Biology & Ecology
Biology
Gram Statusgram-negative
Oxygen Tolerancefacultative anaerobe
Morphologybacillus (rod)
Key Traits
- encapsulated
- lactose fermenter
- motile (peritrichous flagella)
- mucoid colonies
- urease positive
Ecology
Primary Nichesgut, oral cavity
Reservoirenvironment, human
Transmission
- oral-gut
Clinical Profile
Pathobiont
yes
no
context dependent
unknown
Clinical Rolescoloniser; opportunistic pathogen
Typical Specimenbiopsy; stool
Bloom Triggers
dysbiosis ·
inflammation ·
periodontitis
Risk Contextsinflammatory bowel disease (IBD)
Clinical Associations:
E1
E3 — Strong human clinical evidence
E2 — Moderate human evidence
E1 — Limited / preliminary
Klebsiella aerogenes expands in the oral cavity during periodontitis, translocates to the gut, and triggers colitis via NLRP3/caspase-11 inflammasome activation and IL-1β production by intestinal macrophages in multiple mouse models (DSS colitis in SPF mice; germ-free Il10−/− and Rag1−/− gnotobiotic colonization models).
PMID:
32758418
E1
E3 — Strong human clinical evidence
E2 — Moderate human evidence
E1 — Limited / preliminary
Oral gavage of K. aerogenes (strain SK431) exacerbates DSS-induced colitis in SPF mice (worsened body weight loss, colon weight, histological scores); the colitogenic effect is fully reversed by IL-1 receptor antagonist anakinra, establishing a causal IL-1β-dependent mechanism for oral pathobiont-driven gut inflammation.
PMID:
32758418
D003092
Colitis
D000069196
Gastrointestinal Microbiome
D053583
Interleukin-1beta
D007709
Klebsiella
H01227
Inflammatory bowel disease
E1
E3 — Strong human clinical evidence
E2 — Moderate human evidence
E1 — Limited / preliminary
K. aerogenes is the most abundant species in the synthetic ligature-associated oral microbiome (sLOM) that drives colitis in germ-free Il10−/− and Rag1−/− mice; sLOM-colonized mice show significantly elevated fecal Lcn2, worsened colonic histological scores, and increased colonic Th17/Th1 T cells compared to sHOM controls (p<0.05 to p<0.0001 across outcomes).
PMID:
32758418
D003092
Colitis
D000069196
Gastrointestinal Microbiome
D007709
Klebsiella
H01227
Inflammatory bowel disease
E1
E3 — Strong human clinical evidence
E2 — Moderate human evidence
E1 — Limited / preliminary
Oral K. aerogenes and related Enterobacteriaceae prime RORγt+ Th17 effector memory T cells in cervical lymph nodes during periodontitis; these cells express gut-homing markers (α4β7, CCR9), migrate to the inflamed gut, and amplify colitis via antigen-specific expansion — an effect blocked by anakinra, suggesting IL-1β produced by ectopically colonized oral pathobionts further drives Th17 expansion.
PMID:
32758418
Last reviewed: 2026-04-02
Related Taxa
Shared Niche = same body site
Shared Risk = same vulnerable population
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