Fig. 1

Characteristics of the gut microbiota in ARDS/CAP patients. a chao1 index. b observed species. c Shannon index. d Simpson index. e The relative abundances of the gut microbiota at the phylum level. f The ratio of (Bacteroidota + Proteobacteria)/Firmicutes. g PCoA based on the gut microbiota at the genus level. h Volcano plot analysis identifying key gut microbes that significantly altered between ARDS/CAP patients and normal control (CTRL) subjects. i Heatmap showing the key gut microbes between ARDS/CAP patients and CTRL subjects. The statistic difference of various indicators between two groups was evaluated by two-tailed unpaired student’s T test and a statistically significant was defined when p < 0.05. Significant level: *p < 0.05; ***p < 0.001