Diagnosis of C. difficile disease requires careful clinical evaluation as testing is not as straightforward as for most microbiologic conditions. The finding that is most associated with disease is presence of
FREE TOXIN in stool. However, FREE TOXIN testing alone is not sensitive enough and patients with C. difficile disease may be FREE TOXIN negative.
This is the reason we perform two other tests. Both ANTIGEN and NAAT GENE tests detect the presence of the organism in stool and are very sensitive. A negative result in either test strongly suggests that C. difficile is not the cause of diarrhea. However, consider repeat testing if clinical suspicion is very high.