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Mycobacterium avium complex infection

Last updated: September 16, 2021

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Mycobacterium avium complex (MAC) infection is caused by the Mycobacterium avium complex (M. avium and M. intracellulare). It more commonly occurs in patients with advanced immunosuppression and is considered an AIDS-defining condition. Diagnosis is based on isolation of the organism (acid-fast bacilli) on culture and treatment consists of at least two anti-mycobacterial drugs (e.g., a macrolide with ethambutol).

References: [1]

MAC infection often manifests as disseminated disease and typically occurs in patients with advanced immunosuppression (CD4 counts < 50). [1]

Diagnosis of disseminated MAC is based on isolation of the organism in a patient with characteristic clinical features. [1]

Disseminated MAC may mimic disseminated TB. Findings that favor MAC include elevated alkaline phosphatase and gamma-glutamyl transpeptidase, hepatosplenomegaly, and leukopenia. [2]

Manage all patients in consultation with an infectious disease specialist. In patients with HIV, initiate ART (if not already started) concurrently with MAC treatment.

See “Primary prevention of opportunistic infections in HIV.”

  1. Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents with HIV. https://clinicalinfo.hiv.gov/en/guidelines/adult-and-adolescent-opportunistic-infection/introduction?view=full. Updated: August 18, 2020. Accessed: December 18, 2020.
  2. Karakousis PC, Moore RD, Chaisson RE. Mycobacterium avium complex in patients with HIV infection in the era of highly active antiretroviral therapy. Lancet Infect Dis. 2004; 4 (9): p.557-565. doi: 10.1016/s1473-3099(04)01130-2 . | Open in Read by QxMD