Laboratory diagnosis of Bacterial vaginosis caused by Gardnerella vaginalis

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