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