C. difficile Toxin Screen
| Label Mnemonic: | CDABSCN |
| Epic code: | LAB8239 |
| Order form: | Microbiology/Molecular Infectious Disease Requisition |
| Supply order: | Supply Order Form |
| Billing: | Billing Policies |
| CPT code: | 87493 |
Specimen(s):
Stool
Collection Medium:
| Sterile container |
Rejection Criteria:
Specimens will be rejected from patients who were administered
laxatives in the previous 48 hours. Specimens less than 7 days from
a negative result or 14 days from a positive result will be
rejected. Rejection criteria do not apply to outpatient specimens.
Turn Around Time:
4 hours (upon receipt in laboratory)
Comments:
This is a cascading test, where a positive PCR for C. difficile
toxin genes is followed with antigen testing for toxins A and B to
establish gene expression consistent with active C. difficile
disease.
There are three typical outcomes of testing:
1) PCR negative: C. difficile not detected, no further testing performed.
2) PCR positive, toxin antigen negative: Most consistent with C. difficile colonization rather than infection, although infection is possible.
3) PCR positive, toxin antigen positive: Consistent with active C. difficile infection.
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.
There are three typical outcomes of testing:
1) PCR negative: C. difficile not detected, no further testing performed.
2) PCR positive, toxin antigen negative: Most consistent with C. difficile colonization rather than infection, although infection is possible.
3) PCR positive, toxin antigen positive: Consistent with active C. difficile infection.
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:
PCR for C. difficile toxin via Cepheid C. difficile/Epi AND 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). The C. difficile GDH
result is not reported as it is redundant to C. difficile PCR.
Instructions:
Only unformed stools will be accepted for testing.
Sample Processing:
Label transport tube with two patient identifiers, date and time of
collection.
Submit in sterile transport container.
Keep refrigerated and submit to laboratory.
Submit in sterile transport container.
Keep refrigerated and submit to laboratory.
Sample Storage:
Refrigerate.
Transport Instructions:
Transport in cooler with refrigerated coolant packs.