Cavitary status and differential treatment response in refractory or severe Mycobacterium avium complex pulmonary disease: Amikacin liposome inhalation suspension versus intravenous amikacin.

BACKGROUND

Despite guideline-based treatment, Mycobacterium avium complex pulmonary disease (MAC-PD) often fails to achieve culture conversion. The current guideline recommends adding amikacin liposome inhalation suspension (ALIS) or intravenous amikacin (IV AMK) as intensifying treatment for refractory MAC-PD; however, no clear guidance exists for selecting these treatment options. We compared culture conversion between these agents and explored whether the difference varies by cavity status.

METHODS

We conducted a retrospective chart review from August 2019 to July 2025. Included were 57 patients with refractory or severe MAC-PD: 34 receiving ALIS and 23 receiving IV AMK. Treatment efficacy was evaluated by culture conversion within six months. We compared treatment efficacy across these agents and conducted a subgroup analysis by cavity status. Inverse probability of treatment weighting (IPTW) was applied, and the interaction between treatment group and cavity status was evaluated.

RESULTS

While no significant difference in overall culture conversion was detected (ALIS, 55.9%; IV AMK, 47.8%), IPTW-adjusted analysis showed opposite point estimates of hazard ratios (HRs) and a significant interaction with cavity status. The HRs for ALIS with reference to IV AMK were 2.50 (95% confidence interval [CI], 0.76-8.27) without cavity and 0.62 (95% CI, 0.21-1.83) with cavity (p for interaction = 0.043). Furthermore, the upper lung zone cavity involvement showed a similar interaction (p for interaction = 0.012).

CONCLUSION

The difference in culture conversion between ALIS and IV AMK may vary according to cavity status. These findings require confirmation in larger cohorts restricted to refractory disease to optimize treatment selection.