Mycobacterium avium complex
Background
- Mycobacterium avium complex (MAC) is a group of mycobacteria including M. avium and M. intracellulare
- Ubiquitous environmental organism found in soil, water, and food
- Primarily causes disseminated disease in immunocompromised patients (especially HIV with CD4 <50)
- Can also cause pulmonary disease in patients with underlying lung disease
Clinical Features
- Fever, night sweats, weight loss
- Fatigue and malaise
- Abdominal pain, diarrhea
- Lymphadenopathy, hepatosplenomegaly
- Anemia and elevated alkaline phosphatase
Differential Diagnosis
- Tuberculosis
- Lymphoma
- Other opportunistic infections in HIV
Evaluation
- Blood cultures (mycobacterial)
- CBC showing anemia
- Elevated alkaline phosphatase, LDH
- CT showing lymphadenopathy, hepatosplenomegaly
Management
Primary Prophylaxis
- Indicated for HIV patients with CD4 <50
Adult
- Clarithromycin 500mg PO q12h
- OR Azithromycin 1200mg PO weekly (Alt: 600mg PO twice weekly)
Pediatric
- Clarithromycin 20mo-12yrs: 15mg/kg/day PO divided q12h (max 500mg/dose); >13yrs: 500mg PO q12h
Treatment (Disseminated)
Adult
- Clarithromycin 500mg PO q12h (use with ethambutol)
- OR Azithromycin 500-600mg PO daily (use with ethambutol; not 1st-line)
Pediatric
- Clarithromycin 20mo-12yrs: 15-30mg/kg/day PO divided q12h (max 500mg/dose, use with ethambutol); >13yrs: 500mg PO q12h (use with ethambutol)
Secondary Prophylaxis
Adult
- Clarithromycin 500mg PO q12h (use with ethambutol)
- OR Azithromycin 500-600mg PO daily (use with ethambutol; not 1st-line)
Pediatric
- Clarithromycin 20mo-12yrs: 15mg/kg/day PO divided q12h (max 500mg/dose, use with ethambutol); >13yrs: 500mg PO q12h (use with ethambutol)
Disposition
- Admission for severe disseminated disease
- Outpatient management for prophylaxis
- Infectious disease consultation recommended