title: Incident bacterial vaginosis (BV) in women who have sex with women is associated with behaviors that suggest sexual transmission of BV.
abstract: BACKGROUND
  Female same-sex partnerships provide a unique opportunity to study the pathogenesis and transmissibility of bacterial vaginosis (BV) because it can be diagnosed in both members of the partnership. We conducted a nationwide community-enrolled cohort study of women who have sex with women, including women coenrolled with their regular female sexual partner (FSP), to investigate the BV incidence rate and factors associated with incident BV.
  
  
  METHODS
  Women who have sex with women, without prevalent BV in a cross-sectional study, were enrolled in a 24-month cohort study involving 3-monthly questionnaires and self-collected vaginal swabs that were scored by the Nugent method. We assessed the BV incidence rate per 100 woman-years (WY) and used univariate and multivariable Cox regression analysis to establish factors associated with BV acquisition.
  
  
  RESULTS
  Two hundred ninety-eight participants were enrolled in the cohort; 122 were coenrolled with their regular FSP. There were 51 incident cases of BV (rate, 9.75/100 WY; 95% confidence interval [CI], 7.41-12.83). Incident BV was associated with exposure to a new sexual partner (adjusted hazard ratio [AHR], 2.51; 95% CI, 1.30-4.82), a partner with BV symptoms (AHR, 3.99; 95% CI, 1.39-11.45), receptive oral sex (AHR, 3.52; 95% CI, 1.41-8.79), and onset of BV symptoms (AHR, 2.80; 95% CI, 1.39-5.61). Women coenrolled with their BV-negative partner had a greatly reduced risk of incident BV (AHR, 0.26; 95% CI, .11-.61), and high concordance of Nugent category (74%), which was predominantly normal vaginal flora throughout follow-up.
  
  
  CONCLUSIONS
  These data highlight the strong influence of sexual relationships and behaviors on BV acquisition and the vaginal microbiota. They provide epidemiological evidence to support exchange of vaginal bacterial species between women and the concept that BV is sexually transmitted.
authors.affiliation: Melbourne Sexual Health Centre, The Alfred Hospital, Melbourne Centre for Epidemiology and Biostatistics, Melbourne School of Population Health, University of Melbourne, Parkville, Victoria.
authors.forename: Lenka A
authors.initials: LA
authors.lastname: Vodstrcil
authors.affiliation: Melbourne Sexual Health Centre, The Alfred Hospital, Melbourne Centre for Epidemiology and Biostatistics, Melbourne School of Population Health, University of Melbourne, Parkville, Victoria.
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Walker
authors.affiliation: Centre for Epidemiology and Biostatistics, Melbourne School of Population Health, University of Melbourne, Parkville, Victoria.
authors.forename: Jane S
authors.initials: JS
authors.lastname: Hocking
authors.affiliation: The Kirby Institute, University of New South Wales, Darlinghurst.
authors.forename: Matthew
authors.initials: M
authors.lastname: Law
authors.affiliation: Melbourne Sexual Health Centre, The Alfred Hospital, Melbourne Centre for Epidemiology and Biostatistics, Melbourne School of Population Health, University of Melbourne, Parkville, Victoria.
authors.forename: Dana S
authors.initials: DS
authors.lastname: Forcey
authors.affiliation: Melbourne Sexual Health Centre, The Alfred Hospital, Melbourne.
authors.forename: Glenda
authors.initials: G
authors.lastname: Fehler
authors.affiliation: Melbourne Sexual Health Centre, The Alfred Hospital, Melbourne Central Clinical School, Monash University, Melbourne, Victoria, Australia.
authors.forename: Jade E
authors.initials: JE
authors.lastname: Bilardi
authors.affiliation: Melbourne Sexual Health Centre, The Alfred Hospital, Melbourne Centre for Epidemiology and Biostatistics, Melbourne School of Population Health, University of Melbourne, Parkville, Victoria Central Clinical School, Monash University, Melbourne, Victoria, Australia.
authors.forename: Marcus Y
authors.initials: MY
authors.lastname: Chen
authors.affiliation: Centre for Epidemiology and Biostatistics, Melbourne School of Population Health, University of Melbourne, Parkville, Victoria.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Fethers
authors.affiliation: Melbourne Sexual Health Centre, The Alfred Hospital, Melbourne Central Clinical School, Monash University, Melbourne, Victoria, Australia.
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Fairley
authors.affiliation: Melbourne Sexual Health Centre, The Alfred Hospital, Melbourne Centre for Epidemiology and Biostatistics, Melbourne School of Population Health, University of Melbourne, Parkville, Victoria Central Clinical School, Monash University, Melbourne, Victoria, Australia.
authors.forename: Catriona S
authors.initials: CS
authors.lastname: Bradshaw
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D018452:Homosexuality, Female; D006801:Humans; D015994:Incidence; D012307:Risk Factors; D016353:Self-Examination; D013048:Specimen Handling / Q000379:methods; D011795:Surveys and Questionnaires; D014621:Vagina / Q000382:microbiology; D016585:Vaginosis, Bacterial / Q000453:epidemiology* / Q000635:transmission*; D055815:Young Adult
keywords: bacterial vaginosis; lesbian; sexual behavior; sexual partner; women who have sex with women