耐碳青霉烯类肺炎克雷伯菌产酶耐药机制及同源性分析

目的探讨肺炎克雷伯菌对碳青霉烯类抗菌药物耐药的主要产酶机制及同源性。方法收集长沙市第一医院2016年12月-2017年12月临床分离的非重复碳青霉烯耐药肺炎克雷伯菌(CRKP),采用改良碳青霉烯酶灭活试验(mCIM)检测碳青霉烯酶,聚合酶链反应(PCR)法检测常见耐药编码基因。脉冲场凝胶电泳(PFGE)和多位点序列分型(MLST)分析同源性。结果共收集到57株CRKP,mCIM试验阳性率为91.23%(52/57)。PCR共检出6种耐药基因,包括blaSHV、blaCTX-M-9群、blaKPC-2、blaTEM、blaCTX-M-1群和blaNDM-1,检出率分别为94.74%、68.42%、68.42%、56.14%、3.51%和1.75%,其中2株携带blaCTX-M-1群的菌株经测序证实为blaCTX-M-80和blaCTX-M-123,blaCTX-M-9群中1株为blaCTX-M-27,2株为blaCTX-M-14,其余均为blaCTX-M-65。PFGE结果显示,57株CRKP可分为A~H共8种不同的型别,以A型为主,占76.79%,其中A6亚型占32.56%。MLST结果显示,共检出ST11和ST29两种型别,以ST11为主,占75.00%。结论该院临床分离的肺炎克雷伯菌对碳青霉烯类抗菌药物耐药的重要机制为产KPC-2型碳青霉烯酶,且同时携带多种超广谱β-内酰胺酶(ESBLs)耐药基因。PFGE和MLST结果表明:该院临床分离的CRKP存在克隆传播,需加强流行病学监控。

Mechanism of carbapenemase-producing and homology analysis of carbapenems-resistant Klebsiella pneumoniae

OBJECTIVE To explore the main enzyme-producing mechanism and homology analysis of Klebsiella pneumoniae resistance to carbapenems. METHODS Non-duplicated CRKP strains clinically isolated from Dec. 2016 to Dec. 2017 in the First Hospital of Changsha were collected, modified carbapenemase inactivated test(mCIM) was used to detect carbapenemase and PCR assay was used to detected common resistance coding genes. Pulse field gel electrophoresis(PFGE) and multi-site sequence typing(MLST) were used to analyze the homology of CRKP. RESULTS A total of 57 CRKP strains were collected, and the positive rates of mCIM test was 91.23%(52/57). A total of 6 resistance genes were detected by PCR, including blaSHV, blaCTX-M-9 group, blaKPC-2, blaTEM, blaCTX-M-1 group and blaNDM-1, and the detection rates were 94.74%, 68.42%, 68.42%, 56.14%, 3.51% and 1.75%, respectively. Among them, two strains carrying blaCTX-M-1 group were confirmed by sequencing to be blaCTX-M-80 and blaCTX-M-123, respectively, one strains in blaCTX-M-9 group was blaCTX-M-27, and two strains were blaCTX-M-14, and the rest were all blaCTX-M-65. PFGE results showed that 57 strains of CRKP can be divided into 8 different types from A to H, with A type dominated, accounting for 76.79% of which, A6 subtype accounted for 32.56%. The results of MLST showed that ST11 and ST29 were detected, mainly ST11, accounting for 75.00%. CONCLUSION The important mechanism of K. pneumoniae isolated from the hospital for resistance to carbapenems was the production of KPC-2 carbapenemase, and it also carried multiple extended-spectrum-lactamases(ESBLs) resistance genes. The results of PFGE and MLST showed that the clinical isolation of CRKP in this hospital had clonal transmission, and epidemiological surveillance needs to be strengthened.