Group B streptococci (GBS) are one of the most frequent causes of bacterial infections and meningitis in newborn babies; infection may occur as often as 5 in every 1,000 babies. Two forms of infection occur in newborns: early-onset and late-onset. In pregnant women, GBS infections can also cause endometritis, amnionitis and septic abortion.
In adults, GBS can cause infections such as urinary tract infections, gangrenous lesions in people with diabetes, and a number of different infections in people with malignancy or other immunocompromising conditions.
The bacteria are common in gastrointestinal and genitourinary tracts. The bacteria cause serious problems for newborns and those whose immune systems are not adequate.
From 10-30% of pregnant women harbor GBS in their genital tract; approximately 1% of their newborns will develop infection. Risk of invasive GBS infection is greatest for premature newborns.
Transmission from mother to newborn occurs shortly before delivery or during delivery.
In newborns, early-onset disease has a fatality rate of 50%. Early-onset GBS disease produces symptoms within 6 days of birth, usually within the first 24 hours. Symptoms include: respiratory distress, apnea, shock, pneumonia and meningitis.
Late-onset GBS disease in newborns carries a fatality rate of 25%. Late-onset disease usually occurs at 3-4 weeks of age (range, 7 days to 3 months). Symptoms of late-onset disease include: bacteremia and meningitis.
Laboratory cultures of blood or other body fluid. Rapid screening tests may detect antigens to GBS in serum, cerebrospinal fluid, or urine but are not as accurate as a culture. A positive screening test in a symptomatic infant provides presumptive evidence of infection. A positive screening test in an infant without symptoms is not a reliable indication that there is GBS infection.
Penicillin or ampicillin.
One method of preventing GBS infection in newborns is to screen all pregnant women for GBS at 26 to 28 weeks gestation and, if positive, administer antibiotics throughout labor. If no screening test has been done by hospital admission for delivery, risk factors should be evaluated and a rapid screening test considered. Risk factors would include premature gestational age (less than 37 weeks), premature rupture of the membranes (less than 37 weeks), fever during labor, multiple births (twins, etc.), rupture of the membranes beyond 18 hours or previous delivery of a sibling with invasive GBS disease.
At this time, it is not recommended to perform routine testing of infants to determine GBS infection, but infants of mothers receiving antibiotics for GBS should be evaluated based on clinical findings and gestational age.