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Bacterial vaginosis: more common than flu

Researchers are investigating the bacteria that causes a common infection in women called Bacterial vaginosis. Photo by Chelsea Ziegler.

If you heard about a condition that affects one million women every year and develops in one out of every three women, you’d assume it was well known and easily treated. Unfortunately, you’d be wrong. Despite its staggering statistics, the infection known as bacterial vaginosis remains a relative mystery.

Bacterial vaginosis (BV) is a vaginal infection that’s linked to the loss of natural, healthy bacteria at the same time as the growth of harmful bacteria is occurring. While the syndrome is characterized by an increased vaginal discharge and malodour, these unpleasant symptoms are not the only effects of BV.

Since BV mainly develops in women of child-bearing age, it can also increase the risk of complications during pregnancy, including miscarriage and preterm birth. Additionally, if BV is left untreated, it may cause enough damage to result in secondary infections that could subsequently cause sterility.

“Having BV does put you at risk of infectious complications following lower genital tract surgery such as a hysterectomy,” says Dr. Julie van Schalkwyk who heads the Department of Obstetrics and Gynaecology at the University of British Columbia. “It is also associated with subclinical pelvic inflammatory disease”.

Since joining the staff at the Vancouver General Hospital in 2005, van Schalkwyk has assessed hundreds of cases of BV. She emphasizes that its negative effects are unexpected and always unwelcome.

Because many women are too embarrassed to go to the doctor with their symptoms, BV often goes untreated. Unfortunately, prolonged BV in the absence of therapy increases the risk of recurrence.

Ironically, avoiding treatment for BV may be the best course of action for pregnant women who develop BV, since studies indicate that treating asymptomatic BV during pregnancy can actually increase the risk of a preterm birth.

BV is diagnosed by using either a clinical or a laboratory method. The clinical method relies on Amsel’s criteria for diagnosis: discharge, elevated pH, clue cells and odor. The laboratory method involves an assessment of the different kinds of bacteria living in the vaginal microbiome.

Since BV is characterized by the loss of protective bacteria such as Lactobacillus and the presence of harmful bacteria, such as Gardnerella vaginalis, laboratory technicians can detect this shift in the vaginal microbiome by using a Gram stain and investigating the bacteria under a microscope.

Although Gardnerella vaginalis can be benign, some strains have the potential to cause disease by producing molecules known as virulence factors.

These virulence factors are currently the focus of a study led by Dr. Janet Hill from the Western Collage of Veterinary Medicine. She and her research team are working to acquire a better understanding of these virulence factors, particularly vaginolysin.

Vaginolysin is a significant concern because of its ability to lyse or burst open the epithelial cells, causing cell death. Extensive cell death results in tissue damage and an environment that’s more susceptible to secondary infections.

The researchers are hopeful that their study of vaginolysin will provide further insight into the complexities of Gardnerella vaginalis. For example, some patients with large amounts of Gardnerella vaginalis on their vaginal epithelial cells don’t actually develop BV symptoms. That’s because there are both pathogenic and non-pathogenic strains of the bacterium.

Previous studies have determined that there can be more variability between the two strains within the Gardnerella genus than there are between a Gardnerella strain and an entirely different species. That points to genetic differences between the pathogenic and non-pathogenic Gardnerella strains – genetic differences that may determine the presence or absence of the virulence factors.

If researchers like Hill and her team are able to differentiate between pathogenic and non-pathogenic Gardnerella, their results could lead to a new and more reliable method for diagnosing BV.

While the underlying mechanisms that cause BV are still unclear, van Schalkwyk emphasizes that women can reduce their likelihood of developing BV by minimizing certain factors such as smoking, douching and having multiple sexual partners.

Between faulty diagnosing methodologies and an overall poor understanding of how the condition occurs, BV continues to fly under the radar, despite its being the most common vaginal infection of women between the ages of 15 and 44.

“More education is needed,” says van Schalkwyk, “As we continue to research and understand the vaginal microbiome and BV, we will also manage it better”.

For more information, visit http://www.cdc.gov/std/bv/stdfact-bacterial-vaginosis.htm

Chelsea Ziegler is a first-year student in the School of Public Health She is originally from Swift Current, Saskatchewan. Her story is part of a series of articles written by WCVM summer research students.

 

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