Microbiome Makeover: Out With the Bad, In With the Good?

Digestive Disease Week (DDW) 2018

William F. Balistreri, MD


August 08, 2018

In This Article

The Value of Microbiota Manipulation

Because an altered intestinal microbiota dysbiosis has been implicated in the generation of symptoms in patients with IBS, replacement or restoration of the microflora via fecal microbiota transplantation (FMT) has been hypothesized to have a positive effect in affected patients. Studies have addressed this issue. My take: It depends on the patient and on the specific predominant symptom.

Intestinal microbiota dysbiosis is thought to play an important role in the pathophysiology of severe abdominal bloating in patients with IBS. In a double-blind, placebo-controlled, single-center clinical trial,[4] patients with refractory IBS symptoms and predominant abdominal bloating, without constipation, were randomly assigned to transplantation with fresh donor stool or with placebo (patient's own frozen stool) via nasojejunal tube. After 12 weeks, 49% of patients in the active treatment group versus 29% in the placebo group reported adequate relief of general IBS symptoms and abdominal bloating. Statistically significant reductions in discomfort (mean reduction of 19%), number of stools (-13%), urgency (-38%), abdominal pain (-26%), and flatulence (-10%) were noted in the FMT recipients. IBS-related quality-of-life measures improved in the FMT recipients (+16%).

Among responders contacted after 1 year, 27% reported long-lasting effects. Preliminary microbiota analysis of stool samples showed that FMT induced significant changes in microbial composition, and that these appeared to influence therapeutic success.

Aroniadis and colleagues[5] investigated the safety and efficacy of FMT in a randomized, placebo-controlled trial conducted in patients with moderate to severe IBS with predominant diarrhea. Participants were randomized to receive three consecutive days of 25 capsules of FMT (50 g of stool from a healthy donor) or placebo. All participants crossed over into the alternate arm at 12 weeks. Patients in each group had significant improvement in IBS-SSS, quality of life, and Bristol Stool Scale scores between baseline and 12 weeks. However, these clinical response rates did not differ significantly between FMT and placebo recipients.

Subgroup analysis showed a greater improvement after FMT in IBS-SSS scores in subjects with a reported history of postinfectious IBS. Adverse events did not differ significantly between groups. Preliminary analyses of the microbiome at baseline distinguished FMT responders from nonresponders by quantity of bacterial species, including Bacteroides eggerthii, Bacteroides uniformis, Eubacterium dolichum, Bacteroides acidifaciens, and Veillonella dispar.

Halkjær and colleagues[6] performed a randomized, double-blind placebo-controlled trial to investigate whether FMT altered gut microbiota and improved clinical outcome in patients with IBS with predominant diarrhea and pain. Patients were randomized to receive FMT capsules or placebo for 12 days and were followed for 6 months. The investigators noted an increase in biodiversity in patients receiving FMT; the resultant biodiversity resembled that of the donors. In placebo recipients, the biodiversity remained indistinguishable from baseline. No significant difference in improvement in IBS-SSS score was observed 3 months after treatment; patients in the placebo group actually experienced greater symptom relief compared with the FMT group.

In this study, altering the gut microbiota was insufficient to bring about clinical improvement in patients with global symptoms of IBS. The investigators stated that a different study design and larger studies (as well as studies of monosymptomatic patient groups) may be required to fully understand the role of FMT in patients with IBS.


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