Rapid diagnosis of toxinogenic Clostridium difficile in faecal samples with internally controlled real-time PCR.

A real-time PCR assay for Clostridium difficile was developed, based on the tcdB gene, which detected all known toxinogenic reference strains (n = 45), within 30 serogroups and 24 toxinotypes. The analytical sensitivity was 1 x 10(3) CFU/mL, and the detection limit in faeces was 1 x 10(5) CFU/g. The optimal protocol for DNA extraction from faecal samples involved use of the MagnaPure system with a Stool Transport and Recovery (STAR) buffer pre-treatment. In a 1-month prospective study of 85 patients with diarrhoea, the sensitivity, specificity and positive and negative predictive values of the assay were 100%, 94%, 55% and 100%, respectively, compared with the standard cell cytotoxicity assay.