Group B Strep Infection
A common bacterium that can cause serious illness in newborns and some adults
Quick Facts
- Type: Bacterial infection
- Often: Carried harmlessly in the gut or genital area
- Main concern: Serious illness in newborns
- Prevention: Screening in pregnancy and antibiotics in labor
Overview
Group B streptococcus, often shortened to group B strep or GBS, is a type of bacterium that commonly lives in the intestines and genital area of healthy adults, usually without causing any problems. Many people carry it at some point and never know, because it does not normally cause illness in healthy adults.
However, group B strep can sometimes cause serious infections. The greatest concern is in newborn babies, who can become very ill if they are infected around the time of birth. It can also cause infections in pregnant people, older adults, and people with certain chronic health conditions. Because of the risk to newborns, pregnant people are routinely screened for group B strep, and antibiotics given during labor are highly effective at protecting the baby.
Symptoms
Healthy adults carrying group B strep usually have no symptoms. When it causes infection, the signs depend on who is affected.
- In newborns: Fever or low temperature, difficulty feeding, breathing problems, unusual sleepiness or floppiness, irritability, or a bluish color. These can be signs of serious infection such as neonatal sepsis, pneumonia, or meningitis.
- In adults: Fever, chills, and signs depending on the site of infection, such as a urinary infection, skin and soft tissue infection, pneumonia, or bloodstream infection.
A newborn with any of these warning signs needs immediate medical assessment, as group B strep infection in babies can progress quickly.
Causes
Group B strep infection is caused by the bacterium Streptococcus agalactiae. How it causes illness depends on the situation:
- Newborn infection: Babies can be exposed to the bacteria during birth if the mother carries group B strep in the genital area.
- Carriage in adults: The bacteria commonly live in the gut and genital tract without causing harm.
- Adult infection: The bacteria can occasionally cause infection in older adults or those with conditions such as diabetes or a weakened immune system.
Carrying group B strep is not a sexually transmitted infection and is not a sign of poor hygiene; it is simply part of the normal mix of bacteria many people carry.
Risk Factors
- For newborns: a mother who carries group B strep, prolonged labor or early rupture of the membranes, premature birth, or fever during labor
- For adults: older age
- Diabetes
- A weakened immune system
- Other chronic health conditions such as liver or kidney disease
Diagnosis
Testing depends on the situation.
- Screening in pregnancy: A swab of the vagina and rectum, usually taken late in pregnancy, to check whether the mother carries group B strep.
- Cultures: Samples of blood, urine, or spinal fluid grown in a lab to identify the bacteria when infection is suspected.
- Newborn evaluation: Blood tests and other tests if a baby shows signs of infection.
Routine screening in pregnancy is the key tool for preventing newborn infection, as it identifies who should receive antibiotics during labor.
Treatment
Group B strep infections are treated with antibiotics, and prevention in pregnancy is highly effective.
- Antibiotics during labor: Pregnant people who carry group B strep are given antibiotics through a vein during labor, which greatly reduces the chance of the baby becoming infected.
- Treating infection: Newborns or adults with active group B strep infection are treated with antibiotics, often in hospital and through a vein for serious infections.
- Supportive care: Sick newborns may need care in a neonatal unit, including help with breathing and feeding.
With timely antibiotics, most infections respond well, and prevention during labor has substantially reduced serious newborn infections.
Prevention
- Attend prenatal appointments and have the recommended group B strep screening test in pregnancy
- Let your maternity team know if you have previously had a baby affected by group B strep
- Receive antibiotics during labor if you test positive or have risk factors
- Seek prompt care if a newborn shows any signs of illness
- For adults at higher risk, manage chronic conditions such as diabetes well
When to See a Doctor
Seek immediate medical care for a newborn who has any signs of group B strep infection, including:
- Fever or unusually low body temperature
- Difficulty feeding, breathing problems, or grunting
- Unusual sleepiness, floppiness, or being hard to wake
- Irritability, a high-pitched cry, or a bluish color
Adults should seek prompt care for a high fever with chills, severe pain, confusion, or signs of a serious infection. Tell your maternity team if you are pregnant and develop a fever, or if your waters break early.
Frequently Asked Questions
Is carrying group B strep harmful?
For most healthy adults, carrying group B strep causes no harm and no symptoms, as it is part of the normal mix of bacteria many people carry. The main concern is passing it to a newborn during birth, which is why pregnant people are screened and given antibiotics during labor if needed.
How is group B strep prevented in newborns?
Pregnant people are screened for group B strep, usually late in pregnancy, with a simple swab. Those who carry it, or who have certain risk factors, are given antibiotics through a vein during labor. This greatly reduces the chance the baby will become infected.
Is group B strep a sexually transmitted infection?
No. Group B strep is not a sexually transmitted infection. It commonly lives in the gut and genital area of many healthy people without causing illness, and carrying it is not a sign of poor hygiene or anything you have done wrong.
What are the warning signs in a newborn?
Warning signs include fever or low temperature, difficulty feeding, breathing problems, unusual sleepiness or floppiness, irritability, a high-pitched cry, or a bluish color. A newborn with any of these signs needs immediate medical care, as infection can progress quickly.
Can adults get sick from group B strep?
Yes, though it is less common. Group B strep can cause infections such as urinary, skin, lung, or bloodstream infections, especially in older adults and people with conditions like diabetes or a weakened immune system. These infections are treated with antibiotics.
References
- Centers for Disease Control and Prevention (CDC). Group B Strep (GBS).
- American College of Obstetricians and Gynecologists (ACOG). Group B strep and pregnancy.
- MedlinePlus, U.S. National Library of Medicine. Group B streptococcal infections.
- World Health Organization (WHO). Group B streptococcus.