Laboratory diagnosis of Bacterial vaginosis caused by Gardnerella vaginalis

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Last Updated on February 4, 2021 by Sagar Aryal

Laboratory diagnosis of Bacterial vaginosis caused by Gardnerella vaginalis

Specimen: Vaginal discharge specimen

A. Direct Microscopic Examination

  • Bacterial Vaginosis (BV) is characterized by a foul-smelling discharge.
  • A diagnosis/confirmation is done microscopically by examination of gram stains to detect change in vaginal ecology.
  • A smear of vaginal fluid or vaginal swab is gram stained which reveals the presence of Gram negative bacilli sometimes Gram variable.

B. Culture

  • It requires enriched media such as blood agar, loeffler’s serum slope or dextrose starch agar.
  • Optimum temperature is 37°C and optimum pH is 6.8 for growth, incubation for 48 hours.
  • Growth is enhanced by 5% carbondioxide and moisture .
  • Colony morphology : small domed colonies surrounded by beta hemolysis develop in human or rabbit blood agar
  • There is a zone of clearing on dextrose starch agar.

C. Amsel criteria

Besides the Gram stain, BV can be diagnosed by using the Amsel criteria (Clinical Diagnosis):

  • Thin, white, yellow, homogeneous discharge.
  • pH measurement of vaginal fluid >4.5
  • Performance of an amine test: Release of a fishy odor on adding alkali—10% potassium hydroxide (KOH) solution (Whiff Test)
  • Wet mount microscopy of vaginal secretions: observation for clue cells

Treatment of Bacterial vaginosis

  • Oral metronidazole is generally curative.
  • Besides these clindamycin can be suggested as topical use.

Prevention and control of Bacterial vaginosis

  • Personnel hygiene
  • Avoidance of multiple sex partner

1 thought on “Laboratory diagnosis of Bacterial vaginosis caused by Gardnerella vaginalis”

  1. I am conducting research on microbial isolates and antibiotic sensitivity pattern among women with preterm prelabour rupture of membranes in a Nigerian Teaching Hospital. kindly send me articles on laboratory diagnosis of bacterial vaginosis.


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