细菌NDM-1质粒耐药表型与其表达的相关性研究

Correlation analysis betweenthe resistant phenotype and the blaNDM-1 gene expression in NDM-1-producing bacteria

目的探讨NDM-1质粒携带菌株耐药表型与其基因表达的相关性,为临床抗菌药物选择提供理论参考。方法携带NDM-1的质粒电转化入大肠埃希菌TOP10,采用琼脂平板倍比稀释法测定碳青霉烯类药物对野生株和电转化子的最低抑菌浓度(minimal inhibitory concentration,MIC),TaqMan RT-PCR检测碳青霉烯类耐药菌株的blaNDM-1基因表达及亚-MIC亚胺培南诱导对blaNDM-1基因表达的影响。结果12株产NDM-1菌株中共有8株电转化成功,电转化子对碳青霉烯类药物的耐药性与野生菌株基本一致。细菌对碳青霉烯类的耐药性与blaNDM-1基因表达成正比。亚-MIC亚胺培南诱导后菌株对碳青霉烯类药物的MIC值和blaNDM-1基因表达均显著高于野生株。结论碳青霉烯类耐药菌株耐药表型与blaNDM-1基因表达具有正相关性,TaqMan RT-PCR检测可快速准确地为临床治疗提供依据。

Objective To investigate the correlation between the resistant phenotype and the blaNDM-1 gene expression in NDM-1-producing strains,and provide a theoretical reference for the selection of clinical antibacterial drugs.Methods The plasmid carrying NDM-1 was electroporated into Escherichia coli TOP10,and the minimal inhibitory concentrations(MIC)of carbapenems on wild-type strains and electrotransformants were determined by the agar plate dilution method.Taq Man RT-PCR was used to detect the expression of the blaNDM-1 gene in carbapenem-resistant strains and the effect of sub-MIC imipenem on the blaNDM-1 gene expression.Results Eight out of 12 NDM-1-producing strains were successfully transferred into TOP10 by eletrotransformation.The resistance of electrotransformants to carbapenems was similar with that of wild-type strains.There was a positive correlation between carbapenem resistance and the blaNDM-1 gene expression.Moreover,the carbapenem MIC values and the blaNDM-1 gene expression of strains induced with sub-MIC imipenem were significantly higher than those of wild-type strains.Conclusion The resistant phenotype of carbapenemresistant strains showed a positive correlation with the blaNDM-1 gene expression.The detection of the blaNDM-1 gene by Taq Man RT-PCR could provide a rapid and accurate treatment measure.