Understanding Group B-Streptococcus in Pregnancy

Written by yvonnethornton on April 14th, 2014

Group B β-Streptococcus (GBS or GBBS ) is a bacterium commonly found in the rectum, and vagina. Group B Β Streptococcus  should not be confused with the bacteria that causes strep throat (Group A); these are two different types of bacteria. Group B β-Streptococcus  infection is not generally serious for women and can usually be treated easily with antibiotics. But things change when a woman becomes pregnant.

There isn’t a surefire way to keep from passing Group B β-Streptococcus  from mother to baby during delivery. Group B β-Streptococcus  infection can be fatal to a newborn, and although this is rare, it does happen. That’s why it’s so important to do everything possible to minimize the risk.

Group B β-Streptococcus is one of those bacteria that a woman can carry without realizing it. Although it is transmitted sexually, it is not considered to be a sexually transmitted disease, like gonorrhea or syphilis. The chances of passing the bacteria on to the baby during delivery are high, but most babies are not affected. However, a small number will develop a Group B β-Streptococcus  infection, which can cause problems ranging from the mild to the severe, perhaps death.

Screening for Group B β-STREPTOCOCCUS

Some doctors choose to routinely test every pregnant patient for Group B β-Streptococcus between 35-37 weeks of gestation and treat the ones who test positive for the bacteria with antibiotics at the beginning of labor. This is the method that has been shown to be the most effective at catching Group B β-Streptococcus  colonization and preventing infection in newborns.  Because the urine in the bladder is sterile, any Group B β-streptococcal infection found on a urine culture indicates that the mother is a “colonizer” and she will need antibiotics during her labor.

Some doctors, however, choose to treat only mothers who are at high risk for passing Group B β-Streptococcus on to their babies. These women include those who go into labor prematurely, those whose membranes rupture early and labor looks like it will be long, those with unexplained fever, those who have had a baby with Group B β-Streptococcus  infection before, and those who have or have had a kidney or bladder infection caused by Group B β-Streptococcus.

The test itself is simple and painless, and involves inserting a special cotton swab into the woman’s vagina and rectum. The swab is then placed in a solution in which the bacteria will grow if present. This is called a culture.

Treatment for Group B β-STREPTOCOCCUS

When an expectant mother tests positive for Group B β-Streptococcus , or is at high risk for passing it on to her baby, she is given antibiotics when she goes into labor. Giving the antibiotics earlier on, during pregnancy, is not as effective, as this allows the bacteria time to re-grow before delivery.

As for babies, they can develop one of two types of infections. The most common (and most dangerous) is early-onset disease, wherein the baby is infected while moving down the birth canal. Symptoms of this type of infection appear during the first week of the baby’s life, and the infection can be severe and difficult to treat. Antibiotic treatment during labor is designed to prevent this type of Group B  β-Streptococcus  infection in the baby.

The other type of Group B β-Streptococcus  infection is late-onset disease, and babies do not show symptoms of this until after their first week. These babies may have contracted the disease from their mothers during delivery or from contact with her or someone else carrying the disease after birth. This type of infection is not prevented by antibiotic use during labor, but can be treated with antibiotics after the baby is born.

However, whether early- or late-onset, Group B β-streptococcus is an infection not to be taken lightly and could result in disastrous results for your newborn.  So, make sure you keep your prenatal visits during the last weeks of your pregnancy in order to be tested for Group B β-streptococcus.

– Yvonne S. Thornton, M. D., M. P. H


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