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The Journal of the Japanese Society for Clinical Microbiology |
Biblioraphy Information
| ArticleTitle |
Comparison of Two Immunoassays for Detection of Clostridium difficile Toxins A and B in Stool Specimens |
| Language |
J |
| AuthorList |
Akiko Ueda1), Masahiro Toyokawa1), Isao Nishi1), Atsuko Sunada1), Tomomi Sakata1), Keigo Kimura1), Yoriko Inoue1), Seishi Asari2) |
| Affiliation |
1) Laboratory for Clinical Investigation, Osaka University Hospital
2) Department of Infection and Pervention, Osaka University Hospital |
| Publication |
J.J.C.M.: 21 (1), 51-58, 2011 |
| Received |
August 13, 2010 |
| Accepted |
January 21, 2011 |
| Abstract |
We evaluated the usefulness of two rapid immunoassays, ImmunoCard Toxins A & B (ImmunoCard) and TOX A/B QUIK CHEK "NISSUI" (QUIK CHEK) for detection of Clostridium difficile Toxins A & B in stool specimens, in the diagnosis of C. difficile-associated diarrhea (CDAD). In comparison with the cytotoxicity assay as the gold standard for the diagnosis of CDAD, the sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) were 85.2%, 93.2%, 82.1% and 94.4% for ImmunoCard, 74.1%, 93.2%, 80.0% and 90.7% for QUIK CHEK respectively (at a CDAD prevalence of 27%). The sensitivity of ImmunoCard was about 10% higher than that of QUIK CHEK. Furthermore, the detection limit of ImmunoCard was superior to that of QUIK CHEK 2 to 8 times by the dilution test with culture supernatants of toxigenic strains and fresh stool specimens. On the other hand, insufficient absorption of the diluted samples was observed in 38 samples (38%) in ImmunoCard, and two of these samples showed decrease in the limit of detection due to insufficient absorption. It seemed that the sensitivity of ImmunoCard could be increased by application of centrifuge process because such false negative samples showed positive results by application of the centrifuge process just prior to the sample addition to test device. There were more than a few samples which showed false positive by nonspecific reaction in both ImmunoCard and QUIK CHEK, and each PPV fell to 58.2% and 54.6% at the prevalence rate of 10%, respectively. All of these samples were negative on glutamate dehydrogenase (GDH) test, so it seemed very useful to use the two-step approach with ImmunoCard and GDH test for ensuring the high PPV and the correct diagnosis of CDAD. |
| Keywords |
ImmunoCard Toxins A & B, TOX A/B QUIK CHEK, Clostridium difficile toxin, cytotoxicity assay, C. difficile culture |
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