Table 3.
Effect of efflux inhibitors on the MICs of potential substrates of Mmr efflux pump
| M. tuberculosis strain | MIC (μg/ml)d |
|||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Ethidium bromide |
Tetraphenylphosphonium |
Acriflavine |
Safranin O |
CTAB |
||||||||||||||||
| No inhibitor | CCCP | CPZ | VP | No inhibitor | CCCP | CPZ | VP | No inhibitor | CCCP | CPZ | VP | No inhibitor | CCCP | CPZ | VP | No inhibitor | CCCP | CPZ | VP | |
| H37Rv | 2 | 2 | 2 | 0.5 | 12.5 | 3.1 | 12.5 | 12.5 | 3 | 1.5 | 3 | 3 | 1 | 0.5 | 1 | 0.5 | 12.5 | 3.1 | 12.5 | 12.5 |
| MmrKOa | 1 | 1 | 1 | 0.13 | 3.1 | 3.1 | 1.5 | 1.5 | 3 | 1.5 | 3 | 1.5 | 0.5 | 0.5 | 0.25 | 0.5 | 6.25 | 3.1 | 6.25 | 6.25 |
| MmrKO::pCRS5b | 2 | 2 | 2 | 1 | 12.5 | 3.1 | 12.5 | 12.5 | 3 | 1.5 | 3 | 3 | 1 | 0.5 | 1 | 0.5 | 12.5 | 3.1 | 12.5 | 12.5 |
| H37Rv::pCVZ2c | 4 | 2 | 4 | 1 | 12.5 | 6.2 | 12.5 | 12.5 | 6 | 0.18 | 6 | 6 | 2 | 0.06 | 2 | 2 | 12.5 | 0.4 | 12.5 | 12.5 |
a
M. tuberculosis H37Rv with mmr gene inactivated.
b
MmrKO complemented with pCRS5.
c
M. tuberculosis H37Rv containing pCVZ2.
d
CCCP, carbonyl cyanide m-chlorophenylhydrazone; CPZ, chlorpromazine; CTAB, cetyltrimethylammonium bromide; VP, verapamil. Data in bold represent at least a 4-fold reduction, considered to denote a significant MIC reduction in the presence of an efflux inhibitor.