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Test ID: CDPCR Clostridioides difficile Toxin, PCR, Feces

Ordering Guidance

This test is validated for unformed (liquid or soft) fecal specimens collected from patients suspected of having Clostridioides difficile infection.

Specimen Required

The high sensitivity of amplification by polymerase chain reaction requires the specimen to be processed in an environment in which contamination of the specimen by Clostridioides difficile toxin DNA is unlikely.


Submit only 1 of the following specimens:



Specimen Type: Preserved feces

Supplies: Culture and Sensitivity Stool Transport Vial (T058)

Container/Tube: Commercially available transport system specific for recovery of enteric pathogens from fecal specimens (15 mL of nonnutritive transport medium containing phenol red as a pH indicator, either Cary-Blair or Para-Pak C and S)

Specimen Volume: Representative portion of feces; 5 mL

Collection Instructions:

1. Collect fresh fecal specimen and submit in container with transport medium.

2. Place feces in preservative within 2 hours of collection.

Specimen Stability Information: Ambient (preferred) <5 days/Refrigerated <5 days



Specimen Type: Unpreserved feces


Stool container, Small (Random), 4 oz Random (T288)

Stool Collection Kit, Random (T635)

Container/Tube: Fecal container

Specimen Volume: Representative portion of feces

Collection Instructions: Collect fresh fecal specimen and submit representative sample in fecal container.

Specimen Stability Information: Refrigerated (preferred) <5 days/Frozen <5 days

Useful For

Sensitive, specific, and rapid diagnosis of Clostridioides (Clostridium) difficile-associated diarrhea and pseudomembranous colitis


The test is not recommended as a test of cure.

Testing Algorithm

For more information see Laboratory Testing for Infectious Causes of Diarrhea.

Method Name

Real-Time Polymerase Chain Reaction (PCR)/Reverse Transcription-PCR

Reporting Name

C. difficile Toxin, PCR, F

Specimen Type


Specimen Minimum Volume

See Specimen Required

Specimen Stability Information

Specimen Type Temperature Time Special Container
Fecal Varies 5 days

Clinical Information

Clostridioides difficile (formerly Clostridium difficile) is the cause of C difficile-associated diarrhea (CDAD), an antibiotic-associated diarrhea, and pseudomembranous colitis (PMC). In these disorders bacterial overgrowth of C difficile develops in the colon, typically as a consequence of antibiotic usage. Clindamycin and broad-spectrum cephalosporins have most frequently been associated with CDAD and PMC, but almost all antimicrobials may be responsible. Disease is related to production of toxin A and B.


Treatment typically involves withdrawal of the associated antimicrobials and, if symptoms persist, orally administered and intraluminally active metronidazole, vancomycin, or fidaxomicin. Intravenous metronidazole may be used if an oral agent cannot be administered. In recent years, a more severe form of CDAD with increased morbidity and mortality has been recognized as being caused by an epidemic toxin-hyperproducing strain of C difficile (NAP1 strain). Many toxin-hyperproducing isolates also contain the binary toxin gene and are resistant to quinolones. This test does not differentiate between toxin-hyperproducing and nontoxin-hyperproducing strains.


Traditionally, diagnosis relied upon:

1. Clinical and epidemiologic features

2. Culture, which is labor intensive and time consuming

3. Cytotoxicity assays, which are labor intensive and time consuming

4. Toxin detection immunoassays, which are insensitive

This test uses a polymerase chain reaction assay that detects the regulatory gene (tcdC) responsible for production of toxins A and B. This test is used for rapid diagnosis of CDAD and PMC, enabling prompt treatment that may reduce hospital stays for inpatients with CDAD.

Reference Values



Positive: Toxin producing Clostridioides (Clostridium) difficile target nucleic acid is detected.


Negative: C difficile target nucleic acid is not detected.

Clinical Reference

1. Aichinger E, Schleck CD, Harmsen WS, Nyre LM, Patel R: Nonutility of repeat laboratory testing for detection of Clostridium difficile by use of PCR or enzyme immunoassay. J Clin Microbiol. 2008 Nov;46(11):3795-3797

2. Sloan LM, Duresko BJ, Gustafson DR, Rosenblatt JE: Comparison of real-time PCR for detection of the tcdC gene with four toxin immunoassays and culture in diagnosis of Clostridium difficile infection. J Clin Microbiol. 2008 Jen;46(6):1996-2001

3. Verdoorn BP, Orenstein R, Rosenblatt JE, et al: High prevalence of tcdC deletion-carrying Clostridium difficile and lack of association with disease severity. Diagn Microbiol Infect Dis. 2010 Jan;66(1):24-28

4. Karre T, Sloan L, Patel R, Mandrekar J, Rosenblatt J: Comparison of two commercial molecular assays to a laboratory-developed molecular assay for diagnosis of Clostridium difficile infection. J Clin Microbiol. 2011 Feb;49(2):725-727

5. Lawson PA, Citron DM, Tyrrell KL, Finegold SM: Reclassification of Clostridium difficile as Clostridioides difficile (Hall and O'Toole 1935) Prevot 1938. Anaerobe. 2016 Aug;40:95-99. doi: 10.1016/j.anaerobe.2016.06.008

Day(s) Performed

Monday through Sunday

Report Available

Same day/1 day

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
CDPCR C. difficile Toxin, PCR, F 54067-4


Result ID Test Result Name Result LOINC Value
TCDRR C. difficile Toxin, PCR 54067-4
Mayo Clinic Laboratories | Microbiology and Infectious Disease Catalog Additional Information:

mml-giinfections, mml-idsurveillance