ImmunoCard® toxins A and B is a rapid, qualitative, horizontal-flow enzyme immunoassay (EIA) for the detection of Clostridium difficile toxins A and B in stool specimens. This assay is used as an aid in the diagnosis of C. difficile associated disease.

• Sensitive enzyme immunoassay

It consists of a membrane held in a plastic frame with two sample ports and two reaction ports. The membrane carries immobilized antibodies to toxins A and B. The enzyme conjugate reagent consists of antibodies to toxins A and B coupled to horseradish peroxidase. To perform the test, patient stool sample is diluted with sample diluent and enzyme conjugate and the mixture is incubated for five minutes to 24 hours. During the incubation, molecules of toxin, if present, are bound to the anti-toxin antibodies of the conjugate. Following incubation, an aliquot of the mixture is added to each of the two sample ports and the test is incubated for an additional five minutes at 20 to 26 °C. During the second incubation the toxin-conjugate complex is separated from particulate matter as the fluid portion of the sample flows through the membrane to the TEST and CONTROL reaction ports. The toxin-conjugate complexes are then captured at the TEST reaction port by immobilized antitoxin in the reaction membrane.