Functional dysbiosis within the gut microbiota of patients with constipated-irritable bowel syndrome Original paper
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Irritable Bowel Syndrome (IBS)
Irritable Bowel Syndrome (IBS)
Irritable Bowel Syndrome (IBS) is a common gastrointestinal disorder characterized by symptoms such as abdominal pain, bloating, and altered bowel habits. Recent research has focused on the gut microbiota's role in IBS, aiming to identify specific microbial signatures associated with the condition.
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Kimberly Eyer
Kimberly Eyer, a Registered Nurse with 30 years of nursing experience across diverse settings, including Home Health, ICU, Operating Room Nursing, and Research. Her roles have encompassed Operating Room Nurse, RN First Assistant, and Acting Director of a Same Day Surgery Center. Her specialty areas include Adult Cardiac Surgery, Congenital Cardiac Surgery, Vascular Surgery, and Neurosurgery.
Microbiome Signatures identifies and validates condition-specific microbiome shifts and interventions to accelerate clinical translation. Our multidisciplinary team supports clinicians, researchers, and innovators in turning microbiome science into actionable medicine.
Karen Pendergrass
Location
France
Sample Site
Feces
Species
Homo sapiens
What was studied?
This study investigated the functional dysbiosis in the gut microbiota of women diagnosed with constipated-irritable bowel syndrome (C-IBS) compared to healthy controls. Unlike previous studies that focused predominantly on phylogenetic composition, this research employed a function-based approach to analyze metabolic capabilities and the presence of specific functional microbial groups. The primary objective was to identify shifts in microbial populations linked to fermentation processes, short-chain fatty acid (SCFA) production, and hydrogen metabolism that may contribute to the pathophysiology of C-IBS.
Who was studied?
The study included 14 women diagnosed with C-IBS according to Rome II criteria and 12 sex-matched healthy controls. All participants were assessed for gastrointestinal symptoms and underwent fecal sampling to analyze microbial populations and fermentation capabilities. None of the participants had taken antibiotics, probiotics, or experienced gastrointestinal infections for at least two months prior to sampling to minimize confounding microbial shifts.
What were the most important findings?
The study revealed a distinct microbial dysbiosis in the gut microbiota of C-IBS patients characterized by significant shifts in fermentation pathways and hydrogen metabolism. The abundance of beneficial lactate-producing bacteria such as Bifidobacterium and Lactobacillus was markedly reduced in C-IBS patients. In contrast, sulfate-reducing bacteria (SRB) populations were elevated by 100-fold compared to healthy controls. This shift was associated with enhanced hydrogen sulfide (H2S) production, a gas implicated in gut motility disturbance and visceral hypersensitivity. Additionally, methanogenic archaea and reductive acetogens, crucial for hydrogen consumption, were significantly lower in C-IBS patients. The decrease in butyrate-producing bacteria like the Roseburia–E. rectale group further disrupted SCFA profiles, potentially impairing anti-inflammatory and gut barrier functions. In vitro starch fermentation assays demonstrated that C-IBS microbiota produced significantly more hydrogen and sulfides, but less butyrate compared to controls. This altered fermentative output underscores the role of functional dysbiosis in generating gastrointestinal symptoms characteristic of C-IBS, such as bloating, constipation, and abdominal pain.
| Parameter | Findings in C-IBS Patients |
|---|---|
| Microbial Diversity | Reduced abundance of lactate-producing Bifidobacterium and Lactobacillus |
| Sulfate-Reducing Bacteria (SRB) | 100-fold increase compared to healthy controls |
| Hydrogen Metabolism | Decreased methanogens and reductive acetogens, increased hydrogen production |
| Butyrate Production | Lower production due to reduced Roseburia–E. rectale populations |
| Short-Chain Fatty Acid (SCFA) Profile | Less butyrate, more hydrogen sulfide (H2S) |
| In Vitro Fermentation | C-IBS microbiota produced more hydrogen and sulfides, less butyrate |
| Pathophysiological Implications | Linked to bloating, constipation, and abdominal pain through H2S toxicity |
What are the greatest implications of this study?
This study underscores the importance of functional dysbiosis in the pathogenesis of C-IBS. The enhanced presence of sulfate-reducing bacteria and the resulting increase in hydrogen sulfide production point to a mechanistic link between microbial metabolism and the gastrointestinal symptoms of C-IBS. These findings suggest that targeting SRB populations and restoring lactate- and butyrate-producing bacteria may offer therapeutic benefits in mitigating symptom severity. Furthermore, this research supports the need for microbiome-targeted interventions that focus not only on microbial composition but also on metabolic functionality to effectively manage C-IBS.
Irritable Bowel Syndrome (IBS)
Irritable Bowel Syndrome (IBS) is a common gastrointestinal disorder characterized by symptoms such as abdominal pain, bloating, and altered bowel habits. Recent research has focused on the gut microbiota's role in IBS, aiming to identify specific microbial signatures associated with the condition.