About My Health Careers Internship MedBlogs Contact us
Medindia LOGIN REGISTER
Advertisement

Presence Of Group B Streptococcus In Pregnant Women Can Cause Preterm Birth

by Dr. Meenakshy Varier on September 2, 2016 at 11:04 AM
Font : A-A+

Presence Of Group B Streptococcus In Pregnant Women Can Cause Preterm Birth

Approximately 20-30% of women carry bacteria called group B streptococcus (GBS) in their vagina or rectum. In most cases, these bacteria cause no problems, but GBS has been linked to complications during pregnancy, including pre-term delivery.

A study published in PLOS Pathogens reports that GBS produces membrane-bound vesicles containing bacterial factors that can attack the host tissue. In mice, the study shows, these vesicles can move from the vagina to the uterus and cause inflammation of the membranes surrounding the fetus. When injected directly into the amniotic cavity of mice, these vesicles can induce preterm and still births.

Advertisement


Membrane-bound vesicles (MVs) loaded with toxins, immune-modulators, and other bacterial factors, contribute to the survival and virulence (the ability to cause disease) of many pathogenic bacteria.

Whether GBS produces MVs was not known. However, because in pregnant women who carry GBS and deliver prematurely, bacterial infection is rarely found in the womb, Anirban Banarjee, from the Indian Institute of Technology Bombay, and colleagues hypothesized that if GBS produces MVs, they might move up to the womb during pregnancy and cause tissue damage at interface between mother and fetus.
Advertisement

To test this, the researchers started by growing GBS in liquid media. When they removed the bacteria and examined the remaining liquid by electron microscopy, they found numerous spherical structures. Zooming in on the surface of growing bacteria, they detected vesicles that were just budding off the bacterial cell, confirming that GBS produces MVs.

They next examined the protein content of the MVs and identified 8 bacterial proteins, all with predicted properties of virulence factors that can attack the human host and cause disease.

When the researchers mixed MVs and cells of human origin, they found that the MVs can invade and kill these cells, suggesting that GBS MVs are toxic to the human host.

The researchers then deposited the MVs without the bacteria into mouse vagina and hours later found them throughout the uterus and in the developing fetus, indicating that MVs can indeed travel up the birth canal.

Adding MVs to mouse chorio-decidual membrane (which is found at the interface between mother and fetus) caused collagen degradation, reducing the elasticity and weakening the mechanical properties of the membrane.

When the researchers injected MVs directly into the amniotic sac (the fluid-filled cavity surrounding the embryo) of pregnant mice, they observed that 24 hours later the tissue of the interface between mother and fetus was severely disrupted, with broken collagen fibers, hallmarks of inflammation, and signs of extensive cell death. To test whether these changes could lead to pre-term birth, the researchers carefully monitored females whose amniotic sacs had been injected with MVs at day 14.5 of pregnancy (a full-term mouse pregnancy lasts 19 days).

Approximately 60% of the fetuses were born prematurely (by day 18 of pregnancy), compared with only 10% of pups following control injection with saline. Along with preterm birth, the researchers observed an increased frequency of fetal death in utero, and that the pups born to MV injected mothers were too small and some had abnormal morphology. Collectively, these results suggest that GBS MVs can cause preterm birth and fetal injury.

Discussing their results, the researchers emphasize the finding that MVs alone could induce features resembling clinical chorio-amnionitis in the mice. "Clinically", they say, "this observation is highly relevant as 50-80% women with chorio-amnionitis do not have bacteria in their amniotic fluid or the decidual tissue". Based on their study, they hypothesize that "MVs secreted by the pathogens residing in lower genital tract may be responsible for cases with unexplained chorio-amnionitis".

Acknowledging the gap between experimental results in mice following direct injection of MVs into the amnion sac and human pathogenesis, the researchers nevertheless suggest that their findings "provide a novel insight into how GBS while simply sitting in the vagina can orchestrate events at the fetal membrane leading to premature birth". Because MVS are not susceptible to antibiotics, the researchers speculate that instead "new drugs that prevent vesicle production may [...] be a viable therapeutic option to prevent GBS mediated preterm birth".

Source: Medindia
Advertisement

Advertisement
News A-Z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
News Category
What's New on Medindia
Printed Temperature Sensors help with Continuous Temperature Monitoring
Health Benefits of Giloy
Breast Cancer Awareness Month 2021 - It's time to RISE
View all

Medindia Newsletters Subscribe to our Free Newsletters!
Terms & Conditions and Privacy Policy.

More News on:
Rheumatic Fever Breech Presentation and Delivery Pregnancy and Complications Anemia in Pregnancy Iron & Folate Deficiency Anemia In Pregnancy Diet for Anemia in Pregnancy The Magic Feeling of Being A Mother Nocturnal Leg Cramps Scarlet Fever Budd-Chiari Syndrome 

Recommended Reading
Incidence of Group B Streptococcus Rises Among Newborns
A major cause of serious infectious diseases including sepsis, meningitis and pneumonia is the ......
Asymptomatic Bacteriuria Not Associated With Preterm Birth in Low Risk Women
The new research questions a routine policy of screening and subsequent treatment for asymptomatic ....
Preterm Birth Affects Ability to Solve Complex Tasks
Preterm born babies goes hand in hand with an increased risk for neuro-cognitive deficits....
Antidepressants Use during Pregnancy
Depression is common during pregnancy and antidepressants are usually prescribed to overcome it. Is ...
Anemia in Pregnancy
Anemia is the commonest blood disorder that may occur in pregnancy and is usually due to low iron or...
Breech Presentation and Delivery
Breech birth or presentation is delivery of the fetus in a bottom or foot-first position. Causes of ...
Budd-Chiari Syndrome
Budd-Chiari Syndrome (BCS) is a rare disorder caused by narrowing and obstruction (occlusion) of the...
Diet for Anemia in Pregnancy
A modified diet rich in Folate, Vitamin B12 and Iron is essential for the rapid rise in hemoglobin ....
Iron & Folate Deficiency Anemia In Pregnancy
About 95% of the anemia cases are due to iron deficiency....
Nocturnal Leg Cramps
Nocturnal leg cramps are painful muscle contractions, which occur in the calf, foot or thigh muscles...
Pregnancy and Complications
In-depth guide for expecting mothers to overcome health complications related to early or late pregn...
Rheumatic Fever
Rheumatic fever is an inflammatory disease that may develop after an infection with group A Streptoc...
Scarlet Fever
Scarlet fever may follow throat infection caused by bacteria Streptococcus pyogenes or group A strep...
The Magic Feeling of Being A Mother
Selecting the doctor who will help you in your pregnancy is a very personal decision. ...

Disclaimer - All information and content on this site are for information and educational purposes only. The information should not be used for either diagnosis or treatment or both for any health related problem or disease. Always seek the advice of a qualified physician for medical diagnosis and treatment. Full Disclaimer

© All Rights Reserved 1997 - 2021

This site uses cookies to deliver our services. By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Use