Summary of stool tests for Clostridioides difficile

Summary of stool tests for Clostridioides difficile

Test	Sensitivity and specificity	Comments
Rapid tests for organism* (results available in 1 to 4 hours)
NAAT (PCR or loop-mediated isothermal amplification)	Sensitivity: 95% Specificity: >97%	Expensive May be used as standalone test Cannot distinguish between asymptomatic carriage, active infection, or previous infection
EIA for GDH antigen	Sensitivity: 90% Specificity: 94%	Inexpensive Cannot distinguish toxigenic from nontoxigenic strains Must be used in multistep algorithms
Rapid test for toxins* (results available in 1 to 4 hours)
EIA for toxins A and/or B	Sensitivity: 70% Specificity: 98%	Inexpensive Not recommended for standalone test but used in multistep algorithms
Sample multistep algorithms^¶
EIA for GDH followed by NAAT	Sensitivity: 91 to 98% Specificity: 96 to 98%	NAAT is performed only if GDH is positive
EIA for GDH followed by EIA for toxins A and B	Sensitivity: 58 to 84% Specificity: >99%	Toxin EIA is performed only if GDH is positive If GDH is positive and toxin EIA is negative, specimens should be further tested by NAAT
Traditional reference standards (results available in 2 to 5 days)
Toxigenic culture	Reference standard for detecting toxigenic C. difficile	Selective anaerobic culture with toxin testing of C. difficile organisms isolated Labor intensive Permits molecular typing and susceptibility testing
Cell culture cytotoxicity assay	Reference standard for detecting C. difficile toxins	Labor intensive Requires trained personnel

NAAT: nucleic acid amplification test; PCR: polymerase chain reaction; EIA: enzyme immunoassay; GDH: glutamate dehydrogenase.

* Sensitivity and specificity data from Butler M, et al.

¶ Sensitivity and specificity data from Planche TD, et al.

Prepared with data from:

American Society for Microbiology. A practical guidance document for the laboratory detection of toxigenic Clostridium difficile. September 21, 2010.
Bagdasarian N, Rao K, Malani PN. Diagnosis and treatment of Clostridium difficile in adults: a systematic review. JAMA 2015; 313:398.
Butler M, Olson A, Drekonja D, et al. Early diagnosis, prevention, and treatment of Clostridium difficile: Update. Comparative Effectiveness Review No. 172. Agency for Healthcare Research and Quality, Rockville, MD. March 2016. https://effectivehealthcare.ahrq.gov/topics/c-difficile-update/research (Accessed on February 16, 2018).
Planche TD, Davies KA, Coen PG, et al. Differences in outcome according to Clostridium difficile testing method: A prospective multicentre diagnostic validation study of C. difficile infection. Lancet Infect Dis 2013; 13:936.
Tamma PD, Sandora TJ. Clostridium difficile infection in children: Current state and unanswered questions. J Pediatric Infect Dis Soc 2012; 1:230.

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