Bacterial vaginosis is caused by an overgrowth of anaerobic bac-teria and Gardnerella vaginalis normally found in the vagina and an absence of lactobacilli (see Table 47-1). It is characterized by a fish-like odor that is particularly noticeable after sexual inter-course or during menstruation as a result of a rise in the vaginal pH. It is usually accompanied by a heavier-than-normal dis-charge. Risk factors include douching, smoking, and increased sexual activity.
Bacterial vaginosis can occur throughout the menstrual cycle and does not produce local discomfort or pain. More than half of women with bacterial vaginosis do not notice any symptoms. Discharge, if noticed, is gray to yellowish white. The fish-like odor can be detected readily by adding a drop of potassium hy-droxide to a glass slide with a sample of vaginal discharge, which releases amines. Under the microscope, vaginal cells are coated with bacteria and are described as “clue cells.” The pH of the dis-charge is usually above 4.7 because of the amines that result from enzymes from anaerobes. Lactobacilli, a natural host defense, are usually absent. Bacterial vaginosis is usually not a serious condition, but it has been associated with premature labor, endometritis, and recurrent urinary tract infection.
Metronidazole (Flagyl), administered orally twice a day for 1 week, is effective; a vaginal gel is also available. Clindamycin (Cleocin) vaginal cream or ovules (oval suppositories) are also effective. If the infection recurs, the patient’s partner may require treatment. Patients with recurrent bacterial vaginosis should be tested for gonorrhea and chlamydia.