Compliance with ethical standards: the study was approved by the Ethics Committee of the Federal Research and Clinical Center of Intensive Care Medicine and Rehabilitology (Protocol № 2/19/2 dated June 20, 2019). Informed consent was obtained from all study participants or their legal representatives.

Author contribution: Chernevskaya EA, Meglei AYu — taxonomic microbiota profiling, serum biomarker tests, data analysis, manuscript preparation; Beloborodova NV — study design, final version of the manuscript; Buyakova IV, Kovaleva NYu, Gorshkov KM — patient recruitment and treatment, clinical data collection; ZakharchenkoVE — sample collection, final version of the manuscript. All authors read and approved the final version of the manuscript.