In a recent post regarding Next-Generation Treatment for H pylori, the authors denigrated the term “empiric” treatment and said a more accurate term would be “hopeful” therapy. There are a lot of areas in our field in which hopeful therapy is a mainstay, especially in those with non-organic abdominal pain (eg. irritable bowel syndrome). Even with the benefit of a therapeutic ‘regression to the mean,’ treatment is often unsatisfactory.

Thus, it is a very positive sign that a recent article provides an indication of which patients are most likely to benefit from dietary manipulation:

K Vervier et al. Gut 2021;gutjnl-2021-325177. doi: 10.1136/gutjnl-2021-325177. Online ahead of print: Open Access: Two microbiota subtypes identified in irritable bowel syndrome with distinct responses to the low FODMAP diet

Methods: A prospective single centre case–control study recruited participants (n=56 pairs) from 2016 to 2019. The authors included adults (18–68 years of age) meeting the Rome IV criteria for diarrhoea-predominant or mixed type IBS (IBS-D and IBS-M, respectively) with respective household controls. 

Key findings:

• Baseline IBS cases pre-diet identified two distinct microbiota profiles, which we refer to as IBS^P (pathogenic-like) and IBS^H (health-like) subtypes.
• IBS^P microbiomes were enriched in Firmicutes and genes for amino acid and carbohydrate metabolism, but depleted in Bacteroidetes species.
• IBS^H microbiomes were similar to controls.
• On the low FODMAP diet, IBS^H and control microbiota were unaffected, but the IBS^P signature shifted towards a health-associated microbiome with an increase in Bacteroidetes (p=0.009), a decrease in Firmicutes species (p=0.004) and normalization of primary metabolic genes. The clinical response to the low FODMAP diet was greater in IBS^P subjects compared with IBS^H (p=0.02).
• 50% of IBS cases manifested a ‘pathogenic’ gut microbial signature. This shifted towards the healthy profile on the low FODMAP diet; and IBS^P cases showed an enhanced clinical responsiveness to the dietary therapy

My take: Currently, what is a “pathogenic” microbiome is unclear at least to me. However, changes in the microbiome do occur with dietary manipulation and are likely involved in response to treatment for IBS and other disorders.

Related blog posts:

• IBS Part 1 2017
• Irritable Bowel Treatments (part 2 2017)
• Mechanisms of irritable bowel syndrome | gutsandgrowth
• Irritable Bowel After Campylobacter Enteritis
• Psychological Treatments for IBS
• Balanced summary of probiotics & Microbiome effects on brain
• Don’t Skip this Article -Rome IV Summary | gutsandgrowth