Gardnerella vaginalis

The bacterium was discovered and characterized in the 1950s by Hermann L. Gardner and Charles D. Dukes, a microbiologist and a gynecologist, respectively, and named after L. Gardner.

Gardnerella vaginalis is a small, pleomorphic, immobile non-spore-forming rod bacterium that is Gram-labile. However, it belongs to the gram-positive bacteria and is related to Bifidobacterium. In the genus Gardnerella, Gardnerella vaginalis is the only representative.

Gardnerella vaginalis exists in at least 4 different strains, only one of which is significantly common in bacterial vaginosis. Physiologically, it colonizes the vagina in small amounts (10/ml vaginal secretion) . It is therefore also for this reason insignificant to detect Gardnerella vaginalis culturally.

When the normal vaginal flora is disturbed, when lactobacilli are reduced and the pH rises to >4.5, they multiply. Degradation of proteins results in the formation of fish-smelling amines (amine colpitis). In the so-called "bacterial vaginosis", a non-specific vulvovagintis characterized by a thin fluorine, large bacterial numbers of Gardnerella vaginalis are found together with various anaerobes, e.g. Atopobium vaginale , Morbilucus spp, Prevotella bivia, Fusobacterium nucleatum, and Peptoniphilus species (Machado A et. al. 2015). In this disease, so-called clue cells are found in the vaginal smear. These are vaginal epithelial cells that have a dense bacterial lawn on their surface. The current paradigm is that the establishment of a Gradnerella induced biofilm plays a key role in the pathogenesis of bacterial vaginosis.

Detection of the organism on routinely used media is difficult because Gardnerella and other bacteria, such as Lactobacillus and Streptococcus, can produce alpha-hemolysis on media containing sheep blood. However, on media containing human blood, Gardnerella vaginalis produces a characteristic beta hemolysis. Since Gardnerella vaginalis, although often considered gram-negative, is a gram-positive bacterium (gram-labile), it can be selected on media containing colistin and nalixic acid.

Recommended therapy for bacterial vaginosis:

• Metronidazole: 500 mg p.o./2 x daily/5-7 days.
• Clindamycin vaginal cream 2% 5 g intravaginally/1x daily/7 days
• Clindamycin:300 mg p.o./2 x daily/7 days

Alternative therapy:

• Metronidazole: 1 x 2 g as ED
• Tinidazole 1 x 2 g as ED (CAVE: Tinidazole only available through international pharmacy).
• Tinidazole 1g/1x daily for 5 days (CAVE: Tinidazole only available through international pharmacy)
• Dequalinium chloride 10mg vaginal tablets/1x daily/6 days