Which laboratory tests are commonly used to diagnose C. difficile-associated disease?
• Stool culture for C. difficile: This is the most sensitive test available, but the one most often associated with false-positive results due to presence of non-toxigenic strains. Stool cultures for C. difficile also are labor intensive and require the appropriate culture environment to grow anaerobic microorganisms. Results are available within 48-96 hours of the test. • Antigen detection for C. difficile: These are rapid tests (<1 hr) that detect the presence of C. difficile antigen by latex agglutination or immunochromatographicassays. They must be combined with toxin testing to verify diagnosis. • Toxin testing for C. difficile*: • Enzyme immunoassay detects toxin A, toxin B, or both A and B. It is a same-day assay but less sensitive than the tissue culture cytotoxicity assay. • Tissue culture cytotoxicity assay detects toxin B only. This assay requires technical expertise to perform, is costly, and requires 24-48 hr for a final result. It does provide specific and sensitive resul
