摘要
目的调查分析高黏液型肺炎克雷伯菌(HMKP)的荚膜血清分型及分子特征,探究其碳青霉烯类耐药获得的可能机制。方法筛选出南昌大学第一附属医院2012-2016年分离的碳青霉烯类耐药-HMKP(CR-HMKP)菌株,采用PCR检测其荚膜血清分型、毒力基因及耐药相关基因,采用多位点序列分型(MLST)方法及脉冲场凝胶电泳(PFGE)方法进行细菌的同源性分析,并采用接合试验分析碳青霉烯类耐药基因的传播性。结果 2012-2016年临床分离碳青霉烯类耐药肺炎克雷伯菌675株,其中筛选出CR-HMKP菌株18株(2.7%),除1株wzi128-K1型、1株wzi206-K57型和2株wzi2-K2型菌株外,其余荚膜分型均为wzi64-K14.64型。PCR及测序结果显示,blaNDM-1 2株,blaKPC-2 17株,qnr S1 18株,blaCTX-M-3 3株,blaCTX-M-14 18株,blaTEM-1 16株,blaSHV-12 17株,rmt B 5株。CR-HMKP菌株均携带有毒力相关基因,其中rmpA(88.9%,16/18)、mag A(5.6%,1/18)、iro N(83.3%,15/18)、aerobactin(27.8%,5/18)、rmpA2(66.7%,12/18)及mrk D(100%,18/18)。CR-HMKP菌株共有3个ST分型,分别为ST11型15株、ST86型2株、ST412型1株。PFGE显示CR-HMKP分为A、B、C 3群,其中B群和C群分别为ST86型和ST412型,而A群均为ST11型。所有携带KPC-2基因的菌株均为ST11型,接合试验显示5株CR-HMKP接合成功,接合率27.8%。结论本研究表明CR-HMKP菌株以wzi64-K14.64荚膜血清分型为主,部分可通过接合获取KPC-2基因而产生并流行。此外,CR-HMKP菌株既可存在于高流行的ST11型,也可携带K1/K2等高毒力荚膜血清分型,应引起高度重视。
Objective To investigate the capsular polysaccharide （CPS） serotypes and molecular characteristics of carbapenem resistant hypermucoviscous Klebsiella pneumoniae （CR-HMKP） and study the possible mechanism of carbapenem resistance. Methods A retrospective study was conducted on 18 nonduplicate CR-HMKP strains which were collected from the First Affiliated Hospital of Nanchang University from 2012 to 2016. The clinical data were retrieved from medical records. The capsular serotypes, resistance genes and virulence factors were detected by polymerase chain reaction and DNA sequencing. Antimicrobial susceptibility testing was determined on VITEK 2 compact system. The CR-HMKP strains were characterized molecularly by using PCR, multilocus sequence typing （MLST） and pulsed field gel electrophoresis （PFGE）. Modified carbapenem inactivation method was used to screen carbapenemase-producing strains. Plasmid conjugation transfer experiments were carried out to study transmission of carbapenem resistance.Results Eighteen （2.7%） CR-HMKP isolates were identified, which belonged to 4 serotypes, including wzi128-K1 （n=1）,wzi206-K57 （n=1）, wzi2-K2 （n=2）, and wzi64-K14.64 （n=14）. PCR and sequencing analysis identified blaNDM-1 gene in 2 CR-HMKP strains, blaKPC-2 gene in 17 strains, qnrS1 gene in 18 strains, blaCTX-M-3 gene in 3 strains, blaCTX-M-14 gene in 18 strains, blaTEM-1 gene in 16 strains, blaSHV-12 gene in 17 strains, and rmtB in 5 strains. All the 18 CR-HMKP strains carried virulence-associated genes, including rmpA （88.9%, 16/18）, magA （5.6%, 1/18）, iroN （83.3%, 15/18）, aerobactin （27.8%, 5/18）, rmpA2 （66.7%, 12/18） and mrkD （100%, 18/18）. Three sequence types （STs） were identified by MLST, including ST11 （15 strains）, ST86 （2 strains）, and ST412 （1strain）. PFGE resulted in three major PFGE clusters, of which cluster A corresponds to ST1 isolates, and cluster B corresponds to ST86 isolates, and cluster C corresponds to ST412 isolates. All the blaKPC-2- positive strains belonged to ST11. Plasmid conjugation was successful in 5 （27.8%） of the 18 CR-HMKP isolates. Conclusions wzi64-K14.64 is the predominant capsule serotype of the CR-HMKP strains in this hospital. KPC-2 gene conjugationmay contribute to the emergence of CR-HMKP isolates. In addition, CRHMKP strain may be the highly prevalent ST11, and highly virulent CPS serotypes harboring K1/K2.
作者
杜芳玲
梅艳芳
万腊根
魏丹丹
张伟
向天新
刘洋
DU Fangling, MEI Yanfang, WAN Lagen, WEI Dandan, ZHANG Wei, XIANG Tianxin, LIU Yang.(Department of Laboratory Medicine, the First Affiliated Hospital of Nanchang University, Nanchang 330006, Chin)
出处
《中国感染与化疗杂志》
CAS
CSCD
北大核心
2018年第3期278-285,共8页
Chinese Journal of Infection and Chemotherapy
基金
国家自然科学基金(81560323)
江西省卫生厅科研项目(20155140)
江西省科技厅基金项目(20151BAB215028和20161BAB205247)
江西省重点研发计划项目(20171BBG70053)
作者简介
杜芳玲（1994-）,女,硕士研究生,主要从事临床微生物学及常见细菌致病性和耐药机制研究.;通信作者：刘洋,E-mail：ly13767160474@sina.com.
