Why BV keeps coming back: Australian researchers trace the problem to treatment failure and reinfection

Recurrent bacterial vaginosis has a habit of exposing the limits of medicine’s fondness for tidy solutions. Australian scientists now say the infection tends to come back for two separate reasons: in some women it survives the antibiotics, and in others it appears to be reintroduced by a male partner.

The condition, usually known as BV, affects about one in four women worldwide. It is caused by an imbalance in the vaginal microbiome, with too few of the bacteria usually considered beneficial and too many of the mixed species that do the damage. BV can pass without symptoms, which is convenient only until it is not; it can also cause itching, burning and discomfort, and it is linked to a higher risk of other infections as well as complications in pregnancy and childbirth.

The new study builds on research published in March last year, when the same group reported that BV can be sexually transmitted to women by male partners. That earlier finding was not merely academic. Treating women and their partners at the same time with antibiotics reduced recurrence by more than 60%, a result that sounded almost too sensible to be routine medicine.

This latest work, published in The Lancet Obstetrics, Gynaecology & Women’s Health, looked at 188 heterosexual couples. The women received a week-long course of oral antibiotics, while the men were treated with both oral and topical antimicrobials. Even with that arrangement, about 20% of women were not cured, which is where the researchers decided the story became more interesting.

They found two distinct pathways back to BV. One was persistence: the infection had not been cleared by the week-long treatment. The other was reinfection after sex resumed. Dr Lenka Vodstrcil, a senior research fellow at Monash University and Bayside Health’s Melbourne Sexual Health Centre, said that for about two-thirds of women, the day after treatment ended their vaginal microbiome had returned to an optimal state, with healthy Lactobacilli dominating. The remaining third showed signs that they may not have cleared BV at all, and they were nearly three times more likely to have it again within four weeks.

The distinction matters because it changes the treatment question. If the problem is persistence, then the answer is not simply more of the same. The researchers say they now want to test longer treatment courses and combinations of multiple antibiotics. Vodstrcil said the aim is to stop women from having two, three or four courses of antibiotics in a year, which, according to the team, has been happening.

Prof Catriona Bradshaw, who leads research translation and mentorship at Monash University and the Melbourne Sexual Health Centre, said the hope is to combine partner treatment to reduce reinfection with more intensive strategies aimed at the bacteria that survive initial therapy. In plain terms, the plan is to make treatment more tailored and more effective, rather than asking women to keep returning for the same disappointing ritual.

The study is, according to the researchers, the largest to date involving heterosexual couples receiving concurrent BV treatment. Still, its participants were representative of urban Australia, and the authors caution that the results may not apply neatly to other populations, including those in low-income and middle-income countries and in settings where BV is even more common.

One further wrinkle: 30% of the female participants used an intrauterine device, and the study suggests this could help BV persist after treatment in some women, though the researchers say more work is needed. Medicine, as ever, prefers a single cause; biology prefers to be more annoying than that.

Written by Thomas Nussbaumer thomas.nussbaumer@alpineweekly.com