Transient bacteremia due to Mycobacterium avium complex in patients with AIDS

It is generally assumed that Mycobacterium avium complex (MAC) bacteremia, once it develops, is unremitting. On the basis of this presumption, changes in the level of mycobacteremia are used to gauge therapeutic response. In 7 (12%) of 60 patients enrolled in a prospective trial of MAC bacteremia and AIDS, bacteremia became undetectable before the initiation of antimycobacterial therapy. Patients with transient bacteremia reported fewer and shorter symptoms and survived longer than those with sustained bacteremia (59 vs. 31 weeks; P = .022). There was no difference in the duration of AIDS, CD4+ cell count, hematocrit, or body weight between groups. Two additional patients with transient bacteremia were identified outside this study setting. Despite disappearance of detectable mycobacteremia and subsequent administration of antimycobacterial agent(s), bacteremia once again became detectable in 6 patients 4-45 weeks after their negative pretreatment cultures. Patients with disseminated MAC may have fluctuating levels of mycobacteremia that become undetectable in the absence of antimycobacterial therapy.