Mortality of Candida albicans-infected mice is facilitated by superinfection of Escherichia coli or administration of its lipopolysaccharide.

Pathogenesis of complex infection with Candida albicans and gram-negative bacteria was studied by determining the influence of infection with Escherichia coli or injection of E. coli lipopolysaccharide (LPS) on mortality of C. albicans-infected mice. Mice were infected intravenously with lethal doses of C. albicans, then treated intravenously at various times with viable E. coli or E. coli LPS, which individually were not lethal. Treatments 3 h after C. albicans infection clearly facilitated the death of the mice. Corresponding to this facilitated death, production of tumor necrosis factor (TNF) in sera was augmented 2 h after LPS injection into the infected mice. Similar increased production of TNF was also observed in mice treated with a nonlethal combination of heat-killed C. albicans and LPS. The number of viable C. albicans in kidneys of the infected mice was increased by LPS treatment, which was assumed to be the main cause of the greater mortality rate.