Mycobacterium avium Complex in the Respiratory or Gastrointestinal Tract and the Risk of M. avium Complex Bacteremia in Patients with Human Immunodeficiency Virus Infection

Abstract

Mycobacterium avium complex (MAC) is frequently isolated from the respiratory or gastrointestinal tract of patients with advanced human immunodeficiency virus (HIV) infection. Whether they are at increased risk of MAC bacteremia and whether culture of respiratory tract or stool specimens is useful for predicting bacteremia are unclear. HIV-infected patients with < or = 50 CD4+ cells/microL were prospectively studied. The risk of MAC bacteremia was approximately 60% within 1 year for patients with MAC in either the respiratory or gastrointestinal tract and was greater than for those without MAC in these sites (relative hazards for respiratory and gastrointestinal tract, 2.3 and 6.0; 95% confidence intervals, 1.1-4.6 and 2.5-14.6, respectively). Both respiratory tract specimen and stool culture had poor sensitivities (22% and 20%, respectively) but good positive predictive values (approximately 60%) for bacteremia. Symptomatic HIV-infected patients with MAC in the respiratory or gastrointestinal tract are at a substantial risk for developing MAC bacteremia; culture of these sites has limited usefulness as a screening test.

Exposure of BALB/c mice to low doses of Mycobacterium avium increases resistance to a subsequent high-dose infection

“…Thus, our observations indicate that i.n. exposure to low doses induces protective CD4 + T cells in normal hosts, supporting the knowledge that in severely CD4-deficient persons, such as AIDS patients, a M. avium respiratory infection originating from environmental sources is predictive of mycobacterial dissemination (Chin et al, 1994 ;Inderlied et al, 1993).…”

Characterization of Mycobacterium avium complex related mycobacteria isolated from an African environment and patients with AIDS

“…This ability has been frequently described as an important prerequisite for an opportunistic pathogen. Two recent prospective studies have demonstrated that HIV-positive patients with colonization of respiratory or gastrointestinal tract by MAC had a greater risk of MAC dissemination than those without colonization (Havlik et al 1993;Chin et al 1994).…”

Zoonotic aspects of Mycobacterium bovis and Mycobacterium avium-intracellulare complex (MAC)

“…Genomic restriction fragment patterns of Maa from hospital water isolates are similar to those from AIDS patient isolates [5]. Numerous studies have attempted to determine the routes, oral or aerosol, leading to Maa infection in AIDS patients but no evidence was related to one and a combination of both routes is likely [22,83,144].…”