Frequency of Mycobacterium tuberculosis bacteremia in patients with tuberculosis in an area endemic for AIDS

Abstract

Mycobacterium tuberculosis bacteremia has recently been reported in patients infected with the human immunodeficiency virus (HIV). At our institution, tuberculosis occurs commonly among patients with and without HIV infection. We sought to determine the frequency of M. tuberculosis bacteremia among patients with newly diagnosed tuberculosis. During a 4-month period, mycobacterial blood cultures were obtained on all identifiable patients with newly diagnosed tuberculosis. Fifteen percent (9/59) of consecutive patients with tuberculosis had positive blood cultures for M. tuberculosis. Twenty-six percent (7/27) of patients known to be infected with HIV had positive mycobacterial blood cultures; two intravenous drug users who refused HIV-serologic testing also had positive mycobacterial blood cultures. M. tuberculosis bacteremia occurred at a higher rate among HIV-infected patients with an AIDS-defining opportunistic infection in addition to tuberculosis (3/3) than among HIV-infected patients without such an opportunistic infection (4/24; p less than 0.02). M. tuberculosis bacteremia occurred in 83% (5/6) of patients with disseminated tuberculosis and in 8% (4/53) of patients without disseminated tuberculosis (p less than 0.001). In all cases, tuberculosis was diagnosed in patients with M. tuberculosis bacteremia or else they died prior to the blood cultures demonstrating mycobacterial growth (mean time to detection of mycobacterial growth: 43 days). However, the frequent occurrence of M. tuberculosis bacteremia in HIV-infected patients with disseminated tuberculosis suggests that mycobacterial blood cultures may help confirm the diagnosis of tuberculosis in this group of patients.