碳青霉烯类抗生素敏感性下降肺炎克雷伯菌耐药机制及分子流行病学研究

目的:研究临床分离对碳青霉烯类抗生素敏感性下降肺炎克雷伯菌的耐药机制及同源性分析。方法:收集对碳青霉烯类抗生素敏感性下降肺炎克雷伯菌25株。E test法测定10种抗菌药物的MIC值;脉冲场凝胶电泳分析菌株同源性;PCR及克隆测序分析耐药基因型。结果:25株菌株对β-内酰胺类抗生素呈多重耐药,但对多黏菌素E和替加环素敏感。PFGE分型除一株外均为同一克隆(暗示医院内感染)。25株菌株均产KPC-2碳青霉烯酶基因,并同时携带CTX-M、SHV、DHA等多种耐药基因。结论:携带KPC-2基因的肺炎克雷伯菌同时携带多种耐药基因。此类菌株对碳青霉烯类抗生素敏感性下降并对除多黏菌素E和替加环素外抗生素多重耐药。

Study on the antibiotic resistance mechanism and the molecular epidemiology of Klebsiella pneumoniae with reduced susceptibility to Carbapenems

Objective:To investigate antibiotic resistance mechanism and clonal relatedness of Klebsiella pneumoniae with reduced susceptibility to Carbapenems.Methods:25 strains of Klebsiella pneumoniae with reduced susceptibility to Carbapenems were collected.The minimum inhibitory concentrations of these strains to 10 kinds of antibiotics were examined by E test.The homology of these isolates was analyzed by pulse-field gel electrophoresis.The encoding gene of β-lactamases were analyzed by PCR and verified by DNA sequencing.Results:All strains of Klebsiella pneumoniae were multi-resistant to β-lactam antibiotics,while susceptible to Colistin and Tigecycline.They were classified into the same clone(suggest nosocomial infection) except one based on PFGE pattern.All of the 25 strains produced Carbapenemases which were confirmed as KPC-2 by PCR and sequencing.These isolates with positive KPC-2 also carried other resistance genes such as CTX-M,SHV,DHA.Conclusion:All of the positive KPC-2 Klebsiella pneumoniae carried other resistance genes.These strains were low susceptibility to Carbapenems and multi-resistant to other antibiotics except Colistin and Tigecycline.