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Autopsy findings in AIDS patients with Mycobacterium avium complex bacteremia
F J Torriani1, J A McCutchan, S A Bozzette
1Department of Medicine and Pathology, University of California, San Diego.
Abstract:
To study the pathogenesis of Mycobacterium avium complex (MAC) bacteremia, the extent of organ involvement was determined in a retrospective cohort of 44 AIDS patients with MAC bacteremia and complete autopsies between 1988 and 1992. Clinical and microbiologic histories were reviewed and lymph nodes, spleen, liver, bone marrow, small intestine, and colon from each autopsy were systematically evaluated for the presence of mycobacteria or foamy histiocytes. Of the patients, 30% had no histologic evidence of MAC. In the remaining 70%, reticuloendothelial and gastrointestinal involvement was most common, but the number and distribution of involved sites was highly variable. The risk of developing detectable histologic involvement was related to the duration of bacteremia. In contrast to the prevailing concept, our data suggest that MAC bacteremia may precede widespread tissue disease.
Insights
Mycobacterium avium complex (MAC) bacteremia in AIDS patients often shows variable organ involvement. This study suggests MAC bacteremia may precede widespread tissue disease, challenging previous concepts.
Area of Science:
- Immunology
- Infectious Diseases
- Pathogenesis
Background:
- Mycobacterium avium complex (MAC) bacteremia is a significant opportunistic infection in patients with Acquired Immunodeficiency Syndrome (AIDS).
- The precise pathogenesis and extent of organ involvement in MAC bacteremia remain incompletely understood.
- Previous understanding suggested widespread tissue dissemination typically preceded or coincided with MAC bacteremia.
Purpose of the Study:
- To investigate the pathogenesis of Mycobacterium avium complex (MAC) bacteremia.
- To determine the extent and pattern of organ involvement in AIDS patients with MAC bacteremia.
- To evaluate the relationship between MAC bacteremia and tissue disease progression.
Main Methods:
- Retrospective cohort study of 44 AIDS patients with MAC bacteremia and complete autopsies (1988-1992).
- Systematic histological evaluation of lymph nodes, spleen, liver, bone marrow, small intestine, and colon for mycobacteria or foamy histiocytes.
- Review of clinical and microbiologic histories.
Main Results:
- 30% of patients showed no histologic evidence of MAC at autopsy.
- In 70% of patients, reticuloendothelial and gastrointestinal systems were most commonly involved, with highly variable distribution and extent.
- The duration of bacteremia correlated with the risk of developing detectable histologic involvement.
Conclusions:
- MAC bacteremia in AIDS patients can occur without immediate widespread tissue disease.
- The findings suggest that MAC bacteremia may precede extensive organ involvement, challenging the prevailing concept of pathogenesis.
- Understanding this sequence is crucial for timely diagnosis and management of MAC infections in immunocompromised individuals.