Passage through SAGE plates as a function of (A) antibiotic concentration and (B) slope. Averages of three biological replicates are shown. Antibiotic concentrations are given as the maximal concentration in the plate, as a function of MIC. The slope in (A) was 8 mm. (B) The likelihood that the observed differences in movement were due to chance was calculated via a two-tailed unequal variance Student’s T test.*P value < 0.05, **P value < 0.01, ***P value < 0001, ****P value < 0.00001.