Knapp C C, Sandin R L, Hall G S, Ludwig M D, Rutherford I, Washington J A
Department of Microbiology, Cleveland Clinic Foundation, OH 44195.
Diagn Microbiol Infect Dis. 1993 Jul;17(1):7-12. doi: 10.1016/0732-8893(93)90062-c.
Damage to the intestinal mucosa by Clostridium difficile (CD) is toxin mediated. Two enzyme immunoassays (EIAs) for toxin-A detection, the automated Vitek immunodiagnostic assay system CDA (Vidas CDA), and the Premier toxin A (Premier) were tested for their ability to detect toxin A in 301 stool samples and compared with an in-house tissue culture assay for toxin B (TCA). Of these 301 samples, 49 were TCA positive and 252 were TCA negative. Agreement between Vidas CDA and TCA on the initial run was 85% (255 of 301) and increased to 94% (278 of 296) when discordant samples were retested from available frozen specimens. Corresponding levels of agreement for Premier were 91% (272 of 301) and 98% (284 of 288), respectively. If tissue culture positivity at any titer was used as the sole criterion for positivity of the specimen, agreement with positive TCA before and after repeat testing was 57% (26 of 49) and 74% (34 of 46) for Vidas CDA and 65% (32 of 49) and 95% (36 of 38) for Premier. Agreement with negative TCA titers was good: 90% for Vidas CDA and 95% for Premier, and 98% for Vidas CDA and 99% for Premier after repeat testing. Predictive values positive and negative after repeat testing were, respectively, 88% and 96% for Vidas CDA, and 95% and 99% for Premier. Results for the automated and manual EIA methods for detection of C. difficile toxin A were obtained in 2.5 h as compared with 36-48 h for tissue culture.
艰难梭菌（CD）对肠道黏膜的损伤是由毒素介导的。对两种用于检测毒素A的酶免疫测定法（EIA），即自动化的Vitek免疫诊断测定系统CDA（Vidas CDA）和普瑞米尔毒素A检测法（Premier），检测301份粪便样本中毒素A的能力进行了测试，并与内部毒素B组织培养测定法（TCA）进行了比较。在这301份样本中，49份TCA呈阳性，252份TCA呈阴性。Vidas CDA与TCA初次检测的一致性为85%（301份中的255份），当从可用的冷冻样本中对不一致的样本进行重新检测时，一致性提高到94%（296份中的278份）。Premier的相应一致性水平分别为91%（301份中的272份）和98%（288份中的284份）。如果将任何滴度下的组织培养阳性作为样本阳性的唯一标准，Vidas CDA在重复检测前后与阳性TCA的一致性分别为57%（49份中的26份）和74%（46份中的34份），Premier为65%（49份中的32份）和95%（38份中的36份）。与阴性TCA滴度的一致性良好：Vidas CDA为90%，Premier为95%，重复检测后Vidas CDA为98%，Premier为99%。重复检测后的阳性预测值和阴性预测值，Vidas CDA分别为88%和96%，Premier为95%和99%。检测艰难梭菌毒素A的自动化和手动EIA方法在2.5小时内得出结果，而组织培养则需要36 - 48小时。
