Effects of Amikacin Liposome Inhalation Suspension and Amikacin Resistance Development in Patients With Refractory Mycobacterium avium Complex Pulmonary Disease

Background Amikacin liposome inhalation suspension (ALIS) is key for treating refractory Mycobacterium avium complex pulmonary disease (MAC-PD). However, microbiological efficacy by subtype remains unknown. The frequency and mechanism of amikacin (AMK) resistance during ALIS administration are also unclear. Methods We retrospectively analyzed data from refractory MAC-PD patients who received ALIS for at least 6 months as an adjunct to guideline-based therapy at the NHO Kinki Chuo Chest Medical Center. We investigated the efficacy of ALIS and analyzed gene expression and the frequency of AMK resistance. Results We enrolled 44 patients (median age, 72.0 years): 19 (43.2%) with the noncavitary nodular bronchiectatic (NC-NB) subtype and 25 (56.8%) with the cavitary subtype. Overall, sputum culture conversion was 56.8% (25/44): 84.2% (16/19) in the NC-NB subtype and 36.0% (9/25) in the cavitary subtype (P = .001). During intermittent dosing, conversion occurred in 50.0% (9/18). In patients with C-reactive protein (CRP) >= 1 mg/dL, cavitary subtype, and clarithromycin (CLM) resistance, the risk ratio for persistently positive cultures was 10.81 (95% CI, 1.66-70.40) compared with those with CRP <1 mg/dL, NC-NB subtype, and CLM susceptibility. Of all participants, 15.9% (7/44) had isolates with AMK resistance (minimum inhibitory concentration >= 128 <mu>g/mL), and of these 71.4% (5/7) had rrs mutations. Conclusions Regimens that included ALIS achieved higher culture conversion in NC-NB than cavitary MAC-PD cases. High CRP levels, cavitary disease, and CLM resistance predicted persistent culture positivity. AMK resistance acquired during ALIS administration may limit treatment options for refractory MAC-PD.