Table 1.
Performance of the cytotoxicity assay and illumigene C. difficile assay for detection of toxigenic strains of C. difficile
| Assay result | No. of toxigenic culture results: |
Assay performance (95% confidence interval) |
|||||
|---|---|---|---|---|---|---|---|
| Negative | Positive | Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) | Correlation (%) | |
| Cytotoxicity assay | |||||||
| Negative | 423 | 15 | 69.4 (56.5–82.3) | 100 (94.9–98.3) | 100 | 96.6 (94.9–98.3) | 96.8 |
| Positive | 0 | 34 | |||||
| Total | 423 | 49 | |||||
| illumigene | |||||||
| Negative | 419 | 4 | 91.8 (84.2–99.5) | 99.1 (98.1–99.9) | 91.8 (84.2–99.5) | 99.1 (98.1–99.9) | 98.3 |
| Positive | 4 | 45 | |||||
| Total | 423 | 49 | |||||