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Health and Wellness

Group B Beta Streptococcus
Department of Obstetrics,
Multicare Associates of the Twin Cities


Group B beta Streptococcus, or Streptococcus Agalactiae, is a bacterium (germ) that was originally described in 1933. By the early 1970s it became apparent that Streptococcus Agalactiae was a frequent cause of infection in women after delivery, and in newborns. Since the late 1980s antibiotics have been used to prevent infections in high risk newborns. In May of 1996 the Center for Disease Control recommended routine testing and treatment for this bacteria in all pregnant women.


Streptococcus Agalactiae lives in the gastrointestinal tract (rectum and intestines) and can spread to the genitourinary tract (vagina and bladder). About one in five pregnant women are colonized with (carry) this bacteria. If a woman is colonized with these bacteria there is a small chance (1:150 or less than one percent) that her baby will get sick. "Early onset disease" makes babies ill in the first week of life, with most becoming ill in the first six hours after birth. Early onset infections may result in neonatal death (1:16 or six percent). Affected infants may have pneumonia, sepsis, or meningitis. The symptoms are weakness, poor feeding, jaundice (abnormally yellow skin), abnormal temperature, unnatural paleness, and a low blood pressure. There is a second form of disease that can occur between seven days and three months after birth. "Late onset disease" is very rare, only one ill baby for every 1,500 births. The signs are weakness, poor feeding, fussiness, and a temperature above 100.4 o F. If your baby ever has these signs you should call your baby's doctor.


The test for Streptococcus Agalactiae is simple. A cotton swab is placed at the vaginal introitus (opening) and into the rectum. These swabs are then sent to the lab for testing. This is done between the 35th and 37th week of pregnancy.


Treatment of a positive culture for Streptococcus Agalactiae is simple. When you are admitted to the hospital in labor an IV (small plastic tube) will be placed in your vein, and antibiotics will be given to you through this IV. The antibiotics will enter your body and go to your baby through the placenta to protect him or her from being infected with these bacteria. This treatment is very effective (90 percent) in preventing disease. This means that whether your culture was positive or negative in clinic, the chance that your baby will get this illness is very rare, less than one in 1,500. Which means that your baby is less likely to die from this disease than from an auto accident in the first year of life. Risks of treat-ment include mild allergic reactions (0.7 percent to 10 percent), severe allergic reaction (anaphylaxis) which may lead to maternal death (1:100,000), and/or the emergence of antibiotic resistant bacteria.


Why can't I take antibiotics prior to labor to kill the bacteria? These Bacteria will be present in labor 30 percent of the time, even with treatment.

Is Streptococcus Agalactiae a sexually transmitted disease? No.

What if I go into labor early, before the test is done? All women who deliver prior to 37 weeks should receive antibiotics.

What if my tests results are not available when I am in labor? Then the other risk factors are used to determine whether treatment is necessary: fever above 100.4 o F, and /or rupture of membranes more that 18 hours.

What antibiotics are used? Penicillin.

What if I am allergic to Penicillin? Then other another antibiotic, clindamycin, is used.

What if there is not enough time for the antibiotic to protect my baby? If you deliver in less than four hours after the antibiotic is given, your baby may be asked to stay in the hospital for 48 hours after delivery for safety.

What if I had beta streptococcus with my last pregnancy? You should be tested with each pregnancy, and only treated if you are colonized during the current pregnancy. An exception is that if you had a previously affected child then you should be treated.

What if I was tested early in pregnancy and was positive and the last test was negative? You should not receive antibiotics. An exception is that if the bacteria were in your urine, then you should be treated.

What if I have an elective cesarean section? An elective cesarean section carries a very low risk, and most authorities think that treatment is not necessary. Exceptions would be: prior affected child, infected urine, cervix dilated past four centimeters with labor, rupture of membranes, or less that 37 weeks gestation. In these instances, antibiotics should be given prior to you cesarean section by at least two hours if possible and safe.

More Information

If you want more information, please visit the Center for Disease Control web site for Group B Strep.