Streptococcus, Group B

National Organization for Rare Disorders, Inc.

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  • GBS
  • Group B Streptococcal Septicemia of the Newborn
  • Lancefield Group B Streptococcus
  • Sepsis of the Newborn
  • Streptococcus Agalactiae

Disorder Subdivisions

  • None

General Discussion

Group B streptococcus (group B strep) is a type of bacteria that causes infection among newborns, pregnant women or women after childbirth, females after gynecologic surgery, and older male and female patients with other serious diseases.

Group B strep remains the most common cause among newborns (neonates) of infection of the blood (septicemia) and of the brain (meningitis). The responsible bacterium, usually S. agalactiae, may be found most often in the vagina and rectum of females and may be transmitted sexually, as well as to a fetus as the infant passes through the birth canal.

Group B strep infection of newborns may be prevented by giving pregnant women who are carriers antibiotics through the vein (intravenously) during labor. The U.S. Centers for Disease Control and Prevention (CDC) recommend that any pregnant woman who has had a baby with group B strep disease in the past, who has a bladder (urinary tract) infection caused by group B strep, or who tests positive for group B strep during pregnancy should receive antibiotics during labor.

Prevention and prompt treatment are important because group B strep infections may become life-threatening among newborns.

GBS disease is said to be early onset if it is obvious within the first week of life. It is said to be late onset if the disease is evident after the first week of life and before the end of the first three months. Those at greatest risk of GBS disease are newborn children of infected mothers, women after childbirth, females after gynecologic surgery and older male and female patients with other serious diseases.


Infant early onset group B streptococcus disease occurs in the first seven days of life with more than half of the cases occurring within the first twenty-four hours. Within this group, the symptoms may resemble other problems that one might see in a newborn: feeding difficulty, lethargy, fever, and irritability.

Infant late onset group B streptococcus disease is much more rare than early onset disease and occurs between seven days and three months after birth.

Most cases occur in infants at about one-month of age.

Symptoms are similar in both forms, but may vary in intensity. They include: unstable temperature (high or low); poor feeding; breathing difficulties including grunting, flaring of nostrils, rapid breathing (tachypnea), short periods without breathing (apnea), and blue appearance (cyanosis); very rapid heart rate (tachycardia) or very slow heart rate (bradycardia), irregular heartbeat (arrhythmia), lethargy, coma and shock.

Adult onset group B streptococcus disease occurs mainly in women after childbirth or gynecologic examination or treatment, and elderly male and female patients with other serious diseases such as diabetes mellitus, chronic renal failure, cirrhosis of the liver or malignancy. The most common infections caused by GBS in adults are swelling of the mucous membrane that lines the uterus causing fever, pain in the abdomen, discharge and swelling of the uterus (endometritis); and infection of the kidney causing fever, chills, pain, nausea and frequent urination (pyelonephritis). Other symptoms or illnesses that may occur in adults with GBS are: infection of the skin causing heat over the area, pain, and swelling (cellulitis); inflammation of the membranes around the brain or spinal cord causing fever, headache, nausea, vomiting, a stiff neck and/or aching muscles (meningitis); swelling and a build up of fluid in the lungs (pneumonia).


Group B streptococcus infection occurs when the bacteria (S. agalactiae) multiply and colonize in the mucous membranes. S. agalactiae is commonly found in the human gastrointestinal tract and genitourinary tract, and is potentially more dangerous when it colonizes the vagina and rectum.

The recent practice of comparatively widespread screening and treatment of infected pregnant women accounts for the substantial reduction in the incidence of rampant infection of the blood and organs (sepsis) among infants.

Affected Populations

Group B streptococcus disease is found throughout the world. It has been estimated that 15-35% of all women have the GBS bacteria in the vaginal region and/or intestines. In the majority of cases this bacteria will not cause any symptoms in adult females and as a result, many are not aware that they have it.

Approximately 15,000 to 18,000 newborns and adults in the United States are affected by group B strep disease yearly, and of this number between 1,000 and 2,000 may face life-threatening complications. Prompt treatment is essential.

Standard Therapies

Group B streptococcus is diagnosed by isolating the organism from the blood, cerebrospinal fluid, or fluid from the stomach.

Penicillin G and Ampicillin are antibiotic drugs prescribed to treat group B streptococcus. Patients allergic to these drugs may be given other antibiotics such as cephalosporins, erythromycin and/or chloramphenicol.

There is now a rapid screen blood test that detects part of the GBS bacterium within hours. This test can detect if the pregnant woman is infected while in labor, allowing the doctor to administer antibiotics immediately in order to prevent the newborn from acquiring GBS.

Investigational Therapies

Information on current clinical trials is posted on the Internet at All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010


For information about clinical trials sponsored by private sources, contact:

The federal government is supporting research on the development of a vaccine for the prevention of group B strep disease.



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Group B Strep Association

P.O. Box 16515

Chapel Hill, NC 27516



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