Bacterial vaginosis (often called gardnerella or BV) is not actually an STI although it does often occur among sexually active women. It is a bacterial imbalance in the vagina. Under normal conditions, the acidic level in the vagina is in balance. But there are things that can cause an imbalance e.g. washing the vagina with soap or keeping a tampon in too long. A new sexual partner may also bring it on. This imbalance creates an acidic environment in which certain bacteria have the opportunity to multiply.
Symptoms may occur very suddenly. You can also have bacterial vaginosis without noticing it. The bacteria can be passed on to men during sexual contact, but this doesn’t usually cause any symptoms.
Gardnerella is easy to treat, but may recur.
Using a condom prevents transmission of the bacteria during sex. It is best not to have sex during treatment, as this gives your body a chance to heal.