TABLE 3.
Complementation of posttherapy efflux mutants with mexR
| Strain | MIC ratioa
|
||||
|---|---|---|---|---|---|
| Atz | Mer | Nal | Chl | Tmp | |
| PAO1 | 0.5 | 0.5 | 1 | 0.5 | 0.5 |
| 109 | 8 | 4 | 8 | 4 | 2 |
| 92 | 1 | 1 | 4 | 1 | 1 |
| 283 | 2 | 4 | NDb | 2 | 2 |
| 128 | 4 | 4 | 8 | 8 | 4 |
| 17 | 4 | 4 | 8 | 1 | 2 |
a
The MIC ratio is the MIC for pAK1900/MIC for pAKR4. Resistant strains were each transformed with the mexR gene cloned on plasmid pAK1900 (construct named pAKR4) and with the vector alone. MIC ratios of ≥4 are in boldface. For definitions of abbreviations, see footnote a of Table 1.
b
ND, not determined because the pretherapy strain was highly resistant to nalidixic acid (MIC, ≥1,024 μg per ml), suggesting the presence of a gyrA-type mutation.