Effect of colicin K on UPEC strains UL31 (a), UL173 (b), UL114 (c), and UL98 (d) (MIC as detected on plates containing 0.1, 1, 10, and 100 μg/ml, respectively). The experiments were repeated three times, and the means ± standard errors of the means (error bars) are shown. Only one of the two investigated strains from each sensitivity group is depicted; however, the effects of colicin K on both strains were comparable.