Microbiology
Summary
Gardnerella vaginalis is a gram-variable (stains either gram-positive or gram-negative) bacillus that contributes to bacterial vaginosis, a common vaginal infection stemming from an imbalance in the vaginal bacteria.
Alterations in the usual vaginal flora, particularly lactobacilli, can trigger Gardnerella infections. The primary symptom of bacterial vaginosis is a thin, greyish white, malodorous discharge that may have a fishy odor. The discharge typically has a pH higher than 4.5 (around 5-6.5), aiding in distinguishing it from other vaginal discharges. The whiff test, involving a 10% KOH prep, reveals a positive result through a pungent odor. Under microscopic examination, clue cellsÑepithelial cells coated with bacteriaÑare distinctive. Metronidazole is the primary treatment for bacterial vaginosis.
Lesson Outline
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FAQs
Gardnerella vaginalis is a type of bacteria that can grow in the vagina. While it is normally present in small numbers, it can overgrow and lead to bacterial vaginosis. This condition is characterized by an imbalance in the vaginal flora, where beneficial bacteria are outnumbered.
Bacterial vaginosis often presents no symptoms, but when it does, they may include a fishy odor, particularly after intercourse, a grayish-white vaginal discharge, and occasionally vaginal itching or burning. These symptoms are linked to the overgrowth of Gardnerella vaginalis and other anaerobes in the vagina.
Gardnerella vaginalis creates an enzyme that breaks down vaginal mucus into amines, which becomes alkaline. This raises the vaginal pH above 4.5 (normal vaginal pH is between 3.8 and 4.5). The positive 'whiff test' or amine test involves the addition of 10% potassium hydroxide to the vaginal discharge. If a fishy odor is detected, the test is positive and bacterial vaginosis due to Gardnerella vaginalis is suspected.
Clue cells are epithelial cells of the vagina that get covered in bacteria, mainly Gardnerella vaginalis. Their presence is a major criterion for diagnosing bacterial vaginosis. Clue cells can be observed under a microscope in a sample of the vaginal discharge, and their presence confirms an overgrowth of the bacteria.
Metronidazole is often the treatment of choice for bacterial vaginosis caused by Gardnerella vaginalis. It is an antibiotic that can be taken orally or applied topically as a gel. Other antibiotics, such as clindamycin and tinidazole, can also be used in treatment. While these antibiotics effectively handle the condition, recurrence after treatment is common.
