C. difficile Toxin Screen
Label Mnemonic: CDABSCN
Epic Lab Code: LAB8239
Downtime Form: A-1a Clinical Microbiology Laboratory Requisition
Microbiology
BT 6004
356-2591
Bacteriology/Virology Section
Specimen(s):
Stool
Collection Medium:
Sterile container
Rejection Criteria:
Specimen submitted within 10 days of positive result; more than 1 specimen/week.
Turn Around Time:
2 hours (upon receipt in laboratory)
Comments:
This test detects the C. difficile antigen glutamate dehydrogenase (GDH) as a screen for the presence of C. difficile and confirms the presence of toxigenic C. difficile with an antigen assay for toxins A and B.

Patients positive for GDH but negative for C. difficile toxins by antigen assay may be colonized with a nontoxigenic C. difficile strain, colonized with a toxigenic C. difficile strain, or may rarely have a toxin level below the limit of detection of the assay, for example in waxing and waning or treated disease. GDH-positive and toxin-negative patients will be reflexively tested with the Cepheid Xpert C. difficile PCR to divide these patients into those colonized with a nontoxigenic strain (for whom no isolation precautions or treatment is necessary) and the latter two groups. For the latter two groups, clinical assessment must be made regarding colonization vs. infection but all patients with toxigenic C. difficile should be placed under isolation and contact precautions.

It is generally recommended that C. difficile toxin screen be performed only for patients with > 3 liquid stools within a 24 hour period. Since C. difficile colonization rather than infection may exist, only unformed stool specimens from patients with signs and symptoms of C. difficile infection should be tested. The significance of Clostridium difficile and C. difficile toxin detection in infants (<1 year old) is uncertain because of the high rate of asymptomatic C. difficile carriage in this age group.

Once a patient is diagnosed with C. difficile infection, therapeutic response should be based on clinical signs and symptoms; a "test of cure" should not be done since patients may remain colonized with toxin producing strains following recovery.
Methodology:
Rapid Membrane Enzyme Immunoassay for the simultaneous Detection of Clostridium difficile Glutamate Dehydrogenase Antigen and Toxins A and B; C. Diff Quick Chek Complete (Alere)
CPT Code:
87324