TABLE 3.
Susceptibility testing results
| Strain | MIC (μg/ml) |
|||
|---|---|---|---|---|
| Ampicillin | Ampicillin-avibactama | Cephalothin | Imipenem | |
| B. multivorans | ||||
| ATCC 17616 | 1,024 | 4 | ≥4,096 | 64 |
| ATCC 17616 ΔblaAmpC1 | 1,024 | 4 | ≥4,096 | 64 |
| E. coli | ||||
| DH10B pBC SK(+) | 2 | 1 | 2 | 1 |
| DH10B pBC SK(+) blaPenA | 4,096 | 4 | 4,096 | 2 |
| DH10B pBC SK(+) blaAmpC1 | 8 | 4 | 32 | 1 |
a
Ampicillin was varied, and avibactam was held at a constant concentration of 4 μg/ml. CLSI interpretive indices were as follows: Enterobacteriaceae (ampicillin, ≥32 μg/ml, resistant; cephalothin, ≥32 μg/ml, resistant; imipenem, ≥4 μg/ml, resistant; and imipenem, 2 μg/ml, intermediate), nonfermenting Gram-negative bacteria (penicillins, ≥128 μg/ml, resistant; cephalosporins, ≥32 to 64 μg/ml, resistant; and carbapenems, ≥8 to 16 μg/ml, resistant).