TABLE 2.
Sensitivities of acrA, tolC, and emrB mutants to MTX
| Strain | Relevant genotypea | MICb of MTX (μM) |
|---|---|---|
| W4573 | Wild type | >1,024 |
| SK636 | emrB | >1,024 |
| N43 | acrA1 | 256 |
| SK627 | acrA1 emrB | 256 |
| LBB1175 | tolC | 64 |
| SK642 | acrA1 tolC | 64 |
| SK660 | acrA1 tolC emrB | 64 |
a
For a full listing of genotypes, see Table 1.
b
MICs were determined by examining the growth of 2-ml liquid cultures containing twofold serial dilutions of MTX (2 to 1,024 μM) in Luria-Bertani liquid broth. The inoculum (20 μl) contained approximately 105 cells per ml. The MIC was determined as the lowest concentration that prevented visible growth after 8 h on a roller drum at 37°C. All the tested strains grew to saturation in the absence of MTX. The values are the averages of three separate experiments.