May 6, 2019

Background: Management and workup of fever in the neonate has been a long-standing challenge. This unique age group is particularly susceptible to serious bacterial infections (SBI’s) despite their clinical “well” appearance. Newborns, specifically those < 60 days of age are considered high risk for SBI’s (urinary tract infections, bacteremia, bacterial meningitis) primarily due to an underdeveloped immune system. As fragile hosts, simple bacterial infections are easily communicated via hematogenous spread, from one system to another. Once bacteremic, spread of infection through their permeable blood-brain barriers is relatively easy. Through a cascade of cellular events, bacteria are able to easily penetrate the CNS, leading to overwhelming meningitis &/or death.[1] Confounding their vulnerability, is the lack of immunizations in the first month of life. If you recall, at birth, newborns are given just their first hepatitis B vaccine. The remainder of baseline immunizations (Pneumococcal, Haemophilus influenzae type b [Hib], Rotavirus, Diphtheria, tetanus & acellular Pertussis [DTap], and Polio) are traditionally not given until 6 weeks - 2 months of age.[2] Thus infants in the < 60 day age range are dependent on their mothers’ antibodies for protection. Lastly as any clinician who has taken care of a sick newborn can attest, babies at this age rarely manifest an “ill-appearance” until they are critically ill, making their exam in the early stages of bacteremia falsely reassuring. Collectively this makes the workup of fever (38 ℃/100.4 ℉) in this age group particularly challenging.