TABLE 3.
Antimicrobial susceptibilities of P. aeruginosa OprM-deficient strain OCR03T carrying plasmids expressing wild-type or insertion mutant forms of oprM
| Plasmid | OprM/mutant protein expressiona | MICb (μg/ml) of:
|
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| TET | CM | NA | NFX | MERO | CTAX | CFP | CFSD | CARB | ||
| pVLT35 | − (vector) | 0.20 | 0.10 | 1.56 | <0.05 | <0.01 | 1.00 | <0.03 | <0.05 | <0.20 |
| pKW35TM | +++ | 3.13 | 6.25 | 25.00 | 0.20 | 0.20 | 4.00 | 0.25 | 0.78 | 25.00 |
| pKWIN1 | ++ | 1.56 | 3.13 | 12.50 | 0.39 | 0.10 | 1.00 | 0.06 | 0.20 | 50.00 |
| pKWIN2 | +++ | 3.13 | 6.25 | 25.00 | 0.20 | 0.20 | 2.00 | 0.13 | 0.39 | 12.50 |
| pKWIN5 | +++ | 1.56 | 3.13 | 12.50 | 0.10 | 0.10 | 2.00 | 0.13 | 0.20 | 12.50 |
| pKWIN9 | ++ | 1.56 | 3.13 | 12.50 | 0.10 | 0.10 | 2.00 | 0.13 | 0.39 | 12.50 |
| pKWIN10 | ++ | 0.78 | 1.56 | 6.25 | <0.05 | 0.02 | 0.50 | 0.06 | 0.20 | 6.25 |
| pKWIN11 | + | 0.39 | 0.39 | 3.13 | <0.05 | 0.02 | 0.25 | <0.03 | 0.10 | 1.56 |
| pXZL34c | +++ | —d | 12.50 | 50.00 | 0.20 | 0.39 | 4.00 | 0.25 | 1.56 | 25.00 |
| pKPM-2c | +++ | —d | 25.00 | 50.00 | 0.20 | 0.39 | 8.00 | 0.50 | 0.78 | 50.00 |
| pKWIN13c | ++ | —d | 25.00 | 200.00 | 0.39 | 0.39 | 16.00 | 0.50 | 1.56 | 100.00 |
Expression levels ranged from undetectable (−) to strong (+++), and results were obtained from outer membranes of strain OCR03T carrying the various plasmids.
These results were obtained from three identical experiments. Abbreviations: TET, tetracycline; CM, chloramphenicol; NA, nalidixic acid; NFX, norfloxacin; MERO, meropenem; CTAX, ceftriaxone; CFP, cefepime; CFSD, cefsulodin; CARB, carbenicillin. Results in boldface indicate a reduction of at least fourfold compared with cells carrying wild-type OprM.
pXZL34 contains wild-type oprM with the native sequence cloned into pVLT31. pKPM-2 contains oprM* cloned into pVLT31. pKWIN13 was also constructed using pVLT31.
This plasmid carries a tetracycline resistance gene.