Clinical manifestations of <i>Mycobacterium abscessus</i> lung disease according to different morphotypes

Background: Mycobacterium abscessus complex (MABC) displays phenotypic heterogeneity, primarily characterised by two distinct morphotypes: smooth and rough. However, the clinical manifestations, radiographic findings, and treatment outcomes of the two MABC morphotypes remain insufficiently characterised and poorly understood. We aimed to investigate the association between these morphotypes and clinical manifestations in a Taiwanese MABC-lung disease cohort. Methods: We conducted this study at a single centre in northern Taiwan. We enrolled patients diagnosed with MABC-lung disease (LD) and analysed their clinical characteristics in relation to MABC morphotypes. We also evaluated radiographic findings. Results: Among 121 patients with MABC-LD, the MABC isolates of 80 (66.1%) patients were smooth variants, and the remaining 41 (33.9%) were rough variants. Fewer patients with the rough variant of MABC had COPD and were smokers compared to patients with the smooth variant, but there were more patients with the rough variant (22.0%) compared to those with the smooth variant (5.0%) showing a fibrocavitary (FC) pattern on chest imaging (P = 0.017). Multivariable logistic regression analysis identified the rough morphotype as an independent factor associated with the FC pattern (adjusted odds ratio (aOR) = 4.741; 95% CI = 1.403-18.870, P = 0.016). Conversely, the FC pattern was the only significant correlated factor of rough morphotype (OR = 4.196; 95% CI = 1.183-17.771, P = 0.033). Conclusions: MABC-LD patients with rough-variant isolates had a higher rate of FC pattern compared with those with smooth-variant isolates. Given that an FC pattern may indicate poor prognosis, morphotypes of clinical isolates in MABC-LD may serve as a potential marker to guide clinical management, although further validation is needed.