Bacterial vaginosis is a condition caused by the overgrowth of bacteria that normally live in the vagina. Women with bacterial vaginosis often have no symptoms, but some women have vaginal discharge, odor, or itching. Pregnant women with bacterial vaginosis are more likely than women without the condition to have babies who are premature or have low birthweight. Doctors can test for the condition by swabbing the vagina during pelvic examination and sending the swabs to the laboratory. To treat bacterial vaginosis, a woman takes an antibiotic either by mouth or by a gel inserted into the vagina. Unfortunately, bacterial vaginosis frequently persists or occurs again after treatment. It would be helpful if doctors could predict which patients are at high risk for persistent or recurrent bacterial vaginosis. Recently, studies have identified several types of bacteria associated with bacterial vaginosis. It is possible that certain types of bacteria are linked to a high risk for vaginosis that persists or recurs after treatment.