It's an uncomfortable topic, and not considered polite dinner conversation, but Larry Forney's research on the human vagina and the ecology of the vaginal microbial ecosystem has big implications for women.

Forney is a professor of biological sciences and director of the Initiative for Bioinformatics andEvolutionary Studies (IBEST) at the University of Idaho, in Moscow, Idaho. He is focusing his research efforts to increase understanding about normal vaginal microbiota, or bacteria, so that physicians can better identify conditions that make women prone to infections and other diseases, and avoid such health problems.

"For example, approximately 75 percent of women experience at least one yeast infection during their lives, and some 40 to 50 percent of these women experience a recurrence," Forney says. "Nobody dies from yeast infections, and they have no long-term consequences. But they cause misery with such frequency that it deserves our attention."

In a paper published recently in the Proceedings of the National Academy of Sciences (PNAS), Forney and some fellow researchers at the University of Maryland School of Medicine's Institute for Genome Sciences and Emory University note that the delicate balance of microbes in the vagina can vary greatly between healthy women.

The study used genomics-based technologies to examine the vaginal microbes found in a study group of 400 women. The research is an example of an emerging field of genomics: the study of the human microbiome, which refers to all of the microbes that live on and in the human body.

Scientists believe these tiny organisms interact closely with the human host and play a critical role in human health and disease.

In the vagina, these "communities" of microbes are important in maintaining and promoting overall health and protecting women against disease. Vaginal microbes provide protection from what are called urogenital diseases mainly by producing lactic acid.

Common wisdom readily accepts that lactic acid-producing bacteria lower the pH—or measure of acidity—in a woman's vagina, which aid in the prevention of disease.

Research has held for years that pH should consistently be low, says Forney. But his research, as published in the PNAS, shows that the pH varies considerably among women.

"Due to inherent differences among individuals and their personal habits and practices, vaginal communities are likely to vary even among women who have the same fundamental type of bacterial community," Forney says.

Jacques Ravel, associate professor of microbiology and immunology at the University of Maryland School of Medicine and associate director of the Institute for Genome Sciences, says, "The surprising finding here is that some women can be healthy while still harboring different communities of microbes."

Ravel adds, "Even microbes that were previously believed to be detrimental to a woman's health seem to be part of a normal ecosystem in some women, according to this study. Further research is needed to establish the function of these microbes and the communities in which they appear. Some of the seemingly beneficial microbial communities seem to be associated with a higher pH, which is usually considered to be unhealthy."

The research suggests that differences in vaginal bacteria community composition are what ultimately may determine risk factors for bacterial vaginosis, yeast infections, sexually transmitted diseases, and HIV.

Currently, not much is understood about what causes these disturbances in the human vagina or how to treat them. And now, Forney's research suggests that the one size fits all approach to preventing diseases probably doesn't work.

"Our research centers on the distinctive composition and ecology of the vaginal microbial ecosystem of women," Forney says. "We're looking at the differences between humans to try and understand the risk of disease."

Bacterial vaginosis, a bacterial infection of the vagina, causes discomfort in patients and can have serious health effects.

An estimated 25 percent to 30 percent of women have bacterial vaginosis at any point in time, and it's the most common vaginal infection that prompts women of reproductive age to visit their primary care physician. The infection has been associated with an increased risk of such problems as acquiring sexually transmitted infections and even pre-term delivery during pregnancy.

Ravel says, "If we could identify women as being at a high risk for developing bacterial vaginosis, we could develop preventive methods to lower the risk of infection."

Though still undergoing extensive testing, which is being funded through the National Institutes of Health, Forney's research could be the first step toward personalized medicine for women's reproductive health.

Under such a model, differences in the makeup of the vaginal microbiomes of individuals would be taken into account for risk assessment and disease diagnosis and treatment.