TABLE 3.
Comparison of Clostridium difficile toxin immunoassay and real-time PCR results with those of toxigenic culture
| Assay | Result | Comparison to toxigenic culture resultsa
|
|||||
|---|---|---|---|---|---|---|---|
| No. of specimens
|
Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) | |||
| Positive | Negative | ||||||
| Premier toxins A and B | Positive | 21 | 3 | 48 | 98 | 88 | 87 |
| Negative | 23 | 153 | |||||
| Xpect C. difficile A/B | Positive | 21 | 25 | 48 | 84 | 46 | 85 |
| Negative | 23 | 131 | |||||
| Immunocard toxins A & B | Positive | 21 | 2 | 48 | 99 | 91 | 87 |
| Negative | 23 | 154 | |||||
| Triage C. difficile panel (toxin A) | Positive | 14 | 0 | 32 | 100 | 100 | 84 |
| Negative | 30 | 156 | |||||
| LC real-time PCR | Positive | 38 | 4 | 86 | 97 | 90 | 96 |
| Negative | 6 | 152 | |||||
a
Anaerobic culture was performed on the 200 test stools by plating the specimens onto prereduced fastidious anaerobic agar with sheep blood (FAASB) and taurocholate, cycloserine, cefoxitin, fructose agar (TCCFA). All C. difficile culture-positive specimens were tested for the presence of toxin production (as evidenced by detection of the tcdA, tcdB, or tcdC genes) by LC PCR and conventional PCR. PPV, positive predictive value; NPV, negative predictive value.