Effect of rifabutin on disseminated Mycobacterium avium infections in thymectomized, CD4 T-cell-deficient mice.

Disseminated Mycobacterium avium infection is the major cause of bacteremia in patients with acquired immunodeficiency syndrome. We present here a new animal model of this disease, thymectomized C57BL/6 mice that were intravenously infused with monoclonal antibody to selectively deplete CD4+ T cells. The increased susceptibility of such animals to M. avium infection is comparable to that of C57BL/6 beige mice and thus may provide a viable alternative to the latter model. Further, using representative strains of acquired immunodeficiency syndrome-associated M. avium (serotypes 1, 4, and 8 and a rough isolate), we show that the course of such infections in thymectomized, CD4-deficient mice can be markedly restrained and in some cases the infections can be sterilized by treatment over a 120-day period with a regimen containing 40 mg of the new antimycobacterial agent rifabutin per kg (body weight).