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Group-B Streptococcus

Group B streptococcus (GBS) is a type of bacteria that many women carry in their vagina. If passed to the newborn during the birth process, it can cause serious illness.

GBS bacteria live in the intestinal tract and are usually harmless. Between 10% and 30% of pregnant women carry GBS in their birth canal or rectum. Although 99% of infants who come in contact with GBS during the birth process do not become ill, those who do can develop severe, life-threatening complications. Fortunately, treatment is available.

GBS itself is not a disease, but it can cause serious illnesses including sepsis (blood infection), pneumonia, and meningitis. Most infants infected with GBS develop symptoms in their first week of life, but symptoms sometimes appear when the infant is 1 week to 3 months old.

Fifteen to 30% of babies who survive meningitis triggered by GBS may have long-term health problems such as hearing and vision loss, learning disabilities, cerebral palsy, and seizure disorders.

How Do I Know Have It?

When you are 35- to 37-weeks pregnant, your doctor may take a culture by swabbing the outer part of the vagina and rectum and have it tested for GBS as part of the routine workup. Carriers of GBS usually have no symptoms. Results are available in a few days.

Some doctors do not test for GBS; instead, they will treat any woman who has a risk factor associated with GBS infection in newborns, including:

• Labor before 37 weeks gestation.
• Rupture of membranes before 37 weeks gestation.
• 18 hours since the membranes ruptured without a delivery.
• Fever of 100.4 F or more during labor.
• Previous baby infected with GBS.
• History of urinary tract infection caused by GBS.

How Can I Treat It?

If a test indicates you carry GBS, your doctor will give you intravenous antibiotics during your labor and delivery.

If you are not tested for GBS but are considered high-risk, your doctor will give you the same antibiotic treatment.

How Can I Prevent?

There is no way to avoid contracting GBS. While antibiotics can treat GBS infection, the bacteria are very widespread and carriers often have no symptoms. There’s currently no role for treatment with antibiotics prior to labor.

Efforts are underway to create a vaccine that may protect mothers and their newborns in the future.

Frequently Asked Questions

Q: I got strep throat during my pregnancy. Does that mean I have GBS?

A: Strep throat is commonly caused by Group A streptococcus, not Group B. You still may be a GBS carrier, though GBS most likely did not cause your strep throat.

Q: If my test shows I carry GBS, will I be a carrier my whole life?

A: Usually not. GBS tends to come and go.

Review Date: January 14, 2005
Reviewed By: Alison M. Stuebe, M.D., Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Boston, MA. Review provided by VeriMed Healthcare Network.

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