Background: Mycobacterium abscessus, one of the most common species of nontuberculous mycobacterium (NTM), poses a significant clinical challenge due to its natural resistance to antibiotics and high treatment failure rates, particularly in lung diseases. Among its subspecies, M. abscessus subspecies abscessus is especially prone to developing inducible resistance to Clarithromycin. This resistance mechanism is primarily due to the activation of the erm(41) gene,which inhibits Clarithromycin from effectively binding to the bacterial ribosome, diminishing its bactericidal efficacy. Rifabutin, an antibiotic widely used in treating tuberculosis and certain NTM infections, has been shown to inhibit the activation of the erm(41) gene by suppressing the whiB7 protein in M. abscessus, suggesting potential efficacy against inducible resistance. However,current evidence primarily stems from in vitro susceptibility studies and case reports, with a notable lack of systematic clinical trials.

Specific Aims: The primary aim of this study is to evaluate the efficacy and safety of Rifabutin in treating M. abscessus lung disease with inducible Clarithromycin resistance. Specific objectives include:

• Assessing sputum culture conversion rates and clinical improvement when Rifabutin is added to the standard treatment regimen.
• Investigating the effect of Rifabutin on progression-free survival (PFS).
• Evaluating patient tolerance and adverse events throughout treatment.

Inclusion Criteria:

• Adults aged ≥ 18 years
• Diagnosis of pulmonary disease caused by Mycobacterium abscessus confirmed by clinical evaluation and laboratory results
• Antimicrobial susceptibility testing indicating inducible resistance to clarithromycin
• Clinically stable and suitable for antibiotic treatment
• Radiographic evidence of active pulmonary infection
• Willing and able to provide informed consent

Exclusion Criteria:

• Known hypersensitivity to rifabutin or intolerance to other study medications
• Pregnant or breastfeeding women