ROLE OF IRON IN THE PATHOGENESIS OF MYCOBACTERIUM-AVIUM INFECTION IN MICE

Mycobacterial infections are of serious concern to HIV-infected patien ts, and take a heavy toil of such patients. Mycobacterium avium is the most common opportunistic bacterial infection in patients with AIDS. The overload of iron in serum has been implicated in the pathogenicity of a number of bacterial infections. Since iron storage in cells such as macrophages is increased in AIDS, the role of iron as a possible f actor in the pathogenesis of M. avium infection was examined. Suppleme nting iron to normal laboratory chow resulted in accelerated M. avium infection in mice inoculated earlier with the same organism. The bacte rial loads in liver, spleen and lungs were approximately 12-fold highe r in mice receiving iron supplementation compared with control groups. This is attributed to an increased percentage saturation of iron in t he sera of the mice, thus making more iron available for the replicati on of bacteria. The addition of beef fat to the diet, together with hi gh Iron supplementation, further enhanced the infection. Using smaller inocula, mice receiving chow supplemented with high iron and fat deve loped disseminated M. avium infection faster than control mice. The re sults provide strong evidence that iron may play a major role in the p athogenesis of M. avium infection.