Diagnosis of Clostridium difficile infection using real-time PCR

Clostridium difficile is known to cause antibiotic-associated diarrhea and pseudomembranous colitis. Toxinogenic strains of the bacterium produce toxins A (TcdA) and B (TcdB), which are associated with the pathogenicity. The standard methods for diagnosis of C. difficile infection include the cell cytotoxicity assay and the culture of a toxinogenic strain. Due to the long turnaround time of these methods, more rapid methods are preferred. Enzyme immunoassays are fast, but lack sensitivity. Therefore, real-time PCR methods have been developed. The real-time PCR described in this chapter detects tcdB, the gene coding for toxin B. Since toxin A-negative, toxin B-positive strains have been reported to cause disease as well, these strains can also be detected by this method which uses an automated STAR-MagnaPure method for the optimum isolation of DNA from feces. An internal control is included as well to control for inhibition of the PCR method.