RT-PCR for the diagnosis of Clostridium difficile infection: the final answer has yet to come

Real time polymerase chain reaction (RT-PCR) is a powerful tool for quick diagnosis of toxigenic Clostridium difficile determination in diarrhoeic stool specimens. A two-step diagnostic algorithm (membrane enzyme immunoassay for glutamate dehydrogenase (GDH) and RT-PCR for C. difficile toxins) has been recommended by different guidelines,1 with cumulative sensitivity of 90% (80%–100%) and specificity of 88.5% (82%–95%) as compared with cell cytotoxicity assay. However, as previously reported in a subset of samples, the analysis of toxin DNA in the stool specimens is not conclusive, and indeterminate results are recorded, that is, in the case of samples with cycle threshold (CT) for toxin B with values ranging between 37.1 and 39.9.2.