FIG. 6.

Effect of oral phage on the introduction of ampicillin-resistant E. coli in mice pretreated with ampicillin in the drinking water. (A) Seven mice received ampicillin by force-feeding at day 1 and in the drinking water throughout the experiment. At the time points indicated with arrows marked with A/E, six mice were force-fed with ampicillin and ampicillin-resistant E. coli (a control mouse received only buffer instead of E. coli). Both groups of mice received ampicillin in the drinking water, but some mice were in addition exposed to 10⁶ PFU/ml of the phage cocktail in the drinking water (B). Both panels show the fecal counts of ampicillin-resistant cells. The rightmost black data points in panel B refer to a control mouse not receiving ampicillin-resistant E. coli.