Enzyme immunoassay for detection of antibody to toxins A and B of Clostridium difficile.

An enzyme immunoassay (enzyme-linked immunosorbent assay [ELISA]) to detect hamster antibody to toxins A and B of Clostridium difficile was developed in which toxin preparations are used to coat the solid phase. The specificity of the assay was supported by blocking tests with the toxin preparations and proteins from a nontoxigenic strain. Sera from immunized and control hamsters were tested by this technique, and results were compared with those from a cytotoxicity neutralization assay. Antibody to toxins A and B assayed by ELISA showed a close quantitative correlation with antibody titers obtained by cytotoxicity neutralization. The ELISA assays described appear to provide a sensitive, specific, and practical method to define the prevalence of antibody to C. difficile toxins. These assays could be readily applied to human sera to examine and study the immune response of patients with C. difficile-induced disease.