Which are the most sensitive stool assays for assessing Clostridium difficile (C diff) infection (CDI)?

Updated: Jul 25, 2019
  • Author: Faten N Aberra, MD, MSCE; Chief Editor: BS Anand, MD  more...
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Stool assays for C difficile, from the most to the least sensitive, include the following:

  • Stool culture: The most sensitive test (sensitivity, 90-100%; specificity, 84-100%), but the results are slow and may lead to a delay in the diagnosis if used alone

  • Glutamate dehydrogenase enzyme immunoassay (EIA): This is a very sensitive test (sensitivity, 85-100%; specificity, 87-98%); it detects the presence of glutamate dehydrogenase produced by C difficile

  • Real-time polymerase chain reaction (PCR) assay: This test is an alternative gold standard to stool culture (sensitivity, 86%; specificity, 97% [3] ); it may be used to detect the C difficile gene toxin

  • Stool cytotoxin test: A positive test result is the demonstration of a cytopathic effect that is neutralized by a specific antiserum (sensitivity, 70-100%; specificity, 90-100%)

  • EIA for detecting toxins A and B: This test is used in most laboratories (moderate sensitivity, 79-80%; excellent specificity, 98%)

  • Latex agglutination technique: Another means of detecting glutamate dehydrogenase; however, the sensitivity of this test is poor (48-59%), although the specificity is 95-96%

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