Bacterial vaginosis is a vaginal infection that occurs when the balance of bacteria in the vagina is altered.
Many bacteria normally reside in the vagina. One type, called lactobacilli, maintains the normal acidity of the vagina. By doing so, lactobacilli help keep the lining of the vagina healthy and prevent the growth of certain bacteria that cause infections. Bacterial vaginosis, the most common vaginal infection, results when the number of protective lactobacilli decreases and the number of other bacteria that are normally present (such as Gardnerella vaginalis and Peptostreptococcus species) increases. Why these changes occur and whether the disorder is sexually transmitted are unknown. What is known is that bacterial vaginosis is more common among women who have a sexually transmitted disease, who have several sex partners, or who use an intrauterine device (IUD).
Bacterial vaginosis can develop in women who have sex with women, particularly when they have several sex partners.
The vaginal discharge may be gray or white, thin, itchy, and profuse. Usually, the discharge has a fishy odor. The odor may become stronger after sexual intercourse and during menstrual periods.
The infection can lead to serious complications, such as pelvic inflammatory disease and, for pregnant women, infection of the membranes around the fetus, preterm labor and delivery, and infections of the uterus after delivery or after an abortion.
Bacterial vaginosis is treated with an antibiotic (such as metronidazole or clindamycin) applied as a vaginal gel or cream. Metronidazole taken by mouth is also effective but may have bodywide side effects. Women who use clindamycin cream cannot rely on latex products (condoms or diaphragms) for birth control because the drug weakens latex.
Bacterial vaginosis usually resolves in a few days but commonly recurs. If it recurs often, antibiotics may have to be taken for a long time.
Last full review/revision March 2013 by David E. Soper, MD