产blaNDM-1肺炎克雷伯菌的高水平多黏菌素耐药株制备及耐药机制研究

摘要：目的 研究产blaNDM-1肺炎克雷伯菌产生多黏菌素耐药的可能性，并对相关机制进行分析。方法 通过黏菌素肉汤 传代培养研究携带blaNDM-1菌株产生多黏菌素耐药的可能性，并对分离出的耐药株通过PCR、Real-time PCR、脉冲场凝胶电泳等 方法进行耐药分子机制研究。结果 通过黏菌素肉汤传代培养，产blaNDM-1肺炎克雷伯菌可进一步表现高水平多黏菌素耐药表 型。检测发现耐药株中膜孔蛋白基因及双组分调节系统中多黏菌素耐药相关基因发生表达水平变化，可能导致菌株对多黏菌素 高水平耐药。结论 产blaNDM-1肺炎克雷伯菌经黏菌素传代诱导培养后可进一步发展多黏菌素耐药，需要引起临床注意。

High level polymyxin resistantisolates induced by colistin in blaNDM-1 carrying K. pneumoniae and study of the resistance mechanisms

Abstract Objective To study the possibility of polymyxin resistance development in blaNDM-1-carrying K. pneumoniae strains and to analyze the resistance mechanisms of the related isolates. Methods The possibility of polymyxin resistance development in blaNDM-1-carryingstrains was studied by colistin induction in broth. Phenotypic analysis of drug resistance was performed by minimal inhibitory concentration (MIC) determination. The related mechanisms were explored by PCR, Real-time PCR and pulse-field gel electrophoresis analysis (PFGE). Results After colistin induction, the blaNDM-1-carryingstrains demonstrated high level polymyxin resistance phenotype. Further mechanism explorations demonstrated the expression level changes of the membrane porin protein genes and the polymyxin resistance related two-component regulatory system genes in the related isolates, which are the possible reasons for the high level polymyxin resistance. Conclusion The blaNDM-1-carrying K. pneumoniae canfurther develop polymyxin resistance by colistin induction in broth, which deserves attention in clinic.