FIG 1.

Competition experiments to determine in vitro minimal selective concentrations. Linear regression of the ratios of GyrA^D87Y/GyrA^wt (A) and GyrA^S83L/GyrA^wt (C) strains at different concentrations of ciprofloxacin. Plots of the selection coefficients derived from A and C at each specific antibiotic concentration in GyrA^D87Y/GyrA^wt (B) and GyrA^S83L/GyrA^wt (D) with inserted trend lines and standard errors of the slope (calculated from the linear slopes in panels A and C). All concentrations are in micrograms per liter.