Fig 1.
Conceptual model of tolerance and resistance evolution in different antibiotic treatment conditions.
Tolerance is presumably favored when high antibiotic concentrations are applied in growth-restricting conditions (left). On the other hand, resistance is mainly favored when the nutrient concentration is sufficiently high to allow growth, while the antibiotic concentration should not be too high to be overcome by resistance mutations (right). In conditions that select for resistance, a tolerant strain evolves resistance faster than a wild-type strain. It is currently unclear which survival strategy is favored in conditions characterized by other combinations of antibiotic and nutrient concentrations.