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Clostridium difficile Toxin

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Clostridium difficile Toxin, C. diff Toxin

  • Indications for testing
  1. Diarrheal stools and
  2. Antibiotic exposure in last 3 months
  • Testing not indicated
  1. Solid stools
    1. Suggests asymptomatic carrier
    2. No benefit to treating carriers
  2. Re-evaluation after treatment
    1. Carriage is common for 3-6 weeks post-treatment
  • Specimen
  1. Immediate exam of fresh stool specimen
  2. May be kept refrigerated if exam delayed
  • Available tests
  1. Tissue culture Cytotoxicity Assay (Gold Standard)
    1. Test Sensitivity: 67-100%
    2. Test Specificity: 85-100%
    3. Expensive and requires 2 day incubation
  2. Enzyme Immunoassay for Toxins A and B
    1. Test Sensitivity: 63-99% (most are 85-95% sensitive)
    2. Test Specificity: 93-100%
    3. Inexpensive and results available within 2-6 hours
  3. New tests (still in development)
    1. C. difficile combination assay
      1. Glutamate dehydrogenase: 97% sensitivity
      2. Toxins A and B: 97-99% Specificity
  4. Tests not recommended for routine screening
    1. Latex agglutination assay (low accuracy)
    2. C. difficile culture (non-specific)
    3. Toxin A or B PCR (expensive and time intensive)