Table 2.
Induction of β-lactamase activity by three inducers.a
| inducer | Wild-type (PAO1) | Mutant (Z61)b | ||||
|---|---|---|---|---|---|---|
|
|
|
|||||
| Conc. (μg/mL) | β-lactamase inductionc | Conc. (μg/mL) | β-lactamase inductionc | |||
|
|
|
|||||
| Cefoxitind | 512 | 136e | 1555/11.4 | 0.0156 | 4.7e | 4.6/0.98 |
| 2e | 500 | 1.0 | 19.1/19.1 | 100 | 1.4e | 27.5/20.0 |
| 4e | 500 | 1.0 | 19.1/19.1 | 100 | 1.7e | 5.5/3.3 |
| 2ad | -f | 10g | 1.0 | 4.1/4.0 | ||
| 4ad | -f | 100 | 1.0 | 3.6/3.5 | ||
a
Average of two runs.
b
The strain is defective in its outer membrane.
c
The number (the left column) is calculated by lactamase activity in the presence of an inducer divided by that without an inducer (the right column) under the same condition.The enzyme activity was expressed as the nanomole of nitrocefin hydrolyzed per min per mg of protein for wild-type and picomole/min/mg for mutant.
d
Cefoxitin and compounds 2a/4a were used as positive and negative controls for induction, respectively.
e
β-Lactamse activities were significantly different (p < 0.05) between induced and uninduced samples.
f
Not measured.
g
due to limited supply of compound, we could only assess the effect at the lower concentration.