Figure 1
Figure 2
Result of genotypic and phenotypic methods of 50 S_ aureus
| Isolate no. | mecA gene | OSA test | Oxacillin MIC | Cefoxitin disk test | Oxacillin disk | β-Lactamase test |
|---|---|---|---|---|---|---|
| SA1 | + | Growth | 128 (R) | Resistant | Resistant | Positive |
| SA2 | − | No growth | 1 (S) | Susceptible | Susceptible | Negative |
| SA3 | + | Growth | >128 (R) | Resistant | Resistant | Positive |
| SA4 | + | Growth | 64 (R) | Resistant | Resistant | Positive |
| SA5 | + | No growth | 8 (R) | Resistant | Resistant | Positive |
| SA6 | − | No growth | 8 (R) | Susceptible | Resistant | Positive |
| SA7 | + | Growth | >128 (R) | Resistant | Resistant | Positive |
| SA8 | − | Growth | 64 (R) | Resistant | Resistant | Positive |
| SA9 | + | Growth | 128 (R) | Resistant | Resistant | Positive |
| SA10 | + | Growth | 36 (R) | Resistant | Resistant | Positive |
| SA11 | + | Growth | >128 (R) | Resistant | Resistant | Positive |
| SA12 | + | No growth | 128 (R) | Resistant | Resistant | Positive |
| SA13 | + | Growth | >128 (R) | Resistant | Resistant | Positive |
| SA14 | + | Growth | >128 (R) | Resistant | Resistant | Positive |
| SA15 | + | Growth | 4 (R) | Resistant | Susceptible | Positive |
| SA16 | + | Growth | 8 (R) | Resistant | Susceptible | Positive |
| SA17 | + | Growth | 64 (R) | Resistant | Resistant | Positive |
| SA18 | + | Growth | >128 (R) | Resistant | Resistant | Positive |
| SA19 | − | No growth | 32 (R) | Resistant | Resistant | Positive |
| SA20 | − | Growth | >128 (R) | Resistant | Resistant | Positive |
| SA21 | + | Growth | >128 (R) | Resistant | Resistant | Positive |
| SA22 | − | Growth | 8 (R) | Susceptible | Resistant | Positive |
| SA23 | − | Growth | >128 (R) | Resistant | Resistant | Positive |
| SA24 | + | Growth | >128 (R) | Resistant | Resistant | Positive |
| SA25 | − | No growth | 1 (S) | Susceptible | Susceptible | Positive |
| SA26 | + | Growth | >128 (R) | Resistant | Resistant | Positive |
| SA27 | − | No growth | 1 (S) | Susceptible | Resistant | Positive |
| SA28 | − | Growth | 1 (S) | Susceptible | Susceptible | Positive |
| SA29 | − | Growth | >128 (R) | Resistant | Susceptible | Positive |
| SA30 | − | No growth | 64 (R) | Susceptible | Susceptible | Positive |
| SA31 | − | Growth | >128 (R) | Resistant | Resistant | Positive |
| SA32 | − | Growth | 32 (R) | Resistant | Resistant | Positive |
| SA33 | − | Growth | 64 (R) | Resistant | Resistant | Positive |
| SA34 | − | Growth | 2 (S) | Susceptible | Susceptible | Positive |
| SA35 | − | No growth | 1 (S) | Susceptible | Susceptible | Positive |
| SA36 | − | No growth | 0.5 (S) | Susceptible | Susceptible | Positive |
| SA37 | + | Growth | 8 (R) | Resistant | Resistant | Positive |
| SA38 | − | No growth | 1 (S) | Susceptible | Susceptible | Positive |
| SA39 | − | Growth | 64 (R) | Resistant | Resistant | Positive |
| SA40 | + | No growth | 16 (R) | Resistant | Susceptible | Positive |
| SA41 | − | No growth | 2 (S) | Susceptible | Susceptible | Positive |
| SA42 | − | No growth | 1 (S) | Susceptible | Susceptible | Positive |
| SA43 | − | Growth | 1 (S) | Susceptible | Susceptible | Positive |
| SA44 | − | No growth | 0.5 (S) | Susceptible | Susceptible | Positive |
| SA45 | − | Growth | 16 (R) | Resistant | Resistant | Positive |
| SA46 | − | Growth | 8 (R) | Resistant | Resistant | Positive |
| SA47 | − | No growth | 0.5 (S) | Susceptible | Susceptible | Positive |
| SA48 | + | Growth | 8 (R) | Resistant | Resistant | Positive |
| SA49 | − | No growth | 2 (S) | Susceptible | Susceptible | Positive |
| SA50 | − | Growth | 2 (S) | Susceptible | Resistant | Positive |
Correlation coefficient by Pearson's correlation coefficient method for comparison of phenotypic methods
| Phenotypic methods in combinations | Pearson's rank correlation coefficient (r) |
|---|---|
| MIC+CFD | 0.8729 |
| MIC+OD | 0.6910 |
| OD+CFD | 0.6528 |
| CFD+OSA | 0.6052 |
| MIC+OSA | 0.5431 |
| OD+OSA | 0.5172 |
Comparison of phenotypic methods for the detection on methicillin resistance in S_ aureus
| Phenotypic methods | No. of isolates showing mecA MRSA (n = 21) | No of isolates showing non-mecA MSSA (n = 29) | Statistical analysis (%) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of true positive isolates | No. of false negative isolates | No. of true negative isolates | No. of false positive isolates | SN | SP | PPV | NPV | AUC | |
| OSA | 18 | 3 | 14 | 15 | 86 | 48 | 54.54 | 83.35 | 64 |
| MIC | 21 | 0 | 15 | 14 | 100 | 52 | 60 | 100 | 72 |
| OD | 18 | 3 | 15 | 14 | 86 | 52 | 56.25 | 83.3 | 66 |
| CFD | 21 | 0 | 18 | 11 | 100 | 62 | 65.6 | 100 | 78 |