Biology & Ecology
Biology
Gram Statusgram-negative
Oxygen Toleranceobligate anaerobe
Morphologybacillus (rod)
Ecology
Primary Nichesgut
Reservoirhuman
Clinical Profile
Pathobiont
yes
no
context dependent
unknown
Clinical Rolescommensal
Typical Specimenstool
Risk Contextsmelanoma patients receiving immune checkpoint inhibitor therapy (ICB)
Clinical Associations:
E2
E3 — Strong human clinical evidence
E2 — Moderate human evidence
E1 — Limited / preliminary
Parabacteroides merdae was among 8 commensal species significantly enriched in pre-treatment stool of metastatic melanoma anti-PD-1 responders (n=16) versus non-responders (n=26) by integrated 16S rRNA, shotgun metagenomic, and qPCR analysis (P<0.05, permutation test); it was part of a 10-species composite qPCR score significantly higher in responders (P=0.004).
PMID:
29302014
Last reviewed: 2026-04-03
Evidence Timeline
Related Taxa
Shared Niche = same body site
Shared Risk = same vulnerable population
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