What is the treatment for Mycobacterium leprae infection?

Treatment of Mycobacterium leprae Infection

The treatment of Mycobacterium leprae (leprosy) requires multidrug therapy with rifampicin, dapsone, and clofazimine for 12 months for multibacillary leprosy, while paucibacillary leprosy is treated with rifampicin and dapsone for 6 months. 1, 2

Classification of Leprosy

Leprosy is classified into two main types based on bacterial load:

• Paucibacillary (PB) leprosy: Fewer lesions with low bacterial load 1

  • Includes tuberculoid and borderline tuberculoid forms
  • Limited number of skin lesions (typically ≤5)
  • Low bacterial index on skin smears

• Multibacillary (MB) leprosy: Multiple lesions with high bacterial load 1

  • Includes lepromatous, borderline lepromatous, and mid-borderline forms
  • Multiple skin lesions (typically >5)
  • Positive bacterial index on skin smears

Standard Treatment Regimens

Multibacillary Leprosy Treatment

• Duration: 12 months 2
• Regimen:
  • Rifampicin: 600 mg once monthly (supervised) 1
  • Dapsone: 100 mg daily (self-administered) 3
  • Clofazimine: 300 mg once monthly (supervised) and 50 mg daily (self-administered) 1, 4

Paucibacillary Leprosy Treatment

• Duration: 6 months 2
• Regimen:
  • Rifampicin: 600 mg once monthly (supervised) 1
  • Dapsone: 100 mg daily (self-administered) 3

Alternative Regimens

For patients who cannot tolerate standard therapy:

• Single-dose ROM therapy for selected PB cases:

  • Rifampicin: 600 mg
  • Ofloxacin: 400 mg
  • Minocycline: 100 mg 2

• Second-line drugs for drug resistance or intolerance:

  • Ofloxacin: 400 mg daily 1
  • Minocycline: 100 mg daily 1

Management of Leprosy Reactions

Type 1 (Reversal) Reactions

• Characterized by increased inflammation in existing lesions 5
• Treatment:
  • Prednisone: 40-60 mg daily with gradual taper over 3-6 months 5
  • Continue antimicrobial therapy 5

Type 2 (Erythema Nodosum Leprosum) Reactions

• Characterized by painful subcutaneous nodules 1
• Treatment:
  • Thalidomide: 100-300 mg daily (contraindicated in pregnancy) 1
  • Prednisone: 40-60 mg daily if thalidomide is contraindicated 1
  • Clofazimine: May be increased to 300 mg daily for 1 month, then 200 mg daily for several months 1

Monitoring and Follow-up

• Clinical assessment: Every 3 months during treatment and annually for at least 5 years after completion 1
• Nerve function assessment: Regular monitoring for new nerve damage 1
• Relapse monitoring: Patients should be educated about signs of relapse, which may occur after treatment completion 1

Special Considerations

• Pediatric dosing: Adjust based on weight (dapsone 1-2 mg/kg/day, rifampicin 10-20 mg/kg/month) 1
• Pregnancy: Rifampicin and clofazimine are generally considered safe; avoid thalidomide 1
• HIV co-infection: Standard regimens are effective but monitor closely for drug interactions 1

Common Pitfalls and Caveats

• Dapsone adverse effects: Hemolytic anemia, especially in G6PD-deficient patients; monitor complete blood count 3
• Clofazimine side effects: Skin discoloration (red-brown) that may persist for months after discontinuation 1
• Treatment compliance: Poor adherence is a major cause of treatment failure and relapse 2
• Nerve damage: Can occur even after successful treatment of the infection; may require prolonged corticosteroid therapy 5
• Drug resistance: Emerging concern, particularly to dapsone; multidrug therapy helps prevent resistance 1

Early diagnosis and prompt initiation of appropriate multidrug therapy are crucial for preventing disability and reducing transmission of M. leprae 4.