Vaginal Microbiome

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Vaginal Microbiome: Basics - Healthy Harmony

  • Definition: Dynamic, protective microbial ecosystem, primarily bacteria.
  • Dominant Genera: Lactobacillus spp. (e.g., L. crispatus, L. iners, L. jensenii, L. gasseri).
    • 📌 Mnemonic: "Crisp In Jensen's Gas" (Crispatus, Iners, Jensenii, Gasseri)
  • Hallmarks of Health (Eubiosis):
    • High Lactobacillus numbers.
    • Low microbial diversity.
  • Protective Mechanisms:
    • Lactic acid production from glycogen → acidic pH (3.8-4.5).
    • Production of antimicrobial compounds (e.g., $H_2O_2$, bacteriocins).
    • Competitive exclusion of pathogens.
    • Biofilm formation.
  • Estrogen Influence: ↑ Estrogen → ↑ epithelial glycogen → substrate for lactobacilli → ↑ lactic acid → stable low pH.

Lactobacillus crispatus-dominated microbiome is considered the gold standard for vaginal health, offering superior protection. Healthy vs. BV Vaginal Microbiome & Probiotic Treatment

Vaginal Microbiome: Influencers - Balance Beam Act

Vaginal health hinges on a delicate microbial balance, primarily maintained by Lactobacillus spp. producing lactic acid (healthy pH 3.8-4.5). Disruption leads to dysbiosis (pH >4.5, ↑infection risk).

  • Hormonal: Estrogen is pivotal. High estrogen (menarche, pregnancy) supports Lactobacilli. Low estrogen (menopause, pre-puberty) leads to ↑pH, ↓Lactobacilli.
  • Exogenous: Sexual activity (semen pH, microbe transfer), douching, broad-spectrum antibiotics significantly impact flora.

⭐ Bacterial Vaginosis (BV) is characterized by a shift from Lactobacillus to anaerobes (e.g., Gardnerella vaginalis), diagnosed by Amsel criteria or Nugent score (7-10).

Vaginal Dysbiosis: Conditions - Unwanted Guests

Vaginal Infectious Diagnostic Algorithm

FeatureBacterial Vaginosis (BV)Vulvovaginal Candidiasis (VVC)Trichomoniasis (TV)
EtiologyPolymicrobial (↑G. vaginalis, anaerobes)Candida albicans (commonest)Trichomonas vaginalis (flagellated protozoan)
Vaginal pH>4.5Normal (≤4.5)>4.5 (often 5.0-6.0)
DischargeThin, grey-white, homogenous; fishy odor (amine test +ve)Thick, white, curdy, "cottage cheese"Profuse, yellow-green, frothy, malodorous
SymptomsMalodor; mild/no itch/inflammationIntense vulvar pruritus, sorenessVulvovaginal soreness, dysuria, dyspareunia
DiagnosisAmsel's criteria (≥3): pH >4.5, +ve Whiff, clue cells, characteristic discharge. Clue cells on microscopy (≥20%).Pseudohyphae/yeast on KOH wet mountMotile trichomonads on saline wet mount
Unique Sign-Satellite lesionsStrawberry cervix (colpitis macularis) ~2-10%

Vaginal Microbiome: Diagnostics & Impact - Clues & Consequences

  • Diagnostics for Bacterial Vaginosis (BV):
    • Amsel's Criteria (Need ≥3 of 4): 📌 AMSEL
      • Amine test (+ve Whiff test with 10% KOH)
      • Microscopy (Clue cells >20%)
      • Secretion (Homogenous, thin, grayish-white)
      • ELevated pH (>4.5)
    • Nugent Score (Gram stain):
      • 0-3: Normal (Lactobacillus predominant)
      • 4-6: Intermediate
      • 7-10: BV (Definitive)
  • Clinical Impact of Dysbiosis (e.g., BV):
    • ↑ Susceptibility: STIs (HIV, HSV, Chlamydia), Pelvic Inflammatory Disease (PID).
    • Pregnancy: ↑ Risk of preterm birth, Premature Rupture of Membranes (PROM), chorioamnionitis.
    • Recurrent infections.

⭐ Clue cells, epithelial cells stippled with adherent coccobacilli, are a hallmark of Bacterial Vaginosis seen on wet mount or Gram stain.

High‑Yield Points - ⚡ Biggest Takeaways

  • Healthy vaginal microbiome is dominated by Lactobacillus species.
  • Lactic acid production maintains low vaginal pH (3.8-4.5), inhibiting pathogens.
  • Bacterial Vaginosis (BV): dysbiosis with ↓ Lactobacilli, ↑ Gardnerella vaginalis and other anaerobes.
  • Diagnosis of BV: Amsel criteria and Nugent score (Gram stain).
  • Clue cells are pathognomonic for BV.
  • Estrogen levels influence microbiome composition, promoting lactobacilli.
  • Dysbiosis ↑ risk of STIs and preterm birth.

Practice Questions: Vaginal Microbiome

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Amsel's criteria are used for?

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Flashcards: Vaginal Microbiome

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Candida albicans is normal flora of the _____ tract, including the oral cavity.

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Candida albicans is normal flora of the _____ tract, including the oral cavity.

GI

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