Pathology Thread

II. Infectious Diseases

Objectives:

After completing this tutorial the student will be able to:

• list common infectious diseases of the vagina
• specify etiologic agent and mode of diagnosis
• describe clinical presentation
• recognize diagnostic histologic features

1. Gardnerella vaginalis.

Gardnerella infection of the vagina is very common. The organism is a small gram-negative bacillus and causes nonspecific, noninflamatory vaginosis.

Clinical presentation.

About 50% of females who harbor Gardnerella vaginalis are asymptomatic. In others the organism, together of anaerobic organisms, sets up an infection that produces abundant vaginal discharge with an offensive, fishy odor. There is raised vaginal pH above 4.5.

Histology.

There is little inflammation of the vaginal wall. Pap-stained smears show myriads of tiny, adherent organisms coating desquamated epithelial cells, which are referred to as clue cells. There is absence of lactobacilli.

PAP smear showing clue cell.

Diagnosis.

• Examination of saline wet mount preparation or Pap smear shows clue cells.
• 10% KOH added to a drop of vaginal secretion produces a transient fishy odor — the so-called "sniff test".
• Selective culture may be done to isolate the organism.

Question. List some of the complications that can occur following gardnerella infection.

2. Candidiasis (Moniliasis)

The fungus Candida albicans causes this very common infection.

Clinical presentation

The disease presents with pruritus, a thick white vaginal discharge. The vaginal is sometimes only mildly reddened. There may be patches of white membrane or severe inflammation with edema and ulcers.

Histology.

Colonies of the fungus are present on the surface and extend into the epithelium but not into the underlying tissues. Mild edema and chronic inflammatory cells are present. If ulceration develops fungi are seen in the base of the ulcers with marked acute inflammation. Cytological smears show yeast forms and branching pseudohyphae.

Pap smear showing branched and budding Candida albicans.

3. Trichomoniasis

Trichomoniasis is caused by the unicellular flagellated protozoan, Trichomonas vaginalis. It is sexually transmitted. The disease involves not only the vagina but also lower urinary tract.

Clinical presentation

Most infections are asymptomatic and pass unnoticed. Occasionally, a copious, thin, frothy, yellow green to gray offensive discharge is produced. There may be vulvar itching or burning or dyspareunia.

Histology

The stroma of the vaginal wall may show an inflammatory infiltrate of lymphocytes and plasma cells. The organisms are not seen in biopsies because they do not invade the vaginal wall. Diagnosis is made by examination of a saline wet preparation in which the motile trophozoites are seen. The organism can also be found in Pap-stained vaginal smears.

Pap smear showing trophozoites of T. vaginalis.