两种产毒型艰难梭菌分子诊断方法的临床应用评价

Evaluation of clinical application of two molecular assays for detection of toxigenic Clostridium difficile

目的通过与Xpert C．difficile/Epi检测临床粪便样本中艰难梭菌毒素基因方法的对比，系统评价实验室研发的艰难梭菌毒素基因多重荧光PCR检测方法的性能。方法2016年8月1日至12月30日采集杭州市余杭区第一人民医院和宁波市鄞州人民医院临床腹泻患者粪便样本176份，平行采用Xpert C．difficile/Epi和实验室研发的检测方法进行检测，同时进行艰难梭菌分离培养和PCR毒素鉴定。采用SPSS 20.0软件对检测结果进行交叉表分析。结果以Xpert C．difficile/Epi检测结果为标准，本实验室研发方法的敏感度为91.7%（22/24）、特异度为100%（152/152）、阳性预测值为100%（22/22）、阴性预测值为98.7%（152/154），两种方法检测结果的一致性好（Kappa＝0.950，P〈0.001）。以厌氧分离培养和PCR毒素检测结果为标准，本实验室研发方法的敏感度为90.0%（18/20）、特异度为97.0%（152/156）、阳性预测值为81.8%（18/22）、阴性预测值为98.7%（152/154）（Kappa＝0.838，P〈0.001）；Xpert C．difficile/Epi的敏感度为90.0%（18/20）、特异度为96.0%（150/156）、阳性预测值为75.0%（18/24）、阴性预测值为98.7%（150/152）（Kappa＝0.792，P〈0.001）。结论实验室研发的艰难梭菌毒素基因多重荧光PCR检测方法与Xpert C．difficile/Epi检测性能基本一致，可直接用于临床腹泻标本中产毒型艰难梭菌检测。该方法的临床应用为国内临床艰难梭菌感染病例的诊断提供一种国产化的检测方法。

ObjectiveIn comparison with Xpert C. difficile/Epi through detection of Clostridium difficile toxin genes from clinical stool, the performance of a laboratory-developed （LD） assay was evaluated in detail.MethodsA total of 176 stool specimens collected from patients with diarrhea in the First People′s Hospital of Yuhang District and the People′s Hospital of Yingzhou, Ningbo from August 1 to December 30 were detected by the two assays in parallel, and meanwhile the C. difficile strains will be isolated and identified for C. difficile toxin genes by a conventional PCR assay. The Cross-tabs Analysis was used for the results by using SPSS20.0 software.ResultsIn comparison with the results of Xpert C. difficile/Epi as the standard, the LD assay had a sensitivity of 91.7% （22/24）, a specificity of 100% （152/152）, a positive predictive value （PPV） of 100% （22/22）, and negative predictive value （NPV） 98.7% （152/154）. The results of two assays were statistically coherent （Kappa=0.950, P〈0.001）. In comparison with culture and detection of toxin genes results, the LD assay had a sensitivity of 90.0% （18/20）, a specificity of 97.0% （152/156）, a PPV of 81.8% （18/22）, and NPV of 98.7% （152/154）（Kappa=0.838, P〈0.001）, and the Xpert C. difficile/Epi assay had a sensitivity of 90.0% （18/20）, a specificity of 96.0% （150/156）, a PPV of 75.0% （18/24）, and NPV of 98.7% （150/152）（Kappa=0.792, P〈0.001）.ConclusionsThe performance of the LD assay was similar to that of the Xpert C. difficile/Epi kit in detection of toxigenic C. difficile. The LD assay could be directly applied to detection of toxigenic C. difficile from clinical stool samples. The clinical application of this LD assay will also provide a domestic and promising diagnostic assay for diagnosis of C. difficile infection in China.（Chin J Lab Med, 2018, 41： 35-40）