肝脓肿相关肺炎克雷伯菌毒力基因检测及同源性分析

Virulence genes and homology analysis of Klebsiella pneumoniae associated with pyogenic liver abscess

目的探讨肝脓肿相关肺炎克雷伯菌高毒力荚膜血清型及主要毒力基因分布情况,并分析菌株的同源性。方法收集无锡市第二人民医院2016年1月至2017年8月肝脓肿相关肺炎克雷伯菌分离株12株;所有菌株进行黏液丝试验,PCR方法检测高毒力相关荚膜血清型及主要毒力基因;采用多位点序列分型(MLST)技术和脉冲场凝胶电泳(PFGE)分析菌株同源性。结果 12株肝脓肿相关肺炎克雷伯菌黏液丝试验阳性率为75%;检出K1(6株)、K54(1株)和K57(5株)3种高毒力荚膜血清型。毒力基因wca G、rmp A、ure A、fim H、mrk D、uge、Aer和iro NB检出率均为100%;iuc B检出率为83.3%;未检出cf29a基因;mag A、all S和kfu BC基因仅在K1血清型菌株中检出。MLST发现ST23(4株)和ST25(3株)为主要检出型,其次为ST412(2株)以及ST1660、ST1049和ST11各1株;PFGE结果显示12株肺炎克雷伯菌分为8个型,其中3株K1型菌株属于同一克隆型。结论分离的肝脓肿相关肺炎克雷伯菌均为高毒力菌株,ST23和ST25为主要检出ST型别,ST1049型为首次报道。PFGE结果呈现出遗传多样性,K1型肺炎克雷伯菌存在一定的流行。

Objective To investigate the distribution of hypervirulent capsular serotypes and virulence genes of Klebsiella pneumoniae associated with pyogenic liver abscess（PLA）, and analyze the homology of strains. Methods Twelve strains of liver abscess-related Klebsiella pneumoniae were isolated in Wuxi Second People＇s Hospital during January 2016 and August 2017. Among them, five were also detected in blood samples. All the strains were performed the viscous thread test, and the hypervirulent capsular serotypes and main virulence genes were detected by PCR. The homology of the strains was analyzed by the multilocus sequence types（MLST） and pulsed-field gel electrophoresis（PFGE）. Results The positive rate of the viscous thread test for 12 strains of liver abscess-related KlebsieUa pneumoniae was 75%. Three kinds of hypervirulent capsular serotypes, including K1 （6/12, 50%), K54(1/12, 8.3%) and K57 （5/12, 41.7%) , were detected. The positive rates of virulence genes, such as wcaG, rmpA, ureA, fimH, mrkD, uge, Aer and iroNB, were all 100% , while that of iucB was 83.3%. The cf29a gene was not found, and the magA, allS and kfuBC genes were only detected in K1 serotype strains. MLST found that ST23（4/12, 33.3%) and ST25（3/12, 25%) were main sequence types, and then were ST412（2/12, 16.7%), ST1660(1/12, 8.3%), ST1049(1/12, 8.3%) and ST11 （1/12, 8.3%). PFGE showed that 12 strains of Klebsiella pneumoniae were divided into 8 types, and that only 3 strains of K1 serotype belong to the same clonotype. Conclu-sion All the isolated liver abscess-related Klebsiella pneumoniae strains are highly virulent. ST23 and ST25 are main sequence types, and ST1049 is first reported. PFGE results show genetic diversity, and K1-type Klebsiella pneumoniae has a certain epidemic tendency.