Endometrial microbiota in infertile women with and without chronic endometritis as diagnosed using a quantitative and reference range-based method

Chronic inflammation occurs in the uterus of about 9% of infertile women in Hong Kong. This is related to higher levels of certain bacteria identified in our study.

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Volume 112, Issue 4, Pages 707–717.e1

Authors:

Yingyu Liu, Ph.D., Elaine Yee-Ling Ko, B.Sc., Karen Ka-Wing Wong, M.Phil., Xiaoyan Chen, Ph.D., Wing-Ching Cheung, Ph.D., Tracy Sze-Man Law, MB.ChB., Jacqueline Pui-Wah Chung, MB.ChB., Stephen Kwok-Wing Tsui, Ph.D., Tin-Chiu Li, M.D., Ph.D., Stephen Siu-Chung Chim, Ph.D.

Abstract:

Objective

To systematically compare the endometrial microbiota in infertile women with and without chronic endometritis (CE), as diagnosed by a quantitative and reference range-based method.

Design

Case-control observational study.

Setting

University-affiliated hospital.

Patient(s)

One hundred and thirty infertile women.

Intervention(s)

Endometrial biopsy and fluid (uterine lavage, UL) collected precisely 7 days after LH surge, with plasma cell density (PCD) determined based on Syndecan-1 (CD138)-positive cells in the entire biopsy section and culture-independent massively parallel sequencing of the 16S ribosomal RNA gene performed on both the CE and non-CE endometrial fluid samples.

Main Outcome Measure(s)

Relative abundance of bacterial taxa.

Result(s)

Chronic endometriosis was diagnosed if the PCD was above the 95th percentile (>5.15 cells per 10 mm2) of the reference range in fertile control subjects. With this stringent diagnostic criterion, 12 women (9%) were diagnosed with CE. Sequencing was successfully performed on all endometrial samples obtained by UL) (CE, n = 12; non-CE, n = 118). The median relative abundance of Lactobacillus was 1.89% and 80.7% in the CE and non-CE microbiotas, respectively. Lactobacillus crispatus was less abundant in the CE microbiota (fold-change, range: 2.10–2.30). Eighteen non-Lactobacillus taxa including DialisterBifidobacteriumPrevotellaGardnerella, and Anaerococcus were more abundant in the CE microbiota (fold-change, 2.10–18.9). Of these, Anaerococcusand Gardnerella were negatively correlated in relative abundance with Lactobacillus (SparCC correlation magnitude, range: 0.142–0.177).

Conclusion(s)

Chronic endometriosis was associated with a statistically significantly higher abundance of 18 bacterial taxa in the endometrial cavity.

Clinical Trials Registry Number

ChiCTR-IOC-16007882.


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Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility® is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders. The journal publishes juried original scientific articles in clinical and laboratory research relevant to reproductive endocrinology, urology, andrology, physiology, immunology, genetics, contraception, and menopause. Fertility and Sterility® encourages and supports meaningful basic and clinical research, and facilitates and promotes excellence in professional education, in the field of reproductive medicine.

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