Genomic diversity and resistance profile of Mycobacterium avium clinical strains circulating in Portugal between 2018 and 2022

• Autor(a) principal: Rodrigues, Joana
• Data de Publicação: 2024
• Outros Autores: Rodrigues, Irene, Carneiro, Sofia, Silva, Sónia, Santos, Andrea, Macedo, Rita
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://doi.org/10.25761/anaisihmt.453

Introduction: In recent years, opportunistic infections with nontuberculous mycobacteria (NTM) have gained increasing importance in public health, with Mycobacterium avium being the most responsible species for the increase of human disease cases. These infections manifest mainly at the respiratory level, and disseminated infection may also occur, especially in immunocompromised individuals. Currently, the mode of transmission is not established, but environmental exposure is considered the main source of infection. Therefore, epidemiological studies are essential to identify possible foci of infection, and thus improve methods of surveillance, prevention, and control of this type of disease. Objective: Evaluation of the genomic diversity and resistance profile of clinical isolates of Mycobacterium avium circulating in Portugal between 2018 and 2022. Methods: Between 2018 and 2022, the National Reference Laboratory for Mycobacteria (LNR-TB), at INSA received 103 M. avium isolates. Of these, a subset of 42 strains was characterized for genomic diversity using the MIRUVNTR molecular typing methodology. Additionally, 40 (95%) strains were tested for phenotypic susceptibility to clarithromycin, moxifloxacin, and linezolid, and molecular susceptibility, by screening of mutations in the 16S rRNA (rrs) and 23S rRNA (rrl) genes associated with resistance to aminoglycosides and macrolides, respectively. Results: Phenotypic susceptibility testing indicated that 98% (39) of the strains were susceptible to clarithromycin, while only 25% (n=10) and 27.5% (n=11) were susceptible to linezolid and moxifloxacin. There was a high correlation between the results of phenotypic and genotypic susceptibility testing with respect to macrolides. MIRU-VNTR genotyping revealed a high genetic diversity among the strains. Using a threshold of 1 locus and 2 loci between strains, it was observed two molecular clusters and 37 singletons and eight clusters and 20 singletons, respectively. Overall, the MIRU-VNTR methodology allowed a discriminatory power of 0.9988. Conclusion: Although molecular clusters were detected, the analysis of MIRU-VNTR profiles is insufficient to establish concrete epidemiological relationships. In addition to patient demographics, clinical data is needed, which may require consideration of a mandatory reporting system for more assertive laboratory surveillance of M. avium disease.