Bacterial vaginosis can result from an imbalance of normal bacteria in a healthy vagina. This means the pH level (acid/alkaline balance) is upset. Bacterial vaginosis is not an STI.
Bacterial vaginosis can be brought on by anything that changes the balance of micro flora in the vagina, such as vaginal douching, new sex partners or increased sexual activity. However it can occur in women who have never had sexual intercourse.
Bacterial vaginosis is treated by taking tablets orally. You shouldn't drink alcohol while taking these tablets.
Partners do not need treatment.