Comparative histopathology in mouse typhoid among genetically diverse mice.

Genetically resistant CBA and A/J mice and susceptible BALB/c and C57BL/6 mice were challenged with either an identical infective dose or a minimal lethal dose of Salmonella typhimurium. The histopathological progression of the disease was examined in tissue sections prepared by the JB-4 Plus resin embedding method and compared between the resistant and susceptible mice. In a fatal disease, the lesions in both animal hosts began with focal abscesses within the first three days post infection. Mononuclear cell infiltration started by day 4 and transformed the lesions into granulomata. Well-formed granulomata were evident by day 7 and persisted in sublethally infected resistant mice. Massive bacterial proliferation and extensive tissue degeneration marked the terminal stage of a lethal challenge. There were no distinguishable features that would identify the tissue response to infection in a resistant host from a susceptible one, except that the lesions in the sublethally infected resistant mice advanced slower and were discrete and self-limiting.