Figure 1.

Lung microbiota are altered in patients with acute respiratory distress syndrome (ARDS). (A and B) Compared with patients without ARDS, patients with ARDS had increased lung bacterial burden (A) but no difference in community diversity (B). (C and D) Principal component analysis of bacterial communities (C) revealed that the community composition of lung bacteria was distinct in specimens from patients with ARDS (C), driven by members of the Pasteurellaceae and Enterobacteriaceae families (D). (E and F) Rank abundance analysis (E) identified taxa enriched in ARDS specimens (e.g., Enterobacteriaceae), and random forest analysis (F) confirmed that the Enterobacteriaceae family was the most discriminating taxonomic group between ARDS and non-ARDS specimens. Hypothesis testing was performed using the (A) Mann-Whitney U test, (B) Student’s t test, and (C and E) mvabund. Data in A and B are medians and interquartile ranges. *P ≤ 0.05 and **P = 0.002. OTUs = operational taxonomic units; PC = principal component; rRNA = ribosomal RNA.