Mycobacterium avium Complex Infections in Children: Symptoms and Treatment

Clinical Manifestations

Children with MAC infections present differently depending on their immune status and site of infection.

Persistent fever, night sweats, and rigors are hallmark symptoms 1
Progressive weight loss and failure to thrive occur in the majority of cases 2
Anorexia and abdominal pain/tenderness are common gastrointestinal manifestations 2
Worsening anemia develops as disease progresses 1
Elevated alkaline phosphatase indicates hepatic involvement 1
Disseminated MAC occurs almost exclusively when CD4 counts fall below 100 cells/µL (93% of pediatric cases) 2
The median time from symptom onset to positive culture is approximately 9 months 2

Cervical lymph node involvement is the predominant presentation in immunocompetent children 1
Nodes may form masses requiring surgical evaluation 3
This form typically occurs in otherwise healthy children without systemic symptoms 1

All treatment regimens must include at least two antimycobacterial agents to prevent resistance development—never use monotherapy. 1, 4

Either clarithromycin OR azithromycin must serve as the backbone macrolide 1, 4
Ethambutol (15 mg/kg/day) is the essential second agent with additive/synergistic effects 4
Rifabutin (300 mg daily for adults; weight-adjusted for children) can be added as an optional third agent 1, 4

Ethambutol: approximately 15 mg/kg per day for children under 4 years, with doses up to 75 mg/day used safely 1
Higher ethambutol doses up to 25 mg/kg/day can be given for short periods (less than one month) 1
Monthly vision checks are mandatory for children under 12 years receiving ethambutol and adults on >15 mg/kg/day for >1 month 1
Ciprofloxacin is not recommended for patients under 18 years but can be administered when necessary with few serious adverse effects 1

Isoniazid and pyrazinamide have NO role in MAC therapy—they are ineffective 1, 4
Never use clofazimine—it is associated with increased mortality in multiple studies 4
Do not exceed clarithromycin 500 mg twice daily—higher doses are linked to increased mortality 4
Continue therapy for minimum 12 months until CD4+ count remains >100 cells/µL for ≥6 months on antiretroviral therapy with complete symptom resolution 4

Most patients show substantial clinical improvement within 4-6 weeks if the regimen is effective 4
Obtain blood cultures every 4 weeks during initial therapy 4
Clearance of bacteremia typically requires 4-12 weeks, which may lag behind clinical improvement 4
Blood cultures should be performed in symptomatic patients to confirm MAC diagnosis 4

Complete surgical excision of affected lymph nodes is the treatment of choice. 1

Antimycobacterial chemotherapy with rifampicin, ethambutol, and clarithromycin for up to 2 years should be considered when: surgical excision is incomplete, disease recurs, or vital structures prevent complete excision 1
Chemotherapy can be used to debulk disease to permit subsequent excision 1

Consider adding amikacin or streptomycin as injectable agents for treatment failure or severe disease 4, 3
Ciprofloxacin can be used as an additional oral agent 4
Salvage regimens should include at least two new drugs not previously used 4

Never delay treatment while awaiting culture results—empiric therapy should be started promptly when clinical suspicion is high 3, 5
Stopping therapy based on CD4+ recovery alone without completing 12 months risks relapse—all three discontinuation criteria (duration, immune recovery, AND symptom resolution) must be met simultaneously 4
Symptom improvement does not equal microbiologic cure—the full treatment course is essential 4
Children who develop MAC while on rifabutin prophylaxis should receive the same multi-drug treatment regimen as those not on prophylaxis 1
Drug-susceptibility testing should NOT guide initial therapy selection for MAC (unlike tuberculosis) 1

Outcome for children with disseminated MAC is poor, with 75% surviving ≤10 months in the pre-HAART era 2
Children with severe immunodeficiency (CD4 <100) are at particular risk for disseminated disease 2
Localized lymphadenitis in immunocompetent children has excellent prognosis with appropriate surgical management 1, 3