The updated Clinical Practice Guidelines for Clostridium difficile from The Infectious Disease Society of America (IDSA) and the Society of Healthcare Epidemiology of America (SHEA) have been recently published in the journal Clinical Infectious Diseases. The new recommendations emphasize the importance of toxin tests in accurately identifying Clostridium difficile infection (CDI) and suggest that this type of testing is appropriate with or without patient history on all samples due to its high positive predictive value (PPV). In addition, understanding that many hospitals utilize molecular tests (PCR), these tests are highly sensitive and detect colonization and not necessarily the presence of toxin. This can lead to over-diagnosis and over-treatment
Immunoassay toxin testing (EIA) is clinically relevant due to findings that patients who were enzyme EIA toxin positive presented diarrhea of longer duration, exhibited greater CDI-related complications, and suffered increased mortality compared to toxin negative/PCR positive patients.
Molecular testing has limitations as the tests detects only the presence of toxin genes rather than the toxins themselves, therefore providing a lower PPV. To this end, users of this test require strict adherence to test ordering criteria, particularly as the guidelines note that the “great majority of patients with suspected CDI do not have the disease.”
Each year in the United States CDI kills 15,000 to 30,000 and affects 500,000 people and the rate has not dropped since its peak in 2010. Toxin tests are a utilized extensively to aid in the diagnosis of CDI, and a more sensitive toxin test is greatly desired by the healthcare community.
1. McDonald LC et al. Clin Infect Dis. 2018; https://doi.org/10.1093/cid/cix1085