Table 4. Performance of two phenotypic methods in distinguishing serine-carbapenemase and metallo-carbapenemase.
| Carbapenemase classification | Phenotypic method | Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) | Accuracy (%) | Cohen’s kappa |
|---|---|---|---|---|---|---|---|
| Serine-carbapenemase | mCIM + eCIM | 100.0 | 98.4 | 97.6 | 100.0 | 99.0 | 0.979 |
| CDT | 95.0 | 98.4 | 97.4 | 96.8 | 97.0 | 0.938 | |
| Metallo-carbapenemase | mCIM + eCIM | 95.1 | 100.0 | 100.0 | 96.8 | 98.0 | 0.959 |
| CDT | 97.6 | 100.0 | 100.0 | 98.4 | 99.0 | 0.979 |
PPV, positive predictive value; NPV, negative predictive value; mCIM, modified carbapenem inactivation method; eCIM, EDTA-carbapenem inactivation method; CDT, combined disk test.