Neonatal Infectious Diseases and Immunology
Sepsis and congenital infection
Early-onset sepsis presents within 72 hours, often with respiratory distress, temperature instability, and lethargy. Group B streptococcus and Escherichia coli are common. Empiric therapy is ampicillin plus gentamicin, with lumbar puncture when meningitis is suspected. Late-onset sepsis often involves coagulase-negative staphylococci in preterm infants with central lines. Congenital infections have distinct patterns: cytomegalovirus causes periventricular calcifications and sensorineural hearing loss; toxoplasmosis causes hydrocephalus and diffuse calcifications; rubella causes cataracts and heart disease; syphilis causes bone changes and rash. Herpes simplex can present with vesicles, seizures, or disseminated disease and requires high-dose acyclovir.
Traps: relying on a normal CRP to exclude sepsis; forgetting that GBS prophylaxis does not eliminate disease; missing HSV because vesicles are absent; and misattributing thrombocytopenia to sepsis alone.
Worked example: a 12-hour-old term infant has respiratory distress, temperature instability, and a maternal fever. Blood culture is drawn, and ampicillin plus gentamicin are started after the culture. The infant improves, and antibiotics are narrowed when cultures are negative.
Rule of thumb: “Febrile mother plus unwell newborn equals sepsis until cultures are negative; start ampicillin and gentamicin.”