Dissemination and proliferation of Salmonella typhimurium in genetically resistant and susceptible mice

Genetically resistant A/J and CBA mice were inoculated intraperitoneally with either 10(3) or 10(4) organisms of a virulent strain of Salmonella typhimurium; susceptible C57BL/6J and BALB/c mice were inoculated with either 10(2) or 10(3) organisms. Except with the smaller dose in resistant mice, fatal infection ensued. Bacteraemia occurred within 1 h after inoculation, except that it was not detectable during the first 6 h in the susceptible mice inoculated with 10(2) organisms. From day 2, the circulating bacterial population continued to increase in all infected mice, except that it remained under control in the resistant mice inoculated with the lower dose (10(3) organisms). The pathogen proliferated logarithmically in the liver from day 2, and a bacterial count of c. 10(8) cfu/g of tissue was reached when the animals died at 5-7 days; again, the resistant mice inoculated with 10(3) organisms were an exception in which the hepatic bacterial population was kept under control and the mice survived.