Let’s next consider some compounds other than the fluoroquinolones. We have measured MPC with S. aureus and then obtained a value for Cmax from the literature. What you see is that the Cmax for some compounds exceeds MPC and for others it does not. And with some for which Cmax exceeds MPC the half life is so short that it would be difficult to maintain drug concentrations above MPC throughout therapy. How should one use these compounds to avoid selecting resistant mutants? Our current dogma is that if you cannot maintain concentrations above MPC, you should resort to dual-drug therapy.