Bacterial Vaginosis (BV) is a common condition affecting the vaginal environment, stemming from an imbalance in the naturally present microbial community. While BV primarily concerns women, the role of male partners in the persistence and transmission of the bacteria is often confusing. This article clarifies the biological nature of this imbalance and addresses the current clinical guidance on whether male partners require treatment.
The Nature of Bacterial Vaginosis
Bacterial vaginosis is defined as a polymicrobial syndrome involving an overgrowth of several types of bacteria that are already part of the body’s natural flora. The condition is characterized by a significant shift in the vaginal microbiome, where protective Lactobacillus species decline. This decline allows for the proliferation of various anaerobic bacteria, leading to the characteristic symptoms.
The biological cause is an ecological disruption, not the acquisition of a foreign pathogen, which is why BV is not traditionally classified as a sexually transmitted infection (STI). However, sexual activity is strongly associated with the onset and recurrence of the condition, suggesting that the exchange of bacterial communities plays a role. This distinction is important for understanding why the condition affects men differently than women.
Bacterial Presence and Symptoms in Men
Men cannot develop bacterial vaginosis itself because the condition is defined by an imbalance within the vaginal environment. However, male partners of women with BV frequently carry the associated bacteria, such as those from the Gardnerella genus, on the penile skin or within the urethra. This presence is referred to as colonization rather than an active infection, and a majority of male partners are colonized with these bacteria.
For men, this colonization is almost always asymptomatic, meaning they experience no noticeable symptoms like discharge or discomfort. The bacteria are often transient in the male genital tract, meaning they do not thrive long-term or cause a stable infection. In rare instances, colonization is linked to mild symptoms, such as non-gonococcal urethritis, which involves inflammation of the urethra.
Any symptoms a male partner experiences, such as itching or penile discharge, are more likely to be caused by other conditions, including a yeast infection or a different STI. Since the male body does not sustain the bacterial imbalance that defines BV, diagnosing the condition in men is not clinically meaningful. The primary concern regarding men is their potential role as a reservoir for the bacteria, which can then be transmitted back to the female partner.
Clinical Recommendations for Partner Treatment
For decades, major health organizations, including the Centers for Disease Control and Prevention (CDC), have recommended against the routine treatment of asymptomatic male partners. This guidance was based on older studies that failed to show a clear benefit of male partner treatment in preventing BV recurrence in women.
Recent, high-quality research is challenging this long-standing clinical practice, especially in cases of recurrent BV. A 2025 randomized controlled trial found that treating male partners significantly reduced the rate of recurrence in their female partners. Recurrence within 12 weeks dropped substantially for women whose partners also received treatment, compared to women who received standard treatment alone.
The treatment used in the successful trial involved a dual approach for the male partner: an oral antibiotic, such as metronidazole, combined with a topical antibiotic cream, like clindamycin, applied to the penis. This combination aims to clear the bacteria that colonize the penile skin and urethra.
While the CDC’s official guidelines have not yet been updated, the new evidence suggests that a physician may recommend male partner treatment when a woman suffers from repeated BV infections. Patients should consult a healthcare provider to discuss the risks and benefits of this combination therapy, which can include side effects like nausea and a metallic taste from oral metronidazole.