TABLE 1.

Performance of the Xpert C. difficile assay compared to those of direct and enrichment culturesa

Xpert C. difficile tcdB assay resultDirect culture (no. of samples)Enrichment culture (no. of samples)
PositiveNegativeTotalPositiveNegativeTotal
Positive245188433316117433
Negative31,8601,863221,8411,863
    Total2482,0482,2963381,9582,296
  • a Compared to C. difficile direct culture results, the Xpert C. difficile assay had the following results: sensitivity, 98.8%; specificity, 90.8%; positive predictive value (PPV), 56.6%; negative predictive value (NPV), 99.8%; prevalence, 10.8%. Compared to C. difficile enrichment culture, the Xpert C. difficile assay had the following results: sensitivity, 93.5%; specificity, 94.0%; PPV, 73.0%; NPV, 98.8%; prevalence, 14.7%.