Enzyme immunoassay for detection ofClostridium difficile toxins a and b in patients with antibiotic-associated diarrhoea and colitis

A sandwich enzyme immunoassay (ELISA) was developed to detectClostridium difficile toxins A and B in stools from patients with antibiotic associated diarrhoea and colitis. Immune serum to crudeClostridium difficile toxin and non-immune serum were coated onto polystyrene microtiter plates to act as capture antibodies; toxins A and B in human stools were detected by antibodies from rabbits immunized with purified toxins A and B. The ELISA for toxin B showed cross-reactions withClostridium bifermentans andClostridium sordellii and lacked diagnostic sensitivity in clinical samples. The ELISA for toxin A showed no cross-reactions with other clostridiae investigated and was positive in 33 % (62/189) of patients with antibiotic associated diarrhoea. This compared with 38 % (71/189) positive in the tissue culture assay forClostridium difficile cytotoxin. With a predictive value of 96 % in clinical specimens, the ELISA for toxin A constitutes a sensitive and specific tool for diagnosis ofClostridium difficile associated diarrhoea and colitis.