Acceleration of resistance adaptation depends on the strength of selection imposed by previous drug exposures

Despite our continuous improvement in understanding the forces that drive drug resistance adaptation, the interplay between chance, selection, and evolutionary history remain unclear. Previous studies have shown that the strength of the selective pressure imposed by antibiotics determines the rate of resistance adaptation, as well as cross-resistance to other antimicrobial substances.Our findings suggest that cellular hysteresis exhibited by populations evolving under mild selective pressures could have important consequences in the efficacy of drug treatments and could be a relevant parameter to be considered for the design of optimal antibiotic treatments that limit the evolution of drug resistance.