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Incubation period and risk factors support sexual transmission of bacterial vaginosis in women who have sex with women
  1. Christina Ann Muzny1,
  2. Shelly Y Lensing2,
  3. Kristal J Aaron,
  4. Jane R Schwebke
  1. 1 Infectious Diseases, University of Alabama at Birmingham, Birmingham, Alabama, USA
  2. 2 Biostatistics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
  1. Correspondence to Dr Christina Ann Muzny, Infectious Diseases, University of Alabama at Birmingham, Birmingham, AL 35294, USA; cmuzny{at}


Objective The epidemiology of bacterial vaginosis (BV) favours sexual transmission of BV-associated bacteria. We examined incubation period and risk factors for incident BV (iBV) in a prospective study of women who have sex with women (WSW).

Methods Using daily self-collected vaginal swabs, WSW with normal vaginal microbiota (no Amsel criteria and a Nugent score of 0–3) were followed for 90 days or until iBV (Nugent score 7–10 on at least 2–3 consecutive days). Daily diaries of sexual activity and menses were completed. Time to iBV was estimated. Accounting for differing lengths of follow-up and age, rates of sexual activities (per 100 person-days (pd)) were compared according to iBV status. The relationship between menses and iBV was also investigated.

Results Of the 36 WSW, the mean age was 30 years (SD 8) and 92% were African American. The probability of iBV at 30 and 60 days was 20% (SD 7%) and 36% (SD 8%), respectively; 14 (39%) developed iBV by 90 days. In WSW with iBV versus those without iBV, the relative rate of any sexual activity prior to iBV was 40% higher (20.4 vs 14.6 per 100 pd; p=0.010), sex with a woman was 38% higher (14.3 vs 10.3 per 100 pd; p=0.038), digital-vaginal sex was 57% higher (14.3 vs 9.1 per 100 pd; p=0.005) and digital-anal sex was 5.6 times higher (2.9 vs 0.5 per 100 pd; p<0.001). iBV was more likely for those WSW with menses in the prior 2 days as compared with those without recent menses (HR 3.4; p=0.029). Sexual activity occurred in 93% WSW at a median of 4 days (95% CI 2 to 6) prior to iBV.

Conclusion iBV was common and associated with sexual activity in this cohort of predominantly African American WSW. An incubation period of 4 days is consistent with other bacterial STIs.

  • bacterial vaginosis
  • women
  • lesbians

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  • Handling editor Jo-Ann Passmore

  • Contributors CAM and JRS contributed to the conception and design. CAM, KJA and JRS contributed to the acquisition of data. CAM and SYL drafted the manuscript. All authors contributed to the analysis/interpretation of the data, revising it for intellectual content and final approval of the manuscript.

  • Funding This study was funded by the National Institute of Allergy and Infectious Diseases (NIAID) (K23AI106957; CAM, PI). Data from this study were presented as oral abstract #147 on June 28, 2018 in Symposium 4 (Vaginal Microbiome) at the 2018 International Union for Sexually Transmitted Infections (IUSTI) World Congress in Dublin, Ireland.

  • Competing interests CAM has been a consultant for Lupin Pharmaceuticals and BioFire Diagnostics. She has also received honoraria from Roche Diagnostics and Cepheid. JRS has been a consultant for and received research support from Lupin Pharmaceuticals, Hologic/GenProbe, BD Diagnostics, Cepheid, Quidel, Symbiomix, StarPharma and Toltec.

  • Patient consent for publication Not required.

  • Ethics approval This study was approved by the University of Alabama at Birmingham Institutional Review Board (Protocol #F131127001) and the JCDH Research Review Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Additional unpublished data from this study are available to all authors on this manuscript and to NIAID, at their request.