Aminoglycoside susceptibility and treatment outcomes in Mycobacterium avium complex pulmonary disease

BACKGROUND: Treatment with parenteral aminoglycosides is recommended for patients with advanced Mycobacterium avium complex pulmonary disease (MAC-PD). However, the evidence supporting susceptibility-based treatment with aminoglycosides is limited. METHODS: We retrospectively reviewed patients with MAC-PD treated with aminoglycosides for at least eight weeks between October 2005 and December 2018 at a tertiary referral center in South Korea. Patients without drug susceptibility test (DST) results were excluded. RESULTS: Among 951 patients diagnosed with MAC-PD, 46 received at least six months of treatment, including aminoglycosides. Thirty patients with DST results were enrolled in this study. The median age was 57 years (interquartile range [IQR], 50-62 years), with 70 % female. Four patients had received prior treatment for MAC-PD. M. intracellulare was the most common causative species (46.7 %), followed by M. avium (43.3 %). The median duration of follow-up was 41.3 months (IQR 7.6-68.7 months) after treatment initiation. Sputum acid-fast bacilli smear was positive in 43.3 %; cavities were present in 73.3 % of patients. The median treatment duration was 16.4 months (IQR 13.5-27.0 months). Culture conversion and all-cause mortality rates were 60.0 % and 20.0 %, respectively. Amikacin was susceptible in 80.0 % of the patients; however, culture conversion rates did not differ based on susceptibility. Amikacin-susceptible patients had a higher, but insignificant, odds of culture conversion (odds ratio 1.667, 95 % confidence interval 0.275-10.094, p = 0.578) CONCLUSION: Our findings suggest that DST is not correlated with efficacy of aminoglycosides in MAC-PD. Further research is required to clarify its role in treatment decisions.