FIG. 1.

Killing of E. coli by antibiotics. Log-phase bacteria were incubated in the presence of ampicillin (100 μg/ml; solid line) or ofloxacin (5 μg/ml; dotted line), serially diluted, and plated onto solid media for overnight incubation and estimation of survival. The values are averages obtained from three independent samples; error bars, standard deviations.