"Impact of preoperative gastrointestinal microbiota on weight-loss after Roux-en-Y gastric bypass: a pilot study ".

Background information: In recent years the composition of gut microbiome has been linked to development of several diseases. The goal of the following study was to establish whether it is connected to the outcome of bariatric surgery. The objective was to analyze the oral and gut microbiota of patients suffering from morbid obesity who underwent laparoscopic Roux-en-Y gastric bypass (LRYGB).

Methods: The following is a prospective cohort study that was conducted between November 2018 and June 2019. Participants underwent LRYGB surgery. Patients then were assigned to group 1- success (surgical participants who achieved a percentage of excess weight loss [%EWL] >50%), group 2 (surgical participants who achieved a %EWL <50%). The follow up to establish the %EWL was conducted 6 months after the surgery. Before surgery, oral swabs were obtained, and stool samples were provided. The endpoint was the composition of the gut microbiota.

Results: Group 1 consisted of 4 participants; group 2 consisted of 2 participants. No participants were lost to follow-up during the study. Participants in group 1 had an oral microbiota that was enriched in the family Tissirelia of the phylum firmicutes. Gut microbiome of patients in group 1 was enriched with with Tanerella of the Bacteroidetes phylum. Group 2 did not present enriched microbiota by any of the analyzed organisms. Gut microbiota was enriched by deltaprotebacteria class (phylum Proteobacteria), bernesiellaceae of the phylum Bacteroidetes.