We too found that WT and a SPI-1 mutant (invA) invaded the cecum and caused significant inflammation, but we found that WT Salmonella infection spread distally to infect and inflame most of the colon by day 8/9 after infection, while the SPI-1 (invA) mutant remained largely confined to the cecum, as did the pathology. Here, SPI1 is linked to infection.