Bacterial Vaginosis

Written by : Dr.M.D.Mazumdar, MD

Bacterial vaginosis is a condition in which there is an overgrowth of some of the normal bacteria in the vagina. It is not an infection, although the symptoms it produces are typically those of an infectious condition. It is not a sexually transmitted disease (STD)

The vagina normally contains a number of bacteria and other microorganisms which remain in balance with each other - this is known as the vaginal flora or vaginal microbiota. These bacteria maintain a healthy vaginal environment and do not cause symptoms. But an imbalance in the bacteria in relation to each other due to overgrowth of some types of bacteria can cause Bacterial Vaginosis (BV).

Bacterial vaginosis was earlier called Gardnerella Vaginitis since it was believed that a type of bacteria known as the Gardnerella Vaginalis was the main bacteria responsible for this condition. But it is now known as Bacterial Vaginosis (BV) since a number of other bacteria has also been known to cause this condition. It is believed however that Gardnerella Vaginalis is the first bacteria to be affected and overgrowth of this bacteria causes a biofilm which helps other bacteria to grow as well.

Cause of Bacterial Vaginosis:

It is known that the main predisposing factor of BV is a change in the ph (acidity) of the vagina. The normal ph of the vagina is slightly acidic ( about 4.5). An acidic vaginal environment is protective. It creates a barrier that prevents unhealthy bacteria and yeast from multiplying too quickly and maintains the growth of the different bacteria in equilibrium. But if there is a reduction of the normal hydrogen peroxide-producing lactobacilli in the vagina due to any cause, the ph changes to a less acidic one. This change in ph helps in the overgrowth of of other types of bacteria, especially anaerobic bacteria (bacteria that grow in the absence of oxygen). The overgrowth of these bacterias causes the typical symptoms of BV.

Risk Factors of Bacterial Vaginosis:

- Douching: Douching the vagina is one of the important causes of BV. Douching causes washing out of the vagina and upsets the bacterial balance. This changes the ph of the vagina and allows bacteria like gardnerella to grow abundantly and cause BV.

- New or Multiple Sexual partners: Semen is slightly alkaline. A change in the sexual partner or multiple sexual partners can cause the ph of the vagina to be affected.

- Recent antibiotic use: Antibiotics which are used for other infections like a throat infection, can kill off the healthy lactobacilli in the vagina. This causes the ph to change and allows the overgrowth of bacteria like gardnerella.

- Smoking: Smoking causes constriction of blood vessels - this increases the risks of getting BV.

- IUD: The thread of the IUD in the vagina can sometimes act as the locus of infection.

Spread of Bacterial Vaginosis:

BV is not spread from toilet seats, swimming pools or hot tubs or from touching contaminated objects. It generally develops due to change in ph in the vaginal environment .

Symptoms of Bacterial Vaginosis:

About half of all women who have BV do not have any symptoms at all. The BV is an incidental finding during investigation for some other cause.But some of the common symptoms are:

- Vaginal Discharge - The most common symptom of BV is a thin, creamy, vaginal discharge which may be grayish or yellowish in colour. It often smells fishy, the smell increasing after sex or just after the periods. The discharge coats the vaginal walls in a thin layer.

- Some women may have burning while passing urine. This occurs when the urine, which is usually acidic, flows over the inflamed vaginal opening.

- There may be itching or irritation after sex. Irritation occurs due to friction of the penis with the inflamed vaginal walls. Some women complain of pain during sex due to the same reason.

Bacterial Vaginosis
Bacterial Vaginosis

Differential Diagnosis of Bacterial Vaginosis: BV needs to be differentiated from the following conditions:

- Normal vaginal discharge

- Candidiasis (Thrush or yeast infection).

- Trichomoniasis - a STD caused by an organims known as Trichomonas vaginalis

- Menopausal Vaginitnits (Atrophic vaginitis)

- Other conditions whcich cause vaginal discharge like gonorrhea should also be ruled out.

Diagnosis of Bacterial Vaginosis: A swab taken from the vagina should be tested for:

- The Whiff Test : A small amount of potassium hydroxide is added to vaginal discharge placed on a slide. A characteristic 'fishy smell' arises if BV is present. This is known as a positive whiff test.

