Bacterial vaginosis (BV) : Quick Guide to the Commonest Vaginal Infection in the World.


So What is Bacterial Vaginosis?

You may or may not come across it, but BV is the most common “infectious” conditional in the female genital tract

Bacterial vaginosis (BV) is a condition characterized by an overgrowth of certain bacteria in the vagina, disrupting the normal balance of microorganisms present. The exact pathogenesis of BV is not fully understood, but several factors contribute to its development.

How Common is BV

Very Common.  We are talking 1in 3 women at any given time, and rising to 1 in 2 among African American women, as per the CDC.   Despite this, not much is known about how it occurs, how it spreads or how to prevent it. In Kenya we do not have accurate (population wide) statistics but few studies available show bacterial vaginosis is very common.

This is of concern to patients and healthcare providers, more of that later in the post

What Leads to Bacterial Vaginosis?


1. Disruption of vaginal microbiota: 

The vagina normally contains a diverse range of bacteria, including Lactobacillus species, which help maintain a slightly acidic pH and prevent the overgrowth of harmful bacteria. In BV, there is a decrease in the number of lactobacilli, leading to an increase in other bacteria.


2. Overgrowth of anaerobic bacteria:

 BV is associated with an overgrowth of anaerobic bacteria, such as Gardnerella vaginalis, Prevotella spp., and Mobiluncus spp. These bacteria thrive in an environment with reduced oxygen levels, which is characteristic of BV.


3. Biofilm formation: 

Bacterial biofilms are complex structures formed by bacteria that adhere to each other and to the vaginal epithelium. Biofilms provide a protective environment for bacteria, making them more resistant to antibiotics and the body’s immune response. Biofilm formation is thought to play a role in the persistence and recurrence of BV.


4. Loss of vaginal acidity: 

Lactobacilli produce lactic acid, which helps maintain the vaginal pH at around 3.8-4.5, creating an acidic environment that inhibits the growth of harmful bacteria. In BV, the pH becomes more alkaline (above 4.5), favoring the growth of anaerobic bacteria.


5. Sexual activity: 

BV is more commonly observed in sexually active women, suggesting that sexual transmission or the introduction of new bacteria from sexual partners may contribute to its development. However, BV can also occur in women who are not sexually active.

6. Host factors: 

Certain host factors, such as hormonal changes (e.g., during menstruation), smoking, douching, and immune system dysfunction, may increase the risk of developing BV. These factors can disrupt the vaginal microbiota and create an environment conducive to the overgrowth of bacteria.


It is important to note that the exact sequence and interplay of these factors in the pathogenesis of BV are still being studied, and further research is needed to fully understand the mechanisms involved.

Note: This article is part of our Sexually Transmitted Infections Series

Bacterial Vaginosis
Bacterial Vaginosis

Symptoms of BV

The symptoms of bacterial vaginosis (BV) can vary from person to person, and some individuals may not experience any symptoms at all. However, common signs and symptoms of BV include:


1. Vaginal discharge:

 The most common symptom of BV is an abnormal vaginal discharge. The discharge is typically thin, grayish-white, and may have a strong, fishy odor. The odor is often more noticeable after sexual intercourse.


2. Vaginal odor: 

BV can cause a distinct odor that is often described as fishy. This odor is usually more pronounced after sexual activity or during menstruation.


3. Vaginal itching or irritation: 

Some women with BV may experience mild to moderate vaginal itching or irritation. This symptom is less common but can occur in certain cases.


4. Burning sensation during urination: 

BV can sometimes cause a burning sensation or discomfort during urination. This symptom is less common and may be associated with inflammation or irritation of the urinary tract.


It is important to note that these symptoms are not specific to BV and can also occur with other vaginal infections or conditions. Therefore, it is recommended to consult a healthcare provider for an accurate diagnosis if you experience any of these symptoms. They can perform a physical examination, evaluate your medical history, and may conduct laboratory tests to confirm the diagnosis of BV.


