Bacterial Imbalance

In a healthy vagina, there's a natural balance between benign (good) bacteria and harmful bacteria. Sometimes, this balance gets disrupted, and the harmful bacteria proliferate and take over. Gardnerella vaginalis is the scientific name for one of those types of harmful bacteria, hence the resulting infection is sometimes simply called gardnerella.

Not an STD

Gardnerella is not technically a sexually transmitted disease, or STD. The bacteria is already present in the body naturally, and a woman can get gardnerella without being sexually active at all. However, the chances of getting bacterial vaginosis increase with sexual activity, possibly due to abrasion of the vaginal tissues providing an opening for infection. Having women as sex partners also increases the chance of getting infected with gardnerella.

Other Causes

The risk of bacterial vaginosis is also higher if you smoke, and if you douche. Using an IUD for birth control also increases the chances of getting gardnerella.

Symptoms

The primary symptom of gardnerella is unusual vaginal discharge. The discharge is usually grayish-white or yellow, sometimes greenish. It often has a foul, "fishy" smell. Gardnerella may also cause itching or irritation. Some cases of gardnerella have no symptoms at all.

Complications

An active gardnerella infection may increase your risk for acquiring HIV. It also increases the risk of developing a pelvic infection, which in its chronic form is called Pelvic Inflammatory Disease (PID) and contributes to infertility. If you are pregnant, a case of gardnerella increases the chance of miscarriage, and of uterine infection after delivery.

Treatment

A doctor will usually prescribe a course of antibiotics to combat a gardnerella infection. They can be taken either in pill form, or as a cream or capsule used vaginally.

Source:

WebMD.com: Bacterial Vaginosis

May Clinic: Vaginitis