Acute iron overload in mice: pathogenesis of Salmonella typhimurium infection.

The bacterial growth in the tissues of C3D2F1 male mice was measured during an experimental infection with two Salmonella typhimurium strains (high virulence, strain 2386/74; low virulence, strain L15403). This experimental model was used for evaluation of the pathogenesis in normal and iron-overloaded animals. Acute iron overload was accomplished by intramuscular injections of chelated iron (with 2,3-dihydroxybenzoic acid and citrate) with a single dose of 100 micrograms of iron per mouse. Bacteria were given intraperitoneally 1 h after the iron injection. Serum iron levels, transferrin levels, and the bacteria counts in blood and liver were measured simultaneously in all animals. There was a significant increase of bacterial growth in all tissues in the iron-treated animals. Iron abolished the normal clearance of the bacteria with low virulence from the blood. This study demonstrates that a general iron overload, as determined by an increased serum iron level, resulting from preinjection of iron, enhances bacterial growth.