Detection of Clostridium difficile toxin A/B genes by multiplex real-time PCR for the diagnosis of C. difficile infection

Toxigenic Clostridium difficile culture is considered to be the standard diagnostic method for the detection of C. difficile infection (CDI). Culture methods are time-consuming and although enzyme immunoassay is rapid and easy to use, it has low sensitivity. In the present study, the AdvanSure CD real-time (RT)-PCR kit (LG Life Sciences) was evaluated for its ability to detect C. difficile toxin A (tcdA) and B (tcdB) genes, simultaneously. A total of 127 fresh diarrhoeal stool specimens, submitted to the clinical microbiology laboratory for C. difficile culture, were tested. C. difficile toxins and toxin genes were detected with a VIDAS C. difficile A&B (VIDAS-CDAB) enzyme-linked fluorescent immunoassay (ELFA) and the AdvanSure RT-PCR kit, respectively, according to the manufacturers' instructions. Their performance was compared with a standard toxigenic culture method as a reference. The sensitivity, specificity and positive and negative predictive values using the AdvanSure RT-PCR kit were 100%, 98.3%, 84.6% and 100%, respectively, while those of the VIDAS-CDAB system were 63.6%, 100%, 100% and 96.6%, respectively. Four tcdA(+)/tcdB(+) strains of C. difficile were detected with the AdvanSure RT-PCR kit, which offers comparable sensitivity and specificity to the reference method with a turnaround time of similar to 3 hours.