Extra-vaginal Bacterial Colonization and Risk for Bacterial Vaginosis (BV)
Fredricks DN1,2, Plantinga A1, Marrazzo JM3, Fiedler TL1, Wu M1, Srinivasan S1*
1Fred Hutchinson Cancer Research Center, 2University of Washington, Seattle, WA; 3University of Alabama, Birmingham, AL
Women who develop BV acquire anaerobic bacteria in the vagina that may be inoculated by exposure to sex partners. Alternatively, vaginal bacteria may emerge from endogenous reservoirs in women outside the vagina. A previous study in women who have sex with women demonstrated that colonization of extra-vaginal reservoirs with BV-associated anaerobes is a risk for subsequent BV. We sought to confirm or refute these findings in a population of women who have sex with men.
254 women were enrolled in a longitudinal study of the vaginal microbiota using vaginal swabs subjected to taxon-specific quantitative PCR (qPCR) assays. We analyzed data from 24 cases of incident or relapsing BV, compared to 48 control women who did not develop BV. BV was diagnosed by Gram stain of vaginal fluid with Nugent scoring. Samples were collected approximately one month prior to BV diagnosis in cases, and included swabs from the vagina, labia, mouth, and rectum. 16 taxon-specific qPCR assays were employed to measure presence and concentrations of key bacteria.
Both the presence and concentrations of Gardnerella vaginalis (p=0.011 and 0.008, respectively) and Sneathia spp. (p=0.005 and 0.002) in the rectum prior to diagnosis were positively associated with subsequent BV risk; Lactobacillus crispatus concentrations in rectal swabs were negatively associated with BV risk (p=0.006) using FDR adjusted p values. In an exploratory analysis, the presence of oral Dialister propionicifaciens imparted a relative risk of 23.3 for subsequent BV (p=0.002), while labial presence of BVAB2 (RR=6.24, p=0.027), Sneathia (RR=8.11, p=0.002), Megasphaera (RR=4.55, p=0.011), and Eggerthella (RR=3.36, p=0.017) were associated with increased risk for subsequent BV.
Previous findings were largely replicated in this population of women who have sex with men, suggesting that colonization of extra-vaginal sites with BV-associated bacteria is a consistent risk factor for BV regardless of the sexual partner preference. This knowledge can be used to identify women at high risk for BV, and may offer opportunities to reduce BV incidence by eradicating colonization of these extra-vaginal sites with bacteria linked to BV
Funded by NIH R01 AI061628