From the Guidelines
Mycobacterium avium-intracellulare (MAI) infection is a type of nontuberculous mycobacterial disease that requires a multi-drug regimen for effective treatment, with the most recent and highest quality study recommending a combination therapy consisting of clarithromycin or azithromycin, ethambutol, and rifampin 1.
Overview of MAI Infection
MAI infection is caused by the bacteria Mycobacterium avium and Mycobacterium intracellulare, which are commonly found in the environment and can infect people with weakened immune systems. The infection can cause a range of symptoms, including cough, fever, and weight loss.
Treatment of MAI Infection
The treatment of MAI infection typically involves a combination of antibiotics, including:
- Clarithromycin (500mg twice daily) or azithromycin (500mg daily)
- Ethambutol (15mg/kg daily)
- Rifampin (600mg daily) This treatment regimen is recommended because MAI is naturally resistant to many antibiotics, and using multiple medications prevents the development of further resistance 1.
Duration of Treatment
The treatment of MAI infection typically continues for at least 12 months after achieving negative cultures. For severe or disseminated cases, adding amikacin (15mg/kg daily) for the first 2-3 months may be beneficial. Treatment should continue until patients have maintained negative cultures for 12 months.
Monitoring and Follow-up
Regular monitoring of liver function, vision (due to ethambutol's side effects), and follow-up cultures are essential during treatment. This is because the treatment regimen can have potential side effects, and regular monitoring can help identify any issues early on.
Key Points
- MAI infection requires a multi-drug regimen for effective treatment
- The recommended treatment regimen includes clarithromycin or azithromycin, ethambutol, and rifampin
- Treatment typically continues for at least 12 months after achieving negative cultures
- Regular monitoring of liver function, vision, and follow-up cultures are essential during treatment
- The lengthy treatment duration is required because these mycobacteria grow slowly and can persist in tissues, making complete eradication difficult without sustained therapy 1.
From the FDA Drug Label
CLINICAL STUDIES ... Endpoints included the following: ... (2) Clinically significant disseminated MAC disease, defined as MAC bacteremia accompanied by signs or symptoms of serious MAC infection, including one or more of the following: fever, night sweats, rigors, weight loss, worsening anemia, and/or elevations in alkaline phosphatase.
Mycobacterium avium-intracellulare (MAI) infection is a type of MAC (Mycobacterium avium complex) infection, which can cause clinically significant disseminated MAC disease characterized by signs and symptoms such as:
- Fever
- Night sweats
- Rigors
- Weight loss
- Worsening anemia
- Elevations in alkaline phosphatase 2
From the Research
Definition and Overview of Mycobacterium avium-intracellulare (MAI) Infection
- Mycobacterium avium-intracellulare (MAI) infection is caused by mycobacteria of the Mycobacterium avium-intracellulare complex 3.
- MAI infection can cause pulmonary infection, lung disease, and disseminated disease, especially in patients with acquired immunodeficiency syndrome (AIDS) 4, 5, 6.
- The infection can lead to chronic lung disease in immunocompetent patients and disseminated disease in patients with AIDS 5.
Symptoms and Treatment
- Patients with MAI infection may be asymptomatic or symptomatic, with symptoms including pulmonary symptoms and radiologic findings 3, 4.
- Treatment regimens for MAI infection often include a combination of antibiotics, such as macrolides (e.g., clarithromycin, azithromycin), ethambutol, and rifamycins (e.g., rifampicin, rifabutin) 3, 4, 5, 7.
- The effectiveness of treatment regimens can vary, with some patients experiencing adverse effects, relapse, or treatment failure 4, 5, 6, 7.
Prevention Strategies
- Prevention strategies for MAI infection in patients with AIDS include prophylactic regimens using single agents (e.g., rifabutin, clarithromycin, azithromycin) or combination therapy 6.
- The choice of prophylaxis depends on factors such as efficacy, potential drug interactions, and the risk of emerging resistance 6.