Placing MIC near the lower boundary of the selection window contradicts traditional medical teaching in which resistant mutants are thought to be selected primarily when drug concentrations are below MIC (shown in a figure taken from a book published in 2002 (2)). This distinction is important because traditional dosing recommendations to exceed MIC are likely to place drug concentrations inside the selection window where they will enrich resistant mutant subpopulations. While low drug concentrations do not enrich resistant mutants, they do allow pathogen population expansion; consequently, low drug doses indirectly foster the generation of new mutants that will be enriched by subsequent antimicrobial challenge.