Correlation of quantitative bone marrow and blood cultures in AIDS patients with disseminated Mycobacterium avium complex infection

The relationship between Mycobacterium avium complex (MAC) infection of blo od and bone marrow was studied in human immunodeficiency virus-infected pat ients before and during treatment, Quantitative cultures were obtained at b aseline from 17 persons with newly detected MAC bacteremia, Serial blood cu ltures were obtained, and a second bone marrow sample was obtained at 4 or 8 weeks. At baseline, the median MAC load in bone marrow core samples was 3 log(10) higher than in blood. Bone marrow MAC loads ranged widely (866-847 ,315 cfu/g), and no significant correlation was found between MAC load in b lood and that in bone marrow core samples. MAC loads in bilateral bone marr ow biopsy samples from 7 subjects were highly correlated, MAC loads decline d in blood and bone marrow at similar rates during therapy, but blood was s terilized before bone marrow. Length of survival was inversely associated w ith initial bone marrow core MAC load but not with blood MAC load. Initiati on of treatment when tissue MAC load is low may increase the Likelihood of favorable clinical outcome.