BiotaMD · the living gut
Condition

Irritable bowel syndrome (IBS)

47 associated organisms · Highly heterogeneous, so findings are less consistent than in IBD. This is where the contested parasites show up most, with genuinely mixed evidence.

Organisms associated with Irritable bowel syndrome (IBS)
Bifidobacterium Beneficial Reduced in Irritable bowel syndrome (IBS)
Genus

Commonly lower in IBS and a frequent probiotic target, though effect sizes vary widely.

Moderate evidence source: curated sample
Methanobrevibacter smithii Commensal Elevated in Irritable bowel syndrome (IBS)
Archaeon

This methane-producing archaeon is enriched in constipation-predominant IBS and linked to slower transit.

Moderate evidence source: curated sample
Bifidobacterium catenulatum Reduced in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (2 cited studies).

Moderate evidence source: curated sample
Clostridium coccoides Reduced in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Ruminococcus productus Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Clostridium cocleatum Reduced in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Collinsella aerofaciens Reduced in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Coprococcus Beneficial Elevated in Irritable bowel syndrome (IBS)
Genus

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Acidobacteriaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Aeromonadaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Alteromonadaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Anaerovorax Reduced in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Bacillaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Bacteroidaceae Reduced in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Bacteroides Commensal Reduced in Irritable bowel syndrome (IBS)
Genus

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Bacteroides vulgatus Reduced in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Bacteroidetes Reduced in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Cellulomonadaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Clostridiaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Coxiellaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Desulfobacteraceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Desulfovibrionaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Dorea Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Enterobacteriaceae Opportunist Elevated in Irritable bowel syndrome (IBS)
Family

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Eubacteriaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Eubacterium Reduced in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Gammaproteobacteria Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Haemophilus Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Haemophilus parainfluenzae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Lachnospiraceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Nitrospiraceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Paenibacillaceae Reduced in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Pasteurellaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Peptostreptococcaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Polyangiaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Porphyromonadaceae Reduced in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Prevotellaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Promicromonosporaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Proteobacteria Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Ruminococcus Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Streptococcaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Syntrophobacteraceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Thiotrichaceae Elevated in Irritable bowel syndrome (IBS)
Taxon

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Veillonella Commensal Elevated in Irritable bowel syndrome (IBS)
Genus

Reported in HMDAD (1 cited study).

Moderate evidence source: curated sample
Dientamoeba fragilis Contested Mixed in Irritable bowel syndrome (IBS)
Protozoan (protist)

Sometimes implicated in IBS-like symptoms, but just as often found in healthy people — causation is unproven.

Preliminary studies conflict source: curated sample
Faecalibacterium prausnitzii Beneficial Mixed in Irritable bowel syndrome (IBS)
Species

Reported both reduced and unchanged depending on cohort and IBS subtype.

Disputed / mixed studies conflict source: curated sample
Blastocystis Contested Mixed in Irritable bowel syndrome (IBS)
Protozoan (protist)

The contested one: linked to IBS in some studies, yet associated with healthier, high-diversity guts in asymptomatic carriers.

Disputed / mixed studies conflict source: curated sample
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