Evaluation of an oligonucleotide probe and an immunological test for direct detection of toxigenic Clostridium difficile in stool samples.

A 33 basepair oligonucleotide probe, designed from the sequence of the Clostridium difficile toxin B gene, was evaluated for its ability to detect toxigenic Clostridium difficile directly in stool samples, without culture or DNA isolation. Two different labelling techniques were investigated: radiolabelling and digoxigenin-labelling. One hundred ninety-six stools were tested, with a good correlation (96%) obtained between the oligonucleotide probe and the gold standard, the cytotoxicity tissue culture assay. The sensitivity and specificity were 83% and 100%, respectively. In parallel, a new commercially available enzyme immunoassay for the detection of Clostridium difficile toxin A in stool specimens was investigated. In 162 samples tested, a sensitivity of 80% and a specificity of 98% were obtained.