高毒力肺炎克雷伯菌血清型、毒力基因分布及分子标志物探索

Distribution of serotypes and virulence genes in hypervirulent Klebsiella pneumoniae and exploration of molecular markers

为探讨高毒力肺炎克雷伯菌(hypervirulent Klebsiella pneumoniae,HVKP)血清型和毒力基因分布特点并寻找可预测高毒力的分子标志物,本研究收集侵袭综合征肺炎克雷伯菌(Klebsiella pneumoniae,KP)25株(视为HVKP)和单纯血流感染的普通肺炎克雷伯菌(classic Klebsiella pneumoniae,cKP)28株(为cKP组)。采用DNA Kit提取菌株DNA,参照文献分别合成血清型(K1、K2、K5、K20、K54和K57)和毒力基因(wcaG、rmpA、rmpA2、magA、fimH、mrkD、uge、wabG、aero、iucB、iutA、iroNB、ybtA、kfuBC、ureA、alls)的引物序列。通过PCR测定菌株的血清型和毒力基因分布情况。运用统计软件对数据进行统计分析,对2组之间有显著差异的分子标志物分别计算其灵敏度、特异度、准确度和约登指数。结果显示,血清型K1在HVKP组中的阳性率为60%,高于cKP组,有显著差异。毒力基因uge检出率最高,达100%;其次是fimH,占96%;wabG和ybtA也在90%以上。总体上HVKP组的毒力基因阳性率较cKP组更高,尤其是rmpA2、magA、fimH、aero、iutA、kfuBC。根据约登指数,诊断效能由高到低排列:iutA>kfuBC>magA(K1)>aero>fimH>rmpA2。经多因素Logistic回归分析得出,rmpA2、magA、fimH、aero、iutA、kfuBC可作为HVKP的分子标志物,尤其是iutA,在HVKP和cKP组之间有显著差异(P=0.002)。但缺乏100%特异性的分子标志物,仍需要进一步探索。

In order to investigate the distribution of serotypes and virulence genes in hypervirulent Klebsiella pneumoniae(HVKP) and to explore the molecular markers, Klebsiella pneumoniae(K. pneumoniae) strains were collected and divided into the HVKP group and classic K. pneumoniae(cKP) group. The results showed that the positive rate of serotype K1 in the HVKP group was 60%, which was significantly higher than that in the cKP group. The positive detection rates of rmpA2, magA, fimH, aero, iutA, kfuBC in the HVKP group were significantly higher than those in the cKP group. According to the Yoden index, the diagnostic efficacy of these molecular markers ranked from high to low was as follows: iutA > kfuBC > magA(K1) > aero > fimH > rmpA2. Multivariate logistic regression analysis showed that rmpA2, magA, fimH, aero, iutA and kfuBC could be used as molecular markers of HVKP, especially iutA.