Better probiotics for vaginal health

Newly isolated strains of vaginal Lactobacillus bacteria perform better than those currently used in South African vaginal probiotics. This is according to recent research published by an international team led by the University of Cape Town (UCT). The findings could mean more effective treatment for bacterial vaginosis, and a lowered risk of adverse outcomes for pregnancy and sexually transmitted infections, including HIV.

“Bacterial vaginosis is the most prevalent condition affecting reproductive health and HIV risk in South African women, and current standard-of-care – antibiotic treatment – does not lead to a durable cure,” says Dr Jo-Ann Passmore from the UCT Division of Virology.

Micro-organisms that live inside the lower reproductive tracts of healthy women – also known as the vaginal microbiome – play a key role in a woman’s overall health. Lactobacillus species are the main type of bacteria found in the vaginas of healthy women that are thought to protect against sexually transmitted infections.

When the vagina’s microbial balance is disrupted, though, it can lead to bacterial vaginosis. This causes uncomfortable symptoms, but also increases the risk of sexually transmitted infections, including HIV, and can sometimes lead to serious complications, including preterm birth and infertility.

“Bacterial vaginosis is the most prevalent condition affecting reproductive health and HIV risk in South African women.”

Yet most probiotics for vaginal health that are currently commercially available in South Africa do not contain the species of Lactobacillus bacteria commonly found in the vagina. Most strains used in probiotics were isolated more than 30 years ago, with a focus on gut – not vaginal – health, and none came from women from Africa.

“There is an urgent need to improve treatment outcomes in women with bacterial vaginosis, and Lactobacillus-containing probiotics are a promising approach,” Passmore says.

The new research, which formed the basis of UCT postgraduate Anna-Ursula HappeI’s PhD, supervised by Passmore, characterised a large panel of 57 vaginal strains of Lactobacillus from young South African women and compared them to the bacteria in commercial probiotics.

In the laboratory, HappeI compared the growth of the vaginal and probiotic bacteria, their adhesion to host cells and their ability to lower pH, produce lactic acid and to inhibit pathogens. She and her collaborators also sequenced the genomes of the top five performers.

They found that several of the vaginal Lactobacillus species performed much better in terms of their probiotic profiles than those in commercial products. This suggests that they could be harnessed to develop improved vaginal probiotics in South Africa.

The vagina’s microbiome

Lactobacillus bacteria, which are the main type of bacteria found as part of a healthy vaginal microbiome, are beneficial in that they protect the vagina against infections. They do this by producing a mild acid – lactic acid – which lowers the vagina’s pH, making it an unfavourable place for disease-causing micro-organisms to grow.

But disruption of the microbiome balance (ideally dominated by Lactobacillus) is common and leads to bacterial vaginosis.

Although antibiotics are the standard treatment for bacterial vaginosis, most cases recur within six-months. Thus, probiotics have been explored as adjunctive treatment to improve cure and recurrence.

“Developing a women-friendly probiotic for reproductive health, that is acceptable and relevant to women in Africa, is the vision.”

“Making a vaginal probiotic with geo-adapted strains available to South African women might help improve reproductive health and associated adverse outcomes locally,” says Happel.

This project involved collaboration with colleagues from elsewhere in South Africa, France and the United States, including Dr Remy Froissart from the University of Montpellier, France, who co-supervised Happel’s PhD. Froissart did a sabbatical at UCT in 2015/6 and has worked closely on the project. 

“We currently have an South African/French PROTEA grant to take this research further with Dr Froissart,” adds Passmore. PROTEA is a bilateral incentive programme for strengthening South African–French collaborative research co-funded by the French Ministry of Foreign Affairs and the Ministry of Higher Education and Research (from the French side), and the National Research Foundation (from the South African side).

Taking it further

The outcomes of this research could lead to better treatments and less recurrence, and ultimately, better health for women.

To this end, Happel and Passmore have partnered with Dr Marijke Fagan-Endres and Professor Sue Harrison from the UCT Department of Chemical Engineering on formulating and scaling up the top-performing Lactobacillus candidates from this study.

“Developing a women-friendly probiotic for reproductive health, that is acceptable and relevant to women in Africa, is the vision,” concludes Passmore. 

• Happel A-U et al. (2020) Exploring potential of vaginal Lactobacillus isolates from South African women for enhancing treatment for bacterial vaginosis. PLoS Pathogens 16(6): e1008559. doi.org/10.1371/journal.ppat.1008559