Genomic analysis of Mycobacterium abscessus isolates from non-cystic fibrosis patients in Thailand: phylogeny, subspecies distribution, and antimicrobial resistance profiles.

Background: Mycobacterium abscessus (MABS) is a clinically significant nontuberculous mycobacterium, and its drug resistance poses substantial therapeutic challenges. Comprehensive genomic and phenotypic analyses are essential for elucidating the mechanisms underlying this resistance and enhancing understanding of its epidemiology.

Methods: Whole-genome sequencing (WGS) using the Illumina platform was conducted on 61 clinical MABS isolates obtained from patients in Thailand. MABS subspecies classification was performed using FastANI, TYGS, and NTM-Profiler. Phenotypic drug susceptibility testing (pDST) was determined using a broth microdilution method. Resistance mutations were identified through NTM-Profiler and Snippy pipelines.

Results: The analysis classified MABS isolates into three subspecies: subsp. abscessus (40/61, 65.57 %), subsp. massiliense (15/61, 24.59 %), and subsp. bolletii (6/61, 9.83 %). Phylogenetic analysis revealed genetic diversity among the majority of the MABS clinical isolates. These isolates clustered into distinct clades, separate from globally recognized clinical strains and dominant circulating clones. Inducible clarithromycin resistance was detected in 60.66 % of MABS isolates, associated with the T28 variant in erm(41). The Ile80Val mutation in erm(41) was significantly associated with inducible clarithromycin resistance (χ² = 12.61, p < 0.001). Acquired clarithromycin resistance associated with rrl mutations (A2270C, A2270G, A2271C) and amikacin resistance linked to the rrs mutation A1375G were detected in 11.48 % and 4.92 % of isolates, respectively. The categorical agreement between WGS-based DST and pDST was 95.08 %, 88.33 %, and 96.43 % for inducible clarithromycin, clarithromycin, and amikacin, respectively.

Conclusion: This study provides valuable insights into the genomic diversity and antimicrobial resistance of MABS isolates in Thailand, emphasizing regional variations in dominant clones and resistance mechanisms.