Introduction of Gardnerella vaginalis
Gardnerella vaginalis is formerly known as Haemophilus vaginalis or Corynebacterium vaginale. It is normally isolated from the normal female genital tract in low numbers. It causes a condition called bacterial vaginosis.
Morphology of Gardnerella vaginalis
Haemophilus vaginalis is gram-negative but appears gram variable in smears. Non-motile, small pleomorphic rod, which shows metachromatic granules. Gardnerella vaginalis produces minute hemolytic colonies on blood agar, incubated aerobically under 5% CO2 for 24-48 hours. It is catalase, oxidase, indole, and urease negative.
Bacterial vaginosis organisms associated:
It affects women of reproductive age. It is associated with an alternation of the normal vaginal flora, which is as follows. Increase in the concentration of
- Gardnerella vaginalis.
- Mobiluncus (motile, curved, gram-variable, or gram-negative, anaerobic rods).
- Several other anaerobes (Prevotella and some Peptostreptococcus)
- Mycoplasma hominis.
Decrease in the concentrations of lactobacilli (lactobacilli usually maintain the acidic pH of the vagina, thereby inhibiting the growth of pathogenic organisms).
Risk factors
- Coexisting other infections like HIV, Chlamydia trachomatis, & Neisseria gonorrhoeae.
- Recent unprotected vaginal intercourse.
- Vaginal douching.
- Premature rupture of membranes and preterm labor.
Laboratory diagnosis of Gardnerella vaginalis
No associated inflammation. It is clinically diagnosed by Amsel’s criteria.
Amsel’s Criteria:
Bacterial vaginosis is diagnosed if any 3 of the following 4 findings are present:
- Profuse thin (low viscous), white homogeneous vaginal discharge uniformly coated on the vaginal wall.
- a pH of vaginal discharge more than 4.5.
- Accentuation of distinct fishy odor (attributable to volatile amines such as trimethylamine) immediately after vaginal secretions is mixed with 10% solution of KOH (Whiff test).
- Clue cells: They are vaginal epithelial cells coated with coccobacilli, which have a granular appearance and indistinct borders observed on a wet mount.
Nugent’s score:
It is a scoring system followed for the diagnosis of bacterial vaginosis; done by counting the number of Gardnerella vaginalis, Mobiluncus, and lactobacilli present in the Gram-stained smear of vaginal discharge. A score of more than or equal to seven is diagnostic characteristics.
Treatment
Oral metronidazole, given 500 mg twice daily for 7 days.
[embeddoc url=”https://notesmed.com/wp-content/uploads/2020/08/Gardnerella-vaginalis.pdf” download=”all”]