Bacterial Vaginosis (BV) is a common vaginal condition characterized by an imbalance in the natural bacterial community of the vagina. It develops when naturally occurring bacteria overgrow, disrupting the healthy vaginal environment. This article explores the biological processes and factors that lead to BV.
The Balanced Vaginal Microbiome
A healthy vaginal environment is home to a diverse community of microorganisms, collectively known as the vaginal microbiome. This delicate ecosystem is predominantly maintained by beneficial bacteria, primarily Lactobacillus species. These Lactobacillus species convert glycogen, a sugar stored in vaginal cells, into lactic acid. This process keeps the vaginal pH acidic, typically ranging from 3.8 to 4.5.
The acidic environment acts as a natural defense mechanism, inhibiting the growth of many harmful bacteria and other pathogens. Lactobacillus species also produce antimicrobial substances, such as hydrogen peroxide, contributing to this protective barrier. This balanced, Lactobacillus-dominated state supports vaginal health and defense against infections.
The Shift in Bacterial Composition
Bacterial Vaginosis occurs when there is a disruption to this balanced vaginal microbiome. BV is characterized by a decrease in protective Lactobacillus species. This reduction allows for the overgrowth of various anaerobic bacteria, which thrive in environments with less oxygen.
These anaerobic bacteria include Gardnerella vaginalis, Prevotella species, Mycoplasma hominis, and Mobiluncus species. As beneficial Lactobacillus bacteria decline, lactic acid production decreases, causing the vaginal pH to rise above 4.5. This elevated pH creates a more favorable environment for the proliferation of these anaerobic bacteria.
The overgrowing bacteria, particularly Gardnerella vaginalis, contribute to the formation of a “biofilm” on the vaginal cells. This biofilm is a protective layer where bacteria can adhere and multiply, making them more resistant to the body’s natural defenses and some antibiotic treatments. The formation of this polymicrobial biofilm is a significant factor in the development and persistence of BV.
Factors Influencing the Imbalance
Several factors can disrupt the delicate balance of the vaginal microbiome, contributing to the development of Bacterial Vaginosis. Douching involves rinsing the vagina with water or other solutions, which can wash away beneficial Lactobacillus bacteria and alter the natural acidic pH. This practice can create an environment where anaerobic bacteria are more likely to overgrow.
Sexual activity can also influence the vaginal microbiome. While BV is not considered a sexually transmitted infection in the traditional sense, having new or multiple sex partners is associated with an increased risk. This may be due to the introduction of new bacteria or changes in the vaginal environment, such as the alkaline nature of semen temporarily raising vaginal pH.
The use of certain hygiene products can disrupt the natural flora. Harsh soaps, scented washes, or internal feminine hygiene products can irritate vaginal tissues and interfere with the vaginal microbiome’s balance. These products can alter pH levels or directly inhibit the growth of beneficial bacteria, thereby increasing the risk of BV.