Fig. 1

Lung microbiota is altered in patients with VAP (A–C) compared with (N = 37) patients without (N = 53) but showed no difference in compositional richness (D). Principal coordinate analysis showed significant differences between the microbial composition of patients with and without VAP (E), the X-axis indicating principal coordinate (PCoA) 1 and the Y-axis PCoA 2 on Bray–Curtis dissimilarity measure of 16S microbiome data. Despite significant dysbiosis in patients with VAP, compositional variance could not reliably diagnose VAP (F) when comparing evenness, Simpson’s diversity index and Shannon diversity index as predictor variables and in BALF culture as the outcome for all patients (N = 90). Individual patient bar plots split by VAP diagnosis compared with BALF culture-dependent result (G). The relative abundance of the top 10 genera along with all pathogens identified by semi-quantitative culture for each sample is shown. “Other” genus combines remaining genera in each sample