Group B Strep (GBS) Infection

What group B strep is

Group B streptococcus is a different germ from group A strep, which causes strep throat and scarlet fever. GBS normally lives in the intestines and often the vagina, and it comes and goes over time. Carrying it is not a sexually transmitted infection, is not caused by poor hygiene, and does not need treatment outside of pregnancy unless it causes an infection.

Group B strep in pregnancy

Testing

In the US, guidelines from ACOG and the AAP recommend that all pregnant people have a swab of the lower vagina and rectum at 36 0/7 to 37 6/7 weeks. The swab is quick and painless and can usually be done by yourself. The result is valid for about 5 weeks. Some countries, including the UK, use a risk-based approach instead of routine testing.

Who receives antibiotics in labor

IV antibiotics (usually penicillin; alternatives for allergy) are given from the start of labor or when the waters break if:

• the late-pregnancy swab is positive
• GBS was found in the urine at any time in this pregnancy
• a previous baby had GBS disease
• GBS status is unknown and there is preterm labor (before 37 weeks), waters broken for 18 hours or more, or a fever in labor

Antibiotics work best when given at least 4 hours before birth. Taking antibiotics earlier in pregnancy does not clear carriage, because GBS returns. A planned cesarean before labor and with intact waters does not need GBS antibiotics.

GBS in urine

GBS in a urine sample during pregnancy suggests heavy carriage. It should be treated if it causes a urinary tract infection, and it also means antibiotics in labor are needed, without repeat swabbing.

Effects on the pregnant person

Most carriers have no symptoms. GBS can sometimes cause urinary infections, infection of the womb lining and membranes (chorioamnionitis) and infection after delivery. It has also been linked to preterm labor and stillbirth.

Group B strep in babies

Early-onset disease (first week)

Most cases start within 24 hours of birth, from bacteria swallowed or breathed in during labor. Signs include:

• breathing difficulty, grunting, fast breathing or pauses
• fever or low temperature
• poor feeding, floppiness, unusual sleepiness
• pale or blotchy skin, fast or slow heart rate

It usually presents as neonatal sepsis or pneumonia. Antibiotics in labor have reduced early-onset GBS by more than 80% in the US.

Late-onset disease (1 week to 3 months)

This can come from the parent, other caregivers or the community and is not prevented by antibiotics in labor. It more often causes meningitis. Watch for fever, irritability, poor feeding, drowsiness, a bulging soft spot and seizures. Premature babies are at higher risk.

Treatment in babies

Babies with suspected GBS have blood tests, a blood culture and often a lumbar puncture, then IV antibiotics (typically penicillin or ampicillin) for 10 days for bloodstream infection or 14 days or longer for meningitis. Most babies recover fully. About 1 in 20 babies with GBS disease die, and some survivors of meningitis have long-term problems with hearing, vision, learning or seizures.

Breastfeeding is safe and encouraged for GBS-positive parents.

Group B strep in adults

GBS infections in non-pregnant adults have become more common. Risk is highest in people over 65 and in those with diabetes, heart disease, cancer, kidney failure, obesity or liver disease. Types include:

• bloodstream infection (bacteremia) and sepsis
• skin and soft tissue infections such as cellulitis and diabetic foot infections
• bone and joint infections, including infected joint replacements
• pneumonia and urinary tract infections
• rarely, heart valve infection (endocarditis) and meningitis

Infections are diagnosed by culture of blood, urine, fluid or tissue, and treated with penicillin-type antibiotics, sometimes with surgery to drain infection.

How GBS is diagnosed

• Carriage: a vaginal-rectal swab cultured in an enrichment broth, or a rapid PCR test in some labor wards.
• Infection: culture of blood, cerebrospinal fluid, urine or tissue.

Can GBS be prevented?

There is currently no licensed vaccine; candidate maternal vaccines are in trials. For now, prevention relies on testing and antibiotics in labor. Probiotics, garlic, douching and tea tree oil have no proven effect on GBS carriage and should not replace screening.

Frequently asked questions

What does it mean to be GBS positive?

It means the group B strep bacterium was found on your vaginal-rectal swab. It is common and causes no harm to you in most cases. It means you should receive IV antibiotics during labor to protect your baby from early-onset infection.

How do you get group B strep?

GBS is a normal gut bacterium that many people carry naturally. It is not caused by hygiene or diet and is not considered a sexually transmitted infection. Carriage comes and goes, which is why the test is done close to delivery.

Can group B strep be treated before labor?

Treating carriage with antibiotics before labor does not work, because the bacteria come back. Antibiotics are given intravenously during labor, when they lower the amount reaching the baby. GBS urinary infections in pregnancy are treated when found.

What are the signs of group B strep in a newborn?

Signs include fever or low temperature, fast or difficult breathing, grunting, poor feeding, floppiness, unusual sleepiness and pale or blotchy skin. Early-onset signs usually appear within the first 24 hours. Any of these needs emergency medical attention.

Can my baby get group B strep after leaving the hospital?

Yes. Late-onset GBS can occur from 1 week to 3 months of age and is not prevented by antibiotics in labor. Seek urgent care for fever, poor feeding, irritability or drowsiness in a young baby, even if your GBS test was negative.