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Clostridium difficile Toxin

Additional Codes

LAB4886

Performing Laboratory

MBMC-Microbiology

Methodology

Enzyme Immunoassay (EIA):

This assay detects C. difficile antigen, glutamate dehydrogenase (GDH), as a screen for the presence of C. difficile and confirms the presence of toxigenic C. difficile by detecting toxins A/B in unformed fecal specimens from persons suspected of having C. difficile disease.

 

Real-time polymerase chain reaction (RT-PCR) – (available as add on only):

This assay is a real-time polymerase chain reaction (RT-PCR) using the GeneXpert Dx System for the detection of C. difficile Toxin B in unformed (liquid or soft) stool specimens from individuals with high suspicion of having C. difficile infection. 

Note: PCR is performed by request only in situations of positive GDH and negative free toxin, OR will automatically reflex in situations of invalid antigen EIA results. Testing must be added on within 96 hours of specimen collection. Call Laboratory Customer Service at 314-996-4522 to request add-on.

Testing Algorithm

If C.diff result is indeterminate (GDH neg / Toxin Positive), C. diff RT-PCR will be perform with an additional charge.

PCR is performed by request only in situations of positive GDH and negative free toxin, OR will automatically reflex in situations of invalid antigen EIA results. Testing must be added on within 96 hours of specimen collection. Raw stool is required for PCR. Call Laboratory Customer Service at 314-996-4522 to request add-on.

Specimen Requirements

Specimen Type: Fresh, liquid or soft stool; rectal aspirate; or duodenal aspirate.  Formed stool is not acceptable.

Container/Tube: Screw-capped container or Cary Blair transport media vial
Specimen Volume: >1 mL

Collection Information:

1. If patient has had a positive specimen, submit a follow-up specimen only if diarrhea persist following completion of an antibiotic treatment regime.

2. Request for testing on patients with a previous negative within last 96 hours will be canceled

Additional Information: Indicate specimen source.

Specimen Transport Temperature

Ambient/Refrigerate off-site facilities

Day(s) Test Set Up

Monday through Sunday

Turnaround Time:
STAT: 1 hour after receipt in laboratory
Routine: within 4 hours

Reference Values

Negative for Clostridium difficile toxin A/B

 

Test Classification and CPT Coding

87449

87324

87493 (if PCR performed)

Stability

Cary-blair up to 5 days refrigerated or room temperature