UNLABELLED: Mycobacterium abscessus is an emerging opportunistic pathogen affecting patients with chronic lung diseases, primarily cystic fibrosis (CF), or those under immunosuppression. Hence, investigations into the epidemiology and transmission of M. abscessus and accurate antibiotic susceptibility data are essential for the effective treatment of infections caused by this pathogen. This retrospective nationwide study included all clinical M. abscessus isolates (n = 59) from 29 patients diagnosed in the Czech Republic and Slovakia between 2018 and 2023. Whole genome sequencing (WGS) was performed to identify clusters and classify isolates into predominant circulating clones (DCC). Subspecies identification of unique isolates showed subspecies abscessus as the most prevalent (69.0%). The results of drug-susceptibility testing showed that 65.5% of all isolates were resistant to at least three antibiotics tested. CF patients under 24 years of age were the most at-risk group for M. abscessus infection. WGS identified seven clusters (including two cross-border) comprising CF and non-CF patients with a total clustering rate of 48.3%. One cluster involved patients infected with subspecies massiliense strains differing by 0 single nucleotide polymorphisms hospitalized in the same center. Furthermore, we identified representatives of all major DCCs. This study revealed predominant Mycobacterium abscessus complex clones circulating in the Czech Republic and Slovakia. The results show the high discriminatory power of WGS in the molecular epidemiology of M. abscessus and provide supporting evidence of direct or indirect cross-transmission of subspecies massiliense among both CF and non-CF patients. IMPORTANCE: This study highlights the importance of understanding Mycobacterium abscessus transmission because it poses a growing threat to vulnerable populations, especially young cystic fibrosis patients. Investigating how it spreads and which antibiotics work best is crucial for effective treatment. This research used whole genome sequencing to track M. abscessus and found evidence of potential transmission between patients, including across borders. The findings suggest that dominant strains are circulating and some patients may be infected through direct or indirect contact. This knowledge can inform infection control and treatment strategies.

• Klíčová slova
• DCC, M. abscessus, epidemiology, non-tuberculous mycobacteria, resistance, transmission,
• Publikační typ
• časopisecké články MeSH

Mycobacterioses are less frequently occurring but serious diseases. In recent years, at a global level, the incidence of mycobacterioses induced by the rapidly growing species Mycobacterium abscessus (M. a.), which is considered to be the most resistant to antibiotics and most difficult to treat, has been on the rise. Correct identification to the level of the subspecies (M. a. abscessus, M. a. massiliense, and M. a. bolletii) and determination of its sensitivity to macrolides, which are the basis of combination therapy, are of principal importance for the management of the disease. We describe five cases of mycobacterioses caused by M. a., where the sequencing of select genes was performed to identify the individual subspecies and antibiotic resistance. The analysis of the rpoB gene showed two isolates each of M. a. abscessus and M. a. massiliense and one isolate of M. a. bolletii. The complete (full length) erm(41) gene responsible for the development of inducible resistance to macrolides was demonstrated in both M. a. abscessus and M. a. bolletii isolates. A partially deleted and non-functional erm(41) gene was demonstrated in M. a. massiliense isolates. The subsequent sequencing of the full length erm(41) gene products showed, however, the mutation (T28→C) in both isolates of M. a. abscessus, causing a loss of the function and preserved sensitivity to macrolides. The antibiotic sensitivity testing confirmed that both the isolates of M. a. abscessus and M. a. massiliense were sensitive to clarithromycin even after prolonged 14-day incubation. The inducible resistance to clarithromycin was maintained only in M. a. bolletii. Thus, the sequence analysis of the erm(41) gene can reliably identify the preservation of sensitivity to macrolides and serve as an important tool in the establishment of therapeutic regimens in cases of infections with M. abscessus.

• Klíčová slova
• erm(41) gene, macrolide resistance, multiresistance, nontuberculous mycobacteria, rapidly growing mycobacteria,
• Publikační typ
• časopisecké články MeSH