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.)