Clostridium difficile Toxin/GDH with Reflex to PCR
Use
This test employs a two‑step algorithm for detection of toxigenic Clostridium difficile infection. An initial immunoassay evaluates glutamate dehydrogenase (GDH) antigen and toxins A and/or B. If both GDH and toxin are positive, the result indicates toxigenic C. difficile; if both are negative, result is negative. Discordant results (GDH positive/toxin negative or GDH negative/toxin positive) reflex to PCR (NAAT) for toxin gene detection, allowing confirmation of toxigenic strain and hypervirulent ribotype 027/NAP1/toxinotype III when present. This approach increases sensitivity (~90.5%) and specificity (~93%) compared to GDH/toxin testing alone, and aligns with CDC/IDSA guidelines for confirmation by NAAT when initial immunoassay is discordant. Quest validation observes discordant results in ~6% of specimens. (Based on Quest FAQs and test details.)
Special Instructions
Not provided.
Limitations
Not provided.
Methodology
Immunoassay
Biomarkers
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Stool
Volume
5 g or 5 mL unformed stool
Minimum Volume
1 g or 1 mL
Container
sterile, leak‑proof container
Collection Instructions
Collect fresh unformed stool in sterile, leak‑proof container without media, preservative, or metal ion; for diapered patients, line diaper with clean plastic and transfer 5 g or 5 mL from diaper to container.
Causes for Rejection
Formed stool; stool submitted in transport media or swab; unfrozen stool >72 hours old; received at room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 72 hours |
| Frozen | 30 days |
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