Atopobium

Atopobium is a genus of obligate anaerobic, Gram-positive bacteria in the phylum Actinobacteria. The primary species of clinical relevance is A. vaginae (recently reclassified as Fannyhessea vaginae), which is one of the hallmark organisms of bacterial vaginosis (BV) and a key partner in Gardnerella biofilms. Atopobium appears in 20+ files across the WikiBiome vault, predominantly in the context of vaginal and reproductive tract microbiome studies.

Vaginal Microbiome Role

BV Biofilm Partnership

A. vaginae is the second most important organism in BV after gardnerella, forming a polymicrobial biofilm on the vaginal epithelium:

  • A. vaginae embeds within Gardnerella-initiated biofilms, where it is protected from antimicrobial agents — this explains the high BV recurrence rate after metronidazole treatment (Gardnerella is susceptible, but Atopobium within the biofilm is resistant) [1].
  • Produces sialidase — an enzyme that degrades mucin glycans on the vaginal epithelium, compromising the mucosal barrier and facilitating ascending infection [2].
  • Co-enriched with megasphaera, sneathia, and prevotella in Community State Type IV vaginal microbiomes.

HPV and Cervical Cancer

Enriched in HPV16-positive cervical microbiomes alongside Sneathia, Megasphaera, and Prevotella [3]. The sialidase-mediated mucosal degradation may facilitate HPV access to basal epithelial cells.

Preterm Birth

Elevated vaginal Atopobium is associated with preterm birth risk, likely through mucosal barrier degradation and ascending inflammation [4].

Ovarian Cancer

Part of the dysbiotic vaginal-peritoneal microbiome signature in ovarian cancer [5].

Endometriosis — Depletion Pattern

Like megasphaera and gardnerella, Atopobium is depleted in cervical samples of endometriosis patients [6] [7] [8] [9]. This is significant because endometriosis is not simply "vaginal dysbiosis" — the cervical community shifts away from the BV consortium toward Enterobacteriaceae enrichment, representing a distinct ecological state.

Genital tract studies in endometriosis consistently show reduced Atopobium [10] [11] [12].

Adenomyosis and Infertility

Atopobium is part of the altered genital-intestinal microbiota in adenomyosis with associated infertility [13].

Iron and Lactoferrin Context

Mucosal lactoferrin levels modulate Atopobium colonization in the genital tract — lactoferrin's iron-sequestering function creates selective pressure favoring organisms with iron acquisition strategies [2]. Chlamydia co-infection contexts further alter Atopobium dynamics [14].

Cross-References

References (14)

  1. Abdelmaksoud AA, Girerd PH, Garcia EM et al. (2017). Abdelmaksoud 2017 — Association between Statin Use, the Vaginal Microbiome, and Gardnerella vaginalis Vaginolysin-Mediated Cytotoxicity. PLOS ONE. doi:10.1371/journal.pone.0183765
  2. S. A. Roberts, L. Brabin, S. Diallo et al. (2019). Roberts 2019 — Mucosal Lactoferrin Response to Genital Tract Infections Is Associated with Iron and Nutritional Biomarkers. European Journal of Clinical Nutrition. doi:10.1038/s41430-019-0444-7
  3. Qian Yang, Yaping Wang, Xinyi Wei et al. (2020). Yang 2020 — Vaginal Microbiome Alterations in HPV16 Infection by Shotgun Metagenomics. Frontiers in Cellular and Infection Microbiology. doi:10.3389/fcimb.2020.00286
  4. Pamela Pruski, Gonçalo D. S. Correia, Holly V. Lewis et al. (2021). Pruski & Correia 2021 — Direct On-Swab Metabolic Profiling of Vaginal Microbiome Host Interactions During Pregnancy and Preterm Birth. Nature Communications. doi:10.1038/s41467-021-26215-w
  5. Asangba AE, Chen J, Goergen KM et al. (2023). Asangba 2023 — Diagnostic and prognostic potential of the microbiome in ovarian cancer treatment response. Scientific Reports. doi:10.1038/s41598-023-27555-x
  6. Baris Ata, Sule Yildiz, Engin Turkgeldi et al. (2019). Ata 2019 — The Endobiota Study: Comparison of Vaginal, Cervical and Gut Microbiota Between Women with Stage 3/4 Endometriosis and Healthy Controls. Scientific Reports. doi:10.1038/s41598-019-39700-6
  7. Chloe Hicks, Mathew Leonardi, Xin-Yi Chua et al. (2025). Hicks et al. 2025 — Oral, Vaginal, and Stool Microbial Signatures in Patients With Endometriosis as Potential Diagnostic Non-Invasive Biomarkers. BJOG: An International Journal of Obstetrics and Gynaecology. doi:10.1111/1471-0528.17979
  8. Hooi-Leng Ser, Siu-Jung Au Yong, Mohamad Nasir Shafiee et al. (2023). Ser 2023 — Current Updates on the Role of Microbiome in Endometriosis: A Narrative Review. Microorganisms. doi:10.3390/microorganisms11020360
  9. Liping Shen, Wei Zhang, Yi Yuan et al. (2022). Shen 2022 — Vaginal Microecological Characteristics of Women in Different Physiological and Pathological Periods. Frontiers in Cellular and Infection Microbiology. doi:10.3389/fcimb.2022.959793
  10. Camila Hernandes, Paola Silveira, Aline Fernanda Rodrigues Sereia et al. (2020). Hernandes 2020 — Microbiome Profile of Deep Endometriosis Patients: Comparison of Vaginal Fluid, Endometrium and Lesion. Diagnostics. doi:10.3390/diagnostics10030163
  11. Carlos H Miyashira, Fernanda Reali Oliveira, Marina Paula Andres et al. (2022). Miyashira 2022 — The Microbiome and Endometriosis. Reproduction and Fertility. doi:10.1530/RAF-21-0113
  12. Chen S, Gu Z, Zhang W et al. (2020). Microbiome of the lower genital tract in Chinese women with endometriosis by 16s-rRNA sequencing technique: a pilot study. Annals of Translational Medicine. doi:10.21037/atm-20-1309
  13. Ponomaryova IG, Lisyana TO, Trokhimovych OV et al. (2022). Ponomaryova 2022 — Changes in microbiota of genital tract and intestines in patients with adenomyosis and infertility. Medical Research Journal. doi:10.5603/MRJ.a2022.0034
  14. Chen H, Wang L, Zhao L et al. (2021). Chen 2021 — Alterations of vaginal microbiota in women with infertility and Chlamydia trachomatis infection. Frontiers in Cellular and Infection Microbiology. doi:10.3389/fcimb.2021.698840

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