Fig. 4

Respiratory-gut microbiota association of CAP-enriched respiratory microbes. a PCoA plot illustrating the distinct variation in the gut microbiota composition between CAP patients and healthy controls. b Box plots for the 38 differentially abundant species between CAP patients and healthy controls. The central line indicates the median, and the lower and upper hinges indicate the first and third quartiles, respectively. c Differentially abundant species analysis across the respiratory and gut microbiomes between CAP patients and healthy controls. Each point represents a bacterial species, classified as respiratory only (purple), gut only (blue), or both sites (orange), representing two different patterns of microbial presence: site-specific and potential transmission between sites. d Phylogenetic tree of Streptococcus mitis via strain-level analysis with StrainPhlAn. Strain identities between closely related strains are labeled. Strains with potential respiratory-gut transmission within the same patient are shaded, with gut strains labeled in red font