TABLE 3

Increase in drug resistance upon overexpression of enterococcal transporters in L. lactis

Drug testedFold change in MICa with overexpression of:
EfrABEfrCDEfrEFEF0942/41EF1592/93EF1733/32EF2593/92
Ciprofloxacin1121111
Norfloxacinb1.5121111
Ofloxacin2121111
Gentamicin1111111
Kanamycin1111111
Minocycline1111111
Tetracyclineb1.51.51111.51
Rifampin1211111
Daunorubicin21641111
Doxorubicin23281111
Acriflavine2241111
Ethidium4441111
Hoechst 33342b1.5421111
  • 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.