Wallis, Amy, Ball, Michelle, Butt, Henry et al. · Journal of translational medicine · 2018 · DOI
This study tested whether treating an overgrowth of Streptococcus bacteria in the gut could help ME/CFS patients, particularly those with brain fog and sleep problems. Forty-four patients received alternating weeks of an antibiotic and a probiotic for 4 weeks. The treatment reduced the problematic bacteria and improved several symptoms including sleep quality, attention, and memory, though it did not significantly affect fatigue or mood.
This study provides preliminary mechanistic evidence that gut dysbiosis—specifically Streptococcus overgrowth—may contribute to specific ME/CFS neurological symptoms, offering a potential therapeutic target beyond symptom management. The findings could guide more personalized treatment approaches and motivate larger controlled trials to clarify whether microbiota-targeted interventions benefit ME/CFS patients.
This open-label design cannot establish causation or rule out placebo effects, since patients knew they were receiving treatment. The study does not prove that Streptococcus is the primary cause of ME/CFS symptoms, and the lack of change in fatigue and mood suggests the mechanism is incomplete. Sex differences in response require confirmation in larger samples and do not yet explain why microbiota shifts associate differently with outcomes in males versus females.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Wallis, Amy, Ball, Michelle, Butt, Henry, Lewis, Donald P, McKechnie, Sandra, Paull, Phillip, et al. (2018). Open-label pilot for treatment targeting gut dysbiosis in myalgic encephalomyelitis/chronic fatigue syndrome: neuropsychological symptoms and sex comparisons.. Journal of translational medicine. https://doi.org/10.1186/s12967-018-1392-z
BibTeX
@article{mecfsatlas-wallis-2018-open-label,
author = {Wallis, Amy and Ball, Michelle and Butt, Henry and Lewis, Donald P and McKechnie, Sandra and Paull, Phillip and Jaa-Kwee, Amber and Bruck, Dorothy},
title = {Open-label pilot for treatment targeting gut dysbiosis in myalgic encephalomyelitis/chronic fatigue syndrome: neuropsychological symptoms and sex comparisons.},
journal = {Journal of translational medicine},
year = {2018},
doi = {10.1186/s12967-018-1392-z},
note = {PubMed: 29409505},
url = {https://www.mecfsatlas.com/evidence/wallis-2018-open-label},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-25. https://www.mecfsatlas.com/evidence/wallis-2018-open-label
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