Figure 3.

The fitness advantage of SCVs within the mouse gut is modulated by antibiotic treatment. (A and C) Boxplots of the competitive index (CI) of SCVs (CFP) against the ancestral (YFP), during colonization of the mouse gut in mice that did not received antibiotic treatment (A) or in mice that were treated (C) with kanamycin (left), nalidixic acid (centre) or tetracycline (right). CI was calculated as the natural logarithm of the ratio of CFP cfu to YFP cfu. (B and D) Frequency of fluorescent marker/colony size for mice without (B) or with (D) antibiotic treatment. Each panel represents a single mouse and shows the frequency of SCVs (SCV:CFP; dark blue), SCV revertants (REV:CFP; light blue) and ancestral bacteria (Anc:YFP; yellow). Horizontal dashed lines in A–D indicate where SCVs and Anc are competitively equivalent. See Fig. S3 for slopes of CI against time, mean (±2SE) CFP frequency and bacterial loads