Laboratory Diagnosis of BV

Bacterial vaginosis (BV) is typically diagnosed through a combination of clinical evaluation and laboratory tests. The diagnosis is made by a healthcare provider, usually a gynecologist or primary care physician. The following methods are commonly used for diagnosing BV:

1. Medical history and physical examination: 

The healthcare provider will ask about your symptoms, medical history, sexual activity, and any previous vaginal infections. They will also perform a physical examination of the vaginal area to check for signs of BV, such as abnormal discharge or odor.

2. pH testing: 

A pH test may be performed to measure the acidity of the vaginal environment. In BV, the pH is usually higher than 4.5, indicating an alkaline environment.


3. Wet mount microscopy: 

A sample of vaginal discharge may be collected and examined under a microscope. This test helps identify the presence of clue cells, which are vaginal epithelial cells covered with bacteria. Clue cells are a characteristic finding in BV.


4. Whiff test:

 A sample of vaginal discharge is mixed with a solution of potassium hydroxide (KOH). The presence of a fishy odor when the solution is added is considered a positive whiff test, indicating BV.


5. Laboratory cultures:

 In some cases, a sample of vaginal discharge may be sent to the laboratory for culture. This test helps identify the specific bacteria causing the infection and can help rule out other vaginal infections.


It is important to note that self-diagnosis of BV based solely on symptoms is not recommended. Some symptoms of BV can resemble other vaginal infections, such as yeast infections or sexually transmitted infections. Therefore, it is crucial to consult a healthcare provider for an accurate diagnosis and appropriate treatment as outlined below.

The Amsel criteria and Nugent score 


The Amsel criteria and Nugent score are two commonly used methods to diagnose bacterial vaginosis (BV). Here’s a brief description of each:


 Amsel criteria:

The Amsel criteria are a set of four clinical criteria used to diagnose BV. To meet the Amsel criteria, a patient must have at least three of the following four criteria:  

 a. Thin, white, or gray vaginal discharge

   b. Presence of a “fishy” odor, particularly after the addition of KOH during the whiff test

   c. Vaginal pH higher than 4.5

   d. Presence of clue cells on microscopic examination of vaginal discharge (clue cells are vaginal epithelial cells covered with bacteria, which are indicative of BV)

If a patient meets three or more of these criteria, they are typically diagnosed with BV.

Nugent score:

 The Nugent score is a scoring system used to assess the composition of vaginal bacteria and diagnose BV based on microscopic examination of a vaginal smear.

The vaginal smear is stained and examined under a microscope to quantify the presence of three types of bacteria:

👉lactobacilli (healthy vaginal bacteria),

👉Gardnerella vaginalis (bacteria associated with BV), and

👉other anaerobic bacteria (also associated with BV).

The Nugent score ranges from 0 to 10, with a score of 0-3 considered normal (indicating a healthy vaginal microbiome), 4-6 indicating intermediate flora, and 7-10 indicating BV. A higher Nugent score indicates a higher concentration of BV-associated bacteria.

Both the Amsel criteria and Nugent score are widely used in clinical practice to diagnose BV. They provide different approaches to diagnosing BV, with the Amsel criteria relying on clinical symptoms and the Nugent score focusing on microscopic examination of vaginal bacteria. Healthcare providers may use one or both of these methods to make an accurate diagnosis of BV.

Treatment for Bacterial Vaginosis


The treatment of bacterial vaginosis (BV) typically involves the use of antibiotics to eliminate the overgrowth of harmful bacteria and restore a healthy balance of vaginal flora. The specific antibiotic prescribed, dosage, and duration of treatment may vary depending on individual factors and healthcare provider’s discretion. Here are some common treatment options for BV:


1. Oral antibiotics:

 The most commonly prescribed oral antibiotics for BV include metronidazole (Flagyl) and clindamycin. These medications are usually taken for 7 days, but shorter courses may also be effective. It is important to complete the full course of antibiotics, even if symptoms improve, to ensure complete eradication of the infection.


2. Topical antibiotics:

 In some cases, healthcare providers may prescribe topical antibiotic treatments, such as metronidazole gel or clindamycin cream, to be applied directly to the vagina. These treatments are typically used for 5 to 7 days.


