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Understanding Vaginal Infections: Bacterial Vaginosis

Vaginal infection or vaginitis, is a common group of infections that mostly affects females of age 15-49 years. It is the infection and inflammation of the vaginal tract, but can extend into the vulva, cervix, or ascend up into the reproductive organs. It occurs when the vaginal flora and normal vaginal pH are disturbed, causing an imbalance of the microbiome - the native “good” bacteria is displaced by another “bad” microbe that grows inside the vagina, leading to an infection.

Vaginal infections are mostly caused by 3 microbes - Gardnerella vaginalis (a bacteria), Candida species (a fungus), and Trichomonas vaginalis (a parasite). These are responsible for all the common forms of vaginal infections, namely bacterial vaginosis (BV), vulvovaginal candidiasis, and trichomoniasis, respectively.

In this article, we will take a closer look at bacterial vaginosis. Bacterial vaginosis is highly prevalent and the most common vaginal infection that affects women. It is estimated that the global prevalence ranges from 23-29%, and affects around 24% of the population in Asia. The exact prevalence of bacterial vaginosis in Singapore remains unknown and one of the reasons for that is that more than 80% of women infected with it do not experience any symptoms.

What is bacterial vaginosis?

Bacterial vaginosis, or simply “BV”, is the most common cause of abnormal vaginal discharge in females. This condition is characterized by a shift in the vaginal microbial environment away from the native “good” lactobacillus species that is a part of the normal vaginal environment, towards a more diverse “bad” bacterial species, most commonly Gardnerella vaginalis. This overgrowth of a foreign bacteria displaces the native “good” bacteria and results in an altered microbiome, a rise in vaginal pH (normal vaginal pH is less than 4.5), and symptoms that can range from none to very bothersome.

How does bacterial vaginosis occur?

Before getting into the details, it’s important to point out that bacterial vaginosis is not a sexually transmitted infection (STI) in the same way as other STIs like chlamydia or gonorrhea are. However, sexually active females are prone to getting BV and that can increase the risk of contracting other STIs due to changes in the vaginal environment. The risk of getting BV increases with frequency of sexual contact and the number of sexual partners. The risk is higher if one has recently changed sex partners, if one frequently douches (rinses out the vagina with water or a cleansing agent), or if one has a previous history of vaginal infections.

While males cannot get BV, their role in transmitting the bacteria is unclear. Some studies suggest that they may carry the bacteria and pass it on, whereas others present a negative view on that. On the other hand, between female partners, if one partner is affected with BV, the risk of passing the bacteria to an unaffected partner during sex is higher. But concrete evidence for this remains unclear too. Sometimes, the use of antibiotics for other infections can temporarily inhibit the good bacteria in the vagina, leading to an imbalance that may allow bad bacteria to grow, and thereby causing an infection. But it’s important to note that BV cannot be caused by toilet seats, bedsheets, or swimming.

What are the signs and symptoms of bacterial vaginosis? Many women with bacterial vaginosis do not show any signs and symptoms, and the condition can go away on its own without any treatment. That said, here are some clues that might indicate if one has bacterial vaginosis:

  • Thin whitish, gray, or green vaginal discharge

  • Increased vaginal discharge

  • Foul fishy odor, especially after sex

  • Vulvar or vaginal itching

  • Burning sensation during urination

If you notice any unusual signs or symptoms during your cycle, it's advisable to consult a doctor to get a proper diagnosis and treatment.

Possible complications of bacterial vaginosis Even though BV resolves by itself most of the time, if left untreated, it can cause some serious health complications like:

  • Increased risk of contracting other STIs like HIV and herpes

  • Increased risk of passing STIs, especially HIV, to sex partners

  • Possible risk of pelvic inflammatory disease if one contracts chlamydia or gonorrhea due to BV

  • Increased risk of delivering a preterm baby if the mother is not treated

  • Increased risk of infection post gynecological surgery

How is bacterial vaginosis diagnosed? There are specific criteria used to diagnose BV. These are called Amsel criteria and include 4 parameters. A person with suspected BV meets at least 3 out of 4 parameters:

  • Increased white homogenous discharge

  • Vaginal discharge has a PH of more than 4.5

  • Characteristic odor when mixed with a chemical (whiff test)

  • Presence of “clue cells” under the microscope

To perform the last 2 tests, a sample of the vaginal discharge or vaginal smear is required, which can be taken by a doctor or be self-taken using an at-home test kit. These tests also help in differentiating BV from the other two common causes of vaginitis, namely trichomoniasis and candidiasis.

Treatment for bacterial vaginosis Treatment is highly recommended for all symptomatic women, pregnant women, and those undergoing surgical abortion procedures. Treatment for bacterial vaginosis constitutes the following antimicrobials and topical agents:

  • Metronidazole, 2g in a single dose or 500mg twice a day for 5-7 days

  • Clindamycin vaginal cream (2%) applied before bedtime for 7 days

Along with the treatment, it is also advised to avoid vaginal douching or use other artificial cleansers. Probiotics supplements are often advertised as a possible treatment for BV, although substantial clinical evidence of their effectiveness is lacking. Follow-up after treatment If the symptoms resolve, follow-up with a doctor is not needed. The only time follow-up is required is in the case of high-risk pregnant women to check if treatment was successful. Since BV is completely curable, long-term treatments are not recommended and one can resume a healthy sexual life keeping said precautions in mind. Prevention of bacterial vaginosis Here are some ways through which one can protect herself from BV:

  • Use a condom during vaginal sex with male partners - Encourage male partners to use a condom while engaging in vaginal sex. This minimizes chances of recurrence of BV. Using a condom also reduces chances of getting an STI, which in turn, reduces predisposition towards BV.

  • Avoid vaginal irritation - Use mild soaps and unscented tampons or pads. The vagina does not require additional cleaning other than regular bathing. Contrary to popular belief, frequent douching will not clear vaginal infection, but rather cause it.

Treatment of male sex partners does not show a decrease in incidence, therefore it is not recommended. We hope you found this article useful. If you have any questions or concerns, feel free to reach out to us. If you notice any unusual vaginal symptoms, consult one of our doctors or take an at-home test to get a proper diagnosis and treatment. Check out our services here. ___________ References Kasper, D. L., et al. Harrison's principles of internal medicine (20th edition.). New York: McGraw Hill Education., 2018. (pg. 981-983) Ralston, Stuart H. Davidson’s Principles and Practice of Medicine. 23rd ed. Elsevier Health Sciences, 2018. (pg. 335-336)


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