Mycobacterium avium complex

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Last reviewed: 23 Apr 2025

Last updated: 03 Apr 2025

Mycobacterium avium complex (MAC) has variable presenting features including chronic cough, weight loss, and fevers.

Increased incidence in patients with underlying lung disease, heavy smoking, and excessive alcohol consumption.

HIV-infected patients with CD4 cell count <50 cells/microliter are also at increased risk of infection.

Diagnosis of pulmonary disease in non-HIV-infected individuals requires repeated isolation of the organism from respiratory secretions, in addition to compatible symptoms and radiographic presentation.

Combination treatment with at least two drugs is essential.

Definition

MAC, also known as Mycobacterium avium-intracellulare (MAI), consists of two mycobacterium species, M avium and M intracellulare.[1] Although MAC isolates can be identified as M avium or M intracellulare by molecular techniques, there is no prognostic or treatment advantage for doing so.[2]

In humans, MAC traditionally causes three disease syndromes: pulmonary disease, cervical lymphadenitis, and disseminated disease.[3][4][5] A fourth syndrome, a hypersensitivity pneumonitis associated with hot tub use, has also been described.[6]

History and exam

Key diagnostic factors

underlying lung disease
chronic productive cough
dyspnea
weight loss
fatigue
fever
lymphadenopathy
immunocompromised
hot tub use

Full details

Other diagnostic factors

age under 5 years
middle-to-old age
night sweats
abdominal pain
diarrhea
rhonchi/crackles
hepatomegaly
splenomegaly
thin body habitus
pectus excavatum
scoliosis
systolic click and murmur

Full details

Risk factors

underlying lung diseases
smoking
excessive alcohol use
increasing age
hot tub use
HIV/AIDS
severe immunosuppression
genetic cytokine defects

Full details

Diagnostic tests

1st tests to order

CBC with differential
LFT
chest x-ray
sputum culture
blood culture

Full details

Tests to consider

high-resolution CT (HRCT) scanning
bone marrow aspirate for culture
bronchoscopy/bronchial lavage
lung biopsy
lymph node biopsy

Full details

Emerging tests

polymerase chain reaction

Treatment algorithm

ONGOING

pulmonary MAC

disseminated MAC

MAC lymphadenitis

MAC hypersensitivity pneumonitis

Contributors

Authors

Zelalem Temesgen, MD, FIDSA

Professor of Medicine

Director, Mayo Clinic Center for Tuberculosis

Director, HIV Program

Consultant, Division of Infectious Diseases

Mayo Clinic

Rochester

Disclosures

ZT declares that he has no competing interests.

Acknowledgements

Dr Temesgen would like to gratefully acknowledge Dr Dereje S. Ayo, a previous contributor to this topic.

Disclosures

DSA declares that he has no competing interests.

Peer reviewers

Jonathan P. Parsons, MD

Assistant Professor

Division of Pulmonary, Allergy, Critical Care and Sleep Medicine

Ohio State University Medical Center

Columbus

Disclosures

JPP declares that he has no competing interests.

Sandro Vento, MD

Director

Infectious Diseases Unit

Annunziata Hospital

Cosenza

Italy

Disclosures

SV declares that he has no competing interests.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

National Institutes of Health, Centers for Disease Control and Prevention, HIV Medicine Association, and Infectious Diseases Society of America. Panel on Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents with HIV. Guidelines for the prevention and treatment of opportunistic infections in adults and adolescents with HIV: Disseminated mycobacterium avium complex disease. 2024 [internet publication].Full text

Griffith DE, Aksamit T, Brown-Elliott BA, et al. An official ATS/IDSA statement: diagnosis, treatment, and prevention of nontuberculous mycobacterial diseases. Am J Respir Crit Care Med. 2007 Feb 15;175(4):367-416.Full text Abstract

Daley CL, Iaccarino JM, Lange C, et al. Treatment of nontuberculous mycobacterial pulmonary disease: an official ATS/ERS/ESCMID/IDSA clinical practice guideline. Clin Infect Dis. 2020 Aug 14;71(4):e1-36.Full text Abstract

Haworth CS, Banks J, Capstick T, et al. British Thoracic Society guidelines for the management of non-tuberculous mycobacterial pulmonary disease (NTM-PD). Thorax. 2017 Nov;72(suppl 2):ii1-64.Full text

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials
- Pulmonary tuberculosis
- Other nontuberculous mycobacteria (NTM)
- HIV-related lymphoma
More Differentials
Guidelines
- Guidelines for the prevention and treatment of opportunistic infections in adults and adolescents with HIV
- Guidelines for the prevention and treatment of opportunistic infections in children with and exposed to HIV
More Guidelines
Patient information
Quitting smoking
More Patient information
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Mycobacterium avium complex

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic tests

1st tests to order

Tests to consider

Emerging tests

Treatment algorithm

pulmonary MAC

disseminated MAC

MAC lymphadenitis

MAC hypersensitivity pneumonitis

Contributors

Authors

Zelalem Temesgen, MD, FIDSA

Disclosures

Acknowledgements

Disclosures

Peer reviewers

Jonathan P. Parsons, MD

Disclosures

Sandro Vento, MD

Disclosures

References

Key articles

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials

Guidelines

Patient information

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice