The bacteria that colonize the vagina, collectively referred to as the vaginal microbiome, were discovered by the German gynecologist Albert Döderlein in 1892. The amount and type of bacteria present have significant implications for a woman's overall health. The primary colonizing bacteria of a healthy individual are of the genus lactobacilli and the lactic acid

Lactic acid

Lactic acid, also known as milk acid, is a chemical compound that plays a role in various biochemical processes and was first isolated in 1780 by the Swedish chemist Carl Wilhelm Scheele. Lactic acid is a carboxylic acid with the chemical formula C3H6O3...

 they produce, in combination with fluids secreted during sexual arousal

Sexual arousal

Sexual arousal, or sexual excitement, is the arousal of sexual desire, during or in anticipation of sexual activity. Things that precipitate human sexual arousal are called erotic stimuli, or colloquially known as turn-ons. There are many potential stimuli, both physical or mental, which can cause...

, are greatly responsible for the characteristic scent associated with the vaginal area.

Menstruation

During menstruation

Menstruation

Menstruation is the shedding of the uterine lining . It occurs on a regular basis in sexually reproductive-age females of certain mammal species. This article focuses on human menstruation.-Overview:...

, the concentration of vaginal microbiome is observed to decline. The effect of tampon

Tampon

A tampon is a mass of cotton or rayon or a mixture of the two inserted into a body cavity or wound to absorb bodilyfluid. The most common type in daily use is designed to be inserted into the vagina during menstruation to absorb the flow of menstrual fluid...

 use on vaginal flora is debated, but safe application of sterile tampons appears not to significantly modify the balance of bacterial presence.

Disease prevention

A healthy vaginal microbiome aids in the prevention of Bacterial vaginosis

Bacterial vaginosis

Bacterial vaginosis or less commonly vaginal bacteriosis is a disease of the vagina caused by bacteria. The U.S. Centers for Disease Control and Prevention states it is not clear what role sexual activity plays in the development. However, it is known that BV is associated with having a new sex...

, yeast infections and other possible problems by maintaining an acidic pH (< 4.5) that is unfavourable for the growth of common pathogens, such as Gardnerella vaginalis. The lactobacilli present in a healthy vaginal microbiome, also occupy the chemical resources that would otherwise be available for exploitation by pathogenic organisms. However, harmful bacteria or an imbalance in bacteria can lead to infection.

One method of reducing the risk of infection in the local area of the urethra

Urethra

In anatomy, the urethra is a tube that connects the urinary bladder to the genitals for the removal of fluids out of the body. In males, the urethra travels through the penis, and carries semen as well as urine...

is to urinate immediately after sex. Additionally, exclusive use of sterile contraceptives can assist in prevention of infection.