Group B Streptococcal (GBS) Disease and its Prevention in Newborns

All women should be screened for colonization with GBS from the vagina and rectum at 35 to 37 weeks gestation. A swab from the vagina and rectum is sent to the laboratory for culture. The only exceptions to this are women who have already demonstrated GBS in their urine during the current pregnancy or women who had a previous infant with invasive GBS disease.
Prophylaxis During Labor(preventive treatment with an antibiotic) is recommended in the following situations:

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Previous child with invasive GBS disease.
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GBS in the urine culture during this pregnancy.
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Positive GBS screening culture during the current pregnancy, unless a planned cesarean delivery is performed, before the woman goes into labor and before her membranes have ruptured.
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If the GBS status is not known because the culture wasn’t done or is incomplete(was done too recently for the colonization to be documented) or if the results are unknown for any other reason and any of the following circumstances exist:
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Delivery before 37 weeks gestation.
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The membranes have been ruptured for 18 hours or longer(even at greater than 37 weeks gestation).
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A temperature develops in labor of 100.4° F or greater(38.0° C or greater) (this may require a different antibiotic therapy).

Prophylaxis During Labor(preventive treatment with an antibiotic) is not recommended in the following situations:

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Previous pregnancy with a positive GBS screening culture(unless a culture was also positive during this pregnancy).
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Planned cesarean delivery performed in the absence of labor or rupture of membranes(regardless of whether the GBS culture is positive or negative).
* Negative vaginal and rectal GBS screening culture in late pregnancy during the current pregnancy.

Antibiotics are given during labor through an intravenous line. A usual dosage schedule is penicillin G 5 million units for the first dose, then 2.5 million units every 4 hours until delivery. If a woman is known to be penicillin allergic, Cefazolin may be given if she is not considered to be at high risk for serious reaction(anaphylaxis). If she is at high risk for an anaphylactic reaction, then clindamycin or erythromycin may be used. All medications are given intravenously.

If the culture shows the organism to be resistant to these medications, then a very strong antibiotic is used, called vancomycin.

Two risks exist with this treatment:

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some women may have a potentially dangerous allergic reaction to penicillin, and
2.

the development of resistant organisms is possible with widespread treatment.

New Approaches

Currently, researchers are investigating two other approaches: the development of a vaccine against group B strep and the development of a rapid, easily available, and accurate screening test that could be performed in labor with immediate results. A screening test would identify the women who carry GBS at the time of delivery and reduce the overall number of women receiving treatment. Screening tests are currently available but not considered accurate enough to determine treatment to prevent newborn GBS infection.
Informed Consent

To allow for informed consent, women should know the following:

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Approximately 1 in 200 newborns born to a mother colonized with GBS will develop GBS disease early in the newborn period.
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The risk of a newborn’s acquiring GBS from a mother who tests positive for the organism is 29 times higher than the risk for a newborn whose mother had a negative prenatal culture.
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The risk of a newborn’s acquiring GBS in a labor that is preterm or complicated by long duration of membrane rupture or fever is 7 times higher than the risk for newborns born without these labor complications.
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Five to 20 percent of newborns infected with GBS Will die.
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The treated woman’s risk of a mild allergic reaction to penicillin is 1 in 10.
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The treated woman’s risk of a serious allergic reaction to penicillin is 1 in 10,000.
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The risk of dying from an allergic reaction to penicillin is 1 in 100,000 treated women.
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Treatment for GBS before labor is not effective in preventing newborn GBS disease.