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Bacterial Vaginosis

By Dr J Kabyemela, MD

Bacterial vaginosis: The leading cause of vaginal discharge


Of all the causes of vaginal discharge in women of child-bearing age, bacterial vaginosis is the commonest.  Even though most people will know about thrush, bacterial vaginosis is estimated to be three times as common. Bacterial vaginosis is a completely different condition caused by bacteria. Thrush, on the other hand, is simply a proliferation of a yeast or fungus. It is not a bacterial infection.



Bacterial vaginosis features:

A vaginal discharge is the principal feature of bacterial vaginosis. The discharge could be watery in consistency and whitish in colour and have an unpleasant fishy smell but this is not always the case.

Some women will experience itching. Rarely features of slight inflammation with soreness and some swelling of the vulval and/or vaginal tissues are seen. However, many experts believe the presence of such features would be mainly due to co-existing thrush rather than bacterial vaginosis itself.  It is quite variable.

Abdominal or pelvic pain is not a feature of bacterial vaginosis.


Bacterial vaginosis can exist without symptoms and does so in roughly 50% of those affected.



Sexual transmission of bacterial vaginosis:

This heading has been put there deliberately. This is to stress the point that bacterial vaginosis is NOT a sexually transmitted infection

Why women get bacterial vaginosis is not clearly understood. There is no doubt that a change in the vaginal environment is the principal trigger. The vagina in women of child-bearing age is slightly acidic. Any condition which increases the pH of the vagina towards the alkaline range could lead to bacterial vaginosis. A variety of bacteria which proliferate in such an environment cause the discharge. At the same time, the normal, so-called ‘friendly’ bacteria especially Lactobacillus are suppressed.



Diagnosis of bacterial vaginosis

A woman presenting with a vaginal discharge fitting the description will need to have a vaginal examination. Typically, a thin whitish discharge will be seen coating the vaginal walls. The fishy smell may be apparent. A swab will need to be taken for laboratory confirmation of the diagnosis.


There are two main ways of making the diagnosis:

1. The identification of so-called ‘clue cells’ from the swab and releasing a fishy odour when an alkali (10% Potassium hydroxide) to a slide with contents of the swab. This is called the Amsell criteria.

2. Gram-staining of a vaginal swab shows predominantly anaerobic organisms especially Gardnerella and/or Mobilincus species with few or no Lactobacilli. (Hay/Ison criteria)

Once the diagnosis is made, it is time to move on to treatment.



Treating bacterial vaginosis

There are a number of options when it comes to treatment. They are all similarly effective and it may boil down to personal preference and cost considerations. One thing is, however, common to all: Bacterial vaginosis is notorious for recurrence despite apparently successful treatment. One study a few years ago showed that up to a third may have recurrence of symptoms within four weeks of completing the treatment.  There is no easy way around this particular aspect of the condition.


Treatment options are either oral or vaginal and they include:Clindamycin 2% vaginal cream



As mentioned earlier, in practise, there is no difference in efficacy, whichever option is used. Oral Metronidazole and Clindamycin cream appear to be more popular among doctors.



Risks posed by bacterial vaginosis

The presence of a persistent vaginal discharge can have a significant impact on the quality of life of a woman. Besides that, it has been shown that bacterial vaginosis is a risk factor for future development of pelvic inflammatory disease especially after a miscarriage or termination of pregnancy.


In pregnancy, presence of bacterial vaginosis has been associated with late miscarriage, preterm rupture of membranes and pre-term delivery. Pregnant women with symptoms and confirmed to have bacterial vaginosis should be treated.


Bacterial vaginosis has been found to occur in pre-pubescent girls and this has been blamed on poor hygiene techniques where while cleaning herself after a bowel motion, a girl wipes back to front introducing bowel bacteria into the vaginal canal in the process.


Bacterial vaginosis is uncommon in post-menopausal women who are not on HRT.



Preventing recurrence of Bacterial vaginosis

There is no set way backed by evidence that is known to be effective in preventing relapse. Strategies used to try to achieve this are based on the recognised therapeutic methods. One method involves giving a therapeutic course as mentioned above. This is followed by administering twice weekly Metronidazole gel for up to six months as suppressive therapy.


A study reported in the Journal of Nutrition in June 2009 seemed to show that Vitamin D may have a role in preventing bacterial vaginosis. This may be via its influence on the body’s immune system. People with Vitamin D deficiency in the study were found to be more prone to bacterial vaginosis. Optimal plasma Vitamin D level for preventing bacterial vaginosis was found to be 80 nmol/litre. Higher levels did not confer any additional benefit in this regard.



Treating sexual partners:

As mentioned earlier, bacterial vaginosis is not sexually transmitted. Unsurprisingly therefore, treating sexual partners has been shown to offer no value in preventing relapse.



Last update: August 31, 2013





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