From the Guidelines
Mycobacterium avium complex (MAC) infection is primarily contracted through environmental exposure to these bacteria, which are commonly found in soil, water, and dust, and people typically become infected by inhaling or ingesting the bacteria from these sources 1.
Key Points to Consider
- The infection can also occur through direct contact with contaminated materials, and MAC organisms are particularly prevalent in water systems, including tap water, showers, hot tubs, and natural water bodies.
- Most people who are exposed to MAC do not develop illness because their immune systems can fight off the bacteria.
- However, individuals with weakened immune systems, particularly those with HIV/AIDS, chronic lung diseases like COPD or bronchiectasis, or those taking immunosuppressive medications, are at higher risk for developing MAC infection 1.
Risk Factors and Prevention
- The bacteria can cause localized infections in the lungs (pulmonary MAC) or disseminated disease throughout the body in severely immunocompromised patients.
- MAC infection is not typically transmitted from person to person, so it is not considered contagious.
- Prevention strategies include avoiding potential sources of exposure when immunocompromised and maintaining good hygiene practices.
Important Considerations
- Disseminated disease due to NTM in persons with HIV infections occurs only in patients who are severely immunocompromised, as evidenced by very low CD4 T-cell counts 1.
- All persons with less than 50 CD4 T cells/l are at risk of disseminated NTM, with the risk increasing with progressively lower numbers of cells.
From the FDA Drug Label
To reduce the development of drug-resistant bacteria and maintain the effectiveness of clarithromycin and other antibacterial drugs, clarithromycin should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria Clarithromycin immediate-release tablets and clarithromycin for oral suspension are indicated for the prevention of disseminated Mycobacterium avium complex (MAC) disease in patients with advanced HIV infection
The transmission of Mycobacterium avium complex (MAC) infection is not directly addressed in the provided drug label. However, it can be inferred that MAC infection is likely to be opportunistic, affecting individuals with advanced HIV infection.
- The label mentions the prevention of disseminated MAC disease in patients with advanced HIV infection, suggesting that these patients are at risk of contracting the infection.
- However, the exact mode of transmission is not specified in the label 2.
From the Research
How to Contract Mycobacterium Avium Complex (MAC) Infection
- Mycobacterium avium complex (MAC) infection is caused by nontuberculous mycobacteria that are ubiquitous in the environment 3.
- Acquisition of MAC infection occurs through:
- Ingestion of contaminated water or food
- Inhalation of aerosols from soil, water, or biofilms
- People with compromised immune systems, such as those with HIV/AIDS, are more susceptible to MAC infection 4, 5, 6.
- MAC infection can manifest as:
- Disseminated infection
- Soft tissue infection
- Chronic pneumonia
- Hypersensitivity pneumonitis
- The risk of contracting MAC infection is higher in individuals with:
- Advanced HIV disease
- CD4+ cell counts less than 100 cells/mm3
- Preexisting lung disease
- Immunocompromise
Prevention and Treatment
- There is no vaccine available to prevent MAC infection.
- Treatment of MAC infection typically involves a combination of antimycobacterial agents, such as:
- Clarithromycin
- Azithromycin
- Rifabutin
- Ethambutol
- Rifampin
- Prophylaxis with rifabutin or other agents may be recommended for individuals at high risk of MAC infection, such as those with advanced HIV disease 5, 6.