Epidemiology, Diagnosis and Treatment of Clostridium Difficile Infection

Matteo Bassetti; Giovanni Villa; Davide Pecori; Alessandra Arzese; Mark Wilcox

Disclosures

Expert Rev Anti Infect Ther. 2012;10(12):1405-1423. 

In This Article

GDH Antigen Detection

All C. difficile strains appear to produce the cell wall-associated enzyme glutamate dehydrogenase antigen (GDH). GDH appears to be highly conserved among C. difficile ribotypes and most likely independent from PaLoc structure.[95] Rapid tests using immunoenzymatic methods for the detection of GDH alone, or in combination with toxin(s), are increasingly used, notable as screening tests to increase the sensitivity of diagnostic algorithms. Like bacterial culture, tests that detect GDH do not distinguish toxin-producing from nontoxigenic C. difficile isolates.[96–98] The rationale for the approach is indeed that GDH is produced in significantly higher quantities than the C. difficile toxin and should yield a more sensitive assay than solid-phase toxin A/B EIAs. The commercial GDH tests offer a turnaround time of 15–45 min, compatible with lab routine needs. The greatest utility of stool GDH assays appear to be a screen to rule specimens negative and to select specimens for further testing. Indeed, by applying this test, it has been proven that approximately 20% of patients who are positive for the GDH antigen of C. difficile carry a nontoxigenic strain of C. difficile.[85,99] GDH test can therefore be selected as the first screening step in a diagnostic algorithm, with positive samples then confirmed using a toxin(s) test, to distinguish toxinogenic from nontoxinogenic CDI.

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