Pathophysiology
Clinical meaning
Bacterial vaginosis (BV) is the most common vaginal infection in women of reproductive age. It occurs when the protective Lactobacillus bacteria that normally dominate the vaginal environment are replaced by an overgrowth of anaerobic bacteria, primarily Gardnerella vaginalis and Atopobium vaginae. The healthy vagina maintains an acidic pH (3.8-4.5) through lactic acid produced by Lactobacillus. When these protective bacteria are depleted - by douching, new sexual partners, or other disruptions - anaerobic organisms proliferate, raising the vaginal pH above 4.5. These anaerobes produce amines that cause the characteristic fishy odor, especially when exposed to alkaline substances such as semen or potassium hydroxide (KOH). BV is not considered a sexually transmitted infection but is associated with sexual activity.