TABLE 5.
Basal and cefoxitin- and ceftazidime-induced β-lactamase activities of double mutant PAΔDDh3 and triple mutant PAΔDDh2Dh3
| Strain | Avg β-lactamase sp acta ± SD
|
|||
|---|---|---|---|---|
| Basal | Cefoxitin (50 μg/ml) | Ceftazidime (0.5 μg/ml) | Ceftazidime (20 μg/ml) | |
| PAO1 | 1 | 52 ± 13 | 1.6 ± 0.2 | NAb |
| PAΔDDh2Dh3 | 976 ± 165 | 977 ± 114 | 1,050 ± 125 | 995 ± 85 |
| PAΔDDh3 | 210 ± 37 | 1,010 ± 35 | 780 ± 64 | 1,088 ± 122 |
a
Relative values of β-lactamase activity considering 1 the basal activity of reference strain PAO1 (19 nmol of nitrocefin hydrolyzed/min/mg of protein).
b
NA, not applicable (since the MIC for PAO1 is 1 μg/ml).