Table 2.
Comparison of quadruple real-time PCR and traditional methods to detect vanA, vanB, vanM in 403 clinical rectal swabs.
| No. of isolates with each set of results | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Reference + | Reference – | ||||||||||
| Test + | Test — | Test + | Test – | Sensitivity | Specificity | PPV | NPV | Accuracy | Kappa coefficient(P) | ||
| Multiple real-time PCR method | vanA | 34 | 1 | 0 | 368 | 97.14% (85.47, 99.85a) | 100% (98.97, 100a) | 100% (89.85, 100a) | 99.75% (98.63, 99.99a) | 99.76% (98.66, 99.99a) | 0.984 (<0.001)* |
| vanM | 8 | 0 | 0 | 395 | 100% (67.56, 100.0a) | 100% (99.04, 100.0a) | 100% (67.56, 100.0a) | 100% (99.09, 100.0a) | 100.00% (99.11, 100.00a) | 1 (<0.001)* | |
|
vanA+ vanM |
25 | 0 | 0 | 378 | 100% (86.68, 100.0a) | 100% (98.99, 100.0a) | 100% (86.68, 100.0a) | 100% (99.09, 100.0a) | 100.00% (99.11, 100.00a) | 1 (<0.001)* | |
| Traditional method | vanA | 25 | 10 | 14 | 354 | 71.43% (54.95, 83.67a) | 96.2% (93.72, 97.72a) | 64.1% (48.42, 77.26a) | 94.04% (91.27, 96.15a) | 94.17% (91.46, 96.23a) | 0.643 (<0.001)* |
| vanM | 4 | 4 | 6 | 389 | 50% (21.52, 78.48a) | 98.48% (96.73, 99.3a) | 40.0% (16.82, 68.73a) | 97.51% (95.48, 98.8a) | 97.57% (95.58, 98.8 a) | 0.432 (<0.001)* | |
|
vanA+ vanM |
0 | 25 | 0 | 378 | 0.0% (0.0, 13.32a) | 100% (98.99, 100a) | –(0, 1a) | 93.79% (90.98, 95.95a) | 93.93% (91.17, 96.04a) | 0.0(1.00) | |
reference, gold standard. reference +, positive result for the reference. test +, positive result for the indicated test.
a
95% confidence interval.
*
the consistency is good. PPV, positive predictive value. NPV, negative predictive value. vanA, the sample carries vanA only. vanB, the sample carries vanB only. vanM, the sample carries vanM only. vanA+ vanM, the sample carries vanA and vanM gene simultaneously.