Vaccine and Infectious Disease Division

Vaginal microbes in women who have sex with women

Bacterial vaginosis (BV) is a common vaginal infection that is associated with adverse outcomes in pregnancy and increased risk of HIV acquisition, yet the acquisition and etiology of the disease remain poorly understood.  Cross-sectional studies, which only sample one timepoint, have identified a number of factors linked to an increased risk of BV, including having sex with other women. However, prospective studies that track behaviors and incidence of BV over time have not been performed for most higher-risk groups.

Continuing earlier studies into the sources and transmission of the bacteria that characterize BV, University of Washington Department of Medicine associate professor Dr. Jeanne Marrazzo, along with VIDD associate member Dr. David Fredricks and other colleagues, followed a group of 199 BV-negative women who reported having sex with women in the previous year.  At enrollment, the investigators collected patient histories, looked for evidence of any BV-associated bacteria, and performed follow-ups quarterly or after a subject reported BV symptoms, at which time the researchers obtained updated patient histories.  Similar to the researchers’ previous findings in heterosexual women, significant risk factors for incident BV in this group were presence of BV-associated bacteria at enrollment or a follow-up visit within 14 days of the onset of menstruation. Of note, several BV-associated bacteria strongly predicted subsequent development of BV, suggesting that alterations in the vaginal microenvironment may precede BV by weeks or even months.  One additional risk factor was having a new female sexual partner with a history of BV, supporting previous data that suggested that BV may be transmitted by exchange of vaginal fluid in these women.  Interestingly, the observed incidence of BV in this group was comparable to the incidence of BV in a large study of heterosexual women.

Marrazzo JM, Thomas KK, Fiedler TL, Ringwood K, Fredricks DN. Risks for acquisition of bacterial vaginosis among women who report sex with women: a cohort study. PLoS One. 2010 Jun 15;5(6):e11139.