Australian Scientists Identify Two Pathways Behind Recurrent Bacterial Vaginosis

Bacterial vaginosis, commonly called BV, is characterised by an imbalance in the vagina’s naturally occurring bacteria: “good” Lactobacilli are reduced while other mixed bacteria overgrow. It can be asymptomatic or cause vaginal itching, burning and discomfort. Treatment is considered essential because BV can increase susceptibility to other infections and is linked to complications in pregnancy and childbirth.

The new research followed a landmark study published in March last year by the same group, which found BV can be sexually transmitted to women by male partners. That study reported that treating women and their male sexual partners concurrently with antibiotics reduced BV recurrence rates by more than 60%. The scientists then set out to understand why about 20% of women treated alongside their partners were not cured.

The latest study involved 188 couples. Women received a weeklong course of oral antibiotics, while men were treated with both oral and topical antimicrobials. It identified two pathways to recurring BV: persistence of the condition despite antibiotics, and re-infection. For about two-thirds of women, the day after treatment ended, they returned to an optimal vaginal microbiome marked by abundant healthy Lactobacilli bacteria, said study lead author Dr Lenka Vodstrcil, a senior research fellow at Monash University and Bayside Health’s Melbourne Sexual Health Centre.

The other third had microbiomes suggesting they may not have cleared their BV before couples resumed sex after treatment, Vodstrcil said. Those women were nearly three times more likely to get the condition again within four weeks. A better understanding of persistence of infection helps researchers develop new strategies to cure more women, she added.

Among female participants, 30% used an intrauterine device. The study found this “could enhance the persistence of bacterial vaginosis following treatment in some women,” but noted that further research was needed.

The researchers believe the study is the largest to date involving heterosexual couples receiving concurrent BV treatment. They plan to trial longer treatment lengths and combinations of multiple antibiotics. “Our aim is to stop women from having two, three, four courses of antibiotics throughout the year, which was happening previously,” Vodstrcil said.

Study senior author Prof Catriona Bradshaw, head of research translation and mentorship at Monash University and the Melbourne Sexual Health Centre, said: “Using partner-treatment to mitigate re-infection and more intensive strategies that target persistence of BV-bacteria, we hope to create more effective treatment approaches that can be tailored to an individual and achieve higher levels of cure.”

The study noted that while the ethnicities of participants were representative of urban Australia, its results might not be generalisable to other global populations, including those in low-income and middle-income countries and in other settings with a high burden of bacterial vaginosis.