COMPARISON OF 4 METHODS IN THE DIAGNOSIS OF CLOSTRIDIUM-DIFFICILE DISEASE

Nine hundred forty-five stool specimens from patients suspected of having,ing Clostridium difficile disease were examined using a cell culture cytotoxicity assay (CTA), two enzyme immunoassay (EIA) kits (Cytoclone for toxins A and B; VIDAS for toxin A) and a latex agglutination assay (CDT). One hundred nineteen specimens had positive titers (greater than or equal to 90) in the CTA; clinical review of 16 discordant samples and 49 controls supported the significance of 90 as the positive cut-off titer. The performance of the two EIAs and the latex assay was assessed relative to CTA titers of the samples. Sensitivity was less than or equal to 50% for all three assays for the 24 specimens with CTA titers of 90, but it reached 97-100% for the two EIAs and 84% for the latex assay at titers of greater than or equal to 2,250. The Cytoclone EIA exhibited higher sensitivity at the lower positive titers. Overall, specificity of the methods ranged from 96.7% (CDT latex assay)to 99.1% (Cytoclone EIA).