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 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.
Mycobacterium avium complex (MAC), also known as mycobacterium avium-intracellulare (MAI), consists of two mycobacterium species, M avium and M intracellulare. 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. In humans, MAC traditionally causes three disease syndromes: pulmonary disease, cervical lymphadenitis, and disseminated disease. A fourth syndrome, a hypersensitivity pneumonitis associated with hot tub use, has also been described.
History and exam
Key diagnostic factors
- underlying lung disease
- chronic productive cough
- weight loss
- hot tub use
Other diagnostic factors
- age under 5 years
- middle-to-old age
- night sweats
- abdominal pain
- thin body habitus
- pectus excavatum
- systolic click and murmur
- underlying lung diseases
- excessive alcohol use
- older men
- postmenopausal women
- hot tub use
- severe immunosuppression
- genetic cytokine defects
1st investigations to order
- CBC with differential
- chest x-ray
- sputum culture
- blood culture
Investigations to consider
- high-resolution CT (HRCT) scanning
- bone marrow aspirate for culture
- bronchoscopy/bronchial lavage
- lung biopsy
- lymph node biopsy
- polymerase chain reaction
MAC hypersensitivity pneumonitis
- Pulmonary tuberculosis
- Other nontuberculous mycobacteria (NTM)
- HIV-related lymphoma
- Guidelines for the prevention and treatment of opportunistic infections in adults and adolescents with HIV
- Treatment of nontuberculous mycobacterial pulmonary disease
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