3. Alternative treatments: 

Some alternative treatments, such as probiotics or vaginal suppositories containing lactobacillus, may be recommended to help restore the balance of healthy bacteria in the vagina. However, the effectiveness of these treatments in BV is still being studied, and they are not considered standard treatment options.


It is important to note that sexual partners of individuals with BV usually do not require treatment unless they are experiencing symptoms. However, using condoms during sexual activity may help reduce the risk of recurrent BV.


After completing treatment, it is recommended to schedule a follow-up appointment with your healthcare provider to ensure that the infection has been successfully treated. Recurrent BV may require additional or prolonged treatment, and your healthcare provider can guide you on the appropriate steps to take.


It is crucial to follow the prescribed treatment plan and complete the full course of antibiotics, even if symptoms improve, to prevent recurrence and complications. Additionally, it is advisable to avoid douching, as it can disrupt the natural balance of vaginal bacteria and increase the risk of BV.


Complications of Bacterial Vaginosis

If left untreated, bacterial vaginosis (BV) can lead to several complications. Some of the potential complications of BV include:

1. Increased risk of sexually transmitted infections (STIs): 

BV can increase the risk of acquiring or transmitting STIs, such as HIV, herpes simplex virus (HSV), gonorrhea, and chlamydia. This is because the imbalance in vaginal bacteria can disrupt the protective barrier of the vagina, making it easier for STIs to enter the body.


2. Pelvic inflammatory disease (PID):

 BV has been associated with an increased risk of developing PID, which is an infection of the reproductive organs in women. PID can cause severe pelvic pain, infertility, and complications during pregnancy.


3. Preterm birth: 

Pregnant women with untreated BV have a higher risk of preterm birth (delivering the baby before 37 weeks of gestation). Preterm birth can lead to various health problems for the baby, including respiratory issues, developmental delays, and low birth weight.


4. Postoperative infections: 

Women with BV who undergo gynecological procedures, such as hysterectomy or abortion, may have an increased risk of developing postoperative infections.


5. Increased risk of endometritis:

 BV can increase the risk of developing endometritis, which is an infection of the lining of the uterus. This condition can cause pelvic pain, fever, and abnormal vaginal bleeding.


6. Recurrence of Bacterial Vaginosis: 

BV has a high rate of recurrence, with up to 30% of women experiencing a recurrence within three months after treatment. Recurrent BV may require additional or prolonged treatment to prevent complications and manage symptoms.


It is important to seek medical attention and receive appropriate treatment for BV to prevent these potential complications. Regular gynecological check-ups and practicing safe sex can also help reduce the risk of developing complications associated with BV.


Commentary: Is there gender bias in BV Research?


The lack of adequate research in bacterial vaginosis (BV)may  indicate perversive  gender bias in healthcare. While it is true that there are disparities in research funding and attention given to certain health conditions, it is important to consider various factors that contribute to the research gaps in BV.


  1. Historical underrepresentation: Historically, women have been underrepresented in clinical trials and medical research. This underrepresentation can lead to a lack of data and knowledge about conditions that primarily affect women, including BV.


  1. Stigma and taboo: Vaginal health and conditions like BV have often been stigmatized or considered taboo, leading to limited public awareness and discussion. This can result in limited funding and research interest in these areas.


  1. Complex nature of BV: BV is a complex condition with multifactorial causes and a dynamic microbiome. Understanding and studying BV requires sophisticated research methods, including advanced molecular techniques, which can be resource-intensive and challenging to conduct.
  2. Misdiagnosis and underdiagnosis: BV can be easily misdiagnosed or underdiagnosed due to overlapping symptoms with other vaginal infections. This can lead to confusion and difficulty in accurately studying the condition.


While gender bias in healthcare is a valid concern, it is essential to recognize that research gaps can be influenced by various factors, including historical underrepresentation, stigma, and the complexity of the condition.

 Addressing these gaps requires a multi-faceted approach that involves increasing awareness, funding, and research efforts in women’s health, including conditions like BV.


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