What causes recurrent bacterial vaginosis (BV) in patients?

Causes of Recurrent Bacterial Vaginosis (BV)

Recurrent bacterial vaginosis is primarily caused by disruption of the normal vaginal microbiome, with replacement of hydrogen peroxide-producing Lactobacillus species by anaerobic bacteria, without a single definitive cause, requiring a multifaceted treatment approach to address the various contributing factors. 1, 2, 3

Pathophysiology of Recurrent BV

• BV results from replacement of normal H₂O₂-producing Lactobacillus species with high concentrations of anaerobic bacteria (Bacteroides spp, Mobiluncus spp), G. vaginalis, and Mycoplasma hominis 1
• After antibiotic treatment, beneficial strains of Lactobacillus, such as L. crispatus, often fail to recolonize the vagina, leading to recurrence rates of 50-80% within one year 3
• Biofilm formation may protect BV-causing bacteria from antimicrobial therapy, contributing to persistence and recurrence 4

Risk Factors for Recurrent BV

• Sexual activity is associated with BV acquisition, as women who have never been sexually active are rarely affected 1
• Having multiple sexual partners increases the risk of BV acquisition 1
• Although not exclusively considered an STD, sexual behaviors may contribute to recurrence 1, 3
• Smoking has been identified as a modifiable risk factor for recurrence 3
• Hormonal fluctuations and menstruation can disrupt vaginal flora balance 2

Diagnostic Considerations

• Confirm diagnosis using clinical criteria (Amsel's criteria) requiring three of the following four findings:
  • Homogeneous, white, non-inflammatory discharge adhering to vaginal walls
  • Presence of clue cells on microscopic examination
  • Vaginal fluid pH greater than 4.5
  • Fishy odor of vaginal discharge before or after addition of 10% KOH (whiff test) 1, 5
• Gram stain of vaginal secretions is an acceptable laboratory method for diagnosing BV 1
• For recurrent cases, vaginal cultures should be obtained to confirm the clinical diagnosis 2

Treatment Approaches for Recurrent BV

• Standard treatment for initial BV episodes includes:

  • Metronidazole 500 mg orally twice daily for 7 days 1
  • Alternative: Metronidazole 2g orally in a single dose 1

• For recurrent BV, extended treatment regimens are recommended:

  • Extended course of metronidazole (500 mg twice daily for 10-14 days) 4
  • If ineffective, metronidazole vaginal gel 0.75% for 10 days, followed by twice weekly application for 3-6 months 4

• Combination approaches for persistent recurrence:

  • Oral nitroimidazole with simultaneous boric acid (600 mg daily per vagina) for 30 days, followed by twice-weekly vaginal metronidazole gel for 5 months has shown promising results 6

Partner Management

• Traditional guidelines state that treatment of male sex partners has not been shown to alter the clinical course of BV in women during treatment or affect the relapse/reinfection rate 1
• However, for women with recurrent infection, partner treatment may be considered, though evidence for this approach is limited 2

Prevention Strategies

• Consider behavioral modifications:

  • Smoking cessation
  • Consistent condom use
  • Hormonal contraception 3

• Emerging approaches under investigation:

  • Probiotics to restore normal vaginal flora
  • Biofilm disruption techniques
  • pH modulation strategies
  • Vaginal microbiome transplantation 3, 4

Common Pitfalls to Avoid

• Failing to rule out other causes of vaginitis that may coexist with or mimic BV 2
• Not evaluating for underlying conditions that may contribute to recurrent infections 2
• Overlooking the development of vaginal candidiasis during prolonged antibiotic treatment, which frequently complicates extended antimicrobial regimens 6
• Poor adherence to treatment regimens, which may contribute to antimicrobial resistance 4

Follow-Up Recommendations

• Schedule follow-up visits to assess treatment response and adjust therapy as needed 2
• Instruct patients to return if symptoms persist or recur after completing extended treatment regimens 2
• Consider maintenance therapy for patients with multiple recurrences 4