产KPC-2耐碳青霉烯类肺炎克雷伯菌ST2237与ST11的分子流行特征分析

Molecular epidemic characteristics of KPC-2-producing carbapenem-resistant Klebsiella pneumoniae ST2237 and ST11

目的了解耐碳青霉烯类肺炎克雷伯菌(CRKP) ST2237型与ST11型的分子流行特征。方法收集河南科技大学第一附属医院2018年1月至12月63株非重复CRKP,采用琼脂稀释法和微量肉汤稀释法检测菌株最低抑菌浓度(MIC);用PCR及测序方法检测毒力基因(iucA、rmpA2、rmpA、iroN)及耐药基因(blaKPC、blaNDM、blaIMP、blaCTX-M、blaTEM、blaSHV、blaDHA、blacmy和mcr^-1);用多位点序列分型(MLST)和goe BURST软件对菌株进行同源性分析;用SPSS 22软件统计分析不同ST型菌株间耐药性、毒力基因检出和耐药基因检出的差异。结果 63株CRKP对阿米卡星、磷霉素、氯霉素、米诺环素、黏菌素、替加环素和头孢他啶/阿维巴坦耐药率分别为97%、94%、78%、43%、1.6%、1.6%和0。63株菌株均携带blaKPC-2、blaSHV和blaTEM,54株菌株携带blaCTX-M,6株菌株携带blaDHA。49株(77.8%)携带毒力基因。MLST分型显示,院内有ST11 55株(占87.3%)和ST2237 7株(占11.1%)。美罗培南、厄他培南、替加环素、头孢他啶/阿维巴坦、头孢他啶、头孢噻肟、头孢曲松、米诺环素和氯霉素对CRKP ST2237型的MIC值低于ST11型(Z分别为-4.146、-4.535、-2.893、-4.635、-7.803、-6.699、-7.797、-2.223、-3.395,P<0.05)。27.3%(15/55) ST11株携带iucA、rmpA2、rmpA、iroN4种毒力基因,85.7%(6/7) ST2237株携带iut A和rmp A2 2种毒力基因。ST2237型blaDHA携带率(85.7%,6/7)高于ST11型(0,0/55)(Fisher’s精确检验,P=0);ST2237型blaCTX-M携带率(0,0/7)低于ST11型(98.2%,54/55)(Fisher’s精确检验,P=0)。结论 ST2237 CRKP菌株在药物敏感性、耐药基因及毒力基因携带方面与ST11不同,需加强监测。

Objective To explore the molecular epidemic characteristics of carbapenem-resistant Klebsiella pneumoniae( CRKP)ST2237 and ST11 type. Methods A total of 63 isolates of non-duplicated CRKP were collected during the period from January 2018 to December 2018 in the First Affiliated Hospital of Henan University of Science and Technology. The minimum inhibitory concentrations( MICs) were evaluated by agar dilution and microdilution methods. The virulent genes( iuc A,rmp A2,rmp A and iro N) and resistance genes( blaKPC,blaNDM,blaIMP,blaCTX-M,blaTEM,blaSHV,blaDHA,blacmyand mcr-1) were detected by polymerase chain reaction( PCR) and DNA sequencing. The genetic relatedness homology was investigated by multilocus sequencing typing( MLST) and goe BURST software. Statistical analyses were performed using IBM SPSS Statistics( version 22) to analyze differences of the drug-resistance,virulence genes and drug-resistance genes among the strains with various ST types. Results The resistant rates of the63 isolates of CRKP to amikacin,fosfomycin,chloramphenicol,minocycline,colistin,tigecycline and ceftazidime-avibactam were97%,94%,78%,43%,1.6%,1.6% and 0. Among the 63 isolates,all carried blaKPC-2,blaSHV and blaTEM,54 carried blaCTX-M and6 carried blaDHA. 77.8%( 49/63) of CRKP isolates carried virulence genes. MLST analysis revealed that 55 of ST11 isolates( 87.3%)and 7 of ST2237 isolates( 11.1%) presented in the tested 63 CRKP isolates in this hospital. The MICs of meropenem,ertapenem,tigecycline,ceftazidime and avibactam,ceftazidime,cefotaxime,ceftriaxone,minocycline and chloramphenicol for ST2237 clone of CRKP were significantly lower than those of ST11 clone( Z =-4.146,-4.535,-2.893,-4.635,-7.803,-6.699,-7.797,-2.223 and-3.395;P<0.05). 27.3%( 15/55) of ST11 clone carried all the four of tested virulence genes( iuc A,rmp A2,rmp A and iro N),85.7%( 6/7) of ST2237 clone carried two virulence genes( iut A and rmp A2). The presence of blaDHAin ST2237 clone( 85.7%,6/7)was significantly higher than that in ST11( 0,0/55)( Fisher’s exact test,P = 0),while the presence of blaCTX-Min ST2237( 0,0/7)was significantly lower than that of ST11( 98.2%,54/55)( Fisher’s exact test,P = 0). Conclusion KPC-2-producing ST2237 type of CRKP may exhibit its own uniqueness in antibiotic sensitivity,antimicrobial resistance genes and virulence genes different from ST11 clone,which triggers the need for active surveillance.