Fig 5. Early microbiota transfer experiment to test the effect of the microbiota transfer before hilD mutants dominate the fecal population.

(A) Experimental scheme. (B–F) Streptomycin pretreated CON^X mice (n = 8 or n = 9 per group) were infected with a 10⁶:1 mixture of wild-type S. Typhimurium and an isogenic hilD mutant (5 × 10⁷ CFU, by gavage). The first group remained in hygienic isolation (control; pink empty circles; n = 8), while the second group was co-housed from day 4 on with a naïve CON^X mouse (pink, light green filled circles; n = 9). The groups were kept as such until the end of the experiment (day 40 p.i.). (B) Total Salmonella loads detected in the feces by selective plating. Dotted lines indicate the detection limit. Colored lines connect the medians. (C) The C.I. as determined using MacConkey plates with selective antibiotics and shown for wild-type S. Typhimurium versus S.Tm^hilD. The dotted line indicates a C.I. of 1. (D) An ELISA for fecal lipocalin-2 was used to compare gut inflammation between the 2 groups. (E) Representative images of HE-stained cecum tissue sections; scale bar 100 μm. (F) Total Salmonella organ loads. Lines indicate the median. mLN = mesenteric lymph node. The data shown was obtained from 2 independent experiments including comparing both groups. Two-tailed Mann–Whitney U tests were used for statistical analysis (p ≥ 0.05 not significant (ns), p < 0.05 (*), p < 0.01 (**), p < 0.001 (***), p < 0.0001 (****)).Source data can be found in S1 Data file.