Sexually Transmitted Diseases

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Sexually Transmitted Diseases:
doi: 10.1097/OLQ.0b013e31826e880e
Original Study

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

Anderson, Deborah J. PhD*; Politch, Joseph A. PhD*; Pudney, Jeffrey PhD*; Marquez, Cecilia I. MD*; Snead, Margaret C. PhD; Mauck, Christine MD

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Abstract

Background: 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.

Study Design: 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.

Results: 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.

Conclusions: 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.

© Copyright 2012 American Sexually Transmitted Diseases Association

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