New Study Links Mouth Bacteria And Oral Sex To Vaginal Infection

Bacterial vaginosis is the most common vaginal condition in women of reproductive ages. A new study pointed out that a common type of oral bacteria that are associated with gum diseases and dental plaque might support this vaginal infection.

Upon conducting experiments in human vaginal specimens as well as in mice models, the researchers at the University of California found that the mouth bacterium ‘Fusobacterium nucleatum’ aided the growth of other bacteria which caused bacterial vaginosis. The findings are published in the journal PLoS Biology.

Bacterial vaginosis (BV) is one of the most common causes of vaginal symptoms among women, affecting almost 30% of American women aged 14 to 49. But the role of sexual activity in the development of BV has remained unclear, said the Centers for Disease Control and Prevention (CDC).

While 84% of women who developed BV had no symptoms at all, some get a strong-smelling vaginal discharge. BV occurs when there is an imbalance or ‘dysbiosis’ of the vaginal community of microbes and is usually characterized by low levels of beneficial bacteria and overgrowth of harmful bacteria.

Fusobacterium nucleatum is a gram-negative spindle-shaped bacterium that is ubiquitous in the human oral cavity. It has also been isolated from the amniotic fluid of women in preterm labor. Vaginal colonization with this bacterium increases a man’s risk for amniotic fluid infection and preterm birth. Although BV isn’t usually serious, leaving it untreated can make women more vulnerable to developing sexually transmitted diseases and getting urinary infections.

The researchers discovered that F.nucleatum acts in a mutually beneficial relationship and encourages dysbiosis in susceptible vaginal communities. Their findings challenge the simplistic principle that the mere absence of healthy bacteria is the sole mechanism that enables a permissive environment for pathogens. The study suggested a possible mechanism underlying links between oral sex and vaginal dysbiosis, given the ubiquity of F.nucleatum.

Health experts have already believed that BV can be triggered by sex, including between female partners. Other ways via which women develop BV include:

• Having new sexual partners
• Using an intrauterine contraceptive device
• Using perfumed feminine hygiene products

"We know BV is a really complex entity with lots of contributing factors," BBC quoted Prof Claudia Estcourt, spokesperson for the British Association for Sexual Health and HIV. She expressed that this research was very important since it added to the understanding of BV and that oral sex could pass on sexually transmitted infections and other bacteria.

Another recent study pointed out that penis microbes may play a key role in bacterial vaginosis since the male reproductive organ is home to bacterial colonies.