This summary discusses early-onset group B streptococcal infection in neonates. Late-onset group B streptococcal infection is addressed separately.

Diagnosis Overview:
Early-onset (younger than age 7 days) invasive group B streptococcal infection (EO-GBS) is one of the most common serious bacterial infections in neonates worldwide, causing septicemia, meningitis, and pneumonia. Neonates acquire GBS infection via vertical transmission or during the birthing process. Most neonates present with symptoms at or shortly after birth, with almost 95% of cases diagnosed before 48 hours of age. Presenting symptoms include hypothermia, lethargy, tachypnea, respiratory distress, apnea, hypoglycemia, hypotonia, irritability, hypotension, cyanosis, pallor, poor feeding, and, less likely, fever. Persistent pulmonary hypertension, severe cardiopulmonary failure, and neonatal encephalopathy are also seen.

The greatest risk factor for neonates is maternal colonization with GBS, determined from positive cultures of the vaginal and rectal areas or the urinary system. About 20%-30% of women in the United States are colonized with GBS. In the absence of intrapartum antibiotic prophylaxis, 50% of infants born to mothers positive for GBS become colonized, with 1%-2% developing infection. The American College of Obstetricians and Gynecologists (ACOG) recommends universal antenatal testing of all pregnant individuals for GBS colonization using vaginal-rectal cultures at 36 0/7-37 6/7 weeks of gestation or less than 37 weeks in cases of premature rupture of membranes (PROM) or preterm labor. Because of this, it is recommended that all infants born to GBS-colonized mothers who did not receive adequate intrapartum antibiotic prophylaxis should be monitored in the hospital for 36-48 hours.

Other risk factors for EO-GBS infection include prematurity, maternal intrapartum fever, rupture of membranes over 18 hours with unknown maternal GBS status, and history of the mother having a prior baby born with GBS infection. A high index of suspicion is necessary to diagnose and treat these infants as early as possible to prevent complications, including disseminated intravascular coagulation (DIC) and mortality. Blood cultures, blood counts with differential, and inflammatory markers should be ordered for all suspected infants. Intravenous (IV) antibiotics that cover the most common neonatal bacterial diseases (usually ampicillin plus an aminoglycoside) should be given as soon as possible. Urine cultures, blood gases, clotting studies, and cerebrospinal fluid (CSF) cultures may be obtained if clinically indicated, as well as a chest x-ray in case of respiratory symptoms.

Various early-onset sepsis risk scoring systems, such as the Neonatal Early-Onset Sepsis Calculator, have been used to establish a prior probability of newborn sepsis and, when combined with a physical examination, can help guide management.