Which stool test is used to confirm C. difficile infection?

Which stool test is used to confirm C. difficile infection?

• A. Stool testing for C. difficile toxins/antigen
• B. Blood culture for C. difficile
• C. Stool culture for Campylobacter
• D. Urine antigen for C. difficile

Answer: (B)

Diagnosis of C. difficile infection relies on detecting toxin-producing C. difficile in the stool, because the illness is caused by the toxins the bacteria release in the gut. The most appropriate test is a stool assay that detects the toxins themselves or the organism’s antigen/toxin genes, such as direct toxin detection by immunoassay, GDH antigen with confirmatory toxin testing, or a nucleic acid amplification test for toxin genes. This directly indicates active toxin-mediated disease. Blood cultures won’t help because C. difficile rarely causes bloodstream infection. A stool culture for Campylobacter would identify a different pathogen, not C. difficile. Urine antigen testing for C. difficile isn’t used clinically.

Diagnosis of C. difficile infection relies on detecting toxin-producing C. difficile in the stool, because the illness is caused by the toxins the bacteria release in the gut. The most appropriate test is a stool assay that detects the toxins themselves or the organism’s antigen/toxin genes, such as direct toxin detection by immunoassay, GDH antigen with confirmatory toxin testing, or a nucleic acid amplification test for toxin genes. This directly indicates active toxin-mediated disease.

Blood cultures won’t help because C. difficile rarely causes bloodstream infection. A stool culture for Campylobacter would identify a different pathogen, not C. difficile. Urine antigen testing for C. difficile isn’t used clinically.