Intestinal mycobacteria in African AIDS patients [letter]

Dual infection with human immunodeficiency virus (HIV) and Mycobacterium tuberculosis substantially affects the epidemiology of tuberculosis in sub-Saharan Africa. Chronic diarrhea has also become a problem but the etiologic agent varies. Mycobacterium avium complex (MAC) which disseminates in 80% of HIV-infected patients is the dominant mycobacterial species affecting patients with acquired immunodeficiency syndrome (AIDS) in the west; however results of African studies differ. A Zambian study produced no evidence of MAC in AIDS patients with or without diarrhea. One in Zaire by Colebunders and colleagues isolated MAC from 12% of HIV positive patients and 22% of HIV negative patients. At the University Teaching Hospital in Lusaka a cross-sectional study was conducted by the authors of this letter on the prevalence of mycobacteria in 120 fecal samples from 69 individuals (58 with AIDS-defining diagnoses) with HIV-related diarrhea lasting longer than 3 weeks; fecal specimens from 7 of the patients grew mycobacteria (2 MAC 4 M tuberculosis and 1 M flavescens). 2 of the patients had diagnosed pulmonary tuberculosis at the time of endoscopy but had not begun chemotherapy. 1 had a spouse with tuberculosis and 2 others (1 M tuberculosis 1 MAC) died within 2 weeks probably as a result of the diarrhea. Biopsy specimens showed scanty acid-fast bacilli in 1 of the stool positive cases (MAC); the organism was cultured with the specimen. The person also had cryptosporidiosis. There were no apparent differences in nutritional status or villus morphology between patients with mycobacteria and those without. In a parallel London study the rate of recovery of mycobacteria was similar (12%) but 7 of the isolates were MAC and 1 was M tuberculosis. Over the next 6-12 months 50% of the stool-positive cases developed disseminated disease. In summary the authors findings indicate that M tuberculosis and MAC colonize the gut in 10% of African patients with HIV-related diarrhea but there is little evidence of the small intestinal infiltrative mycobacterial disease seen in industrialized countries and M tuberculosis is not a substantial contributor despite high rates of infection in AIDS patients.