Background: Sexual behaviors are prone to reporting bias. Use of biomarkers such as Y-chromosome detection in vaginal fluid are one approach to reduce this bias. This is of particular interest when evaluating WSW for female-to-female transmission of STIs. The objective of this study was to perform Y-chromosome testing on vaginal specimens from a cohort of exclusive African American WSW who denied recent sex with men to determine the accuracy of their self-reported sexual behaviors.
Methods: Provider-collected vaginal specimens from 77 WSW presenting to an urban STI clinic and participating in a study of partnership characteristics and STIs were used. DNA was extracted from 100 µL of vaginal wash using a two-step digest (50 U/µL Ready-Lyse lysozyme (EpiCentre Technologies, Madison, WI) at 37ºC overnight, followed by 1 hour at 56ºC with 120 nG/µL Proteinase K and 60 mM DTT) which was fed into a standard column-based extraction (DNeasy Blood and Tissue, Qiagen Inc., Valencia, CA). Y-chromosomes were detected using the Quantifiler Y Human Male DNA Quantification Kit (Life Technologies, Carlsbad, CA).
Results: Mean age of the cohort was 26.7 (SD ±8.0) years; median # of female partners in the past 30 days was 1 (IQR 1-1). None of the women reported sex with men during the past 30 days. Only 1/77 (1.3%) had Y-chromosome detected. This participant was a 20-year-old who identified as homosexual, reported no female partners in the past 30 days, 1 female partner during the past 3 months, 2 lifetime female partners, no lifetime male partners, and no history of pregnancy or STI; she was a contact to trichomoniasis and diagnosed with BV.
Conclusions: The very small proportion of WSW with a Y-chromosome detected in their vaginal fluid suggests that these women accurately reported their recent sexual behaviors with men. Y-chromosome testing may be useful in future WSW studies.