A Quantitative Glycogen Assay to Verify Use of Self-Administered Vaginal Swabs

and ‡CONRAD, Eastern Virginia Medical School, Arlington, VA.
Sexually transmitted diseases (Impact Factor: 2.84). 12/2012; 39(12):949-53. DOI: 10.1097/OLQ.0b013e31826e880e
Source: PubMed


Self-administered swabs are used to sample vaginal contents for a variety of clinical purposes including detection of sexually transmitted infections, condom breakage, and vaginal product use. The goal of this study was to determine whether a quantitative glycogen assay can be used to assess whether a swab has been exposed to the vagina to assure study compliance.
Buccal, skin, or vaginal samples were tested to determine whether a commercial quantitative glycogen assay can differentiate vaginal specimens. In addition, archived remnant de-identified vaginal swabs from clinical trials were tested. Periodic acid-Schiff stain was used to identify glycogen-positive cells as a confirmation test.
Glycogen concentrations in eluates of vaginal swabs from reproductive-aged women were significantly higher than those from unused swabs (mean ± SE, 964 ± 135 μg/mL vs. 14.7 ± 2.5 μg/mL, P < 0.001) and swabs exposed to buccal and finger/hand epithelia (40.3 ± 4.8 and 18.5 ± 5.4 μg/mL, P < 0.001). Glycogen concentrations were lower and more variable in vaginal swabs from older perimenopausal/menopausal women (mean ± SE, 235 ± 123, P < 0.01). Semen and sample storage longer than 1 year did not affect glycogen detection. Using a cutoff of 100 μg/mL of glycogen, 30 of 30 vaginal swabs from reproductive-aged women versus 0 of 28 control swabs were positive, for an assay sensitivity of 1 (95% confidence interval, 0.86-1) and specificity of 1 (95% confidence interval, 0.85-1). Periodic acid-Schiff stain correlated with soluble glycogen results but was less specific.
The quantitative glycogen assay provides a simple and inexpensive method to validate the use of self-administered swabs for sampling vaginal contents in clinical studies.

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Available from: Margaret Christine Snead, Nov 19, 2015
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    ABSTRACT: Abstract Biomarkers of semen exposure have been used in studies investigating the safety and efficacy of barrier methods of contraception. They have been used as objective indicators of semen exposure when studying sexual behaviors and in human immunodeficiency virus/sexually transmitted infection research interventions where participants are advised to avoid unprotected sex. Semen biomarkers have also been used to assess or validate self-reported sexual behaviors or condom use in reproductive health settings. Prostate-specific antigen (PSA) and Y chromosome DNA (Yc-DNA) have each been evaluated in the past as semen biomarkers and are the most widely used in the field. While both are considered reliable for evaluating exposure to semen, each has unique characteristics. In this report, we summarize the literature and provide some considerations for reproductive health researchers who are interested in using PSA or Yc-DNA as semen biomarkers. We also synthesize our previous published work on the optimal conditions of collecting and storing specimens and assay performance in the presence of other vaginal products that may influence various assays. Semen biomarkers are innovative and promising tools to further study and better understand women's reproductive and sexual health and behavior. More research is needed to better understand the strengths, limitations, and optimal performance conditions of specific assays in vivo.
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