 strains contain blaNDM-5 and blaNDM-1 genes,2 strains contain blaKPC-2 and the rest 2 strains contain blaNDM-7 and blaIMP genes.A total of 28 strains were positive for efflux pump inhibition test,all strains carried acra/acrb genes.Conclusion The main resistance mechanism of Escherichia coli to carbapenems are carbapenemase producing and efflux system.ndm-1 and ndm-5 are the main genes of carbapenem.The main efflux pump is AcrAB-TolC system.