TABLE 2.
Colistin MICs and expression levels of pmrA and pmrK genes of KPB-1 and KPB-2 and of the corresponding transformants carrying the pACYC184, pACYC-pmrB, and pACYC-pmrBT245G plasmidsa
| Strain | Chromosomal pmrB status | pACYC184 pmrB status | Colistin MIC (μg/ml) | Relative expression level |
||
|---|---|---|---|---|---|---|
| pmrA | pmrB | pmrK | ||||
| KPB-1 | WTb | 0.06 | 1 | 1 | 1 | |
| KPB-1(pACYC-pmrBT245G) | WT | T245G (L82R) | 0.125 | 1.06 ± 0.07 | NDc | 0.89 ± 0.02 |
| KPB-2 | T245G (L82R) | 4 | 10.23 ± 1.02 | 4.53 ± 0.92 | 4.33 ± 0.08 | |
| KPB-2(pACYC184) | T245G (L82R) | 4 | 11.51 ± 0.32 | ND | 3.85 ± 0.11 | |
| KPB-2(pACYC-pmrB) | T245G (L82R) | WT | 0.125 | 0.98 ± 0.21 | ND | 0.68 ± 0.05 |
| KPB-2(pACYC184-pmrBT245G) | T245G (L82R) | T245G (L82R) | 64 | 11.23 ± 0.61 | ND | 4.78 ± 0.13 |
a
Expression levels for the pmrA and pmrK genes were normalized against the values obtained with KPB-1. For each strain, the chromosomal status of pmrB and of the pmrB allele harbored by pACYC184 are also indicated.
b
WT, wild-type.
c
ND, not determined.