Febrile infant
Formal Definition
A clinical presentation of fever (rectal temperature ≥38.0°C/100.4°F) in an infant, with distinct risk stratification protocols based on age: neonates (0-28 days) are considered high-risk and typically require full sepsis workup with hospitalization; infants 29-60 days undergo risk stratification using clinical criteria; infants 61-90 days may be managed with lower-risk protocols if well-appearing and meeting specific criteria.
How It's Used on the Ward
"Febrile neonate" or "febrile infant protocol" or "rule out sepsis in a baby" — fever in a young infant is treated as a potential emergency until proven otherwise.
Example
""3-week-old brought in with rectal temp 38.2C, fussy but consolable. Full sepsis workup per protocol: CBC, blood culture, urinalysis, urine culture, LP for CSF cell count, glucose, protein, culture. Admitted for empiric ampicillin and gentamicin IV pending cultures. At this age, no risk stratification — all neonates with fever get admitted and treated.""
Clinical Context
Age-based risk tiers (Rochester/Philadelphia/Boston criteria, now updated to AAP 2021 guidelines): 0-21 days: full evaluation, admit, empiric antibiotics regardless of appearance. 22-28 days: full evaluation, admit; risk stratify with inflammatory markers. 29-60 days: SBI risk varies by inflammatory markers (procalcitonin, ANC, urinalysis); well-appearing, low-risk infants may be discharged with close follow-up. 61-90 days: most risk stratify by appearance and markers. Lumbar puncture: indicated in all neonates <28 days; risk-based in 29-60 days. Common pathogens: neonates — GBS, E. coli, Listeria; older infants — Streptococcus pneumoniae, N. meningitidis, UTI pathogens. Temperature measurement: rectal only in infants <3 months (axillary, temporal, tympanic are unreliable).