Iron and Mycobacterium tuberculosis infection.

Background: iron is known to play a role in the susceptibility to and outcome of several infections. In view of the increasing worldwide problem of tuberculosis, it may be important to ascertain whether this is also the case with this infection.

Objectives: (1) to review studies conducted in vitro, in experimental animals, and in humans that provide evidence that iron status may influence the occurrence and outcome of tuberculosis. (2) To perform an in vivo study in mice, examining the effect of iron loading on experimental infection caused by a virulent strain of Mycobacterium tuberculosis.

Results: we studied the effect of iron loading on the growth in spleen and lungs of a virulent strain of M. tuberculosis, injected i.v. in female Balb/C mice. At sacrifice on day 42 after the experimental infection, the iron-loaded mice presented a significantly enhanced multiplication of M. tuberculosis in both the spleen and the lungs, when compared to the mice without iron loading.

Conclusion: Most of the studies, including our experimental study in mice, tend to suggest that an excess of iron may enhance the growth of M. tuberculosis and worsen the outcome of human tuberculosis.