Detection of toxigenicClostridium difficile in fecal samples by colony blot hybridization

A hybridization assay for detection of toxigenicClostridium difficile in fecal samples was developed and compared with the classical tissue culture cytotoxicity assay. A DNA fragment probe specific for the toxin B gene ofClostridium difficile was synthesized by the polymerase chain reaction and labelled with digoxigenin. Fecal samples were cultured for 24 hours, replica-plated and hybridized with the probe. The hybridization assay had a sensitivity of 100 %, specificity of 96.7 %, positive predictive value of 86.7 % and negative predictive value of 100 % compared with the cytotoxicity assay.