Detection of toxigenic Clostridium difficile in pediatric stool samples: an evaluation of Quik Check Complete Antigen assay, BD GeneOhm Cdiff PCR, and ProGastro Cd PCR assays

The performance of C. Diff Quik Chek Complete (QCC), BD GeneOhm Cdiff PCR (BD), and ProGastro Cd PCR (PG) assays was evaluated in detecting Clostridium difficile infection (CDI) in children using 200 frozen stool specimens. The results of the tests were compared to the toxigenic culture (TC) as ‘gold standard.’ The sensitivity, specificity, positive predictive value, and negative predictive value were as follows. QCC antigen (GDH + Toxin-A/B) = 70.8%, 97.4%, 89.5%, and 91.4%; BD PCR = 89.6%, 96.7%, 89.6%, and 96.7%; PG PCR = 100%, 93.4%, 82.8%, and 100%. Polymerase chain reaction (PCR) assays detected an additional 11 positives missed by TC, 7 of which were confirmed positive by an alternate tcdB gene PCR assay. However, retrospective clinical chart review indicated CDI in only 3 of the 11 patients in whom C. difficile was detected by PCR only. A 2-step algorithm utilizing QCC antigen test as a screening test followed by confirmation of GDH-positive and toxin-negative samples with either BD or PG PCR assay will provide rapid and accurate results for majority of the samples and reduce laboratory testing cost.