C. difficile PCR with Reflex to EIA if Positive




Test Mnemonic

CDREFL

CPT Codes

  • 87493 - QTY (1)

Performing Laboratory

Cleveland Clinic Laboratories


Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
5 mLStoolSterile container RefrigeratedFormed stools, samples from patients <2 yrs old, and specimen received in preservative, frozen, on swabs or wooden applicator sticks will be rejected.

Stability

Environmental Condition Description
Ambient24 hours
FrozenUnacceptable
Refrigerated72 hours

Days Performed

Sun - Sat

Turnaround Time

1 - 3 days

Methodology

Name Description
Polymerase Chain Reaction (PCR) 

Special Info

Unformed stools are tested for the presence of C. difficile toxin B gene by PCR. Stool specimens positive for C. difficile toxin by PCR will be followed by toxin enzyme immunoassay (EIA) testing within 8 h. A negative toxin EIA result is reported with the following comment “Toxin EIA is less sensitive than cell cytotoxin and PCR assays. Clinical correlation of PCR positive/toxin EIA negative results is required to distinguish C. difficile colonization from disease.” Whenever possible, this test should be performed on specimens that are less than 24 hours old.

Clinical Info

A positive PCR result for C. difficile may represent infection or colonization. This multistep algorithm was implemented in response to 2017 IDSA guidelines recommending PCR testing as a stand-alone test for C. difficile infection (CDI) only if clinicians agree at the institutional level to NOT submit stool specimens on patients receiving laxatives and to submit stool specimens only from patients with unexplained and new onset of 3 or more unformed stools in 24 h for testing for CDI. Observational studies have reported higher CDI-related complications among patients with EIA toxin positive specimens in comparison to patients with EIA toxin negative/PCR positive results.

Reflex Tests

The following additional test(s) may be ordered depending on results: