Clostridium difficile Toxin

Aka: Clostridium difficile Toxin, C. diff Toxin

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II. Indications for testing

  1. Diarrheal stools and
  2. Antibiotic exposure in last 3 months

III. 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

IV. Specimen

  1. Immediate exam of fresh stool specimen
  2. May be kept refrigerated if exam delayed

V. 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)

VI. References

  1. Brazier (1998) J Antimicrob Chemother 41:29-40 [PubMed]
  2. Kyne (2001) Gastroenterol Clin North Am 30(3):753-77 [PubMed]

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