TABLE 4.
MICs of β-lactam antibiotics and specific activities of AmpC in P. aeruginosa mutants carrying wild-type ampDE and in AmpD-defective mutant
| Strain and plasmid | MIC (μg/ml)
|
β-Lactamase activitya
|
||
|---|---|---|---|---|
| Ampicillin | Cefotaxime | Noninduced | Inducedb | |
| PAO1 | 512 | 32 | 7 ± 0.5 | 687 ± 32 |
| PAO1-D | 4,096 | 1,024 | 256 ± 14 | 5,560 ± 239 |
| PAO4254 | 2,048 | 32 | 80 ± 3 | 3,100 ± 90 |
| PAO4254/pUCP26 | 1,024 | 32 | 92 ± 5 | 2,875 ± 158 |
| PAO4254/pHUL4DE26 | 1,024 | 32 | 83 ± 4 | 2,288 ± 170 |
| Ps50SAI−con | 2,048 | 256 | 3,780 ± 150 | 5,900 ± 220 |
| Ps50SAI−con/pHUL4DE26 | 1,024 | 512 | 2,870 ± 192 | 3,397 ± 200 |
| M1405 | 4,096 | 512 | 10,550 ± 350 | 12,650 ± 400 |
| M1405/pHUL4DE26 | 2,048 | 512 | 7,286 ± 393 | 8,931 ± 518 |
| M2297−con | 2,048 | 512 | 8,200 ± 300 | 9,330 ± 320 |
| M2297−con/pHUL4DE26 | 1,024 | 512 | 6,949 ± 324 | 6,834 ± 513 |
a
Nanomoles of nitrocefin hydrolyzed per minute per milligram of protein.
b
Induction was carried out with 50 μg of cefoxitin/ml for 2 h.