Figure 1. ST313 S. Typhimurium isolate D23580 hyperdisseminates to systemic sites.

(A–I) Streptomycin-pretreated C57BL/6 mice were orally infected with each Salmonella isolate. Mice were sacrificed at 1 (A–D) or 2 (A–I) days post infection (dpi) as indicated, and Salmonella burden was enumerated by plating. The colony-forming units per gram (CFU/g) for the gut tissues (A–C) and systemic sites (D–F) are presented. CFU/organ for the MLN and Peyer’s patches are presented in Figure S1. (G–H) Representative images of immunostaining of S. Typhimurium (red) and phalloidin (blue) in MLN infected for 2 days with either ST19 SL1344 (G) or ST313 D23580 (H). Arrows indicate select clusters of Salmonella and the scale bars represent 50 μM. Experiments were repeated twice with 2–3 mice per group. (I–J) Streptomycin-pretreated C57BL/6 mice were infected intraperitoneally and sacrificed 2 dpi. Salmonella burden was enumerated by plating in the spleen (I) and liver (J). (K) Streptomycin-pretreated C57BL/6 mice were orally infected with SL1344 ΔaroA or D23580 ΔaroA. Salmonella CFU in the MLN was enumerated 2 dpi. (A–F, I–K) Data is the combination of two independent experiments with 4–5 mice per group. Statistical significance was determined using Mann-Whitney test, bars represent the geometric mean, and dots individual mice.

*P≤0.05, ** P≤0.01, *** P≤0.001, **** P≤0.0001. See also Figure S1 and Table S1.