Only liquid stool specimens should be collected or processed for C. difficile detection, as a positive test in the absence of diarrhea likely represents C. difficile colonization. Diagnostic gains are minimal with repeat C. difficile nucleic acid amplification testing within 7 days of a negative test. Repeat C. difficile toxin testing by enzyme immunoassay within 7 days of a prior negative test is also of little incremental diagnostic yield but may be warranted in select cases. Test of cure in patients with recent C. difficile infection is also not recommended. Prior investigations have shown that the use of hospital information systems to restrict ordering of repeat tests for these reasons resulted in a 91% reduction in repeat testing.

Conditions: Clostridium difficile, c. difficile infection.

Diagnostic Tests: C. difficile nucleic acid amplification test

Sources

• Aichinger E, Schleck CD, Harmsen WS, et al. Nonutility of repeat laboratory testing for detection of Clostridium difficile by use of PCR or enzyme immunoassay. J Clin Microbiol. 2008 Nov;46(11):3795-7. (PubMed)
• Luo RF, Banaei N. Is repeat PCR needed for diagnosis of Clostridium difficile infection? J Clin Microbiol. 2010 Oct;48(10):3738-41. (PubMed)
• Luo RF, Spradley S, Banaei N. Alerting physicians during electronic order entry effectively reduces unnecessary repeat PCR testing for Clostridium difficile. J Clin Microbiol. 2013 Nov;51(11):3872-4. (PubMed)