Initial clarithromycin monotherapy for Mycobacterium avium-intracellulare complex lung disease

Area of Science:

• Pulmonary Medicine
• Infectious Diseases
• Microbiology

Background:

• Mycobacterium avium-intracellulare (MAI) complex lung disease treatment has suboptimal sputum conversion rates (50-80%) with current multi-drug regimens.
• Existing therapies often involve three to five antituberculosis agents, highlighting a need for more effective treatments.

Purpose of the Study:

• To evaluate the efficacy of initial clarithromycin monotherapy for treating Mycobacterium avium-intracellulare (MAI) lung disease in HIV-negative patients.
• To assess microbiologic improvement as the primary endpoint in patients receiving clarithromycin.

Main Methods:

• A prospective, open-label, noncomparative trial was conducted.
• 30 HIV-negative patients with MAI lung disease received clarithromycin 500 mg twice daily for 4 months.
• Sputum conversion, culture reduction, and radiographic changes were primary outcome measures.

Main Results:

• Of 19 patients with pretreatment clarithromycin MIC < 16 µg/ml, 58% achieved sputum negativity and 21% showed significant reduction in sputum positivity.
• A significant reduction in heavily positive sputum cultures was observed (64% to 6%, p < 0.0001).
• 95% of patients demonstrated improvement in sputum cultures, chest radiographs, or both, with only 7% discontinuing due to adverse events. Clarithromycin resistance developed in 16% of isolates.

Conclusions:

• Clarithromycin monotherapy is the first single agent demonstrated to be efficacious in treating MAI lung disease.
• The drug shows significant microbiologic and clinical improvement in susceptible patients.
• Further research into optimal dosing and resistance patterns is warranted.