Group B streptococci (also known as Steptococcus Agalactiae ) are bacteria that may be found in the genitourinary tract and/or the gastrointestinal tract of humans. Most people are unaware that they have the bacteria because they usually cause no symptoms. Occasionally, however, these bacteria can cause urinary tract infections and endometritis (infection of the uterus) and even life-threatening diseases such as meningitis and endocarditis (infection of the heart valves). In 2001, there were 349 cases reported among New York City residents (rate of 4.4 cases per 100,000 person).
Infants may get severe forms of Group B streptococcus disease, including meningitis (infection of the brain) and bacteremia (infection in the blood), transmitted through the birthing process. Adults with factors predisposing them to infections (like diabetes, liver disease, and malignancy) are more likely to have the severe Group B streptococcus disease like bacteremia, pneumonia, and soft tissue or wound infections. Group B streptococcus may also cause urinary tract infections and endometritis (infection of the uterus) after childbirth in otherwise health women.
Group B Streptococcus has been found in the genitourinary or gastrointestinal tract cultures of 5% to 40% of women. Most of these women had no symptoms to indicate they had group B streptococcus. The rate of serious infections in infants is 0.3. to 0.7 per 1000 live births in the United States. It is estimated that 4.4 per 100,000 non-pregnant adults per year develop serious Group B streptococcus infection. Many of the non-pregnant adults with a serious Group B streptococcus disease have a predisposing illness.
An infant may become infected by passing through the birth canal of a woman with symptomatic or asymptomatic GBS. In adults, the gastrointestinal tract appears to be the major reservoir of Group B streptococcus infection, with frequent spread to the genitourinary tract.
Group B streptococcus disease occurs when the bacteria gets past a person's immune system defenses. Health conditions that decrease a person's immunity to infection also make invasive disease more likely (i.e., diabetes, liver disease, malignancy).
Infants born to mothers who have asymptomatic or symptomatic Group B streptococcus are at risk for serious disease. Although healthy adults can get Group B streptococcus disease, people with predisposing conditions like diabetes, liver disease, and malignancy are at higher risk.
In infants, early signs and symptoms of serious Group B streptococcal disease may be difficulty breathing, poor feeding, lethargy, or abnormal temperature. In adults, the symptoms will depend on the part of the body infected.
Women can be tested during pregnancy to see if they have Group B streptococcus. If the test is positive for the bacteria, or if the mother had a previous baby with Group B streptococcus disease, or had Group B streptococcus in her urine sometime during the pregnancy, the mother should be treated with antibiotics during delivery to prevent her baby from getting ill. Prevention of Group B streptococcus in infants is one of many reasons why all pregnant women should seek prenatal care.
Group B streptococcal disease in infants and adults can be treated with antibiotics, usually an antibiotic from the penicillin family. Alternative antibiotics exist for patients with penicillin allergies.
No. The development of Group B streptococcal disease is not thought to be dependent on person-to-person transmission, except for neonatal transmission. Therefore, testing and treatment of close contacts is not recommended.
Last Updated: March 2003