MYCOBACTERIUM-AVIUM COMPLEX IN THE RESPIRATORY OR GASTROINTESTINAL-TRACT AND THE RISK OF MYCOBACTERIUM-AVIUM COMPLEX BACTEREMIA IN PATIENTSWITH HUMAN-IMMUNODEFICIENCY-VIRUS INFECTION

Mycobacterium avium complex (MAC) is frequently isolated from the resp iratory or gastrointestinal tract of patients with advanced human immu nodeficiency virus (HIV) infection. Whether they are at increased risk of MAC bacteremia and whether culture of respiratory tract or stool s pecimens is useful for predicting bacteremia are unclear. HIV-infected patients with less than or equal to 50 CD4(+) cells/mu L were prospec tively studied. The risk of MAC bacteremia was similar to 60% within 1 year for patients with MAC in either the respiratory or gastrointesti nal tract and was greater than for those without MAC in these sites (r elative 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 (simila r to 60%) for bacteremia. Symptomatic HIV-infected patients with MAC i n the respiratory or gastrointestinal tract are at a substantial risk for developing MAC bacteremia; culture of these sites has limited usef ulness as a screening test.