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What is bacterial vaginosis?

Bacterial vaginosis (BV) is a vaginal infection characterized by a “fishy” smell, vaginal discharge, and a burning sensation in the vagina. BV is the most common vaginal infection causing women to seek medical care worldwide, with nearly 1 in 3 women of reproductive age affected at some point in their lives.1,2 BV is associated with a variety of adverse outcomes including preterm birth and pelvic inflammatory disease. Additionally, patients with BV are more susceptible to acquiring and transmitting a range of sexually transmitted infections (STIs), including HIV.3,4

In the United States, BV prevalence is highly dependent on race, occurring in 52% of black women and 23% of white women. This disparity remains unexplained.1

What are the common symptoms?

About 60% of BV cases are symptomatic. BV-related bacteria degrade vaginal mucus, leading to the primary symptom: an abnormal, malodorous, and off-white or gray vaginal discharge. They also produce vaginal redness and swelling, which leads to burning and itchy sensations in the vagina.4,5

BV is associated with a less-acidic vaginal pH. A healthy vagina should be acidic (pH 3.5 to 4.5), which prevents bacterial overgrowth. Higher pH values (>4.5) can allow the overgrowth of a bacterial species other than Lactobacillus.4

What are the causes?

Despite efforts to associate a specific microbiological agent to BV, the exact cause remains unclear. Many studies support a polymicrobial hypothesis, stating that BV is caused by a group of anaerobic pathogenic bacteria, and a complex interaction between the microbes and host.5,6 More specifically, scientists believe that the vaginal microbiota shifts from a predominance of Lactobacillus to a diverse anaerobic bacteria predominance, mainly of Gardnerella vaginalis. However, the trigger event for this shift in the microbiota is unknown.

There are several sexual risk factors associated with BV, such as7:

  • High number of lifetime sexual partners
  • High frequency of vaginal intercourse
  • Young age at the time of first intercourse

Other risk factors include4,7:

  • Smoking
  • Underlying immune deficiencies
  • Regular douching (vaginal washes)
  • History of pregnancy
  • Antibiotic treatment

How does this topic relate to my microbiome?

In most healthy vaginas, 90-95% of the microorganisms are Lactobacillus species, which maintain the vaginal pH between 3.5 and 4.5. In a patient with BV, the microbiome is imbalanced towards a polybacterial environment, where anaerobic pathogenic bacteria overgrow. It is still unclear how these bacteria play a role in the cause and symptoms of BV, but it is believed that Gardnerella vaginalis is the triggering pathogen for the disease.8

Several studies have implicated a series of microbial pathogens – alone and in combination – in the disease process. The ever-expanding list of possible pathogens include: Gardnerella, Atopobium, Prevotella, Peptostreptococcus, Mobiluncus, Sneathia, Leptotrichia, Mycoplasma, and BV-associated bacterium 1 (BVAB1) to BVAB3.4

Which diseases/topics are related to bacterial vaginosis?

BV is a type of vaginitis that involves inflammation and infection of the vagina. Other types of vaginitis include vaginal yeast infection, caused by an overgrowth of yeast; and trichomoniasis, caused by a sexually transmitted parasite.

The presence of BV increases the risk of acquiring sexually transmitted infections (STIs) via intercourse, including herpes, syphilis, gonorrhea, chlamydia, and HIV. It is believed that a higher vaginal pH (>4.5) may allow pathogens to adhere and survive.7 Other health issues related to BV include preterm birth and pelvic inflammatory disease.5,7

How can I take action?

BV should not be self-diagnosed nor self-treated. Visiting a health care provider is highly recommended, where a sample of vaginal discharge will be taken for lab tests so the provider can rule out other diseases. Treatment for BV usually consists of oral antibiotics or the application of gel or cream based intravaginal antibiotics. It is very important to take the entire course of antibiotics and follow the given instructions correctly to avoid BV recurrence.

Preventive measures include5,9:

  • Avoiding douching and/or the use of soaps inside or around the vagina
  • Circumcision of male partners
  • Limiting the number of sexual partners
  • Oral and intravaginal probiotics

References

1. Esber, A., Vicetti Miguel, R. D., Cherpes, T. L., Klebanoff, M. A., Gallo, M. F., & Turner, A. N. (2015). Risk of Bacterial Vaginosis Among Women With Herpes Simplex Virus Type 2 Infection: A Systematic Review and Meta-analysis. Journal of Infectious Diseases, 212(1), 8–17.

2. Srinivasan, S., et al. (2015). Metabolic signatures of bacterial vaginosis. MBio, 6(2), e00204-15.

3. Kenyon, C., Colebunders, R., & Crucitti, T. (2013). The global epidemiology of bacterial vaginosis: a systematic review. American Journal of Obstetrics and Gynecology, 209(6), 505–523.

4. Onderdonk, A. B., Delaney, M. L., & Fichorova, R. N. (2016). The Human Microbiome during Bacterial Vaginosis. Clinical Microbiology Reviews, 29(2), 223–238.

5. Marrazzo, J. M., & Hillier, S. L. (2013). Bacterial Vaginosis. In Sexually Transmitted Diseases (pp. 463–498).

6. Machado, A., & Cerca, N. (2015). Influence of Biofilm Formation by Gardnerella vaginalis and Other Anaerobes on Bacterial Vaginosis. Journal of Infectious Diseases, 212(12), 1856–1861.

7. Bautista, C. T., Wurapa, E., Sateren, W. B., Morris, S., Hollingsworth, B., & Sanchez, J. L. (2016). Bacterial vaginosis: a synthesis of the literature on etiology, prevalence, risk factors, and relationship with chlamydia and gonorrhea infections. Military Medical Research, 3(1), 4.

8. Schwebke, J. R., Muzny, C. A., & Josey, W. E. (2014). Role of Gardnerella vaginalis in the Pathogenesis of Bacterial Vaginosis: A Conceptual Model. The Journal of Infectious Diseases, 210(3), 338–343.

9. MacPhee, R. A., Hummelen, R., Bisanz, J. E., Miller, W. L., & Reid, G. (2010). Probiotic strategies for the treatment and prevention of bacterial vaginosis. Expert Opinion on Pharmacotherapy, 11(18), 2985–2995.