Table 2. Evaluation of different methods for determination of oxacillin resistance in S. aureus with their sensitivity and specificity.
| Test | Staphylococcus aureus (126) |
Sensitivity % | Specificity % | Positive Likelihood Ratio | Negative Likelihood Ratio | PPV# % | NPV+ % | |||
|---|---|---|---|---|---|---|---|---|---|---|
|
*PCR for mecA | ||||||||||
| mecA +ve (98) (MRSA) |
mecA −ve (28) (MSSA) |
|||||||||
| True positive | False negative | True negative | False positive | |||||||
| Oxacillin Screen Agar | 96 | 2 | 21 | 7 | 97.96 | 75 | 3.92 | 0.03 | 93.20 | 91.30 |
| MTT based method | 97 | 1 | 27 | 1 | 98.98 | 96.43 | 27.71 | 0.01 | 98.98 | 96.43 |
| Easy MIC test | 96 | 2 | 25 | 3 | 97.96 | 89.29 | 9.14 | 0.02 | 96.97 | 92.59 |
| Oxacillin Disc Diffusion (1 ug) | 92 | 6 | 7 | 21 | 93.88 | 25.00 | 1.25 | 0.24 | 81.42 | 53.85 |
| Agar Dilution | 95 | 3 | 24 | 4 | 96.94 | 85.71 | 6.79 | 0.04 | 95.96 | 88.89 |
*Reference method.
#Positive Predictive Value.
+Negative Predictive Value.