The most common laboratory tests for the detection of C. difficile are enzyme immunoassays (EIA) that detect C. difficile Toxin A and Toxin B. The immunoassays are simple to perform and provide rapid results. However, the sensitivities of these tests are not as good as culture, CCNA, or molecular methods.
Only liquid stool samples should be processed. Due to the fact that the colonization rate is high, a positive result with a normal stool sample proves that the patient is colonized with C. difficile but not necessarily infected.
There are many test kits available commercially for the detection of C. difficile toxins. Results are available in 15 minutes to two hours, depending on the assay. Initially, Toxin A was thought to be the toxin responsible for the majority of the effects of C. difficile disease. Therefore, most early test kits only detected Toxin A, based on monoclonal anti-Toxin A antibodies. With the discovery that there are strains that cause infection and produce aberrant or no Toxin A (A-), it is now recommended that a kit is used that detects both toxins.
