infectious diseases
Nontuberculous Mycobacterial Infections
Disseminated disease
Mycobacterium aviumcomplex (MAC) causes disseminated disease commonly in patients with advanced AIDS and occasionally in those with other immunocompromised states, including organ transplantation and hairy cell leukemia. In patients with AIDS, disseminated MAC usually develops late (unlike tuberculosis, which develops early), occurring simultaneously with other opportunistic infections. Disseminated MAC disease causes fever, anemia, thrombocytopenia, diarrhea, and abdominal pain (features similar to Whipple Disease ). Diagnosis of disseminated MAC infection can be confirmed by cultures of blood or bone marrow or by biopsy (eg, percutaneous fine-needle biopsy of liver or necrotic lymph nodes). Organisms may be identified in stool and respiratory specimens, but organisms from these specimens may represent colonization rather than true disease. Combination therapy to clear bacteremia and alleviate symptoms usually requires 2 or 3 drugs; one combination isclarithromycin500 mg orally 2 times a day orazithromycin600 mg orally once/day, plusethambutol(EMB) 15 to 25 mg/kg once/day. Sometimesrifabutin300 mg once/day is also given. After successful treatment, chronic suppression withclarithromycinorazithromycinplus EMB is necessary to prevent relapse. Patients with HIV infection who were not diagnosed before presenting with disseminated MAC should receive 2 weeks of antimycobacterial treatment before starting antiretroviral therapy to decrease the risk of developing the Immune reconstitution inflammatory syndrome (IRIS) (IRIS). Patients with HIV infection and a CD4 count<100 cells/mcL (0.01 × 109/L) require prophylaxis for disseminated MAC withazithromycin1.2 g orally once/week orclarithromycin500 mg orally 2 times a day. 