CHICAGO — The biggest risk factor for bacterial vaginosis among gay or bisexual women is having a sex partner with a history of the infection—an association that increases the chances of bacterial vaginosis by more than 400%, Dr. Jeanne Marrazzo said at a meeting on the prevention of sexually transmitted diseases.
Sharing sexual toys almost doubled the risk of developing bacterial vaginosis (BV) among these women, said Dr. Marrazzo of the University of Washington, Seattle. And although this association was not statistically significant, when it is combined with the risk of a partner's positive history, it suggests that the exchange of vaginal fluids plays a key role in the development of BV for this population, she said.
Dr. Marrazzo presented the preliminary results of a 1-year longitudinal study examining the rates of bacterial vaginosis in 335 women, including 47 couples (94 women). Their median age was 25 years; 88% were white. Most (305) reported sexual activity within the last 3 months; of these, 276 reported having had at least one female partner, and 18% reported both male and female partners. For those reporting sex with a male within the last 3 months, only 25% reported having used a condom.
A third of the women had a history of bacterial vaginosis—a somewhat high prevalence, especially in light of the group's very low rate of douching (6%), a behavior that is strongly associated with the infection. Dr. Marrazzo said.
All of the women completed a detailed computer survey of their sexual habits. Their symptoms were assessed clinically by Amsel criteria; bacterial vaginosis was confirmed with Gram stain of vaginal fluid and Nugent criteria. The overall prevalence of BV was 29%, which is higher than that usually seen at clinics in the United States, Dr. Marrazzo said. Of these women, 40% were symptomatic at the time of clinical assessment.
All of the sexually active women had experienced receptive vaginal or oral sex, including penetration with fingers, a penis, or toys; 40% had experienced receptive anal sex with fingers, penis, or toys; and 22% reported sharing a vaginal toy with a female partner.
In the univariate analysis, only having a partner with a history of BV was associated with a significant increase in the risk of developing BV (odds ratio 5.0). Other positive but nonsignificant associations included age younger than 26 years, sharing a sex toy (OR 2.0), and using vaginal lubricant (OR 2.0).
In the multivariate analysis, having a partner with a history of BV was still significantly associated with an increased risk (OR 4.5). Shared vaginal toys and the use of vaginal lubricant were still associated with a nonsignificant doubling of risk.
“We did not see any significant relationships with the two most consistently prominent risk factors, race and douching,” Dr. Marrazzo said. “Sexual activity did seem to be important, but not the behaviors that we expected.”
She then examined the prevalence of BV in the subset of 47 couples in the study. Partners were negative for BV in 22 couples, discordant in 5, and positive in 20.
“This degree of concordance for the presence or absence of the infection is strikingly different than what we would expect if we calculated the likelihood of BV based on the overall population prevalence,” Dr. Marrazzo said. “If [it were] just a random sample, it would be about 13 couples negative, 11 discordant, and 24 positive. This supports the idea that there may be some mechanistic process involved in being in a sexual relationship with a woman with BV.”
The association with sexual toys and vaginal lubricant is difficult to untangle, she said, because the two are most often used simultaneously. She noted that one of the most popular brands of lubricant contains hexachloradine, which may interfere with normal vaginal flora. In addition, “the pH of the most commonly used lubricants ranges from 5.8 to 6.1, so they may modify the vaginal pH directly, and if used persistently, they may contribute to the increased risk,” said Dr. Marrazzo.