Bacterial Vaginosis

Bacterial vaginosis (BV) is an infection of the vagina characterised by an excessive growth of bacteria. It is also known by other names, including anaerobic vaginositis, non-specific vaginitis, vaginal bacteriosis, and Gardnerella vaginitis.

BV often manifests with an increased vaginal discharge that smells like fish, and the discharge is typically white or grey in colour. While itching is uncommon, burning with urination may occur. BV can double the risk of infections such as HIV/AIDS and increase the likelihood of early delivery in pregnant women.

Signs and Symptoms

Approximately 50% of women with BV are asymptomatic. However, when symptoms do occur, they include increased vaginal discharge with a fishy odour. The discharge may coat the walls of the vagina without causing significant irritation, pain, or redness, although mild itching can sometimes occur. There is often a notable difference in the consistency and amount of discharge throughout the menstrual cycle, with the normal vaginal discharge being clearest at ovulation. BV is occasionally misdiagnosed due to the asymptomatic nature in many women.

Vaginal squamous cell with normal vaginal flora versus bacterial vaginosis on Pap stain

Complications

BV can lead to increased susceptibility to sexually transmitted infections, including HIV. It is associated with a higher risk of sexually transmitted infections like herpes simplex virus type 2 and human papillomavirus (HPV). Additionally, BV may increase the risk of pregnancy complications such as chorioamnionitis, miscarriage, preterm birth, premature rupture of membranes, and postpartum endometritis. Women undergoing in vitro fertilisation with BV also face lower implantation rates and higher rates of early pregnancy loss.

Causes

BV is caused by an imbalance in the vaginal microbiota, characterised by a decrease in Lactobacillus species and an overgrowth of bacteria such as Gardnerella vaginalis, Prevotella, and Bacteroides. Risk factors include douching, new or multiple sex partners, antibiotics, and using an intrauterine device. Douching is particularly discouraged as it disrupts the natural vaginal microbiota.

Diagnosis

Diagnosis involves obtaining a vaginal swab for testing. A Gramme stain can confirm BV by showing the depletion of lactobacilli and overgrowth of Gardnerella vaginalis. The "whiff test," which involves adding potassium hydroxide to a sample of vaginal discharge, can also indicate BV if a fishy odour is released. Additionally, a pH greater than 4.5 and the presence of clue cells under a microscope are suggestive of BV.

Phase contrast microscopy of clue cells in a vaginal swab

A pH indicator to detect vaginal alkalinisation (here showing approximately pH 8), and a microscope slide to microscopically detect clue cells

Gramme stain of cells from the vagina (the same magnification) with normal bacterial flora (top) and the bacteria that cause vaginosis (bottom)

Prevention

Preventive measures include avoiding douching, limiting the number of sex partners, and possibly using probiotics. Although probiotics may help prevent recurrence, the evidence is not strong enough to recommend their use definitively. Treating male partners does not appear to affect the recurrence of BV in women.

Treatment

The primary treatment for BV involves antibiotics such as metronidazole or clindamycin, which can be administered orally or vaginally. Although effective, recurrence rates are high, with about 10% to 15% of women not responding to the first course of antibiotics. Probiotics containing high doses of lactobacilli may help, particularly when administered intravaginally. Topical antiseptics such as dequalinium chloride and povidone-iodine may also be used, especially in non-pregnant, immunocompetent women.

In conclusion, while BV can be managed effectively with antibiotics, recurrence is common, necessitating further research into preventive measures and alternative treatments.

Self-assessment MCQs (single best answer)

Which of the following is NOT another name for Bacterial Vaginosis?

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What is the primary symptom of Bacterial Vaginosis?

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Which of the following complications is associated with Bacterial Vaginosis?

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What bacterium is commonly overgrown in cases of Bacterial Vaginosis?

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Which diagnostic test involves adding potassium hydroxide to a sample of vaginal discharge?

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What is a common risk factor for developing Bacterial Vaginosis?

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Which of the following is NOT a recommended treatment for Bacterial Vaginosis?

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What is the approximate percentage of women with BV who do not respond to the first course of antibiotics?

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Which of the following preventive measures is NOT supported by strong evidence?

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Which microscopic feature is suggestive of Bacterial Vaginosis?

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