Research Tracker›Biomarker Atlas›Long COVID›Faecalibacterium prausnitzii

Faecalibacterium prausnitzii in Long COVID

Faecalibacterium prausnitzii, also described as Commensal bacterium, is a microbiome marker reported as reduced in Long COVID (PASC, Post-Acute Sequelae of COVID-19) when patients are compared with healthy controls. Clinically, it has been associated with butyrate production deficit. The evidence summarised here comes from Baalbaki et al. 2025 and reflects averages across cohorts rather than any single patient's result.

↓ ReducedMicrobiome

Summary

Direction in Long COVID↓ Reduced — lower than in the comparison group
CategoryMicrobiome
Also described asCommensal bacterium
Compared againstHC (healthy controls)
Associated symptomsButyrate production deficit
Test typeBlood test (serum / plasma / whole blood)
SourceBaalbaki et al. 2025 — doi:10.1111/all.16526
Condition atlasLong COVID Biomarker Atlas

Related Microbiome markers in Long COVID

Full list: Long COVID Biomarker Atlas.

Frequently asked questions

Is Faecalibacterium prausnitzii high or low in Long COVID?

Reduced. Studies summarised in the OSMF atlas report lower Faecalibacterium prausnitzii in Long COVID than in healthy controls. Source: Baalbaki et al. 2025.

What symptoms is Faecalibacterium prausnitzii associated with in Long COVID?

The cited literature associates this marker with Butyrate production deficit. These are population-level associations and do not mean the marker causes the symptoms.

Which test measures Faecalibacterium prausnitzii?

It is measured as a blood test (serum / plasma / whole blood). Many of the cited studies used research-grade assays, so clinical availability may vary.

Is one abnormal Faecalibacterium prausnitzii result diagnostic of Long COVID?

No. No single biomarker is diagnostic of Long COVID. Faecalibacterium prausnitzii findings come from group comparisons, overlap considerably between patients and controls, and vary with study design, timing and comparison group. A result should be interpreted by a clinician alongside symptoms, history and other tests.

Cite this page

Open Source Medicine Foundation. (2026). Faecalibacterium prausnitzii in Long COVID: direction, evidence and what it means. OSMF Research Tracker. Retrieved October 7, 2026, from https://research.opensourcemed.info/biomarkers/long-covid/faecalibacterium-prausnitzii.html
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Last reviewed: 2026-06-29 · Page generated from long-covid.json · Browse: Long COVID atlas · Biomarker Index · All marker pages

Disclaimer: This page is an educational synthesis of published, peer-reviewed research and is not medical advice. Biomarker findings vary across studies with case definitions, comparison groups, timing and assay methods. Direction of change reflects the predominant finding in the cited source and does not establish a diagnostic threshold. Discuss any test result with a qualified clinician.