title: Comparison of the TOX A/B test to a cell culture cytotoxicity assay for the detection of Clostridium difficile in stools.
abstract: The TOX A/B Test (Techlab, Blacksburg, VA, USA) was compared to cell culture cytotoxicity assay on 1109 consecutive diarrheal stool samples collected from patients with the presumptive diagnosis of Clostridium difficile disease. The TOX A/B Test is an enzyme immunoassay in a microtiter format that detects both toxins A and B. The procedure used for this study takes approximately 1.5 h to perform. Cell culture cytotoxicity was performed by using a fibroblast cell line in a microtiter format read at 4 h, 24 h, and 48 h. One hundred ninety-four of the 1109 samples were positive by the "gold standard" cytotoxicity assay, whereas 189 were positive by EIA. There was a 98.5% agreement between the two assays. When compared to the cytotoxicity assay, the EIA had an initial sensitivity of 94.3% and a specificity of 99.3%. However, after resolution of six discrepants using another ELISA for toxin A detection the sensitivity, specificity, positive and negative predictive values for the TOX A/B test are as follows: 94.5%; 100%; 100%; 98.8%. The corresponding values for the cytotoxicity assay are: 97%; 100%; 100%; and 99.3%. This test seems to have excellent sensitivity and specificity as compared to an in-house cell culture cytotoxicity assay. It is sensitive enough to use as a stand-alone test for the detection of C. difficile toxin in laboratories that do not have cell culture cytotoxicity testing capability.
authors.affiliation: Associated Regional and University Pathologists, Inc. Salt Lake City, UT 84108, USA. Aldeenwe@ARUP-lab.com
authors.forename: W E
authors.initials: WE
authors.lastname: Aldeen
authors.forename: M
authors.initials: M
authors.lastname: Bingham
authors.forename: A
authors.initials: A
authors.lastname: Aiderzada
authors.forename: J
authors.initials: J
authors.lastname: Kucera
authors.forename: S
authors.initials: S
authors.lastname: Jense
authors.forename: K C
authors.initials: KC
authors.lastname: Carroll
mesh_terms: D018929:Cell Culture Techniques; D016360:Clostridioides difficile / Q000302:isolation & purification*; D003967:Diarrhea / Q000382:microbiology*; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000382:microbiology*; D006801:Humans; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity
chemical_list: D011933:Reagent Kits, Diagnostic