TABLE 3.
Comparative susceptibilities to antibiotics of parental strains and their MDR-derived mutantsa
| Antibiotic | Sm206 |
CIP 54.90 |
CIP 60.77T (ATCC 13637) |
||||||
|---|---|---|---|---|---|---|---|---|---|
| Parent (MIC, μg/ml) | MDR mutant (MIC×) (n = 26) |
Parent (MIC, μg/ml) | MDR mutant (MIC×) (n = 14) |
Parent (MIC, μg/ml) | MDR mutant (MIC×) (n = 13) |
||||
| Range | Mode MIC | Range | Mode MIC | Range | Mode MIC | ||||
| Ciprofloxacin | 2 | 4-64 | 16 | 1 | 16-32 | 32 | 0.5 | 16-128 | 64 |
| Moxifloxacin | 0.5 | 4-64 | 16 | 0.25 | 32-64 | 32 | 0.0625 | 8-64 | 64 |
| Nalidixic acid | 16 | 2-16 | 2-4 | 8 | 8-16 | 8 | 4 | 32-64 | 64 |
| Norfloxacin | 16 | 2-64 | 8 | 8 | 16-128 | 64 | 4 | 16-128 | 32 |
| Tetracycline | 8 | 1-8 | 2 | 4 | 4-8 | 4-8 | 1 | 1-8 | 2 |
| Chloramphenicol | 4 | 1-16 | 4 | 8 | 2-4 | 4 | 4 | 8-64 | 16-32 |
| Erythromycin | 128 | 1-4 | 4 | 256 | 2-4 | 2 | 16 | 0.5-1 | 1 |
| Trimethoprim | 8 | 1-16 | 8 | 8 | 2-4 | 4 | 16 | 8-32 | 32 |
| Sulfamethoxazole | 8 | 2-4 | 1 | 8 | 0.125-0.5 | 0.5 | 16 | 1-8 | 2 |
| Cotrimoxazole | 8 | 1-4 | 1 | 4 | 1 | 1 | 4 | 1-16 | 4 |
| Ticarcillin plus CAb | 16 | 1-2 | 1 | 16 | 0.5-1 | 1 | 8 | 0.5-2 | 1 |
| Cefepime | 16 | 1-4 | 1 | 2 | 2-4 | 2 | 8 | 0.5-4 | 2 |
| Amikacin | 64 | 0.125-4 | 0.5 | 16 | 0.25-0.5 | 0.5 | 4 | 1-4 | 1-2 |
a
n, Number of tested MDR mutants; MIC×, multiple of the MIC compared to that for the parental strain. The range gives the lowest and highest increases in MICs, and the mode MIC corresponds to the value obtained for the majority (at least half) of the strains.
b
CA, clavulanic acid at a fixed concentration of 2 μg/ml.