CAJ | 학술논문

目的研究广州地区携带blaCTX-M-15质粒的分子特征.方法以2007年到2008年期间来源于广州9家医院确证产CTX-M-15 ESBL的38株大肠埃希菌和47株肺炎克雷伯菌为研究对象,脉冲场凝胶电泳(PFGE)和多位点序列分型(MLST)法检测blaCTX-M-15阳性株的同源性,MIC法检测菌株对常用抗生素的敏感性.血清凝集试验确定大肠埃希菌血清型.接合试验了解携带blaCTX-M-15质粒的可接合性,限制性内切酶分析质粒的同源性.PCR分析大肠埃希菌的系统发育群,流行质粒的不相容群和耐药基因构成.结果 blaCTX-M-15阳性的大肠埃希菌和肺炎克雷伯菌分别用PFGE确定为28个和30个基因型.携blaCTX-M-15大肠埃希菌的系统发育群以D群(67.8%)和A群(21.4%)为主.大肠埃希菌血清型呈散在分布,未发现O25:H4血清型.大肠埃希菌和肺炎克雷伯菌的ST型无明显集中趋势,大肠埃希菌中发现非O25血清型的ST131,肺炎克雷伯菌中发现2个新的tonB基因和2个新的ST型.58个独立克隆的代表菌株中有40株可将携blaCTX-M-15的质粒传递给受体菌E.coli C600(Rif),其中大肠埃希菌有19株,肺炎克雷伯菌有21株.57.9%(11/19)的大肠埃希菌中携带blaCTX-M-15的质粒大小为65 kb,85.7%(18/21)的肺炎克雷伯菌中携带blaCTX-M-15的质粒大小为92 kb.限制性内切酶分析显示,这2种质粒属流行质粒,分别命名为p15-e和p15-k.通过PCR调查,p15-e存在blaCTX-M-15和ISEcpI;p15-k上存在blaCTX-M-15、ISEcpI、aac(6')-Ⅰ b、aac(3')-Ⅲ、blaOXA-1、qnrB、qnrS、blaDHA-1、blaTEM-1.p15-k同时被证实属于质粒不相容群FⅡ群.结论广州地区存在携带blaCTX-M-15流行质粒的传播,且流行质粒的大小和基因结构与国外报道不同;无克隆株传播证据.
목적 연구엄주지구휴대blaCTX-M-15질립적분자특정.방법 이2007년도2008년기간래원우엄주9가의원학증산CTX-M-15 ESBL적38주대장애희균화47주폐염극뢰백균위연구대상,맥충장응효전영(PFGE)화다위점서렬분형(MLST)법검측blaCTX-M-15양성주적동원성,MIC법검측균주대상용항생소적민감성.혈청응집시험학정대장애희균혈청형.접합시험료해휴대blaCTX-M-15질립적가접합성,한제성내절매분석질립적동원성.PCR분석대장애희균적계통발육군,류행질립적불상용군화내약기인구성.결과 blaCTX-M-15양성적대장애희균화폐염극뢰백균분별용PFGE학정위28개화30개기인형.휴blaCTX-M-15대장애희균적계통발육군이D군(67.8%)화A군(21.4%)위주.대장애희균혈청형정산재분포,미발현O25:H4혈청형.대장애희균화폐염극뢰백균적ST형무명현집중추세,대장애희균중발현비O25혈청형적ST131,폐염극뢰백균중발현2개신적tonB기인화2개신적ST형.58개독립극륭적대표균주중유40주가장휴blaCTX-M-15적질립전체급수체균E.coli C600(Rif),기중대장애희균유19주,폐염극뢰백균유21주.57.9%(11/19)적대장애희균중휴대blaCTX-M-15적질립대소위65 kb,85.7%(18/21)적폐염극뢰백균중휴대blaCTX-M-15적질립대소위92 kb.한제성내절매분석현시,저2충질립속류행질립,분별명명위p15-e화p15-k.통과PCR조사,p15-e존재blaCTX-M-15화ISEcpI;p15-k상존재blaCTX-M-15、ISEcpI、aac(6')-Ⅰ b、aac(3')-Ⅲ、blaOXA-1、qnrB、qnrS、blaDHA-1、blaTEM-1.p15-k동시피증실속우질립불상용군FⅡ군.결론 엄주지구존재휴대blaCTX-M-15류행질립적전파,차류행질립적대소화기인결구여국외보도불동;무극륭주전파증거.
Objective To study the molecular characteristic of the epidemic plasmids carrying blaCTX-M-15 in Guangzhou. Methods A total of 38 strains of E. coli and 47 strains of K. pneumoniae both producing CTX-M-15 ESBLs were collected from nine hospitals in Guangzhou from 2007 to 2008. The clonal relationship of isolates carrying blaCTX-M-15 was determined by PFGE and MLST. Antimicrobial susceptibility was determined by microdilution test for all isolates. Conjugative plasmids carrying blaCTX-M-15 were obtained by mating and were subject to restriction analysis. PCR was used to determine phylogenetic groups of E. coli,and to study replicon type and the genetic contexts of the plasmids harboring blaCTX-M-15. Serum agglutination test was used to detect the serotype of E. coli. Results The 37 strains of E. coli were classified into 28 genotypes, while the 47 strains of K. pneumoniae were divided into 30 genotypes. ST131 was found in E. coli but not O25 serotype. Two novel-alleles of tonB and new ST were determined in K. pneumoniae. Forty out of 58 isolates represented independent genotypes have been succeeded to transfer the plasmid carrying blaCTX-M-15 to the E. coli C600(Rif) by conjugation. The sizes of plasmids carrying blaCTX-M-15 are 65 kb in 57.9% isolates of E. coli and 92 kb in 87.5% isolates of K. pneumoniae. Two epidemic plasmids were detected in E.coli and K. pneumoniae by restriction enzyme, designated p15-e and p15-k respectively. The blaCTX-M-15 and ISEcpI were identified on p15-e, and the blaCTX-M-15 ,ISEcpI,aac(6')- Ⅰ b,aac(3')-Ⅲ ,blaOXA-1 ,qnrB,qnrS,blaDHA-1 , blaTEM-1 were determined on p15-k. The p15-k also was identified to belong to the incompatible group FⅡ. Conclusion The local dissemination of blaCTX-M-15 appears to be due to the spread of epidemic plasmids harboring blaCTX-M-15. No evidence supports the dissemination of clone strains which carried blaCTX-M-15.