 |
For emphasis we restate that as
a rule mutants are not selectively enriched at drug concentrations below MIC. As an aside,
we note some selective pressure exists at concentrations below the standard MIC because it
measures inhibition of growth of a large number of cells (100,000). Indeed, some
enrichment of mutants does occur upon repeated serial passage of a strain (6). These data
stress that the bottom boundary of the window can be fuzzy. That is why we define it to be
MIC(99), the minimal concentration that blocks growth of 99% of the cells in a
culture. MIC(50) would be a more precise lower boundary, but it is more
difficult to determine experimentally. |
