Gut Microbiota Imbalance Can Be Associated with Non-malabsorptive Small Bowel Shortening Regardless of Blind Loop

Some traditional bariatric surgery procedures may lead to functional gut shortening, which may unsettle the fine-tuned gastrointestinal physiology and affect gut microbiota balance.

Evaluate the gut microbiota behavior in rat models facing gut shortening due to intestinal bypass.

Wistar rats (n = 17) were randomly distributed in three groups: (1) sham group (n = 5); (2) blind loop group (n = 6); and (3) resection group (n = 6). Intestinal samples and feces were analyzed to measure bacterial concentrations (small intestinal bacterial overgrowth-SIBO) 12 weeks after the experimental procedures. Bacterial translocation (BT) was investigated in the mesenteric lymph node (MLN), liver, spleen, and lung of the animals. In addition, inflammatory aspects were investigated in their liver and small bowel through histological analysis.

Regardless of blind loop, gut shortening groups recorded similar high level of bacterial concentrations in intestine compartments, greater than that of the sham group (p ≤ 0.05). BT was only observed in the MLN of gut shortening models, with higher percentage in the blind loop group (p ≤ 0.05). The gut and liver histopathological analysis showed similar low-grade chronic inflammation in both gut shortening groups, likely associated with SIBO/BT events.

Sustained SIBO/BT was associated with proximal gut shortening in half regardless of blind loop, whereas the GI tract's ability to restore gut microbiota balance after a surgical challenge on the small bowel appears to be linked to the functional remaining gut.