Related Experiment Video
Updated: Jun 4, 2026

A Murine Model of Group B Streptococcus Vaginal Colonization
Published on: November 16, 2016
Subtle perturbations of genital microflora alter mucosal immunity among low-risk pregnant women
Brenna L Anderson1, Susan Cu-Uvin, Christina A Raker
1Department of Obstetrics and Gynecology, Warren Alpert Medical School of Brown University, Providence, RI, USA. banderson@wihri.org
Objective:
Alteration in the vaginal flora has been associated with adverse pregnancy outcomes. The objective of this study was to examine the impact of changes in individual microflora on genital immunity among low-risk pregnant women in early pregnancy.
Design:
Cross-sectional study.
Setting:
Large, tertiary care, academic hospital clinic.
Population:
Low-risk women were enrolled prior to 14 weeks' gestation.
Methods:
Women were included if they had no medical or previous obstetrical complications, were non-smokers, had no sexually transmitted infections and no intercourse in the last 48 hours. Consenting women underwent speculum examination for collection of vaginal culture and Dacron swabs for cytokine analysis. Semi-quantitative vaginal cultures were performed in a reference laboratory.
Main Outcome Measures:
Concentrations of immune mediators were compared in the presence of various organisms. Concentrations were converted to multiples of the median to standardize the values of each mediator. Regression analyses were performed to control for race.
Results:
We enrolled 47 women. The frequencies of genital microorganisms were: H(2)O(2) -producing lactobacilli (70%), Ureaplasma urealyticum (66%), Gardnerella vaginalis (45%), anaerobic non-pigmented Gram-negative rods (ANPGNR, 40%), anaerobic pigmented Gram-negative rods (APGNR, 17%). After adjusting for race and body mass index, interleukin-1β, interferon-γ, tumor necrosis factor-α and granulocyte macrophage-colony stimulating factor were increased in the presence of G. vaginalis, ANPGNR, and APGNR. There was no consistent impact on the other markers of immune activation.
Conclusion:
The presence of individual species impacts genital immunity among low-risk pregnant women. Perturbations in genital immunity could partially explain heterogeneity in adverse pregnancy outcomes.
Related Concept Videos
Microbiota of the Urogenital Tract
Development of Human Microbiota
Microbiota Modulation by Antibiotics
Development of the Oral Microbiota
Factors Affecting the Risk of Infection
The integrity and count of the white blood cells help the body resist pathogens and fight infection. When impaired, it reduces the body's resistance to pathogens. The acidic pH levels of the gastrointestinal, genitourinary tracts, and skin create...
Surface Membrane Barriers
The outer layer of the skin, the epidermis, is a robust barrier comprising layers of closely packed keratinized cells. This dense arrangement prevents microbes from penetrating the body. The periodic shedding of epidermal cells...

