Fig. 1

Treatment of stationary-phase cultures with specific β-lactams impairs persister formation. Cell cultures were treated with 200 μg/mL piperacillin (PIP) (a and b) or mecillinam (MEC) (c and d) at t = 4 h. Cells in control culture were treated with an equal volume of solvent, which was water (untreated). At 24 h, cultures were washed to remove chemicals and diluted in fresh LB containing 200 μg/mL ampicillin or 5 μg/mL ofloxacin. Survival fractions were monitored at the indicated time points. CFU/mL at the indicated time points are provided in Additional file 10: Figure S19. * p < 0.05 (t- test). Data represent three or more biological replicates. Each data point was denoted as mean ± s.e