Gut microbiota differs a decade after bariatric surgery relative to a nonsurgical comparison group.

Background: Few studies have assessed differences in the gut microbiota composition after bariatric surgery in the long term or whether differences are correlated with remission of type 2 diabetes.

Objectives: This observational study assessed differences in the gut microbiota between individuals at up to 13 years after surgery and a comparison group of individuals with severe obesity. The relationship between type 2 diabetes remission and the gut microbiota was also assessed.

Setting: University.

Methods: Stool samples were collected from individuals completing bariatric surgery (surgery group; n = 16) and individuals with severe obesity that did not receive surgery (nonsurgery group; n = 19) as part of the 12-year follow-up in the Utah Obesity Study. Metabolic health data were collected at baseline and the follow-up examination. The gut microbiota was quantified by sequencing the V4 region of the 16 S rRNA gene. Significant differences in microbiota composition with surgery and other covariates were determined by Unifrac distance analysis and permutational multivariate analysis of variance. Significant differences in the relative abundance of individual bacterial taxa were assessed using analysis of composition of microbiomes software.

Results: The surgery group had higher relative abundances of Verrucomicrobiaceae (5.7 ± 1.3% versus 1.1 ± .3%) and Streptococcaceae (6.3 ± 1.0% versus 3.2 ± .8%), but lower relative abundances of Bacteroidaceae (8.8 ± 1.8% versus 18.6 ± 2.3%) 10.6 years after surgery. In a small subset of 8 individuals, a higher relative abundance of Akkermansia muciniphila was correlated with type 2 diabetes remission.

Conclusions: Differences in the gut microbiota are evident a decade after bariatric surgery compared with individuals with severe obesity that did not undergo surgery. The observed long-term differences are consistent with previous findings.