Table 1.
MICs of 22 antibiotics for clinical strains and axyY::Tic mutants
| Antibiotic | MIC (μg/ml) for straina: |
|||||
|---|---|---|---|---|---|---|
| AXX-A | AXX-A-ΔY | AXX-D | AXX-D-ΔY | AXX-H | AXX-H-ΔY | |
| Ticarcillinb | 0.25 | >256 | 0.25 | >256 | 0.25 | >256 |
| Tobramycin | 16 | 1.5 (10) | 24 | 0.5 (48) | 32 | 1 (32) |
| Amikacin | 256 | 2 (128) | 96 | 0.25 (384) | >256 | 3 (>85) |
| Netilmicin | 32 | 2 (16) | 64 | 0.75 (85) | 192 | 1 (192) |
| Gentamicin | 48 | 1 (48) | 12 | 0.094 (127) | 48 | 0.75 (64) |
| Kanamycin | 32 | 2 (16) | >256 | 3 (>85) | >256 | 12 (>21) |
| Ceftazidime | 4 | 2 (2) | 48 | 24 (2) | 48 | 24 (2) |
| Cefepime | 16 | 8 (2) | >256 | 24 (>10) | >256 | >256 |
| Imipenem | 1 | 0.5 (2) | 1.5 | 1 (1.5) | 4 | 1 (4) |
| Meropenem | 0.094 | 0.047 (2) | 0.064 | 0.032 (2) | 12 | 2 (6) |
| Doripenem | 0.19 | 0.047 (4) | 0.25 | 0.19 (1.3) | 16 | 1.5 (10) |
| Tetracycline | 48 | 12 (4) | >256 | 32 (>8) | >256 | >256 |
| Doxycycline | 8 | 3 (2.7) | 48 | 12 (4) | 128 | 24 (5) |
| Tigecycline | 4 | 0.75 (5.3) | 8 | 1 (8) | 6 | 2 (3) |
| Nalidixic Acid | 24 | 12 (2) | >256 | >256 | >256 | >256 |
| Norfloxacin | 8 | 4 (2) | >256 | 24 (>10) | >256 | 128 (>2) |
| Ofloxacin | 2 | 1.5 (1.3) | >32 | 24 (>1.3) | >32 | >32 |
| Levofloxacin | 0.75 | 0.75 (1) | 16 | 4 (4) | >32 | 8 (>4) |
| Moxifloxacin | 1.5 | 1 (1.5) | >32 | 2 (>16) | >32 | 24 (>1.3) |
| Ciprofloxacin | 0.75 | 0.5 (1.5) | >32 | 3 (>10) | >32 | 8 (>4) |
| Chloramphenicol | 12 | 8 (1.5) | >256 | >256 | >256 | 192 (>1.3) |
| Erythromycin | 64 | 16 (4) | >256 | 6 (>42) | >256 | >256 |
a
Values in parentheses represent the relative MIC decreases (ratio of the MIC for the parent strain to the MIC for the mutant strain).
b
The ticarcillin resistance observed in the mutants is caused by the production of the penicillinase encoded by the bla gene from the pUC19 vector.