TABLE 3.
Antibacterial activities of gatifloxacin and other quinolones against norA transformant NY12a
| Quinolone | Hydrophobicity (log P) | MIC (μg/ml)
|
MIC ratio | |
|---|---|---|---|---|
| SA113 (parent) | NY12 (norA transformant) | |||
| Nalidixic acid | +1.87 | 25 | 50 | 2 |
| Sparfloxacin | +1.52 | 0.025 | 0.10 | 4 |
| Tosufloxacin | +1.07 | 0.0125 | 0.20 | 16 |
| Gatifloxacin | +0.69 | 0.05 | 0.39 | 8 |
| Ofloxacin | +0.68 | 0.20 | 3.13 | 16 |
| Fleroxacin | +0.66 | 0.39 | 3.13 | 8 |
| Lomefloxacin | +0.09 | 0.39 | 6.25 | 16 |
| Enoxacin | −0.03 | 0.78 | 25 | 32 |
| Ciprofloxacin | −0.14 | 0.20 | 12.5 | 64 |
| Norfloxacin | −0.59 | 0.78 | 50 | 64 |
| Pipemidic acid | −0.85 | 12.5 | 800 | 64 |
a
Log P is the apparent partition coefficient between chloroform and 0.1 M phosphate buffer (pH 7.4). The MIC ratio was calculated as the ratio of the MIC for norA transformant NY12 to the MIC for parent strain SA113. The increase in the MICs of the quinolones for the norA transformant (log MIC ratio) were negatively correlated with their hydrophobicity (log P) (correlation coefficient, −0.93; P < 0.01).