Group B Streptococcus (GBS) Infection

Definition:
Infection with Group B Streptococcus (GBS), also known as ‘Streptococcus agalactiae’ and more colloquially as Strep B and group B Strep, can cause serious illness and sometimes death, especially in newborn infants, the elderly, and patients with compromised immune systems. Group B streptococci are also prominent veterinary pathogens, because they can cause bovine mastitis (inflammation of the udder) in dairy cows. The species name “agalactiae” meaning “no milk”, alludes to this.

Streptococcus is a genus of spherical, Gram-positive bacteria of the phylum Firmicutes. Streptococcus agalactiae is a gram-positive streptococcus characterized by the presence of Group B Lancefield antigen, and so takes the name Group B Streptococcus.

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This type of bacteria (not to be confused with group A strep which causes “strep throat”) is commonly found in the human body, and it usually does not cause any symptoms. However, in certain cases it can be a dangerous cause of various infections that affect pregnant women & their newborns .

Group B streptococcal infections affect one in 2,000 babies born every year in the UK and Ireland. About 340 babies a year will develop group B streptococcal infection within seven days of birth (early group B streptococcus disease).

Causes:
The bacteria is found living harmlessly in the vaginal and gastrointestinal tracts of up to 50 per cent of healthy women (and in many men too). It may be passed on to a baby either while the baby is still in the womb or during delivery. Although about 50 per cent of babies born to mothers carrying group B streptococcus pick up the micro-organism, only about one to two per cent of these newborns then go on to develop severe group B streptococcal disease.

Group B streptococcal sepsis is most likely to develop when the baby is premature or if there has been prolonged rupture of the membranes, with many hours passing before the baby is born, or if the baby has no antibodies to group B streptococci.

In the last 30 years it’s been show to be a cause of serious infection in non-pregnant adults too. It’s extremely rare in healthy people and is almost always associated with underlying problems such as diabetes or cancer, or less often, problems with:

•Heart and blood vessels
•Genitourinary system
•Liver disease
•Kidney disease

About five per cent of affected adults will eventually experience a second episode of group B streptococcal disease.

How is group B strep transmitted?
In newborns, GBS infection is acquired through direct contact with the bacteria while in the uterus or during delivery; thus the infection is transmitted from the colonized mother to her newborn. However, not every baby born to a colonized mother will develop GBS infection. Statistics show that about one of every 100-200 babies born to a GBS-colonized mother will develop GBS infection.

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There are maternal risk factors, however, that increase the chance of transmitting the disease to the newborn:

•labor or membrane rupture before 37 weeks
•membrane rupture more than 18 hours before delivery
•urinary tract infection with GBS during pregnancy
•previous baby with GBS infection
•fever during labor
•positive culture for GBS colonization at 35-37 weeks
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Group B strep infection is not a sexually transmitted disease (STD).

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Symptoms :
If a pregnant woman is carrying (or ‘colonised with’) group B streptococcus, there is a chance she could pass it to her unborn baby. Most babies will not be harmed and will simply carry the bacteria themselves, but it can cause:

•Early birth
•Stillbirth
•Late miscarriage and complications
Group B streptococcal disease in newborns is divided into early and late disease. Early group B streptococcal neonatal sepsis appears within 24 hours of delivery (and up to seven days afterwards) and accounts for over 80 per cent of cases. Typically it causes signs of pneumonia (breathing problems) or, less often, meningitis. Most of these babies will make a full recovery.

Late group B streptococcal neonatal sepsis appears between one week and three months after birth, and is more likely to cause meningitis. One in ten infected babies will die of blood poisoning, pneumonia or meningitis, while one in five will be affected permanently by cerebral palsy, blindness, deafness or serious learning difficulties.

Once a baby has reached three months of age, group B streptococcal infection is extremely rare.

In vulnerable adults, group B streptococcus can cause a range of different infections at different sites in the body.

Diagnosis:
In pregnant women, routine screening for colonization with GBS is recommended. This test is generally performed between 35-37 weeks of gestation. The test involves using a swab to collect a sample from both the vaginal and rectal area, and results are usually available within 24-72 hours.

In newborns, GBS infection can be diagnosed with blood tests and/or spinal-fluid analysis. Similar testing may be used to diagnose the disease in adults.

Treatment:
For women who test positive for GBS during pregnancy and for those with certain risk factors for developing or transmitting GBS infection during pregnancy, intravenous antibiotics are generally recommended at the time of labor (before delivery). The administration of antibiotics has been shown to significantly decrease GBS infection in newborns. If a pregnant carrier of GBS receives intravenous antibiotics prior to delivery, her baby has a one in 4,000 chance of developing GBS infection. Without antibiotics, her baby has a one in 200 chance of developing GBS infection.

In adults who develop GBS infection, whether they are pregnant women or individuals with chronic medical conditions, intravenous(IV) antibiotics are also recommended.

At this point in time, the best treatment for GBS infection is prevention through routine screening during pregnancy. This testing has served to decrease the overall number of GBS infections in newborns, and there is currently research underway to develop a GBS vaccine.

Should all at-risk women be treated?
Some women prefer not to receive antibiotics if their risk is only slightly increased. Experts advise that the risk of infection in the baby must be balanced against the wishes and beliefs of the woman in labour and against her risk of an adverse reaction to the antibiotics. If a group B streptococcus carrying woman had a healthy baby in a previous pregnancy, she is unlikely to be at greater risk with following pregnancies.

Scientists are trying to develop a vaccine for group B streptococcus, but technical problems mean that it’s likely to be some years before one is available.

Prevention:
Through collaborative efforts clinicians, researchers, professional organizations, parent advocacy groups, and the public health community developed recommendations for intrapartum prophylaxis to prevent perinatal GBS disease. Many organizations have developed perinatal GBS disease prevention and education programs to reduce the incidence of the disease. Information about the recommendations and the prevention programs can be found in medical journals and on the internet. Simple anti-septic wipes do not prevent mother-to-child transmission

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://www.medicinenet.com/group_b_strep/article.htm
http://www.bbc.co.uk/health/physical_health/conditions/group_b_streptococcus_infection.shtml
http://en.wikipedia.org/wiki/Group_B_streptococcal_infection
http://www.trying-to-conceive.com/pregnancy/preventing-group-b-strep-%E2%80%93-is-it-possible/
http://www.medicaldaily.com/news/20110211/5422/third-trimester-group-b-streptococcus-test-doesnt-accurately-predict-presence-during-labor.htm

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