TABLE 1.
Susceptibility results for 271 Enterobacter isolates using BMD, Etest on MHA (BD), and Etest on Iso-Sensitest agar
| Method and medium | Manganese concn in medium (mg/kg) | MIC (mg/liter) |
Susceptibility rate (%)a: |
|||
|---|---|---|---|---|---|---|
| 50% | 90% | Geometric mean ± SDb | EUCAST (S ≤ 1) | FDA (S ≤ 2) | ||
| BMD on BD MH broth | 0.029c | 0.25 | 1 | 0.42 ± 0.41* | 97** | 100** |
| Etest | ||||||
| BD MH agar | 0.043c | 1.5 | 3 | 1.94 ± 1.6* | 30** | 82** |
| Iso-Sensitest agar | 0.48 | 0.5 | 1.5 | 0.88 ± 1.2* | 88** | 94** |
a
Susceptibility rates found by using EUCAST and FDA susceptibility breakpoints (S), which were ≤1 and ≤2 mg/liter, respectively. **, P < 0.001 for comparisons of susceptibility rates between each detection method using the Fisher exact test.
b
*, P < 0.001 for comparisons of MICs between each detection method using a t test.
c
The higher manganese concentration in the BD MH agar compared to BD MH broth could be explained by the manganese content of pure agar (0.002 mg/kg).