September 27, 2019

Current C. difficile testing methods are very sensitive and capable of detecting very small quantities of the organism. However, the test may be positive when C. difficile is only colonizing the patient and is not the cause of the diarrhea. For this reason, testing should be limited to symptomatic patients after ruling-out other factors that may explain diarrheal symptoms. Do NOT perform repeat testing for cure on patients previously testing positive for C. difficile during the hospitalization, as they will likely still be colonized. Treatment continuation for these patients should be based on symptoms.

In addition, selection of testing methods is important to differentiate active disease from colonization. Molecular tests are very sensitive and determine whether a C. difficile strain carries the toxin gene, but they do not determine whether the toxin is being actively produced in vivo. On the other hand, C. difficile infection is a toxin-mediated disease. Most C. difficile related complications occur in patients with positive toxin immunoassay test results.

Current recommendations suggest starting with a very sensitive method such as the molecular tests to detect the presence of potential toxigenic strains followed by a Toxin test as an indicator of active disease. Effective October 2, 2019, the TriHealth C. difficile Test algorithm change can be found in the latest Infection Prevention Update.

For more Infection Prevention information and past updates, visit their page here.