Microbiome linked to IBD surgery outcomes

Dr Amy Hamilton

Differences in the luminal microbiota may predict the risk of Crohn’s disease (CD) recurrence following surgery, according to Australian-led research.

The cohort was 130 patients from the multicentre Post-Operative Crohn’s Endoscopic Recurrence (POCER) study who underwent a bowel resection for CD indications such as perforation or obstruction.

Most patients (82%) were stratified as high risk for recurrence and had a follow-up colonoscopy at six months, while all patients had a colonoscopy to assess endoscopic disease recurrence at 18 months, according to researchers led by Dr Amy Hamilton of the department of gastroenterology, St Vincent’s Hospital, Melbourne.

A total of 288 faecal samples for microbiome analysis were obtained at various time points from baseline to 18 months.

The study found there were no differences in baseline alpha-diversity between patients in remission and those with recurrence at the six-month colonoscopy.

However, alpha diversity at six months in patients who subsequently developed endoscopic recurrence at 18 months was lower than in those with subsequent remission.

Alpha diversity at 18 months did not differ between patients with recurrence or those in remission.

In terms of beta diversity, the study found Enterobacteriaceae were enriched in samples from the early post-operative period and associated with an increased risk of recurrence at 18 months.

Corynebacteriaceae and Aerococcaceae were significantly increased in patients with disease recurrence at 18 months while Lachnospiraceae was associated with a reduced risk of recurrence at 18 months.

The investigators said the study highlights structural community changes in the luminal microbiota after surgery for Crohn’s disease and its association with disease recurrence.

“The ecology of butyrate-producing genera is altered by surgery; obligate anaerobes are depleted in the immediate post-operative period by local environmental changes (exposure to oxygen, altered pH, and mucosal changes in active inflammation) combined with the effect of antibiotics.”

They said their findings on Enterobacteriaceae expansion and its association with intestinal inflammation and disease recurrence, and the association between Lachnospiraceae dominance and remission, are consistent with other data.

“This information now needs to be considered in relation to the mucosal changes after surgery, to provide an integrated overview about the microbiota in relation to disease,” they concluded.

Senior investigator Professor Michael Kamm, from St Vincent’s Hospital and the University of Melbourne, told the limbic there was no doubt that organisms in the gut drive CD inflammation. 

And there were different ecosystems in the lining and in the lumen of the bowel that co-exist and were probably interrelated.

“When we resect the bowel because of a complication of CD, it’s an opportunity to look at those people in whom the disease comes back and the difference in their organisms compared to those where it doesn’t come back.”

Earlier work from the team has identified Proteus in mucosal biopsy samples appeared to be strongly associated with recurrence of disease after surgery.

Professor Kamm said there was clearly more work to be done. 

“The obvious thing to do is to see if we can target these organisms; see if they are critically important both in disease coming back after surgery but maybe even in CD in total.”

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