Longitudinal Phenotypic and Antimicrobial Resistance Evolution of Mycobacterium Abscessus Subsp. Abscessus During Chronic Pulmonary Infection in a Patient with Cystic fibrosis
Abstract
Background
Mycobacterium abscessus infection represents one of the most challenging non-tuberculous mycobacterial infections in patients with cystic fibrosis (CF), owing to intrinsic antimicrobial resistance, prolonged persistence within the respiratory tract, and poor therapeutic outcomes. Comprehensive microbiological characterization may support diagnosis, treatment selection, and long-term clinical management.
Methods
Four sequential M. abscessus subsp. abscessus isolates recovered from bronchoalveolar lavage samples collected between 2017 and 2025 from a cystic fibrosis patient were analyzed. Species and subspecies identification, together with detection of resistance-associated determinants, were performed using MALDI-TOF MS and GenoType NTM-DR assays. Antimicrobial susceptibility testing was conducted by broth microdilution according to CLSI recommendations. Biofilm-forming capacity was evaluated using the crystal violet assay. Phenotypic relatedness of sequential isolates was assessed by Fourier-transform infrared (FT-IR) spectroscopy using the IR Biotyper platform.
Results
Repeated respiratory isolation of M. abscessus together with progressive radiological abnormalities and impaired lung function supported the diagnosis of chronic pulmonary disease. All analyzed isolates were identified as M. abscessus subsp. abscessus. Molecular analysis identified a functional erm(41) determinant consistent with inducible macrolide resistance. Antimicrobial susceptibility testing showed sustained susceptibility to linezolid and temporal changes in susceptibility to amikacin and clarithromycin, with resistance to cefoxitin, moxifloxacin, ciprofloxacin, doxycycline, and trimethoprim-sulfamethoxazole. The isolates demonstrated biofilm-forming ability. FT-IR analysis demonstrated high similarity of spectral profiles among sequential isolates collected during the follow-up period
Conclusions
Chronic M. abscessus infection in this patient was characterized by repeated recovery of isolates with highly similar FT-IR spectral profiles over eight years, along with temporal changes in antimicrobial resistance and biofilm-forming capacity. While these findings are consistent with persistence of a phenotypically related population, confirmation of clonality and within-host microevolution would require whole-genome sequencing.
© 2026 Katarzyna Kania, Katarzyna Wójcik, Magdalena Grzesiak, Adrian Szczepański, Iwona Gross-Sondej, Krzysztof Sładek, Karolina Klesiewicz, published by Polish Society of Microbiologists
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