Global study reveals diversity in healthy vaginal microbiomes

Seeking to understand what constitutes a healthy vaginal microbiome, a global research collaboration that includes a Rutgers-New Brunswick scientist has reported a series of findings, including identifying which bacteria thwart vaginal disease and determining that microbiomes vary significantly across human populations.

Authors of the study, published in Trends in Microbiology, are part of a Belgium-based initiative called the Isala Sisterhood. Members of the group aim to inspire research on microbiomes worldwide by creating a "reference map" of vaginal microbiota. Launched in 2020 at the University of Antwerp, the project has expanded to include more than 3,000 participants working in North and South America, Asia, Africa and Europe. The group includes microbiologists, health care workers, members of governmental organizations and public citizens.

The study is important for many reasons. One key reason is that understanding vaginal microbiome diversity can lead to improved diagnostics and treatments."

Maria Gloria Dominguez- Bello, the Henry Rutgers Professor of Microbiome and Health at the Department of Biochemistry and Microbiology in the Rutgers School of Environmental and Biological Sciences and an author of the study 

Vaginas host a complex microcosm of bacteria and yeasts – known as the vaginal microbiome – that can fluctuate over time. However, little is known about these microbial communities and their roles in a person's health. The project researchers are working to change that, with the study and its insights representing an important step forward, Dominguez-Bello said.

The bacteria Lactobacillus crispatus was identified by the researchers as a key protective bacterium in the vaginal microbiome. Not all strains, however, confer the same benefits, they found.

Aiming to explore the diversity of the vaginal microbiome in women across different geographical and ethnic backgrounds, the researchers confirmed that vaginal microbiomes vary significantly across populations. Lower levels of Lactobacillus species were more commonly reported in women of African and Latin American descent than in women of European and Asian descent.

They also sought to determine how variations in the vaginal microbiome correlated with women's health, particularly concerning bacterial vaginosis, the most common vaginal infection in women of childbearing age. Bacterial vaginosis, often defined by a reduction in Lactobacillus, isn't necessarily a disease but a microbial imbalance that can have varying health consequences, the researchers said.

The study also touched on the issue of research gaps and potential biases. Dominguez-Bello said she and her colleagues are working to obtain data from more geographical areas as most studies focus predominantly on women from higher income countries. There is a need for broader global representation and more precise definitions of "healthy" vaginal microbiota, Dominguez-Bello said.

"The findings highlight disparities in women's health research and advocate for a more inclusive approach that considers diverse populations," she said. "By addressing gaps in research representation, the study encourages equitable distribution of scientific resources and expertise, especially in low- and middle-income countries."

The authors emphasized the importance of continuing to study the vaginal microbiome. Largely unexplored, they said, are the roles of several other types of microbes that exist in vaginal microbiomes – including yeasts, viruses and other types of bacteria.

In addition, the microbiome's connection to a person's overall health is still not well understood and could be explored through studies that focus on geographical and socioeconomic diversity and consider social and cultural factors.

"To promote better preventive, diagnostic and therapeutic strategies for women affected by conditions associated with the vaginal microbiota, more research on the functions and diversity of the vaginal microbiota is urgently needed in different parts of the world," the authors wrote. "This way, we can better understand what a healthy vaginal microbiome looks like in each geographical location."