Fig. 1

Distribution and diversity of microbial species in different respiratory tract sites. A) The relative abundance of microbial species in the nose, nasopharynx, and lungs. Each color represents a different species, with the key below indicating the specific organisms. B) The principal coordinate analysis (PCoA) based on weighted UniFrac distances, comparing the microbial communities from the nose (orange), nasopharynx (blue), and lungs (green). C) The beta-diversity comparison across the three respiratory sites uses the complement of the ThetaYC index (1 - ThetaYC dissimilarity index), where individual data points represent distinct samples.​​ Higher values of this index denote higher similarity in the microbial communities across different respiratory sites. D) Boxplots of alpha-diversity metrics: Shannon index, Inverted Simpson index, and species richness across the sampled sites. These visualizations collectively suggest distinct microbial profiles and diversity within the upper and lower respiratory tracts, with nasal swabs demonstrating higher species richness and diversity indices, making them potential non-invasive diagnostic biomarkers for lower respiratory tract disorders