TABLE 3.
Activities of β-lactams against M. abscessus
| Growth mediuma | Strainb | MIC (μg/ml)c |
||
|---|---|---|---|---|
| Cefoxitin | Imipenem | Ceftaroline | ||
| CaMH | CIP104536 | 32 | 8 | >256 |
| CaMH + Avi | CIP104536 | 32 | 8 | 32 |
| CaMH | ΔblaMab strain | 32 | 4 | 16 |
| 7H9sB | CIP104536 | 16 | 4 | 8 |
| 7H9sB + Avi | CIP104536 | 8 | 2 | 1 |
| 7H9sB | ΔblaMab strain | 8 | 2 | 2 |
a
CaMH, cation-adjusted Mueller-Hinton broth; 7H9sB, Middlebrook 7H9 medium supplemented with 0.05% (vol/vol) Tween 80 and 10% (vol/vol) oleic acid, albumin, dextrose, and catalase; + Avi, the medium was supplemented with 4 μg/ml of avibactam.
b
ΔblaMab strain, β-lactamase-deficient derivative of CIP104536 obtained by deletion of gene blaMab.
c
Data are the median results from at least three independent experiments. The breakpoints recommended by CSLI for cefoxitin and imipenem MICs determined in CaMH medium are as follows. Cefoxitin: susceptible, ≤16 μg/ml; intermediate, 32 to 64 μg/ml; resistant, ≥128 μg/ml. Imipenem: susceptible, ≤4 μg/ml; intermediate, 8 to 16 μg/ml; resistant, ≥32 μg/ml.