Group B Streptococcal Septicemia of the Newborn

Overview, Causes, & Risk Factors

This form of infection is caused by group B streptococcus Streptococcus agalactiae, a bacterium which is commonly found in the human gastrointestinal (GI) and genitourinary tracts.

Early onset of the disease occurs from birth to 6 days of life, generally in the first 24 hours. Late onset of the disease is generally seen in newborns from 7 days to 3 months of age, with most cases occurring in babies around 1 month old.

Group B streptococcus was formerly responsible for about three-fourths of sepsis (overwhelming infection of the blood and organs) cases in infants. However, this has decreased since the institution of screening and treatment of pregnant women at risk.

Risk factors include a mother who is known to have group B streptococcus in her GI or genitourinary tracts, rupture of membranes more than 18 hours prior to delivery, prematurity (less than 37 weeks), and maternal fever during labor.

Group B streptococcus may infect the fetus by traveling from the mother's bloodstream through the placenta or through ruptured membranes as the infant passes through the birth canal. The infant may also become infected after delivery, but this produces a later appearance of illness.