SCIENCE & NATURE

What is the vaginal microbiome and what role do lactobacilli play in it?

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The vaginal microbiome is the community of microorganisms, mainly bacteria, that live in the vagina. Lactobacilli are the dominant beneficial bacteria that maintain vaginal health by producing lactic acid, which keeps the environment acidic and prevents harmful bacteria from growing.

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Primary bacteriaLactobacilli make up about 90% of healthy vaginal bacteria
Main functionProduce lactic acid to maintain acidic pH (3.8-4.5)
Protection mechanismAcidic environment prevents growth of harmful pathogens
Common speciesLactobacillus crispatus and Lactobacillus gasseri are most abundant
Health indicatorLow lactobacilli levels are associated with bacterial vaginosis

What is the vaginal microbiome?

The vaginal microbiome is a collection of trillions of microorganisms, primarily bacteria, that naturally live in the vagina. This ecosystem is unique to each person and plays an important role in reproductive health. The microbiome helps protect against infections, supports fertility, and maintains overall vaginal wellness.

The role of lactobacilli

Lactobacilli are rod-shaped bacteria that are the most important microorganisms in a healthy vaginal microbiome. These bacteria produce lactic acid as a byproduct of their metabolism. The lactic acid lowers the pH of the vaginal environment, making it acidic. This acidic environment is hostile to many harmful bacteria and pathogens that could cause infections.

How lactobacilli protect health

Besides producing lactic acid, lactobacilli create additional protective substances called bacteriocins that directly inhibit the growth of harmful bacteria. They also maintain a balanced ecosystem by competing with pathogenic bacteria for nutrients and space. This natural defense system helps prevent common infections like bacterial vaginosis, yeast infections, and urinary tract infections.

Factors that affect lactobacilli

Lactobacilli levels can be reduced by antibiotics, hormonal changes, sexual activity, douching, and certain hygiene products. Pregnancy, menopause, and menstrual cycles also affect the vaginal microbiome composition. Maintaining adequate lactobacilli is important for vaginal health throughout life.

Microbiome types

Researchers have identified different vaginal microbiome types based on which lactobacilli species are dominant. Type 1 microbiomes are dominated by Lactobacillus crispatus and are considered the most protective. Other types are dominated by different lactobacilli species and may be less protective against infections.

Sources

  1. cdc.gov (cdc.gov)
  2. nih.gov (nih.gov)
  3. womenshealth.gov (womenshealth.gov)