Longitudinal non-cystic fibrosis trends of pulmonary Mycobacterium abscessus disease from 2010–2017 - spread of the “globally successful clone” in Asia

Background Mycobacterium abscessus (MAB) has emerged as the predominant pulmonary non-tuberculous mycobacterial pathogen in parts of Asia, including Taiwan. The reasons for the significant increase in MAB infections in the non-cystic fibrosis (CF) populations are poorly understood. The study aimed to elucidate whether this increase is related to the spread of the globally successful clone of MAB.

Methods We performed multi-locus sequence typing (MLST) of 371 non-duplicated MAB pulmonary isolates from 371 patients sampled between 2010–2017 at 7 hospitals across Taiwan.

Results In total, 183 (49.3%) isolates were M. abscessus subsp. abscessus (MAB-a), 187 (50.4%) were M. abscessus subsp. massiliense (MAB-m), and 1 (0.3%) was M. abscessus subsp. bolletii (MAB-b). MAB-a sequence type 1 (ST1) [23.7%] and ST127 [3.8%], followed by MAB-m ST48 [16.2%], ST117 [15.1%], ST23 [8.6%] were commonest overall. Of MAB-a strains, 50 (27.3%) belonged to novel STs and 38 (10.2%) were singleton strains, while of MAB-m strains, only 10 (5.3%) were novel and 8 (2.2%) were singletons. From 2010 to 2017, the frequency of the historically dominant ST1 declined from 28.6% to 22.5%, whereas the recently emerged globally successful clonal cluster 3, ST23 and ST48, increased from 14.3% to 40.0%.

Conclusions The dominance of ST1 particularly in the last 2 years of this study appears to be declining whilst ST23, reported in outbreaks among CF and post-surgical cohorts across the Americas and Europe, alongside the closely related ST48, is present among non-CF populations in Taiwan. These trends need to be confirmed with further ongoing studies to track the molecular epidemiology of clinical MAB isolates worldwide.