A 35-year-old woman complains of vaginal discomfort for 2 weeks. Physical examination reveals a scanty vaginal discharge. The fluid develops a "fishy" odor after treatment with 10% potassium hydroxide. A Pap smear taken during the pelvic examination shows squamous cells covered by coccobacilli ("clue" cells). Which of the following is the most likely etiology of vaginal discomfort in this patient?: (A) Chlamydia trachomatis, (B) Gardnerella vaginalis, (C) Herpes simplex virus, (D) Human papillomavirus
Answer is B. Sexual transmission of G. vaginalis, a Gram-negative coccobacillus, causes a substantial proportion of cases classified as nonspecific vaginitis. The diagnosis of Gardnerella infection is best established by identifying the organisms either in a wet mount specimen of a vaginal discharge or in a Papanicolaou-stained smear. The "clue cell" is pathognomonic and shows squamous cells covered by coccobacilli. Other aids to the diagnosis are a thin, homogeneous, milk-like vaginal discharge, a vaginal pH above 4.5, and the presence of a "fishy" odor from the discharge once alkalinized with 10% potassium hydroxide. Viruses (choices C and D) do not produce vaginal discharge. Choices A and E are not associated with "clue" cells.Diagnosis: Vaginitis, cervicitis