- Ph of the vaginal discharge: Normally, the ph (acidity) of the vagina is lower than 7 (between 3.8 and 4.5), which indicates a moderately acidic environment. The ph is tested by placing a swab of the vaginal discharge on a litmus paper. A ph greater than 4.5 is considered suggestive of the presence of Bacterial Vaginosis.

- Clue cells: Clue cells are specific cells characteristic of BV. If sodium chloride is added to vaginal discharge and the discharge examined under a microscope, presence of clue cells is diagnostic of BV.

BV is diagnosed when:

(1) vaginal discharge is present with any two positive tests.

(2) If vaginal discharge is not present, all the three tests must be positive.

Do you have an Obgyn question? Something you are concerned about? Consult Dr. Mazumdar - Ask a question and get a reply within 24 hours. Consultation fees - $20 only through Paypal.

Treatment of Bacterial Vaginosis:

Treatment of Bacterial vaginosis is with antibiotics - usually Metronidazole or Clindamycin. They can be taken either orally or vaginally. Metronidazole is more effective than Clindamycin. But, in pregnancy, Clindamycin is preferred over Metronidazole. Another antibiotic which can be used is Tinidazole belonging to the same family as metronidazole. It can be given for a longer duration of time and is the preferrred drug in recurrent BV.

Other antibiotics that may work include macrolides, lincosamides, nitroimidazoles and penicillins.

Boric acid capsules are also available - these are inserted into the vagina to help increae the acidity of the vagina and decrease the growth of harmful bacteria.

Probiotics are supplements which help maintain the ph of the vagina. The most preferred probiotics for BV are those containing high doses of lactobacilli (around 109 CFUs). Intravaginal administration is preferred to taking them by mouth, especially in pregnancy.

Recurrence of Bacterial Vaginosis:

The recurrence rate of BV is quite high, especially in the first three months after treatment. Many people need to take a second course of antibiotics within a month. If recurrence is more than twice in 6 months, then a long course of antibiotics may be needed. It will also be necessary to identify any factor which could be causing recurrence of the BV.

Recurrence is more in women who are diabetic or anemic, who are obese and whose general health condition is not good. A low immune status increases the risk of bacterial vaginosis.

Complications of Bacterial Vaginosis:

Most cases of BV does not cause any health complications. But in some cases, there may be some harmful effects:

- If pregnancy occurs while a woman has BV, the risks of miscarriage, stillbirth, preterm labour and postpartum endometritis increases.

- If surgical procedures like caesarian sections and hysterectomies are done in the presence of BV, the risks of pelvic infections increases.

- Risks of getting infected are higher in a woman who has BV and is exposed to STDs like HIV. A woman with both BV and HIV are more likely to transmit it to her partner than a woman aithout BV. The risks of contacting other STDs like chlamydia, herpes, gonorrhea and HPV are also higher.

- Males exposed to BV from their female partners can carry it in the penis, coronal sulcus, and male urethra.

Prevention of Bacterial Vaginosis:

Bacterial vaginosis can be prevented by taking a number of precautions:

- Douching of the vagina should be avoided since it disturbs the normal ph of the vagina. Vaginal deodorants and washes should also be avoided as far as possible.

- Limiting the number of sex partners. The more the number of sex partners, the more the risk of BV.

- Taking probiotics , especially those containing lactobacillus can help prevent occurance as well as recurrence. 200 gms of yogurt with live bacilli should be taken daily.

- Women with recurrent BV should take showers rather than baths to prevent water from running into the vagina and affecting the ph.

- Using condoms during sexual intercourse will help prevent the alkaline semen from disturbing the ph of the vagina.

Also Read-

Do you have a gynecological or obstetrical problem? Would you like to discuss it in private? Consult our online gynecologist Dr.M.D.Mazumdar, MD (O&G), at any time you want and get your reply within 24 hours.We charge a nominal fee of USD 20 ($20) per question through

The procedure of asking a question is quite simple. Clicking on the link below takes you to the Paypal website where the payment is made. After the payment goes through, you will be directed back to this website where you can ask your question. And rest assured, you will get your answer within 24 hours. And usually, even sooner.