Functional and Resistome Profiling of Paediatric Airway Microbiota in Asthma Using Shotgun Metagenomics

Background/Objectives: Asthma affects millions of patients worldwide and impacts their quality of life, particularly among children. Colonisation or an imbalance within natural resident microbiota may drive inflammatory responses in asthma; antibiotic resistance genes (ARGs) have also been investigated in asthma microbiome studies. However, research on the association between airway microbiota and ARGs remains limited. Therefore, we elucidated functional-level characterisation at the level of ARGs, virulence factors, and active pathways among a paediatric asthma cohort relative to a healthy control. Methods: Overall, 29 children with asthma and 20 control subjects were enrolled, and 3 swabs (2 nasal and 1 oropharyngeal) were obtained from each participant. Genomic DNA was extracted and sent for shotgun sequencing, after which bioinformatic analysis was conducted to remove human reads and analyse the microbiota pattern in the samples. The abundance of antibiotic resistance genes was evaluated along with the distribution of virulence genetic markers. Functional investigation of the most prevalent metabolic pathways was also performed. Results: Upper airway microbiome functional capacity varied by anatomical location, with oropharyngeal communities exhibiting greater metabolic breadth than nasal communities, suggesting the sample source to be the dominant factor shaping gene content, pathway profiles, and community structure. Asthma-related functional differences were modest, and no biological pathways remained significant following false discovery rate correction. Enrichment of antimicrobial resistance genes was observed, particularly those conferring resistance to β-lactams, macrolides, and tetracyclines. Conclusions: Different anatomical niches exhibit differential activities, and further exploration in this direction could aid in the development of diagnostic and therapeutic biomarkers for asthma.