Lab Update 9 – Bacterial Vaginosis Multiplex PCR

June 2019
Ampath | ampath.co.za

Overview

Bacterial vaginosis (BV) is a condition characterised by an imbalance in the vaginal flora. It is one of the most common causes of vaginal discharge in women of reproductive age. BV is associated with several complications, including:

• Increased risk of acquiring sexually transmitted infections (STIs), including HIV.
• Development of pelvic inflammatory disease (PID).
• Adverse reproductive outcomes, especially preterm delivery.

Timely diagnosis and treatment of BV is essential to avoid these complications.

Limitations of Traditional Diagnosis

Common diagnostic methods such as:

• Amsel’s criteria
• Nugent scoring system

...are subjective and often lack adequate sensitivity and specificity.

Introduction of a Molecular Diagnostic Panel

Ampath has introduced a multiplex molecular assay for the diagnosis of bacterial vaginosis. This test offers improved sensitivity and specificity, particularly useful in recurrent vaginitis/vaginosis cases.

How the Assay Works

• The test determines the ratio of beneficial vaginal bacteria to BV-associated bacteria, similar to the Nugent score.
• Candida species and Trichomonas vaginalis are also detected, as they are common causes of vaginitis/vaginosis.

Organisms Detected and Result Interpretation

✅ Bacterial Vaginosis Panel

• Beneficial vaginal bacteria detected:
  • Lactobacillus species
• BV-associated bacteria detected:
  • Gardnerella vaginalis
  • Atopobium vaginae
  • Megasphaera-1 (grouped under BV-associated bacteria-2)
• Result reporting:
  • Positive
  • Negative
• Comment:
  • Result reflects the ratio of beneficial vs. BV-associated bacteria.

✅ Candidiasis Panel

• Detected Candida groups and species:
  • Candida group (includes):
    • Candida albicans
    • Candida tropicalis
    • Candida parapsilosis
    • Candida dubliniensis
  • Candida species reported separately:
    • Candida glabrata
    • Candida krusei
• Result reporting for each:
  • Positive
  • Negative
• Comments:
  • C. glabrata and C. krusei are reported separately due to likely resistance to azole antifungal therapy.
  • A positive Candida result should only be treated if clinical signs of vulvovaginal candidiasis are present.

✅ Trichomoniasis Panel

• Pathogen detected:
  • Trichomonas vaginalis
• Result reporting:
  • Positive
  • Negative
• Comment:
  • Offers improved sensitivity compared to microscopy.

Sample Requirements

• Suitable sample: Dry vaginal swab
  • Can be collected by the clinician or self-collected by the patient
• Unsuitable sample: High cervical swab
  • Not appropriate for diagnosing vaginitis/vaginosis

Test Details

• Test Mnemonic: BVPCR
• Turnaround Time: 24 to 48 hours

📌 For further information, please contact your local Ampath pathologist.