Bacterial vaginosis is an abnormal vaginal condition that is characterized by vaginal discharge and results from an overgrowth of atypical bacteria in the vagina. It is not a true bacterial infection but rather an imbalance of the bacteria that are normally present in the vagina. Usually treatment is with an antibiotic, such as clindamycin or metronidazole. BV is the most common vaginal infection in women of reproductive age. BV is linked to an imbalance of “good” and “harmful” bacteria that are normally found in a woman’s vagina. Bacterial vaginosis results from overgrowth of one of several bacteria naturally found in your vagina. Usually, "good" bacteria (lactobacilli) outnumber "bad" bacteria (anaerobes). But if there are too many anaerobic bacteria, they upset the natural balance of microorganisms in your vagina and cause bacterial vaginosis.