Bacterial Vaginosis (BV) is a common condition resulting from an imbalance in the natural bacterial environment of the vagina. While not caused by a single outside pathogen, its association with sexual activity creates confusion about whether a male partner requires treatment. This article clarifies the nature of BV and the medical guidelines surrounding the treatment of male partners.
What is Bacterial Vaginosis
Bacterial vaginosis occurs when the normal, protective balance of bacteria within the vagina is disrupted. The healthy vaginal environment is typically dominated by Lactobacillus species, which produce lactic acid to maintain a low, acidic pH. When BV develops, an overgrowth of various anaerobic bacteria, such as Gardnerella vaginalis, replaces the Lactobacilli. This shift causes the vaginal pH to rise above its normal acidic range.
Symptoms can include a thin, off-white or gray vaginal discharge and a distinct, foul or “fishy” odor that often becomes stronger after sexual intercourse. Up to 84% of people with BV may not experience any noticeable symptoms at all. Although considered a mild infection, BV can increase the risk of more serious health issues, including pelvic inflammatory disease and the acquisition of other sexually transmitted infections.
BV and Sexual Transmission
Bacterial vaginosis is not categorized as a traditional sexually transmitted infection (STI), like chlamydia or gonorrhea. This is because BV is not caused by a single external organism but by an internal change in the existing bacterial community. However, the condition is strongly associated with sexual activity, particularly with having new or multiple partners. The exchange of bodily fluids during sexual contact appears to be a factor that can initiate the bacterial imbalance.
Exposure to semen, which has a higher, alkaline pH, can temporarily disrupt the naturally acidic vaginal environment. This pH shift can suppress the growth of protective Lactobacillus bacteria, allowing BV-associated bacteria to overgrow. Research shows that male partners can harbor BV-associated bacteria, such as Gardnerella vaginalis, on the skin of the penis. Although men do not develop BV itself, this presence of bacteria may lead to the reintroduction of the organisms to the female partner following her successful treatment.
The classification of BV is currently being debated because studies show its profile is similar to established STIs. The exchange of bacteria with a sexual partner appears to contribute to the condition’s development and recurrence. This understanding of the male partner’s penile microbiota challenges the long-standing view that BV is purely an endogenous condition.
When Male Partners Need Treatment
For many years, standard medical guidelines, including those from the Centers for Disease Control and Prevention (CDC), have recommended against the routine antibiotic treatment of male sexual partners. This was based on past studies that did not show a clear benefit in preventing recurrence when male partners received only oral antibiotics. Treatment goals remained focused on relieving the female partner’s symptoms.
Emerging research is beginning to challenge this established practice, particularly in cases of recurring BV. A recent randomized controlled trial showed a significant reduction in BV recurrence when the male partner was treated concurrently. Recurrence rates within 12 weeks were 35% for couples where both partners received treatment, compared to 63% when only the woman was treated. This dual treatment involved a combination of oral metronidazole and a topical clindamycin cream applied to the penile skin.
This evidence suggests that the male partner may act as a reservoir for the BV-associated bacteria, leading to re-infection. While current guidelines have not yet been updated, a healthcare provider may discuss this option for women who experience persistent or frequent BV recurrence. The decision to treat a male partner is not standard practice but can be a strategy considered in difficult cases.
Preventing BV Recurrence
BV often returns, with recurrence rates exceeding 50% within a year for some women, making long-term prevention important. Behavioral adjustments can help maintain the natural balance of the vaginal environment after antibiotic treatment. Avoiding practices that introduce alkalinity or disrupt the natural flora is a primary preventative measure.
It is advised to avoid douching, as this practice can flush out protective Lactobacillus bacteria and raise the vaginal pH. Simple external washing with water or a mild, unscented soap is sufficient for hygiene. Using condoms consistently during sexual activity can also be protective by limiting the exchange of bacteria and preventing exposure to alkaline semen.
Some women find benefit in probiotic supplements containing Lactobacillus species to help recolonize the vagina with beneficial bacteria. These can be taken orally or administered vaginally after a course of antibiotics to help restore the healthy microbiome. Research suggests that using hormonal contraceptives may be associated with a reduced risk of BV, while non-hormonal options like the copper intrauterine device (IUD) may increase the risk.