The effects of bariatric surgery procedures on the gut microbiota, features of genetically mediated predisposition to obesity, forecasting algorithms for surgical treatment outcomes. Literature review

Obesity is one of the major challenges facing modern medicine in the 21st century. Medically complicated obesity cases lead to a significant deterioration in quality of life and are associated with excess morbidity and increased mortality. According to the WHO, more than 24 % of the world's population over 18 years of age is overweight. About 3.9 million people of working age died in 2018 due to obesity and its complications. Today, bariatric surgery is the most effective in treating obesity, as it allows achieving optimal metabolic outcomes. After bariatric surgery, the desired effect can be produced by the response of the intestinal microbiome to postoperative anatomical and physiological changes in the gastrointestinal tract. The aim of this study was to conduct a comprehensive literature review and evaluate the effects of bariatric surgery on the human intestinal microbiome. The literature review revealed a stable correlation between quantitative and qualitative characteristics of the intestinal microbiota and bariatric surgery, regardless of the type of a bariatric surgical operation. Roux‑en‑Y Gastric Bypass, Mini‑Gastric Bypass and Sleeve Gastrectomy are the most commonly used bariatric operations in the world. The outcomes of these procedures show a sharp change in the proportion of different microbial phyla, including Firmicutes, Bacterioides and Escherichia, as well as changes in the gene expression parameters of these groups at different time periods after surgery. An increasing number of the reported bariatric interventions worldwide necessitates the study of pathophysiological mechanisms of intermicrobial relationships, which can contribute to better outcomes of surgical treatment of obesity and the development of algorithms for predicting them.