TABLE 3.
Increase in drug resistance upon overexpression of enterococcal transporters in L. lactis
| Drug tested | Fold change in MICa with overexpression of: |
||||||
|---|---|---|---|---|---|---|---|
| EfrAB | EfrCD | EfrEF | EF0942/41 | EF1592/93 | EF1733/32 | EF2593/92 | |
| Ciprofloxacin | 1 | 1 | 2 | 1 | 1 | 1 | 1 |
| Norfloxacinb | 1.5 | 1 | 2 | 1 | 1 | 1 | 1 |
| Ofloxacin | 2 | 1 | 2 | 1 | 1 | 1 | 1 |
| Gentamicin | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Kanamycin | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Minocycline | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Tetracyclineb | 1.5 | 1.5 | 1 | 1 | 1 | 1.5 | 1 |
| Rifampin | 1 | 2 | 1 | 1 | 1 | 1 | 1 |
| Daunorubicin | 2 | 16 | 4 | 1 | 1 | 1 | 1 |
| Doxorubicin | 2 | 32 | 8 | 1 | 1 | 1 | 1 |
| Acriflavine | 2 | 2 | 4 | 1 | 1 | 1 | 1 |
| Ethidium | 4 | 4 | 4 | 1 | 1 | 1 | 1 |
| Hoechst 33342b | 1.5 | 4 | 2 | 1 | 1 | 1 | 1 |
a
Calculated as the MIC for cells expressing the wild-type transporter divided by the MIC for cells expressing the inactive E-to-Q mutant. MICs were determined in GM17, 5 μg/ml chloramphenicol, and 1:5,000 (vol/vol) nisin after 16 h at 30°C from a minimum of three independent experiments.
b
MICs were determined using a narrow series of drug concentrations, which allowed the measurement of MIC differences of <2-fold.