Group B streptococcus is a bacterium normally found in the reproductive tract of up to 30% of women. Group B strep (also called beta hemolytic strep) is not related to strep throat. Expectant mothers who are harboring group B strep are at an increased risk for intrauterine infection as well as passage of the infection onto their newborn. Fortunately, only a small percentage of babies born to women with this organism become infected.
Factors other than maternal genital tract colonization can increase a newborn baby's risk of GBS infection. These include women who have premature labor, preterm ruptured membranes, a prolonged period of ruptured membranes (usually greater than 24 hours), maternal fever, GBS urinary tract infection or a history of another baby with GBS infection at birth.
If GBS infects a newborn, which only occurs in three out of every 1000 babies born, the illness takes one of two forms. In early onset infection, the baby becomes sick within 24 hours after birth. Symptoms might include breathing problems, gastrointestinal problems, or blood pressure instability. In late onset infection, which occurs a week or more after birth, meningitis - infection of the membranes and fluids around the brain - usually results.
While group B strep remains one of the most devastating pathogens to newborns, recent reports suggest that the outcome of group B strep infections has improved with early recognition and treatment of infected newborns.
More and more commonly, doctors are screening for GBS in pregnancy. This is typically done at the end of the third trimester (36 weeks) and simply involves swabbing the vaginal wall and rectum with a cotton tipped culture swab. A speculum examination is not necessary.
Antibiotics, such as ampicillin or penicillin, are administered in labor to colonized women or women with high risk factors. Patients who are allergic to penicillin may be treated with other equally effective antibiotics. This has been shown to decrease infection significantly in their infants.