This summary discusses late-onset group B streptococcal infection in neonates. Early-onset group B streptococcal infection is addressed separately.

Diagnosis Overview:
Neonatal late-onset group B streptococcal infection (LO-GBS) occurs in neonates who are 7-89 days old with an incidence of 3.1-4 cases per 10 000 live births. Ninety-three percent of neonates with LO-GBS present with bacteremia, 30% present with meningitis, and 2%-4% present with bone and joint infections or cellulitis / adenitis.

GBS is a gram-positive diplococcus that frequently colonizes the gastrointestinal (GI) and genital tracts of pregnant individuals. Most infected infants are thought to have acquired GBS from their mothers at the time of birth or thereafter; however, horizontal transmission from other caregivers has been implicated in some cases. Risk factors for LO-GBS include maternal colonization with GBS, young maternal age, maternal HIV infection, and infant prematurity. Intrapartum antibiotic prophylaxis of mothers with positive GBS surveillance cultures does not impact the incidence of LO-GBS as it does for early-onset disease.

Most infants present with bacteremia without an identifiable focus. Signs and symptoms are often nonspecific and include fever, irritability, lethargy, respiratory distress, poor feeding, vomiting, and rarely apnea, often with a history of a preceding or intercurrent upper respiratory tract infection. Infants presenting with LO-GBS meningitis have similar symptoms to those with bacteremia but may also have nuchal rigidity, a bulging fontanel, or seizures. Bone and joint infections, including osteomyelitis and septic arthritis, often present in the lower extremities with pain on manipulation of the extremity or decreased movement. Fever is often absent. LO-GBS cellulitis / adenitis presents with swelling and erythema of the skin, often in the submandibular area.