P375 Risk factors for incident bacterial vaginosis among heterosexual women

Background The exact etiology of bacterial vaginosis (BV) is unknown and it is controversial whether BV is a sexually transmitted infection (STI). Gardnerella vaginalis is present in 95–100% of BV cases. However, it is also found in women with normal vaginal flora and colonization is not sufficient for BV development. We investigated risk factors for incident BV (iBV) in a longitudinal study of heterosexual women. Methods Women ages 18–45 with no Amsel criteria, Nugent score 0-3, no recent antibiotic use, and no evidence of STI were followed for iBV (Nugent score 7-10 on 3 consecutive days) with daily self-collected vaginal swabs for 8 weeks. Vaginal swabs were also obtained at enrollment for G. vaginalisquantitative PCR. Time to iBV was estimated and baseline participant characteristics were compared according to development of iBV or not. All analyses were conducted using SAS v9.4. Results Between January 2015-May 2018, 164 eligible heterosexual women were enrolled, of which the majority were African American (73%). Of those enrolled, 29 (17.7%) developed iBV at a median time of 21 (range 6–50) days. Women with iBV were significantly more likely to be older (33±7 years vs 30±7 years; p=0.02), African American (93% vs 69%; p=0.02), have a BV history (72.4% vs 48.2%; p=0.02), and have a pregnancy history (78% vs 54%; p=0.02). They were also significantly more likely to have detectable G. vaginalis by quantitative PCR at enrollment (81% vs 60%; p=0.04) with a higher median number of copies/µL (4,850 [1,890–30,100] vs 1,340 [217–9,550]; p=0.03). No significant difference was found between women with iBV and those without regarding current tobacco use, history of bacterial STI, and lifetime number of sexual partners. Conclusion This study confirms previous cross-sectional findings of risk factors for iBV among heterosexual women and examines the potential role of G. vaginalis in iBV pathogenesis. Disclosure No significant relationships.