Infection caused by bacterial overgrowth in the vagina. Most affected women are asymptomatic. When symptoms occur, they include foul-smelling vaginal discharge, vaginal itching, and burning. Risk factors include sexual activity with multiple partners and the use of vaginal douches and intrauterine devices. Up to a third of cases resolve without treatment. Antibiotic treatment is recommended when symptoms are present and for women that are pregnant at the time of infection.