How do lactobacilli limit infections in the vagina? Select all that apply. (NCLEX/HESI/TEAS)
a. They competitively exclude potential pathogens.
b. They make hydrogen peroxide.
c. They ferment fructose to make lactic acid.
d. They lower the vaginal pH, which limits pathogen growth.
e. They increase the rate of vaginal mucus secretion.

Verified step by step guidance

1. Understand the role of lactobacilli in the vaginal microbiota. Lactobacilli are beneficial bacteria that help maintain a healthy vaginal environment.
2. Consider how lactobacilli can competitively exclude potential pathogens. This means they occupy space and resources that pathogens might otherwise use.
3. Examine the production of hydrogen peroxide by lactobacilli. Hydrogen peroxide is a substance that can inhibit or kill certain pathogens.
4. Explore the fermentation process of lactobacilli. They ferment sugars like fructose to produce lactic acid, which is crucial for maintaining a low pH.
5. Analyze how a lower vaginal pH, resulting from lactic acid production, can limit the growth of pathogens, as many harmful bacteria cannot thrive in acidic environments.

Key Concepts

Competitive Exclusion

Competitive exclusion is a principle where established microorganisms, like lactobacilli, occupy ecological niches and utilize available resources, thereby preventing potential pathogens from colonizing. This mechanism is crucial in maintaining a healthy microbiome, as it reduces the likelihood of infections by limiting the growth of harmful bacteria.

Lactic Acid Production

Lactobacilli ferment carbohydrates, such as fructose, to produce lactic acid. This process not only provides energy for the bacteria but also contributes to a lower vaginal pH. The acidic environment created by lactic acid is inhospitable to many pathogens, thus playing a significant role in infection prevention.

Hydrogen Peroxide Production

Some strains of lactobacilli produce hydrogen peroxide as a metabolic byproduct. This compound has antimicrobial properties, which can inhibit the growth of various pathogens. By producing hydrogen peroxide, lactobacilli further enhance the vaginal environment's defense against infections.