CHANGES IN GUT MICROBIAL FLORA AFTER ROUX-EN-Y GASTRIC BYPASS AND SLEEVE GASTRECTOMY AND THEIR EFFECTS ON POST-OPERATIVE WEIGHT LOSS

Introduction Bariatric surgery affects gut microbial flora due to the anatomical and physiological changes it causes in the gastrointestinal tract. Understanding the interaction between the gut flora, type of bariatric surgery and weight loss may help improve bariatric surgery outcomes. This study was designed to compare the effects of Roux‐en‐Y Gastric Bypass (RYGB) and Sleeve Gastrectomy (SG) on two main phyla of the gut microbiota in humans and evaluate their potential effect on weight changes. Materials and Methods Thirty morbidly obese patients were divided into two groups and underwent laparoscopic SG or laparoscopic RYGB. The patients were evaluated for weight changes and fecal sampling was performed on them at baseline and six months after the surgery. A microbial flora count was carried out of the phyla Bacteroidetes and Firmicutes and Bacteroides Fragilis. Changes in the abundance of the flora and their correlation with weight loss were analyzed. Results After six months, the patients with a history of RYGB showed a decrease in stool Bacteroidetes, with a non‐significant reduction in the SG group. Firmicutes abundance was almost unchanged following SG and RYGB. There was no significant change in Bacteroides Fragilis abundance in either of the two groups, but a positive correlation was observed between Bacteroides Fragilis and weight loss after SG and RYGB. Conclusion Bariatric surgery can affect the gut microbiota. It can be concluded that these changes are dependent on many factors and may play a role in weight loss.