Research at Washington University School of Medicine in St. Louis points to a common species of Gardnerella vaginalis bacteria as an important contributor to bacterial vaginosis, a condition linked to preterm birth and increased risk of sexually transmitted diseases.
The condition affects one in every three women, making it more common than yeast infections. But bacterial vaginosis often does not cause significant symptoms, leaving many women unaware they have it.
“Bacterial vaginosis can precipitate significant health problems, but it is not a common topic of conversation between patients and their gynecologists,” said Amanda Lewis, PhD, assistant professor of molecular microbiology. “Our findings, which come from new experimental models of the condition, may be a first step toward a better understanding of how to treat bacterial vaginosis and prevent serious complications linked with the condition.”
Bacterial vaginosis occurs when the typical mix of microbes in the vagina is knocked off-kilter. In some cases, bacterial vaginosis causes a change in the consistency of vaginal fluids and an unpleasant odor. The condition is diagnosed through examination of the vagina and tests of the vaginal fluids. Doctors typically treat it with antibiotics, but the condition often recurs.
The new research provides evidence that mucus layers and cells lining the surface of the vagina are damaged in women with bacterial vaginosis and suggests that a single organism, Gardnerella vaginalis, is likely the cause.
G. vaginalis is commonly found in the vaginal fluids of women with bacterial vaginosis and in some women who don’t have the condition. The latter had led many researchers to dismiss the bacterium’s potential contributions to bacterial vaginosis.
Working in mice to simulate this condition, Nicole Gilbert, PhD, postdoctoral fellow, showed that G. vaginalis causes increased shedding of the outermost cells covering the vaginal lining.
“We think the vaginal lining is shed as part of the body’s effort to eliminate bacteria,” Gilbert said. “However, this shedding may also expose sensitive underlying tissues. This may be important for understanding why women with bacterial vaginosis are more susceptible to sexually transmitted diseases and urinary tract infections.”
Based on their observations in mice, the researchers compared vaginal samples from women with and without bacterial vaginosis and found that the outermost cells from the lining of the vagina are shed in higher numbers during bacterial vaginosis.
“This is the first time that a bacterium associated with vaginosis has been shown to participate in mucus degradation,” Lewis said. “This is significant because infection of the uterus is a common cause of preterm birth and likely requires degradation of the mucus plug, a physical structure that protects the pregnant uterus from bacteria in the vagina.”