Table 3.
Characterization of 10 ciprofloxacin-resistant clones isolated after 5 days of ciprofloxacin treatmenta
| Strain | Ciprofloxacin MIC (μg/ml) | Mutation |
Membrane permeabilityb | ||
|---|---|---|---|---|---|
| gyrA | parC | marR | |||
| ΔmutS clone 1 | 1 | S83L | —c | — | 1.08d |
| ΔmutS clone 2 | 2 | S83L | A140T | — | 1.01 |
| ΔmutS clone 3 | 0.75 | S83L | — | — | 0.90d |
| ΔmutS clone 4 | 1 | S83L | — | — | 0.94d |
| ΔmutS clone 5 | 2 | S83L | — | — | 0.74d |
| ΔmutS clone 6 | 2 | S83L | — | — | 1.30d |
| ΔmutS clone 7 | 2 | S83L | — | — | 0.91d |
| WT clone 1 | 1.5 | S83L | — | — | 0.91d |
| WT clone 2 | 1 | S83L | — | — | 0.91d |
| WT clone 3 | 0.25 | S83L | — | — | 0.98 |
| WT S83L | 0.25 | S83L | — | — | 1.01 |
| WT | 0.008 | — | — | — | 1.00 |
a
Mutants were selected in the presence of 200 ng/ml ciprofloxacin. MICs were determined by using E tests (BioMérieux). The QRDRs of gyrA, parC, and the marR gene were sequenced following PCR amplification. Membrane permeability was measured by a previously established Hoechst 33342 fluorescent dye accumulation assay (see reference 43).
b
Relative Hoechst dye accumulation.
c
—, no mutation.
d
P < 0.05 (Mann-Whitney U test).