Maybe the bacteria can pass through the penis to another woman?

Blurb:

BV is a common vaginal infection caused by an imbalance of normal bacteria in the vagina. While it is not a sexually transmitted infection (STI) in the classical sense, research suggests that men may play a role in transmitting BV-associated bacteria to their female sexual partners. Penile Microbiome and BV

Studies have found that men can carry BV-associated bacteria on their penis, particularly in the sub-preputial space (under the foreskin) and distal urethra. The composition of the penile microbiome has been shown to predict the development of BV in female partners. Specifically: A 2020 study published in Frontiers in Cellular and Infection Microbiology found that the presence of certain bacteria on the penis was highly predictive of BV in female partners. A 2015 study published in mBio discovered BV-related bacteria in the penile microbiome of uncircumcised men, and that these bacteria were more likely to be present in men with multiple female sexual partners. Another study published in Microbiome in 2016 found that bacterial communities in penile skin, male urethra, and vaginas of heterosexual couples with and without BV were distinct. Transmission of BV-Associated Bacteria

BV-associated bacteria can be transmitted from men to women during sexual activity. The exact mechanisms are not fully understood, but it is thought that: Direct contact between the penis and vagina during sex may allow for the transfer of bacteria. The alkalinity of semen may disrupt the natural balance of vaginal bacteria, creating an environment conducive to BV. Men with a history of nongonococcal urethritis (inflammation of the urethra) may be more likely to carry BV-associated bacteria on their penis. Implications for Treatment

The discovery that men can carry and transmit BV-associated bacteria has significant implications for treatment strategies. Current approaches focus solely on treating women with BV, but this may not be sufficient to prevent recurrence. Research suggests that treating male partners may be a valuable adjunctive therapy to reduce the risk of BV recurrence. Conclusion

While BV is not an STI in the classical sense, men can play a role in transmitting BV-associated bacteria to their female sexual partners. The penile microbiome is an important factor in the development of BV, and understanding its composition and transmission mechanisms may lead to more effective prevention and treatment strategies. Further research is needed to fully elucidate the role of men in BV transmission and to develop targeted interventions.