Bacterial vaginosis — the causes, the symptoms, and the treatments

Irish Examiner

02-05-2025

TikTok's recent 'kitty drinks' trend — which suggested the consumption of various fruit juice combos would make your vagina 'sweeter' and 'clear all fishy smells' — not only highlighted the prevalence of pseudoscience on the social media platform, it promoted the myth that vaginas need cleaning — they don't.
A fishy-smelling vagina is actually a classic symptom of bacterial vaginosis, a common condition which new research suggests is a sexually transmitted infection (STI).
Mary-Kate* (42) first experienced bacterial vaginosis (BV) three years ago, when she had symptoms of 'a burning sensation, itching and an unpleasant, smelly discharge'.
Having visited her GP, who tested for BV and for STIs — 'which was really embarrassing, but she said it was just to rule things out' — Mary-Kate was diagnosed with BV and prescribed antibiotics, which cleared up the infection.
Three months later, however, the BV 'came back and continues to recur every few months. I'm at my wits' end and don't feel the antibiotics are really helping'.
Mary-Kate's experience of recurrent bacterial vaginosis (BV) is a common one. For more than 50% of women, BV — which is caused by an imbalance in the vaginal flora — recurs within three to six months of antibiotic treatment.
A new Australian study recently published in the New England Journal of Medicine, found that simultaneously treating the male partner of a BV sufferer (with a combination of oral and topical antibiotics) drastically reduced the infection's recurrence rate in the female partner. The trial involved 164 heterosexual couples in monogamous relationships, of which 81 were in the partner-treatment group.
Commenting on the findings, professor Catriona Bradshaw, a co-author of the study, said: 'Our trial has shown that reinfection from partners is causing a lot of the BV recurrence women experience, and provides evidence that BV is in fact an STI.'
Previous studies had discounted this possibility, but 'these studies had design limitations, and none used a combination of oral and topical antibiotics to adequately clear BV bacteria in men, especially from the penile-skin site,' Bradshaw said.
According to the HSE, around one in 10 women will get BV during their lifetime, while a recent review by the WHO found that, globally, the prevalence of the condition among women of reproductive age was between 23 to 29%.
Some women experience no symptoms, but the most common one is a 'discharge' which has 'a fishy smell', says Dr Breffini Anglim O'Regan, a consultant obstetrician and gynaecologist at the Coombe hospital.
BV 'doesn't cause harm except if you're pregnant,' she says. 'It could potentially cause a small baby, so growth restriction, or result in a preterm birth.' Additionally, if untreated, BV can cause an infection of the lining of the womb post-birth, she says.
'Good' and 'bad' bacteria
In the main, BV affects sexually active women of childbearing age, but it can affect women who are not engaging in sexual activity, or occur post menopause.
'Basically, your vagina is made up of 'good' and 'bad' bacteria,' says Catriona Keye, an advanced nurse practitioner at Scholarstown Family Practice in Dublin. Lactic-acid-producing lactobacilli are the 'good' bacteria of the vaginal microbiome, she explains, and in a healthy vaginal ecosystem, keep the 'bad' bacteria, of which there are several strains, in check.
BV occurs when an increase in the 'bad' Gardnerella strain disrupts the delicate balance of the vaginal flora, which, in turn, affects the pH level of the vagina (normally slightly acidic).
Studies have shown that vaginal microbiomes can vary significantly among different racial groups. Black and Hispanic women have a higher prevalence of BV. This may be because of lower levels of lactobacilli in their vaginal flora but studies are as yet unconclusive.
Sex has long been known to trigger a recurrence of BV, other factors can also be responsible. Synthetic leggings, combined with a sweaty exercise session, create an ideal environment for Gardnerella to flourish.
In recent years, Keye has noticed an uptick in BV in the cohort of women habitually wearing such gear. Her advice is to 'Make sure you change out of your underwear and your yoga gear as soon as you finish your exercise.'
Douching — flushing, squirting, or spraying water or other cleaning products into the vagina — can also disrupt the vaginal flora, leading to BV. 'You shouldn't be using any body washes around your vulva and vaginal area,' says Dr Anglim O'Regan.
'If you [do] it's going to affect the bacterial make up of your vagina.'
The characteristic fishy odour of BV can prompt some women to douche or use scented body washes in an attempt to banish the smell but doing so will only make the problem worse, she says.
She advises wearing 'no underwear to bed or loose cotton underwear,' and laundering with non-bio detergent. BV is uncommon in post-menopausal women, but for those who do develop it, vaginal oestrogen may be a helpful adjunct to treatment as it increases the amount of lactobacilli in the microbiome, she says, while for someone with recurrent BV in the more commonly affected age groupings 'a probiotic is definitely not a bad idea'.
Relationship impact
Women who experience recurrent BV often find their relationships are negatively affected. Julie* (36) has had BV on and off for two years and says it has taken a huge toll on her mental health and on her sexual relationship with her current partner.
'Sex was a huge part of our relationship,' she says, but she now 'avoids sex' as the BV makes her feel self-conscious. 'I miss being able to have sex without thinking about how I smell.'
While she has been treated with antibiotics multiple times, her partner has not, so the findings of the Australian study may provide a pathway to resolving her BV.
The study focused on heterosexual couples in a long-term relationship, but for a woman with multiple partners, the solution may not be as clear-cut. 'A lot of my young patients, students, would have multiple partners.
They aren't in a relationship, and would be with different boys at the weekends,' Keye says, pointing out the unlikelihood of casual partners adhering to a course of antibiotics.
'Why would they want to take them? Because it doesn't affect them, in the sense that they have no symptoms.'
Like the vagina, the penis also has a microbiome made up of 'good' and 'bad' flora, Keye explains. 'A few years ago, studies came out to show that the men were carrying a bacteria that can trigger bacterial vaginosis.
"They don't have bacterial vaginosis, but they have bacteria on or under the foreskin, or around the penis, or inside the urethra. Then when they have sex, they can transfer that bacteria and that bacteria can trigger the Gardnerella overgrowth in a woman.'
She adds that semen can also alter the vaginal flora, leading to BV.
BV can also increase the risk of contracting other STIs, she says, as the altered flora and more alkaline environment it creates in the vagina creates a favourable environment for other infections — including HIV — to take hold.
'The take-home message is really exciting,' Keye says of the Australian study findings, but she has some caveats: 'It needs to be done on a larger scale, and with a more diverse population.'
She's also concerned of the possible stigma that could result from BV being reclassified as an STI.
'At the moment, like there is no stigma attached to having BV,' she says, noting that STIs still retain an element of stigma, particularly among older women. She emphasises that being diagnosed with an STI is not an indication that a partner has been unfaithful.
'You can have an STI from donkey's years ago and be asymptomatic and you'd never know it unless you were screened.'
*Names changed by request
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