Longitudinal Changes in Vaginal Microbiota Composition Assessed by Gram Stain Among Never Sexually Active Pre- and Postmenarcheal Adolescents in Rakai, Uganda

Thoma, Marie E.; Gray, Ronald H.; Kiwanuka, Noah; Aluma, Simon; Wang, Mei-Cheng; Sewankambo, Nelson; Wawer, Maria J.

doi:10.1016/j.jpag.2010.07.002

« Previous Next »Journal of Pediatric and Adolescent Gynecology
Volume 24, Issue 1 , Pages 42-47, February 2011

Longitudinal Changes in Vaginal Microbiota Composition Assessed by Gram Stain Among Never Sexually Active Pre- and Postmenarcheal Adolescents in Rakai, Uganda

Marie E. Thoma, PhD, MHS
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, Rockville, Maryland, USA
- Address correspondence to: Marie E. Thoma, PhD, DESPR/NICHD/NIH, 6100 Executive Blvd, Room 7B13E. Bethesda, MD 20892-7510.
Ronald H. Gray, MD, MSc
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
Noah Kiwanuka, MB ChB, PhD
- Makerere University School of Public Health and Rakai Health Sciences Program, Kampala, Uganda
Simon Aluma, SLT, BBLT
- Rakai Health Sciences Program, Kalisizo, Uganda
Mei-Cheng Wang, PhD
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
Nelson Sewankambo, MB ChB, MMed, MSc
- Makerere University College of Health Sciences, Kampala, Uganda
Maria J. Wawer, MD, MHS
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA

published online 16 August 2010.

Abstract

Study Objective

To describe changes in vaginal microbiota and pH over time among never sexually active adolescents at different menarcheal stages.

Design

A cohort of 49 sexually inexperienced Ugandan adolescents provided weekly self-collected vaginal swabs and behavioral/health information for up to two years. Menarcheal stage was classified as: not experiencing menarche during follow-up (premenarcheal, n = 9), achieving menarche during follow-up (perimenarcheal, n = 20), and being postmenarcheal (n = 20) at enrollment. Vaginal microbiota were characterized as morphotypes of large gram-positive rods, small gram-negative or variable rods, and curved gram-negative rods based on Nugent Gram-stain criteria. Baseline measures were compared using nonparametric tests. Mean changes (β) in morphotypes and pH over time were estimated using longitudinal mixed-effects models.

Results

The baseline median (IQR: interquartile range) Nugent score was 8 (7–8) in premenarcheal, 4.5 (1–8) in perimenarcheal, and 1 (0–3) in postmenarcheal girls (P = 0.001). For each respective menarcheal stage, the median (IQR) counts of gram-positive rods were 0 (0–0), 10 (0–30), and 30 (18–30) (P = 0.002) and gram-negative or variable rods were 30 (30–30), 16 (0.5–30), and 0.5 (0–2.5) (P = 0.002) at enrollment. Counts of gram-positive rods increased (β = 0.259, 95% CI: 0.156, 0.362) and gram-negative or variable rods decreased (β = -0.201, 95% CI:-0.298,-0.103) significantly over time in premenarcheal girls, but not in other groups. Vaginal pH declined significantly in peri- and postmenarcheal girls only.

Conclusion

Vaginal microbiota composition varied by menarcheal stage at enrollment. Over time, significant changes in vaginal morphotypes occurred in premenarcheal girls, suggesting this may be an important period of transition.

Key Words: Vaginal microbiota, pH, Menarche, Lactobacilli, Bacterial vaginosis, Gram stain, Nugent score