ObjectiveTo investigate the dynamic characteristics of microbiota in the respiratory and upper gastrointestinal tract in patients with acute respiratory distress syndrome (ARDS).

MethodsThe bronchoalveolar lavage fluid (BALF) and gastric juice (GJ) from 7 ARDS patients and BALF from 4 healthy volunteers were collected.The gene sequences of bacterial 16S rDNA in all samples were obtained via high-throughput sequencing, and its bio-informatics was analyzed to understand the composition, evolution and correlation of microbiota.

ResultsThe abundance of phylum Firmicutes (88.99%) significantly increased in the lung microbiota of ARDS patients compared with the healthy subjects (38.56%), and the difference of which was statistically significant (P < 0.05).The abundance of phylum Bacteroidetes in ARDS patients (7.69%) significantly decreased, and the difference of which between ARDS patients and healthy subjects (24.50%) was statistically significant (P < 0.05).The abundance of phylum Proteobacteria in ARDS patients (2.55%) significantly decreased compared with the control group (10.54%) (P < 0.05).With the intubation time prolonging, the relative abundance of phylum Proteobacteria in lung microbiota of ARDS patients increased from 2.55% to 74.65%, and the relative abundance of phylum Firmicutes decreased from 88.99% to 9.81%.The change of microbiota of upper gastrointestinal tract of ARDS patients was found during intubation, which was not statistically significant (P>0.05), and the relative abundance of phylum Acinetobacter significantly increased in the genus level (0.53% vs 53.70%, P < 0.05).

ConclusionsThe microbiota diversity in respiratory tract changes, and has similarity with that of the upper gastrointestinal tract in patients with ARDS.The microbiota of the respiratory tract may involve in the onset and progress of ARDS, which can serve as a possible biomarker in the diagnosis and prognosis of ARDS.