A disrupted microbial network and an ecological shift towards anaerobes in NTM-infected cystic fibrosis patients.

Nontuberculous mycobacteria (NTM) are increasingly recognized as opportunistic pathogens in people with cystic fibrosis (pwCF), but the ecological factors shaping their presence remain poorly understood. This study characterized the airway microbiota associated with NTM-positive culture using 16S rRNA gene sequencing of sputum from 108 pwCF (36 NTM-positive and 72 NTM-negative), matched by age, sex at birth, and CFTR genotype. Analyses integrated diversity metrics, differential-abundance modeling, multivariate regression, and microbial network inference, while accounting for Pseudomonas aeruginosa colonization. NTM-positive individuals exhibited slightly higher α-diversity and enrichment in strictly anaerobic taxa such as Alloprevotella tannerae, Stomatobaculum spp., and Prevotella nanceiensis, alongside reduced network connectivity. P. aeruginosa remained the dominant ecological driver, strongly reducing community diversity and structure. Partial Least Squares regression revealed that CFTR modulators (lumacaftor/ivacaftor) use and lung function (FEV₁%) were associated with distinct, commensal-enriched communities. In contrast, NTM status was associated with a distinct axis, indicating an independent ecological niche. Overall, NTM-positive cultures were associated with an anaerobe-enriched but less structured microbiota, likely reflecting localized hypoxia and biofilm-associated microenvironments rather than a direct effect of disease severity or modulator therapy. These findings highlight the role of airway microecology in NTM presence and provide a framework for understanding host-microbe interactions in chronic CF airway infections.