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Streptococcus, Group B

Synonyms of Streptococcus, Group B

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

Disorder Subdivisions

  • Adult Onset Streptococcus, Group B
  • Infant Early-Onset Streptococcus, Group B
  • Infant Late-Onset Streptococcus, Group B

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.

Related Disorders

The following disorders may be associated with Group B Streptococcus or may have other causes. Comparisons may be useful for a differential diagnosis:

Infectious Arthritis is an infection of tissues in a joint by bacteria, viruses or fungi. Symptoms of this disorder depend upon which agent has caused the infection. The symptoms may include fever, chills, general weakness and headaches, followed by inflammation of one or more joints. The affected joint or joints often become very painful, swollen, slightly red and stiff within a few hours or days. Rapid onset of symptoms may indicate that a bacterium is the cause. (For more information on this disorder choose "Infectious Arthritis" as your search term in the Rare Disease Database.)

Infective Endocarditis is a bacterial infection of the inner lining of the heart muscle (endocardium). This inner lining also covers the heart valves, and it is these valves which are primarily affected by infective endocarditis. There are several forms of infective endocarditis. Two types that have similar symptoms but are caused by different bacteria are acute bacterial endocarditis and subacute bacterial endocarditis. Acute bacterial endocarditis may affect normal heart valves, while subacute bacterial endocarditis more commonly affects heart valves which have been previously damaged by disease. A third type of infective endocarditis, prosthetic valvular endocarditis (PVE), may develop in patients who have previously had artificial (prosthetic) valve replacement or tissue valve replacement. (For more information on this disorder, choose "Endocarditis " as your search term in the Rare Disease Database.)

Listeriosis is a disorder caused by a bacterial infection (Listeria monocytogenes) transmitted to humans through contaminated food products,usually improperly pasteurized milk or cheese. Some cases have been transmitted through contact with other infected persons or animals. Cases range in severity from a transient carrier state with no apparent symptoms, to acute (suddenly occuring) spread of bacteria throughout the blood stream. Listeriosis of pregnancy may exhibit no symptoms or may be marked only by a fever and back pain. This condition can be mistaken for a bacterial infection of the kidney (pyelonephritis). (For more information on this disorder choose "Listeriosis" as your search term in the Rare Disease Database.)

Meningitis is a disorder characterized by inflammation of the membranes (meninges) around the brain or spinal chord. The disorder can occur in three different forms: adult, infantile, and neonatal. This inflammation can be caused by different types of bacteria, fungi, or malignant tumors. Chemical reactions to certain injections into the spinal canal can also cause meningitis. In it's acute form the disorder is characterized by fever, headache, a stiff neck and vomiting. (For more information on the disorder choose "Meningitis" as your search term in the Rare Disease Database.)

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.

Streptococcus, Group B Resources



Edwards MS, Baker CJ. Streptococcus Agalactiae. In: Mandell GL, Bennett JE, Dolan R. Eds. Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases. 4th ed. Churchill Livingstone Inc. New York, NY; 1995:1835-45.

Baker CJ, Edwards MS. Group B streptococcal conjugate vaccines. Arch Dis Child. 2003;88:375-78.

Platt JS, O'Brien WF. Group B streptococcus: prevention of early-onset neonatal sepsis. Obstet Gynecol Surv. 2003;58:191-96.

Carey JC. Screening and management protocols for Group B streptococcus in pregnancy. Curr Womens Health Rep. 2002;2:238-44.

Berner R. Group B streptococci during pregnancy and infancy. Curr Opin Infect Dis. 2002;15:307-13.

Ke D, Bergeron MG. Molecular methods for rapid detection of group B streptococci. Expert Rev Mol Diagn. 2001;1:175-81.

Luck S, Torny M, d'Agapeyeff K, et al. Estimated early-onset group B streptococcal neonatal disease. Lancet. 2003;361:1953-54.

Sander TR, Roberts CL, Gilbert GL. Compliance with a protocol for intrapartum antibiotic prophylaxis against neonatal group B streptococcal sepsis in women with clinical risk factors. Infect Dis Obstet Gynecol. 2002;10:223-29.

Velaphi S, Siegel JD, Wendel GD Jr, et al. Early-onset group B streptococcal infection after a combined maternal and neonatal group B streptococcal chemoprophylaxis strategy. Pediatrics. 2003;111:541-47.

Jolivet RR, Centers for Disease Control and Prevention (CDC). Early-onset neonatal group B streptococcal infection: 2002 guidelines for prevention. J Midwifery Womens Health. 2002;47:435-46.

Petrova A, Smulian JC, Ananth CV. Obstetrician preferences for prenatal strategies to reduce early-onset group B streptococcal infection in neonates: a population based survey. Am J Obstet Gynecol. 2002;187:709-14.

Schrag S, Gorwitz R, Fultz-Butts K, et al. Prevention of perinatal group B streptococcal disease. Revised guidelines from the CDC. MMWR Recomm Rep. 2002;51(RR-11):1-22.

Farley MM. Group B streptococcal disease in nonpregnant adults. Clin Infect Dis. 2001;33:556-61.

Jackson LA, Hilsdon R, Farley MM. Risk factors for group B streptococcal disease in adults. 1995;B123:415-20.

MEDLINEplus. Medical Encyclopedia. Group B streptococcal septicemia of the newborn. Update Date: 7/29/2002. 3pp.

FDA Talk Paper. FDA clears new lab test for group B strep in pregnant women. U.S. Food and Drug Administration. November 18, 2002. 2pp.

Group B Streptococcal Disease (GBS). CDC Division of Bacterial and Mycotic Diseases. Last reviewed, October 1, 2001. 4pp.

Group B Strep Disease. Frequently Asked Questions. CDC. Last revised date: November 8,2002. 5pp.

Group B Strep Disease. Prevention of Perinatal Group B Streptococcal Disease. nd. 2pp.

Group B Strep Disease. Adult Disease. Last update: December 2002. 2pp.

Group B Strep Disease.
"Awareness of Group B Streptococcus Infection During Pregnancy" The Group B Strep Association. nd. 5pp.

Group B Streptococcus. Dartmouth-Hitchcock Medical Center. nd. 3pp.

High Risk Newborn - Group B Streptococcus. Lucile Packard Children's Hospital. nd. 2pp.

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Report last updated: 2009/05/12 00:00:00 GMT+0

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