Is Bacterial Vaginosis a Sexually Transmitted Disease?
Bacterial vaginosis is not classified as a sexually transmitted disease, though it is strongly associated with sexual activity and is often diagnosed in women being evaluated for STDs. 1
The Nuanced Classification of BV
Official Position from CDC Guidelines
The CDC explicitly states that "bacterial vaginosis is not usually transmitted sexually," though it acknowledges the condition is included in STD treatment guidelines because these infections are frequently diagnosed during STD evaluations. 1
The CDC notes that "it is unclear whether BV results from acquisition of a sexually transmitted pathogen," indicating the mechanism remains incompletely understood despite strong epidemiological associations with sexual behavior. 1
Key Evidence Against Classic STD Classification
Treatment of male sex partners has not been beneficial in preventing BV recurrence, which is a critical distinction from true sexually transmitted infections where partner treatment is essential. 1, 2
Women who have never been sexually active rarely develop BV, but the condition can occur in virginal women and adolescent girls, contradicting that sexual transmission is a necessary prerequisite. 1, 3
Evidence Supporting Sexual Association
BV is strongly associated with having multiple sex partners, frequency of intercourse, and douching, creating an epidemiological profile that mirrors established STDs. 1, 3
The condition is enhanced by both penetrative sexual contact and non-penetrative behaviors including digito-genital contact and oral sex, suggesting that sexual activity itself—rather than coital transmission specifically—plays a role. 3
BV is common among women-who-have-sex-with-women, relating at least in part to non-coital sexual behaviors, further supporting that sexual activity broadly (not just heterosexual intercourse) influences BV development. 3
Current Understanding of Pathogenesis
The "Sexually Enhanced Disease" Model
BV may be better conceptualized as a "sexually enhanced disease" (SED) rather than a sexually transmitted disease, where frequency of intercourse is a critical factor but not necessarily involving pathogen transmission from partner to partner. 3
Two distinct mechanisms may explain the sexual association: (1) alkalinization of the vaginal environment during unprotected intercourse enhances the shift from lactobacilli-dominated flora to BV-associated flora, and (2) mechanical transfer of perineal enteric bacteria is enhanced by coitus regardless of protection status. 3
Microbial Ecology Rather Than Single Pathogen
BV results from replacement of normal H2O2-producing Lactobacillus species with high concentrations of anaerobic bacteria (Prevotella, Mobiluncus), Gardnerella vaginalis, and Mycoplasma hominis—representing an ecological shift rather than acquisition of a single sexually transmitted pathogen. 1
Recent research has identified 13 different species within the genus Gardnerella, suggesting that healthy women may be colonized by nonpathogenic species while virulent strains are involved in BV development, though this doesn't necessarily indicate sexual transmission. 4
Clinical Implications for Practice
Partner Treatment Considerations
Traditional guidelines state that routine partner treatment is not recommended, as six older randomized trials showed no benefit in preventing recurrence. 2, 5
However, newer evidence from 2025 suggests that for women with truly recurrent BV, treating male partners with metronidazole 400 mg orally twice daily for 7 days plus 2% clindamycin cream applied to penile skin twice daily for 7 days may be beneficial. 2
Counseling Patients
When discussing BV with patients, emphasize that while it's not a classic STD requiring partner notification and treatment like gonorrhea or chlamydia, sexual activity does influence its development and recurrence. 1, 3
Condom use is slightly protective against BV, and male circumcision might also provide protection, supporting behavioral modification counseling. 3
Common Pitfalls to Avoid
Don't automatically treat partners as you would for true STDs—this has not been shown effective in most cases and represents unnecessary antibiotic exposure. 1, 5
Avoid labeling BV as an STD in documentation or patient discussions, as this creates unnecessary stigma and misrepresents the condition's pathogenesis. 1
Don't assume that BV in a monogamous relationship indicates infidelity—the condition can develop through mechanisms unrelated to partner transmission, including douching, loss of protective lactobacilli, and mechanical factors during intercourse. 1, 3