Multicenter evaluation of a new enzyme immunoassay for detection of Clostridium difficile enterotoxin A

Abstract

The Premier Clostridium diffwile toxin A enzyme immunoassay (PTA ETA) (Meridian Diagnostics, Inc., Cincinnati, Ohio) for rapid diagnosis of antibiotic-associated colitis (AAC) was evaluated in a multicenter study. Stool samples from 421 patients suspected of having AAC were tested for toxin A by the PTA EIA and for toxin B by three tissue culture assays (TCA) employing WI-38 cells (New England Deaconess Hospital) in conventional tubes or foreskin fibroblasts (Children's Hospital) or Vero cells (Beth Israel Hospital) in microwells. The tubes and plates were examined at 24 and 48 h for cytotoxicity. Clinical criteria, repeat testing at another site, and culture of frozen stool samples for C. diJficik were used to evaluate discrepant results. Of 504 samples, 66 were positive and 409 were negative by both tests. Eight samples had indeterminate PTA EIA results and were excluded from this analysis. Of 21 discrepancies, 9 were PTA EIA positive and TCA negative and 12 were PTA EIA negative TCA positive. Following resolution of the discrepancies, 11 of 12 PTA EIA-negative-TCA-positive and 5 of 9 PTA EIA-positive-TCA-negative samples were considered true positive for AAC. The sensitivity and specificity were, respectively, 86.6 and 99.0% for the PTA EIA and 93.9 and 99.8% for TCA. The predictive values of positive and negative tests were, respectively, 94.7 and 97.4% for the PTA EIA and 98.7 and 98.8% for TCA. We conclude that the PTA EIA is a rapid, simple EIA technique whose accuracy in detecting enterotoxin A approaches that of reference TCA methods for detection of cytotoxin B.

European Society of Clinical Microbiology and Infectious Diseases (ESCMID): Data review and recommendations for diagnosing Clostridium difficile-infection (CDI)

“…Of the 71 potentially relevant papers retrieved for more detailed assessment, 28 were excluded from further analysis: 15 studies investigated tests that were no longer commercially available; three studies did not test all samples with the reference test; three studies used an inappropriate reference standard; two studies comprised non‐clinical human stool samples; two studies did not report sufficient information to allow us to calculate sensitivity and specificity; one study using CCA did not report if neutralization of the cytopathic effect was executed; and for two studies, full text articles were not available. Therefore, a total of 43 studies was included in this systematic review [6–10,12–15,21–23,23–54].…”

Rapid detection of Clostridium difficile toxin A in stool specimens

“…They can be performed in approximately 2 h and have generally shown good specificity. Nevertheless, their sensitivity varies from 53% to 100% according to different studies [9–11,13–18], with discrepancies explained by the criteria used for the diagnosis of CDAD. In the present study, the sensitivity of the ToxA test was estimated to be 77.4%, which is lower than the 84.6% reported by Schué et al [16] using the the same clinical criteria for diagnosis of CDAD.…”

“…Laboratory diagnosis relies on culture of the microorganism and/or detection of the toxins in stool specimens [8]. Many immunoenzymatic assays that detect either toxin A or toxins A+B have become commercially available in the 5 last years [9–18]. They represent good alternatives to cytotoxicity assays for laboratories without cell‐culture facilities.…”

Comparison of three enzyme immunoassays, a cytotoxicity assay, and toxigenic culture for diagnosis of Clostridium difficile-associated diarrhea

“…Nevertheless, this method is timeconsuming (up to 48 h of incubation), requires expertise in tissue culture techniques, and lacks standardization. The purification of toxins A and B has permitted the production of monoclonal antibodies against toxins A and B and the development of new and rapid immunoassays to detect these toxins in stool specimens (2,(8)(9)(10)27).…”

“…So far, the cytotoxicity assay (tissue culture assay) for toxin B has been considered the "gold standard," although it requires experience in tissue culture techniques and up to 48 h of incubation. Recently, several enzyme immunoassays (EIAs) based on monoclonal antibodies against toxin A and/or B have become available (2,(8)(9)(10)27). The aim of this study was to evaluate and compare two EIAs detecting toxin A (Premier C. difficile Toxin A; Meridian, Osi; Vidas C. difficile Toxin A; bioMerieux) and one EIA detecting both toxin A and toxin B (Cytoclone A + B EIA; Cambridge Biotech Corp., Codiapharm) for the diagnosis of CDAD.…”