TABLE 1.
Comparison of the Vitek system, the E test, and the disk diffusion test for identification of mecA-positive CoNSa
| Compared method | Susceptibility category (criterion) | No. (%) of strains with mecA result:
|
|
|---|---|---|---|
| Negative | Positive | ||
| Broth microdilutionb | Susceptible (≤0.25 μg/ml) | 22 (17.9) | 3 (2.4) |
| Resistant (≥0.5 μg/ml) | 2 (1.6) | 96 (78.1) | |
| Disk diffusionc | Susceptible (≥18 mm) | 21 (17.1) | 0 (0.0) |
| Resistant (≤17 mm) | 3 (2.4) | 99 (80.5) | |
| E testb | Susceptible (≤0.25 μg/ml) | 19 (15.4) | 0 (0.0) |
| Resistant (≥0.5 μg/ml) | 5 (4.1) | 99 (80.5) | |
| Vitekb | Susceptible (≤0.25 μg/ml) | 21 (17.1) | 2 (1.6) |
| Resistant (≥0.5 μg/ml) | 3 (2.4) | 97 (78.9) | |
a
A total of 123 strains (24 mecA negative and 99 mecA positive). Excludes two strains of S. lugdunensis not claimed under these study results. Strains were confirmed to be mecA positive by PCR.
b
NCCLS reference method (4) with results interpreted by revised criteria.
c
NCCLS standardized method (5) with results interpreted by revised criteria.