A two-step approach improves the diagnosis of Clostridium difficile infection.

Clostridium difficile infection (CDI) is a major cause of health care-associated diarrhea. The aim of the present study was to evaluate a two-step approach for the diagnosis of CDI. The two-step procedure consisted of GDH-toxin A/B EIA (Enzyme immunoassay targeting enterotoxin A and Cytotoxin B), followed by PCR detecting toxigenic C. difficile. Results indicate that EIAs provide a rapid screening assay for the laboratory diagnosis of CDI but, in GDH-positive and toxins-negative samples, EIA should be always followed by PCR to distinguish toxigenic vs nontoxigenic strains. GDH-toxin A/B EIA-rapid test has high specificity but low sensitivity to detect CDI. The implementation of a two-step procedure significantly increases the diagnostic accuracy to detect CDI and provides a toxigenic type characterization of C. difficile isolates.