Group B Strep Infection: GBS

Group B Streptococcus also known as Group B Strep Infection (GBS) is a type of bacterial infection that can be found in a pregnant woman’s vagina or rectum. This bacteria is normally found in the vagina and/or rectum of about 25% of all healthy, adult women. Women who test positive for GBS are said to be colonized. A mother can pass GBS to her baby during delivery.
GBS affects about 1 in every 2,000 babies in the United States. Not every baby who is born to a mother who tests positive for GBS will become ill. Although GBS is rare in pregnant women, the outcome can be severe. As such, physicians include testing as a routine part of prenatal care.

How can I find out if I have Group B Strep infection?

The Centers for Disease Control and Prevention (CDC) has recommended routine screening for vaginal strep B for all pregnant women. This screening is performed between the 35th and 37th week of pregnancy. Studies show that testing done within 5 weeks of delivery is the most accurate at predicting the GBS status at birth.
The test involves a swab of both the vagina and the rectum. The sample is then taken to a lab where a culture is analyzed for any presence of GBS. Test results are usually available within 24 to 48 hours. The American Academy of Pediatrics recommends that all women who have risk factors PRIOR to being screened for GBS (for example, women who have preterm labor beginning before completing 37 gestational weeks) are treated with IV antibiotics until their GBS status is established.

How does someone get group B strep?

Group B strep is not a sexually transmitted disease (STD). The bacteria that causes group B strep normally lives in the intestines, vagina, or rectum, and approximately 25% of all healthy women carry group B strep bacteria. For most women, there are no symptoms of carrying the GBS bacteria.

What if I test positive for Group B Strep?

If you test positive for GBS, this simply means you are a carrier. Not every baby who is born to a mother who tests positive for GBS will become ill. Approximately 1 out of every 200 babies whose mothers carry GBS and are not treated with antibiotics will develop signs and symptoms of GBS. There are, however, symptoms that may indicate you are at a higher risk of delivering a baby with GBS.
These symptoms include:

  • Labor or rupture of membranes before 37 weeks
  • Rupture of membranes 18 hours or more before delivery
  • Fever during labor
  • A urinary tract infection as a result of GBS during your pregnancy
  • A previous baby with GBS

In this case, your physician will want to use antibiotics to protect your baby from contracting GBS during delivery.
According to the CDC, if you have tested positive and are not high risk, your chances of delivering a baby with GBS are:

  • 1 in 200 if antibiotics are not given
  • 1 in 4000 if antibiotics are given

How can I protect my baby from Group B Strep?

If you test positive for GBS and meet the high-risk criteria, your physician will probably recommend giving you antibiotics through an IV during your delivery to prevent your baby from becoming ill. Taking antibiotics greatly decreases the chances of your baby developing early-onset group B strep infection.
For women who are group B strep carriers, antibiotics given before labor begins are not effective at preventing the transmission of the group B bacteria. Since they naturally live in the gastrointestinal tract, the bacteria can come back after taking antibiotics. A woman may test positive at certain times and negative at others. This is why it is important for all pregnant women to be tested for group B strep between 35 to 37 weeks of every pregnancy.

How does Group B Strep affect a newborn baby?

Babies may experience early or late-onset of GBS.
The signs and symptoms of early-onset GBS include:

  • Signs and symptoms occurring within hours of delivery
  • Sepsis, pneumonia, and meningitis, which are the most common complications
  • Breathing problems
  • Heart and blood pressure instability
  • Gastrointestinal and kidney problems

Early-onset GBS occurs more frequently than late-onset. Intravenous antibiotics are used to treat mothers and newborns with early-onset GBS.
The signs and symptoms of late-onset GBS include:

  • Signs and symptoms occurring within a week or a few months of delivery
  • Meningitis, which is the most common symptom

Late-onset GBS could have been passed during delivery, or the baby may have contracted it by coming in contact with someone who has GBS.

Frequently Asked Questions:

How serious is GBS?

GBS can cause bladder and uterine infections for the mother. In serious cases, GBS can cause meningitis, sepsis, pneumonia, or stillbirth.

If I test positive for GBS, does that mean my baby is going to get it also?

No. Approximately 1 out of every 200 babies who are born to mothers who carry GBS will become ill. However, there are certain symptoms that put a mother at a higher risk than others.

What can I do to prevent my baby from getting GBS disease?

Intravenous antibiotics (given through IV) are recommended during delivery to reduce the chance of your baby becoming sick. It is recommended that antibiotics are given once labor has begun and every four hours during active labor until the baby is delivered.

If I am having a cesarean delivery. Do I need to be treated for GBS?

If you tested positive for GBS and labor has not begun and/or your water has not broken, then you do not need to be treated for GBS during delivery. If you are GBS positive, labor has begun and/or your water has broken, most health care providers will still require you to be treated for GBS even if you are having a cesarean delivery.

If I had a positive Group B strep culture done early in pregnancy, will they test me again?

The CDC states that if a woman has a positive culture anytime during the current pregnancy, she will not need to be re-screened and will automatically need to be treated with antibiotics during labor.

Is Group B Strep-related to strep throat?

No, the two are not related.

Can a woman who tests positive take oral antibiotics before delivery?

Treating the mother with oral antibiotics during the pregnancy may decrease the amount of GBS for a short time, but it will not eliminate the bacteria completely and will leave the baby unprotected at birth. Also, waiting to treat the baby with antibiotics after birth is often too late to prevent illness if the baby is at high risk of contracting GBS.

Are antibiotics safe for the baby?

Penicillin (Category B) is commonly used during pregnancy in non-allergic patients. There are substitute drugs for those who are allergic to penicillin, but these may cause an allergic reaction in some women as well. It is best to discuss the pros and cons of taking antibiotics with your health care provider.

Want to Know More?

Compiled using information from the following sources:

1. Williams Obstetrics Twenty-Second Ed. Cunningham, F. Gary, et al, Ch. 58.
Centers for Disease Control and Prevention

1. March of Dimes