Gardnerella vaginalis is a common bacterium frequently associated with bacterial vaginosis (BV) in women, a condition involving an imbalance in the vaginal microbiome. A common question concerns its presence and effects in men. This article explores whether Gardnerella vaginalis can affect men, how it may be transmitted, and its implications.
What is Gardnerella vaginalis?
Gardnerella vaginalis is a type of bacteria naturally found within the vaginal microbiome. It is a facultative anaerobic Gram-variable rod, meaning it can survive with or without oxygen. While present in healthy vaginal flora, an overgrowth of Gardnerella vaginalis is a significant contributor to bacterial vaginosis.
Bacterial vaginosis occurs when the delicate balance of vaginal flora is disrupted, particularly when beneficial lactobacilli decrease, allowing Gardnerella and other associated bacteria to proliferate. BV is a common vaginal infection in women, characterized by symptoms like thin, grayish-white discharge and a distinct “fishy” odor. This imbalance, rather than Gardnerella alone, defines BV.
How Gardnerella vaginalis Affects Men
While Gardnerella vaginalis is primarily associated with the vaginal microbiome, it can be transmitted to men through sexual contact with an infected partner. Despite this, Gardnerella vaginalis is not typically classified as a sexually transmitted infection (STI) in men like common STIs. Its presence in men usually represents colonization rather than a symptomatic infection. Men often carry Gardnerella on their penile microbiome, within semen, or in the urethra.
The bacterium does not typically cause a recognized “infection” in men because the male genital tract has a different environment and pH compared to the vagina. Therefore, Gardnerella in men rarely leads to significant symptoms or disease progression. However, it has been found as the most frequent bacterium in the genitourinary tracts of men with symptoms or concerns after unprotected sex. Some studies suggest the male genitourinary tract may harbor Gardnerella species, which could be a source of unexplained urinary or urethral symptoms.
Recognizing and Addressing Gardnerella vaginalis in Men
The presence of Gardnerella vaginalis in men is most often asymptomatic. In rare instances, men might experience mild, non-specific symptoms such as slight penile irritation, mild discharge, or inflammation of the foreskin and head of the penis (balanoposthitis). Urethritis, an inflammation of the urethra, has also been uncommonly reported.
Routine testing for Gardnerella vaginalis in men is not standard practice due to the infrequent occurrence of clear symptoms or disease progression. If identified, it might occur when a male partner of a woman with recurrent bacterial vaginosis is being investigated, or during evaluations for other urinary or genital issues. Diagnosis can be challenging. Treatment for men is generally not indicated unless specific, rare symptoms are present, or as part of a strategy to prevent recurrence in a female partner.
Impact on Female Partners and Recurrence
While men typically do not experience illness from Gardnerella vaginalis colonization, their carriage of the bacterium can be relevant to their female partners. Male colonization might contribute to the recurrence of bacterial vaginosis in women. BV has a high recurrence rate, with over half of treated women experiencing the condition again within three months.
Recent research indicates that treating male partners with a combination of oral and topical antibiotics can significantly reduce the recurrence rate of bacterial vaginosis in female partners. For example, a trial showed women whose male partners received treatment had a significantly lower BV recurrence rate. This suggests that male partners can harbor BV-associated bacteria and potentially reintroduce them, even if asymptomatic. Therefore, in cases of persistent or recurrent BV in women, healthcare providers may discuss partner treatment as a potential strategy to improve outcomes.