Evaluation of the Selective Enrichment Culture to Recover Clostridium difficile

To evaluate the recovery rates to increase toxigenic C. difficile, the selective enrichment broth culture methods were compared with commonly used cytotoxin assays and toxigenic culture. First, the enrichment culture, using the selective medium broth for 2 to 5 days, was performed and then, toxigenic C. difficile was confirmed by C. difficile toxin gene-specific PCR after being cultured on C. difficile selective agar. The sensitivity of C. difficile from the enrichment culture (100%) was higher than that of C. difficile selective agar culture (93.8%), while positive predictive values (PPV) were low; 72.7% (16/22) and 88.2% (15/17). PPV of the enrichment culture are not high. Recently, combinations of C. difficile selective agar culture, C. difficile A & B assays, glutamate dehydrogenase, and nucleic acid amplification method are widely used. The enrichment culture was disadvantageous in PPV, turn-around time, and cost. So, what we performed is not considered as a common method of diagnosis of C. difficile-associated diarrhea.