ABSTRACT
Objective:To analyze the differences and similarities of pre-treatment and post-treatment lung microbiome of acute respiratory distress syndrome (ARDS) and find out the change rules of the lung microbiome in the progression of ARDS according to different prognosis.Methods:A retrospective study was conducted. Patients with ARDS caused by severe pneumonia admitted to intensive care unit (ICU) of Jiangmen Central Hospital from February 2019 to January 2020 were enrolled as the study subjects. The patients were divided into pre-treatment (ARDS-preT) group (24 cases), post-treatment survival (ARDS-poT-Survival) group (17 cases), and post-treatment death (ARDS-poT-Dead) group (7 cases). ICU patients with mild pulmonary infection and non-ARDS admitted to ICU during the same period were enrolled as control group (25 cases). The similarities and differences of lung microbiome in four groups were analyzed and compared, and the possible pathogenic bacteria (potential risk factors for death) and probiotics (potential survival and protective factors) related to death caused by ARDS were screened.Results:In terms of pathogenic microorganisms, the positive rates of Escherichia coli and Candida albicans in the ARDS-poT-Dead group were significantly higher than those in the ARDS-poT-Survival group [57.1% (4/7) vs. 5.9% (1/17) and 57.1% (4/7) vs. 0% (0/7), both P < 0.05]. In the screening of background bacteria, the decrease of bacteria in the ARDS-preT group compared with the ARDS-poT-Survival group, the ARDS-poT-Dead group compared with the ARDS-poT-Survival group, the ARDS-poT-Dead group compared with the control group, the reduced bacteria might be pulmonary probiotics (potential protective factor for ARDS). The screening result was Hydrobacter [ARDS-preT group vs. ARDS-poT-Survival group: 62.5% (15/24) vs. 94.1% (16/17); ARDS-poT-Dead group vs. ARDS-poT-Survival group: 14.3% (1/7) vs. 94.1% (16/17); ARDS-poT-Dead vs. control: 14.3% (1/7) vs. 96.0% (24/25), all P < 0.05]. In the screening of background bacteria, the increase of bacteria in the ARDS-poT-Dead group compared with the ARDS-preT group, the ARDS-poT-Dead group compared with the ARDS-poT-Survival group, the ARDS-poT-Dead group compared with the control group, and the increased bacteria might be potential pulmonary pathogen (potential risk factor for death of ARDS), which belonged to Enterobacteria: Edwardsiella, Enterobacteriaceae, Escherichia, Klebsiella, Kluyvera, Lelliottia, Pantoea, Raoultella. Conclusions:The results revealed the increase of Escherichia coli or Candida albicans in pulmonary pathogenic microorganisms, or the increase of Enterobacteria in background bacteria may be the risk factors for the death of ARDS. Additionally, background bacteria Hydrobacter probably is a protective factor for the survival of ARDS. Whether it can be used as a novel treatment for ARDS is worth further investigation.