FIG 1.

Concentration-dependent killing of E. coli persisters by colistin. E. coli strain W3110 was grown overnight to stationary phase, and then different concentrations of colistin (Col at 5, 10, 25, or 50 μg/ml) or ofloxacin (Ofl at 5 μg/ml) were added to the culture directly. At different times of drug exposure, the viability of the bacteria was determined by CFU counts. The horizontal dashed line represents the limit of detection. The data represent average values and plus-and-minus standard errors from three independent biological replicates.