RT Journal Article SR Electronic T1 Amikacin exposure and susceptibility of macrolide-resistant Mycobacterium abscessus JF ERJ Open Research JO erjor FD European Respiratory Society SP 00154-2018 DO 10.1183/23120541.00154-2018 VO 5 IS 2 A1 Shelby Daniel-Wayman A1 Shamira Shallom A1 Nabila Azeem A1 Kenneth N. Olivier A1 Adrian M. Zelazny A1 D. Rebecca Prevots YR 2019 UL http://openres.ersjournals.com/content/5/2/00154-2018.abstract AB Mycobacterium abscessus is associated with antibiotic resistance and poor treatment outcomes. We described within-patient changes in M. abscessus resistance to clarithromycin and amikacin.Patients with amikacin exposure and a >50-month interval between M. abscessus isolates were identified. Antimicrobial susceptibility testing was performed on the first and last isolates by broth microdilution, and genetic markers of resistance were identified.16 patients were identified with a median amikacin exposure of 2.3 years (range 0.6–8.6 years). 15 patients also received macrolides (median 7.2 years, range 1.3–10.7 years). All initial isolates were resistant to clarithromycin (minimum inhibitory concentration (MIC) ≥8 µg·mL−1). Two patients had later susceptible isolates, which were of a different subspecies (M. abscessus subsp. massiliense) than the initial isolates (M. abscessus subsp. abscessus). All initial isolates were susceptible or intermediately resistant to amikacin, and only one patient had a resistant final isolate (MIC >64 µg·mL−1), accompanied by an A→G mutation at position 1408 of the 16S ribosomal RNA. Forced expiratory volume in 1 s decreased significantly over the study period, while smear quantity and the proportions of patients with elevated C-reactive protein or cavitary lesions all increased significantly.Despite prolonged, mostly inhaled amikacin exposure, development of amikacin resistance was uncommon in this patient population; however, disease progression continued.Patients with long-term amikacin treatment rarely develop resistance but their disease continues to progress http://bit.ly/2V7k0kH