Vaginal Flora

Clue cells are vaginal epithelial cells that are covered in bacteria. They are one way of diagnosing bacterial vaginosis. Photo Courtesy of the Public Health Image Library; CDC/M. Rein

What are the Vaginal Flora?

The vaginal flora are the bacteria that live inside the vagina. The normal vaginal flora are dominated by various lactobacillus species, which help to keep the vagina healthy by producing lactic acid, hydrogen peroxide, and other substances that inhibit the growth of yeast and other unwanted organisms. They maintain the vagina at a healthy pH of around 4. This mildly acidic environment helps protect against infection.

Why is a Healthy Vaginal Flora Important?

A hallmark of bacterial vaginosis (BV) is disruption of this normal vaginal flora and a loss of lactobacilli. This can not only be unpleasant in and of itself. It can also leave a woman more susceptible to HIV and other sexually transmitted infections. Bacterial vaginosis is actually caused by an overgrowth of bacteria that normally exist at low levels in the vagina. When the lactobacillus population is disrupted, these bacteria take over.

The bacteria associated with BV make a number of volatile amines, which is what causes the distinctive odor associated with BV. This odor tends to be more present after sex, particularly unprotected sex. This is because the amines become smellier at the higher pH associated with semen. However, despite the association, BV is not caused by sperm. In fact, the greatest evidence for sexual transmission of bacterial vaginosis is in lesbians.

How Can Healthy Vaginal Flora Be Restored?

One of the difficulties in treating BV and related conditions, such as yeast infections, is figuring out how to restore the normal vaginal flora. Sometimes the bacterial populations return to normal proportions after treatment. Other times they don't. In order to help restore a lactobacillus dominated flora, a number of researchers are looking at probiotic pills and suppositories.

These treatments would contain lactobacillus species, with the hope that they would grow and recolonize the vagina. To date, results have been somewhat positive, if preliminary. Still if they are borne out, probiotics may be a new way to improve vaginal health.

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