Fecal metagenomic profiles in subgroups of patients with myalgic encephalomyelitis/chronic fatigue syndrome.
Nagy-Szakal, Dorottya, Williams, Brent L, Mishra, Nischay et al. · Microbiome · 2017 · DOI
Quick Summary
This study looked at the bacteria living in the gut of 50 ME/CFS patients and 50 healthy people to see if differences in gut bacteria might explain some ME/CFS symptoms. The researchers found that ME/CFS patients have unusual patterns of gut bacteria, and these patterns are different depending on whether the patient also has irritable bowel syndrome (IBS). Importantly, the type and balance of gut bacteria were linked to how severe patients' fatigue, pain, and other symptoms were.
Why It Matters
This research identifies measurable differences in gut bacteria that could help diagnose ME/CFS and distinguish patient subgroups, potentially leading to personalized treatment approaches. Understanding how gut dysbiosis relates to symptom severity may open new therapeutic avenues, such as targeted probiotics or dietary interventions. The finding that IBS masks some ME/CFS-specific bacterial changes suggests future studies should account for this co-morbidity to better understand the disease.
Observed Findings
ME/CFS patients have distinct fecal bacterial profiles compared to healthy controls, with composition varying based on IBS co-morbidity status.
Patients with ME/CFS and IBS show increased unclassified Alistipes and decreased Faecalibacterium compared to controls.
Patients with ME/CFS without IBS show increased unclassified Bacteroides and decreased Bacteroides vulgatus compared to controls.
Certain bacterial metabolic pathways (unsaturated fatty acid biosynthesis deficiency and atrazine degradation elevation) are altered in ME/CFS independent of IBS status.
Severity of pain, fatigue, and reduced motivation correlated with specific bacterial taxa and metabolic pathway abundances.
Inferred Conclusions
IBS co-morbidity is a major modifier of dysbiotic patterns in ME/CFS, potentially obscuring disease-specific bacterial signatures when patient subgroups are not distinguished.
ME/CFS-associated dysbiosis is not a single phenotype but rather comprises distinct bacterial and metabolic signatures that may require subgroup-specific diagnostic and therapeutic approaches.
Dysbiotic metabolic disturbances independent of IBS status suggest core ME/CFS-associated microbiome dysfunction beyond secondary effects of co-morbid conditions.
Remaining Questions
Does dysbiosis cause ME/CFS symptoms, or are bacterial changes a consequence of the disease and its associated physiological changes?
What This Study Does Not Prove
This study shows correlation between gut bacteria and ME/CFS but does not prove that dysbiosis causes ME/CFS symptoms—bacteria changes could be a consequence rather than a cause. The cross-sectional design captures only a single time point, so it cannot establish whether bacterial changes precede symptom onset or persist over time. The study also does not demonstrate that treating dysbiosis would improve ME/CFS symptoms.
Would restoring dysbiotic bacterial composition or metabolic function improve ME/CFS symptoms, and which interventions would be most effective for each patient subgroup?
How do these dysbiotic patterns change over time, and are certain bacterial signatures predictive of disease progression or treatment response?
What mechanisms link specific bacterial taxa and metabolic pathways to individual symptoms like fatigue, pain, and cognitive dysfunction?