检测艰难梭菌感染的五种方法比较

目的 比较分析用于美国医院临床微生物实验室的5种艰难梭菌感染检测方法 ,从中选择1种适于早期诊断艰难梭菌感染的灵敏、特异、简单、快速及经济的实验方案.方法 对174份临床送检的腹泻患者粪便标本同时用TGC、Premier Toxin A&B EIA(A/B-EIA)、C.Diff Quick Chek Complete(D-EIA)、BD GeneOhm Cdiff assay(BD-PCR)和实验室发展的PCR(LD-PCR)方法 进行艰难梭菌的检测.以金标准TGC法作为参比标准,评价各种检测方法 的敏感度、特异度、阳性预测值、阴性预测值.结果 TGC法检测174份腹泻患者大便标本,艰难梭菌感染的阳性率为13.8%(24/174).与TGC法比较,4种检测方法 的敏感度、特异度、阳性预测值、阴性预测值分别为:A/B-EIA 62.5%、99.3%、93.8%、94.3%;D-EIA 66.7%、98.7%、88.9%、94.9%;BD-PCR 83.3%、98.7%、90.9%、97.4%;LD-PCR 79.2%、93.3%、65.5%、96.6%.所有标本中,至少1种方法 检测为阳性的标本共计34份,其中15份标本5种方法 检测结果 均为阳性.D-EIA法检测结果 中,18份标本GDH及毒素A/B均为阳性,23份仅GDH阳性,133份GDH及毒素A/B均为阴性.18份D-EIA检测阳性标本全部与BD-PCR检测结果 一致,16份与TGC法检测结果 一致.24份TGC阳性标本中,有22份包括在41份GDH抗原呈阳性的标本中.D-EIA检测为假阴性的8份标本中,4份BD-PCR检测为阳性.根据本实验结果 ,D-EIA与BD-PCR相结合的二步法检测方案灵敏度、特异度、阳性预测值、阴性预测值分别为83.3%、98.7%、90.9%、97.4%.结论 从技术角度评价,以BD-PCR法为最优.结合D-EIA与BD-PCR的二步法检测方案,是对临床送检标本进行艰难梭菌感染检测的灵敏、特异、简便、快速、经济的检测方案.

Comparison of five methods used for detection of Clostridium difficile infection

Objective To evaluate five detection methods for the laboratory diagnosis of Clostridium difficile infection in the hospitals of USA, and explore a sensitive, specific, accuracy and rapid regimen for the early diagnosis of Clostridium difficile infection. Methods A total of 174 stool specimens submitted to the clinical microbiology laboratory for Clostridium difficile testing were separately tested by five methods including toxigenic culture (TGC), Premier Toxin A&B EIA( A/B-EIA), C. Diff Quick Chek Complete( DEIA), BD G eneOhm Cdiff assay(BD-PCR) and Laboratory-developed PCR(LD-PCR). The gold standard of TGC was used as a reference criterion, and the sensitivity, specificity, positive predictive value ( PPV )and negative predictive value (NPV) of A/B-EIA, D-EIA, BD-PCR and LD-PCR assays were determined. Results Among the 174 specimens studied, 24 were defined as true positives for Clostridium difficile infection by TGC assay, giving a positive rate of 13.8% (24/174). In comparison to the standard,the sensitivity, specificity, PPV and NPV were 62.5%, 99.3%, 93.8% and 94.3% for A/B-EIA;66.7%, 98.7%, 88.9% and 94.9% for D-EIA; 83.3%, 98.7%, 90.9% and 97.4% for BD-PCR;79.2%, 93.3%, 65.5% and 96.6% for LD-PCR. Among all tested specimens, 34 were positive by atleast one of five methods, and of which 15 were concordant by all five methods. The D-EIA results were divided into three groups depending on results of GDH and (or) toxins A/B: 18 were positive for both GDH and toxins A/B, 23 were positive for only GDH, and 133 were negative for both GDH and toxins A/B. Of 18 positive specimens by D-EIA assay, all were concordant with results of BD-PCR assay and 16 were agreement with results of TGC assay. Twenty-two of 24 positive specimens by TGC assay were included in 41 specimens that were positive for GDH. Among eight false negative specimens by D-EIA assay, four were differentiated as positive results by BD-PCR. According to the present study, the sensitivity, specificity,PPV and NPV of a two-step detection algorithm in combination with D-EIA and BD-PCR assays were 83.3%, 98.7%, 90.9% and 97.4%, respectively. Conclusions From the point of technological evaluation, BD-PCR is preferable. A two-step detection algorithm combining D-EIA with BD-PCR is proposed for the laboratory diagnosis of Clostridium difficile infection. This algorithm has demonstrated an excellent sensitivity and specificity, as well as decreased test turnaround time and test cost.