(a) (i) Mice were infected with P. aeruginosa, and gut colonization was studied for 7 days. The mice were then given EcN, and P. aeruginosa in faeces was quantified and compared with the infection control group. (ii) Colonization of P. aeruginosa was assessed by faecal counting of bacteria for two different numbers of cells given by oral gavage. (iii) Colon tissue was homogenized and plated for viability testing to confirm GI infection by P. aeruginosa (1010 cfu) over time. (b) (i) The bacterial count relative to average P. aeruginosa infection at day 0 was tracked over 6 days post-treatment with EcN cells. All EcN expressing E7 are shown for comparison with the lysis controls. Other non-lysis EcN controls (EcN wild-type and Sensor mutant) are shown in Supplementary Fig. 6. (ii–iii) Total viable P. aeruginosa cell counts from faecal (ii) and (iii) colon samples at day 6 post-treatment. The data from two independent experiments are shown (n=8–10). *P<0.01 (Kruskal–Wallis test with Dunn correction). Data are presented in box plots with median as centre line, 10 and 90% confidence limits, and minimum and maximum values.