Loop ileostomy-mediated fecal stream diversion is associated with microbial dysbiosis

Abstract

Loop ileostomy is an effective procedure to protect downstream intestinal anastomoses. Ileostomy reversal surgery is often performed within 12 months of formation but is associated with substantial morbidity due to severe post-surgical complications. Distal ileum is deprived of enteral nutrition and rendered inactive, often becoming atrophied and fibrotic. This study aimed to investigate the microbial and morphological changes that occur in the defunctioned ileum following loop ileostomy-mediated fecal stream diversion. Functional and defunctioned ileal resection tissue was obtained at the time of loop-ileostomy closure. Intrapatient comparisons, including histological assessment of morphology and epithelial cell proliferation, were performed on paired samples using the functional limb as control. Mucosal-associated microflora was quantified via determination of 16S rRNA gene copy number using qPCR analysis. DGGE with Sanger sequencing and qPCR methods profiled microflora to genus and phylum level, respectively. Reduced villous height and proliferation confirmed atrophy of the defunctioned ileum. DGGE analysis revealed that the microflora within defunctioned ileum is less diverse and convergence between defunctioned microbiota profiles was observed. Candidate Genera, notably Clostridia and Streptococcus, reduced in relative terms in defunctioned ileum. We conclude that Ileostomy-associated nutrient deprivation results in dysbiosis and impaired intestinal renewal in the defunctioned ileum. Altered host-microbial interactions at the mucosal surface likely contribute to the deterioration in homeostasis and thus may underpin numerous postoperative complications. Strategies to sustain the microflora before reanastomosis should be investigated.

Impact of temporary ileostomy on long‐term quality of life and bowel function: a systematic review and meta‐analysis

“…This study has shown that an ileostomy is associated with an increased risk of major LARS. While it was not possible to prove a causal relationship, it is plausible due to the potential impact of ileostomy on colonic inflammation, nutrition and atrophy . Information regarding functional outcome and quality of life therefore needs to be considered and conveyed to patients along with other factors influencing the risk/benefit ratio in stoma formation.…”

“…Despite these findings, there is a paucity of literature from well‐designed clinical trials comparing functional and quality of life outcomes for patients with and without an ileostomy. If diversion of luminal content contributes to inflammation and atrophy, it is plausible that the duration of this disruption may play a role in the ultimate functional outcome.…”

Effects of probiotics on bowel function restoration following ileostomy closure in rectal cancer patients: a randomized controlled trial

“…Recently, several studies have shown that reshaped gastrointestinal (GI) environments post-surgery affect microbiota in the GI tract, altering the composition of the microbiome [9,10]. Diversion colitis, also known as disuse colitis, is a well-known postoperative condition associated with dysbiosis and is described as an imbalance between potentially beneficial and pathogenic bacteria residing in the GI tract [11].…”

Preoperative bowel stimulation prior to ileostomy closure to restore bowel function more quickly and improve postoperative outcomes: a systematic review

“…In patients who undergo delayed ileostomy closure, it is possible that preoperative stimulation of the defunctioned colon may be beneficial. The rationale for this is that it may reverse the microbial dysbiosis and villous atrophy observed in defunctioned bowel , as these factors impair absorptive capacity . Alteration in the microbiome of diverted bowel has been well‐studied with Clostridium difficile infection, a recognized complication of ileostomy closure .…”