Fig 2. S. Typhimurium 4/74 is associated with an overall increased tissue burden in “Salmonella-susceptible” inbred chickens relative to D23580.

14-day-old lines 7₂, 15 and Cb4 White Leghorn chickens were infected with 10⁸ CFU of S. Typhimurium 4/74 or D23580 and assessed at 3, 7 and 12 days post-oral infection. Each group contained four to seven birds. Statistical comparison was made using a Mann-Whitney test. NS: not significant, P > 0.05. Viable counts (CFU/g) of S. Typhimurium D23580 and 4/74 in spleen (A), liver (B) and caecal content (C) are shown. Counts are shown for individual birds with the bar representing the median value. A heatmap summarises the bacterial burden in all birds inoculated with 4/74 or D23580 (D). The heatmaps represents bacterial burden as a yellow (0 log₁₀ CFU/g) to red (6 log₁₀ CFU/g) colour scale and data are shown as percent of infected birds. Statistical modelling of the “Salmonella-susceptible” inbred chicken infection data showed that 4/74 was associated with an average increased tissue burden of 0.9 log₁₀ CFU/g tissue (P < 0.001).