When a diagnosis of Bacterial Vaginosis (BV) is received, the association with sexual activity can understandably lead to questions about a partner’s fidelity. Bacterial Vaginosis is the most common vaginal condition globally, characterized by an imbalance of the natural bacteria in the vagina. Because BV is often discussed in relation to sexual health, understanding the medical facts about its causes and classification is important to provide clarity.
Is Bacterial Vaginosis Considered a Sexually Transmitted Infection?
Bacterial Vaginosis is not classified as a traditional Sexually Transmitted Infection (STI) like chlamydia, gonorrhea, or syphilis. A traditional STI is caused by the external introduction of a specific, foreign pathogen into the body. BV, by contrast, is a polymicrobial syndrome, meaning it results from an overgrowth of certain types of bacteria that are already naturally present in the vaginal environment.
The condition is defined as an imbalance, or dysbiosis, of the vaginal flora, rather than an acquired infection from an outside source. This distinction is significant because it means the condition can develop in individuals who have never been sexually active. While BV is not considered an STI, its presence can increase susceptibility to acquiring true STIs. A BV diagnosis is not evidence of a new infection transmitted from a partner, but rather a localized change in the existing microbial ecosystem.
Primary Causes and Non-Sexual Risk Factors for BV
The underlying mechanism of BV involves a shift in the vaginal microbiome away from its healthy, protective state. In a healthy environment, the vagina is predominantly colonized by Lactobacilli species, which produce lactic acid and hydrogen peroxide. These substances maintain a low, acidic pH, typically between 3.5 and 4.5, which naturally suppresses the growth of other bacteria.
Bacterial Vaginosis occurs when there is a significant decrease in these protective Lactobacilli, allowing an overgrowth of anaerobic bacteria, including Gardnerella vaginalis, Atopobium vaginae, and Prevotella species. The proliferation of these bacteria increases the vaginal pH to 4.5 or higher, which further encourages their growth. This disruption can be triggered by many factors entirely unrelated to a partner’s sexual history.
Douching is a well-established non-sexual risk factor because the practice flushes out the protective Lactobacilli and disturbs the delicate pH balance. Similarly, using scented feminine hygiene products, soaps, or bubble baths can irritate the tissues and alter the environment. Hormonal fluctuations, such as those that occur during menstruation, pregnancy, or menopause, also affect the vaginal environment and can predispose an individual to BV.
The presence of an intrauterine device (IUD) is also associated with an increased occurrence of BV. While these non-sexual factors are significant, sexual activity is also recognized as a risk factor, though not in the typical sense of transmission. The introduction of semen, which is alkaline, can temporarily raise the vaginal pH, providing a window for anaerobic bacteria to overgrow. This mechanism explains why sexual activity is a factor without necessitating the conclusion that a foreign pathogen was introduced.
Diagnosis, Treatment, and Partner Considerations
Diagnosis of Bacterial Vaginosis typically involves a clinical assessment, including an examination of symptoms like thin, grayish-white discharge and a characteristic fishy odor. A healthcare provider will often test the vaginal pH, with a result of 4.5 or higher suggesting BV. Microscopic examination of a sample may reveal “clue cells,” which are vaginal cells heavily coated with the overgrowing bacteria, confirming the diagnosis.
Treatment for BV involves a short course of antibiotics, such as metronidazole or clindamycin, administered orally or as a vaginal gel or cream. It is important to complete the entire course of medication, even if symptoms improve quickly, to ensure the infection is fully addressed. However, recurrence rates are high, with many individuals experiencing BV again within a year of treatment.
When considering male sexual partners, treatment is often not recommended because men cannot develop the vaginal dysbiosis that defines BV. However, research suggests that BV-associated bacteria can colonize the penis asymptomatically. Treating the male partner simultaneously with the affected individual can significantly reduce the high rate of recurrence. For individuals with a female partner, simultaneous testing and treatment are often recommended, particularly if the partner is also symptomatic.