CTX-M型超广谱β内酰胺酶肺炎克雷伯菌的分子流行病学研究

Characterization of CTX-M-type Extended Spectrum Beta-lactamase-producing Klebsiella Pneumoniae

目的了解湖北地区产CTX-M型超广谱β内酰胺酶(ESBLs)肺炎克雷伯菌的流行基因型,为有效预防和控制该类感染提供理论依据。方法临床分离的无重复产ESBLs的肺炎克雷伯菌70株,采用NCCLS表型筛选和确证试验检测ESBLs,采用聚合酶链反应(PCR)检测CTX-M基因型,并采用PCR-RFLP检测blaCTX-M基因分型,质粒接合试验探讨产CTX-M型ESBLs菌株的传播机制。结果70株产ESBLs的肺炎克雷伯菌中,产CTX-M基因型的肺炎克雷伯菌有26株(37%),PCR-RFLP及DNA测序证实其均为CTX-M-1亚组,其中CTX-M-3型最常见,质粒接合试验证实CTX-M型ES-BLs介导的耐药可以水平转移。结论湖北地区存在着CTX-M基因的流行,且产CTX-M型ESBLs菌株的传播机制以质粒介导的为主,可以水平传播,应加强湖北地区产CTX-M型ESBLs菌株的分子流行病学检测。

Objective To explore the molecular transmission mechanisms of CTX-M-type β-lactamases in clinical isolates of Klebsiella pneumoniae for rational use of antibiotics in clinic. Methods A total of nonrepetitive 70 K. pneunoniae isolates with ESBLs were detected by phenotypic confirmatory test based on NCCLS criteria for ESBLs ;CTX-M gene were detected by PCR,and PCR-RFLP and DNA sequencing were carried for blaCTX-M typing;Plasmid conjugatable test was applied to examine whether CTX-M gene was located in conjugatable plasmid or not. Results The incidences of CTX-M-producing were 37% in ESBLs-producing isolates,and all of them were in subgroup of CTX-M-1 ,and majority of which were CTX-M-3 producing strains. CTX-M gene were on transferable plasmids. Conclusion The transmission of CTX-M producing strains is mainly mediated by transferable plasmids,and which force us intensive investigation and effective controll to CTX-M type ESBLs-producing isolates in Hubei province.