Bacterial Vaginosis Affects One in Three Women: Groundbreaking Study Shows That Men are the Missing Link in the Chain

A groundbreaking study shows that bacterial vaginosis (BV), a condition that affects nearly one-third of women worldwide and leads to infertility, premature birth, and neonatal mortality, is in fact a sexually transmitted infection (STI). This paves the way for a revolution in the treatment of this condition.

Significantly Higher Cure Rates When Both Partners are Treated Simultaneously

Researchers at Monash University and Alfred Health at the Melbourne Sexual Health Centre say their findings, published in the New England Journal of Medicine, hold the key to reducing the stubborn and distressing recurrence rates of bacterial vaginosis in women. The authors, Professor Catriona Bradshaw and Dr. Lenka Vodstrcil, say that the standard practice of treating BV as an imbalance (disorder) of the vaginal microbiome results in more than 50 percent of all women experiencing a recurrence within three months of standard one-week treatment with an oral antibiotic.

In their study of 164 couples with BV in monogamous relationships, they found that treating BV as a sexually transmitted infection, with both sexual partners treated at the same time, leads to significantly higher cure rates than the current practice of treating women only. In fact, they stopped the study early when it became clear that the recurrence rate of bacterial vaginosis was reduced by half in the group where both partners were treated, compared to treating women alone. “This successful intervention is relatively inexpensive and short, and has the potential not only to improve the cure rate of BV in women, but also opens up exciting new possibilities for the prevention of BV and its serious complications,” said Professor Bradshaw.

In the multicenter randomized trial, all women received the recommended first-line antibiotics. Male partners were randomly assigned to either partner treatment, in which they received both an oral antibiotic and a topical antibiotic cream for one week, or a control group. The control group in this study received only antibiotic treatment for women and no partner treatment, which is the recommended practice worldwide. The couples took the antibiotics for only one week but were then followed up for 12 weeks to determine how effective this intervention was in curing bacterial vaginosis over a 3-month period.

Bacterial Vaginosis is Indeed a Sexually Transmitted Infection

Dr. Vodstrcil explained that BV is already known to be a risk factor for other sexually transmitted infections. Researchers have long suspected that it is a sexually transmitted infection (STI) because it has a similar incubation period (after sexual intercourse) to most STIs and is associated with the same risk factors as STIs such as chlamydia, e.g., changing sexual partners and not using condoms. Professor Bradshaw emphasized that while studies had shown that men can harbor bacterial species associated with bacterial vaginosis on the skin of the penis and inside the penis, previous studies involving male partners did not show improved cure rates in their female partners.

“This was interpreted as evidence against sexual transmission,” said Professor Bradshaw. However, these studies had methodological limitations, and none used a combination of oral and topical antibiotics to adequately eliminate BV bacteria in men, particularly on the penis skin. The current study has shown that reinfection by partners causes a large proportion of BV recurrences in women and provides evidence that bacterial vaginosis is indeed an STI. Part of the difficulty in determining whether BV is sexually transmitted has been that researchers still do not know exactly which bacteria cause it, but advances in genome sequencing are helping to unravel this mystery.

The findings have already led the Melbourne Sexual Health Centre to change its clinical practice for treating couples. A new website for healthcare professionals and consumers provides all the information needed to prescribe and access partner treatments. “This information has been developed in collaboration with consumers, study participants, and healthcare professionals to make it accessible to everyone,” said Professor Bradshaw. “Changes to national and international treatment guidelines always take time, so we felt it was important to provide accurate information online and in downloadable formats at the time the study results were published.”