TABLE 3.
Expression of ampC, mexB, mexD, mexF, and mexY in selected isolates
| Strain | MIC (mg/liter)
|
Relative mRNA level with respect to that in reference strain PAO1a
|
|||||
|---|---|---|---|---|---|---|---|
| CAZ | FEP | ampC | mexB | mexD | mexF | mexY | |
| PAO1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| 109351-07 | 4 | 16 | 0.9 ± 0.5 | 1.4 ± 0.6 | 4.1 ± 2.9 | 1.0 ± 0.4 | 27.2 ± 10.5 |
| 87999-07 | 2 | 16 | 3.1 ± 1.7 | 2.5 ± 0.1 | 5.0 ± 2.3 | 1.7 ± 0.1 | 25.4 ± 4.3 |
| 95818-07 | 8 | 16 | 1.7 ± 0.9 | 1.9 ± 0.6 | 4.0 ± 2.3 | 2.3 ± 0.7 | 23.8 ± 5.3 |
| 71702-07 | ≤1 | 16 | 1.2 ± 0.6 | 0.4 ± 0.1 | 2.5 ± 1.5 | 1.5 ± 0.8 | 32.3 ± 9.1 |
a
Strains were considered AmpC, MexCD-OprJ, MexEF-OprN, or MexXY-OprM hyperproducers when the relative level of expression of the corresponding gene was at least 10-fold higher than that in reference strain PAO1. The breakpoint used for MexAB-OprM hyperproduction was threefold higher expression than that for PAO1.