What is the diagnosis and treatment for Gardnerella vaginalis (Bacterial Vaginosis)?

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Last updated: May 13, 2025View editorial policy

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From the Guidelines

Gardnerella vaginalis infections should be treated with oral metronidazole 500 mg twice daily for 7 days or metronidazole gel 0.75% intravaginally once daily for 5 days to relieve symptoms and prevent complications. Gardnerella vaginalis is a bacterium commonly associated with bacterial vaginosis (BV), a vaginal infection characterized by an imbalance in the normal vaginal flora. Treatment typically involves antibiotics, with metronidazole being the first-line option, as recommended by the CDC guidelines 1. The goal of therapy is to relieve vaginal symptoms and signs of infection, and to reduce the risk of infectious complications associated with BV during pregnancy 1.

Treatment Options

  • Oral metronidazole 500 mg twice daily for 7 days
  • Metronidazole gel 0.75% intravaginally once daily for 5 days
  • Clindamycin cream 2% intravaginally at bedtime for 7 days as an alternative option

Special Considerations

  • All symptomatic pregnant women should be tested and treated because BV is associated with premature rupture of the membranes, preterm labor, and preterm birth 1
  • High-risk pregnant women (i.e., those who have previously delivered a premature infant) who are asymptomatic may be screened, and those with BV can be treated with metronidazole 250 mg orally three times a day for 7 days 1
  • A follow-up evaluation should be done one month after completion of treatment to verify that therapy was effective 1

From the Research

Gardnerella Vaginalis Overview

  • Gardnerella vaginalis is a bacterium associated with bacterial vaginosis (BV), a common cause of vaginitis worldwide 2.
  • BV is linked to serious reproductive health outcomes, including increased risk of preterm birth, sexually transmitted infections, and pelvic inflammatory disease 2.

Treatment of Gardnerella Vaginalis

  • The current FDA-approved treatment regimens for BV are antibiotics, such as metronidazole and clindamycin 2.
  • Pivampicillin has been shown to be a useful alternative to metronidazole therapy in the treatment of Gardnerella vaginalis associated bacterial vaginosis 3.
  • Clindamycin therapy has been found to have a better clinical efficacy than metronidazole in cases of recurrent bacterial vaginosis 4.

Antibiotic Resistance

  • Studies have shown that Gardnerella vaginalis isolates are often resistant to metronidazole, with resistance rates ranging from 58.82% to 87.5% 4, 5, 6.
  • Clindamycin has been found to be more effective against Gardnerella vaginalis, with lower resistance rates ranging from 23.33% to 27.3% 4, 5, 6.
  • Biofilm formation by Gardnerella vaginalis can contribute to antibiotic resistance, making treatment more challenging 5, 6.

Biofilm Formation

  • Biofilm formation by Gardnerella vaginalis has been observed in clinical isolates, with 11 out of 24 samples forming biofilms in one study 6.
  • The minimum biofilm eradication concentration (MBEC) of metronidazole and clindamycin has been found to be high, indicating that neither antibiotic is able to effectively eradicate vaginal biofilms 5, 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Antimicrobial Susceptibility Testing of Metronidazole and Clindamycin against Gardnerella vaginalis in Planktonic and Biofilm Formation.

The Canadian journal of infectious diseases & medical microbiology = Journal canadien des maladies infectieuses et de la microbiologie medicale, 2020

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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