Rothia

Rothia is a genus of Gram-positive, facultatively anaerobic bacteria in the family Micrococcaceae (phylum Actinobacteria). The most commonly identified species in microbiome studies are Rothia dentocariosa and Rothia mucilaginosa, both of which are primary inhabitants of the oral cavity — found in saliva, dental plaque, and the pharynx. Rothia is a normal commensal of the human mouth but can become pathogenic in immunocompromised hosts.

From a WikiBiome perspective, Rothia is significant because it bridges oral and systemic health through two mechanisms: its nitrate-reducing activity influences systemic nitric oxide biology, and its detection in the gut, peritoneum, or duodenum often signals oral-gut microbial translocation — a hallmark of disrupted mucosal barriers.

Metal Dependencies

  • Iron: Required for cytochrome-based electron transport in aerobic and anaerobic respiration. Rothia species possess siderophore uptake systems for iron acquisition.
  • Manganese: R. mucilaginosa uses manganese-dependent superoxide dismutase (MnSOD) for oxidative stress defense, enabling survival in oxygen-variable environments from the aerobic oral cavity to the microaerobic gut.

Key Enzymes and Virulence Factors

  • Nitrate reductase: Rothia is among the key oral nitrate-reducing bacteria that convert dietary nitrate (from leafy greens) to nitrite, which is subsequently reduced to nitric oxide (NO) in the stomach. This enterosalivary nitrate-nitrite-NO pathway contributes to blood pressure regulation and antimicrobial defense. Its disruption (e.g., by antiseptic mouthwash) has been linked to hypertension.
  • Urease: Some Rothia strains produce urease, enabling survival in acidic environments and contributing to nitrogen cycling in the oral cavity.
  • Biofilm formation: Rothia participates in multi-species oral biofilms and can contribute to dental caries when ecological balance is disrupted.

Ecological Role

Rothia occupies a unique position as an oral ecosystem engineer with systemic reach:

  • In the healthy oral cavity, Rothia is a dominant member of the supragingival plaque community and a key partner in the nitrate reduction cascade.
  • Its detection in gut, duodenal, or peritoneal samples is often a marker of oral-gut translocation — indicating that oral bacteria have survived gastric transit (often due to PPI use or achlorhydria) and colonized distal sites.
  • In Crohn's disease, Rothia was enriched alongside Fusobacterium, Streptococcus, and Collinsella in CD-specific metagenomics ([1], cross-sectional).
  • Thonzonium bromide, a repurposed drug for dental caries, specifically disrupted Rothia in oral swabs of rodent models, demonstrating its central role in oral biofilm ecology ([2], animal-model).

Conditions Associated

Enriched in:

  • Crohn's disease: Enriched in CD alongside other oral-origin taxa; part of the facultative anaerobe expansion pattern seen in IBD ([1], cross-sectional).
  • Cerebral palsy with epilepsy: Significantly enriched (0.62 +/- 0.82%) in CPE children alongside Streptococcus, Veillonella, and other oral-origin taxa; paradoxical high diversity reflecting pathobiont expansion ([3], cross-sectional).
  • GERD/NERD: Rothia sp. was a discriminatory taxon for non-erosive reflux disease (NERD) by LEfSe analysis ([4], cross-sectional).
  • Pancreatic cancer: Found in duodenal microbiota of PC patients alongside Bifidobacterium, Enterococcus, and Neisseria ([5], expert-opinion).

Depleted in:

  • Endometriosis: Rothia significantly decreased in peritoneal fluid extracellular vesicles from women with advanced endometriosis, alongside Propionibacterium and Actinomyces ([6], cross-sectional).

Protective associations:

  • Chronic kidney disease: Mendelian randomization identifies Rothia species as causally protective against elevated urinary albumin-to-creatinine ratio (UACR) (IVW OR = 0.99, 95% CI 0.99-1, p = 0.03), possibly by inhibiting inflammatory pathways that damage the glomerular filtration barrier ([7], quasi-experimental).

Oral biomarker:

  • Colorectal cancer: Rothia dentocariosa and Rothia mucilaginosa were among the top 10 CRC-associated salivary microbes in an Iranian cohort, present in CRC patients but absent from healthy controls. This supports oral microbiome-based cancer screening ([8], cross-sectional).

Key Studies

StudyFindingEvidence Level
[7]Causally protective against elevated UACR in CKDQuasi-experimental
[8]R. dentocariosa and R. mucilaginosa as salivary CRC biomarkersCross-sectional
[1]Enriched in Crohn's disease metagenomicsCross-sectional
[6]Depleted in peritoneal fluid in endometriosisCross-sectional
[2]Disrupted by thonzonium bromide in oral biofilmAnimal model

Cross-References

References (9)

  1. Kang DY, Park JL, Yeo MK et al. (2023). Diagnosis of Crohn's Disease and Ulcerative Colitis Using the Microbiome. BMC Microbiology. doi:10.1186/s12866-023-03084-5
  2. Aurea Simon-Soro, Dongyeop Kim, Yong Li et al. (2021). Impact of the Repurposed Drug Thonzonium Bromide on Host Oral-Gut Microbiomes. npj Biofilms and Microbiomes
  3. Congfu Huang, Yinhu Li, Xin Feng et al. (2019). Huang 2019 — Distinct Gut Microbiota Composition and Functional Category in Children With Cerebral Palsy and Epilepsy. Frontiers in Pediatrics. doi:10.3389/fped.2019.00394
  4. Sugihartono T, Fauzia KA, Miftahussurur M et al. (2022). Analysis of gastric microbiota and Helicobacter pylori infection in gastroesophageal reflux disease. Gut Pathogens. doi:10.1186/s13099-022-00510-3
  5. Ghazaleh Pourali, Danial Kazemi, Amir Shayan Chadeganipour et al. (2024). Microbiome as a biomarker and therapeutic target in pancreatic cancer. BMC Microbiology. doi:10.1186/s12866-023-03166-4
  6. Lee SR, Lee JC, Kim SH et al. (2021). Altered Composition of Microbiota in Women with Ovarian Endometrioma: Microbiome Analyses of Extracellular Vesicles in the Peritoneal Fluid. International Journal of Molecular Sciences. doi:10.3390/ijms22094608
  7. Zhiwei Liu, Zhiyao Liu, Weixia Sun et al. (2026). Liu 2026 — Causal Association between Oral Microbiome and Chronic Kidney Disease: Two-Sample Mendelian Randomization. Archives of Medical Science. doi:10.5114/aoms/211613
  8. Rezasoltani S, Looha MA, Aghdaei HA et al. (2024). 16S rRNA Sequencing Analysis of the Oral and Fecal Microbiota in Colorectal Cancer Positives Versus Colorectal Cancer Negatives in Iranian Population. Gut Pathogens. doi:10.1186/s13099-024-00604-0
  9. Baiqiang Lin, Fuya Zhao, Yang Liu et al. (2022). Lin 2022 — Probiotics alleviate oral-gut microbiota dysbiosis in thyroid cancer patients after thyroidectomy: RCT. Frontiers in Endocrinology. doi:10.3389/fendo.2022.834674

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