Initial Assessment
- Confirm fever by rectal temperature (≥38.0°C).
- Review immunization status.
- Classify appearance:
| Category |
Findings |
| Well-appearing |
Normal alertness, good color, normal cry, responds appropriately to interaction |
| Ill-appearing |
Lethargy, poor perfusion, abnormal cry, overall unwell gestalt |
Appearance alone does not exclude serious bacterial infection in this age group and must be paired with laboratory and risk-score data before any disposition decision [1].
Laboratory Evaluation
Obtain CBC, CRP, procalcitonin, and urinalysis on every febrile infant ≤60 days.
| Marker |
Threshold |
Interpretation |
| WBC |
>15,000 or <5,000/µL |
Suggests possible infection [1] |
| Left shift / I:T ratio |
I:T ratio >0.2 |
Suggests acute infection; low specificity, seen in many viral illnesses [1] |
| CRP |
>10 mg/L |
Indicates inflammation; not specific to bacterial vs. viral etiology [1] |
| Procalcitonin |
<0.5 ng/mL |
Reassuring in a well-appearing infant [1] |
| Procalcitonin |
>2 ng/mL |
Substantial bacterial infection risk [1] |
Integrate values in the Febrile Infant Markers Calculator →
Caution. No single marker rules out serious bacterial infection. Interpret CBC, CRP, and procalcitonin together with appearance and urinalysis before deciding on antibiotics or discharge [1].
Urinary Tract Infection
- UTI accounts for 5-10% of febrile infants under 90 days and is the most common serious bacterial infection in this age group [2].
- Obtain a catheterized specimen. Bag urine specimens are not reliable for diagnosis.
- Positive findings: leukocyte esterase, nitrites, pyuria (>5 WBC/hpf), or bacteriuria.
- Urine culture takes 24-48 hours to result. If treatment is started empirically, adjust once culture results return.
Estimate UTI probability in UTICalc →
Meningitis
Infants do not present with the classic meningitis signs seen in older children. Neck stiffness is not a reliable finding in this age group. Fever with poor feeding and irritability should raise concern.
Risk factors for bacterial meningitis:
- Age <30 days
- Ill appearance
- Elevated procalcitonin
Findings that confirm the diagnosis on lumbar puncture:
- CSF pleocytosis
- Positive Gram stain
- Seizures
A validated clinical prediction rule can help identify infants with CSF pleocytosis who are at very low risk of bacterial meningitis and may guide the decision to withhold empiric antibiotics pending culture [4].
Empiric antibiotic coverage by age:
| Age |
Regimen |
Rationale |
| ≤28 days |
Ampicillin plus gentamicin |
Ceftriaxone avoided: calcium-ceftriaxone precipitation risk and inadequate Listeria/Enterococcus coverage [3] |
| 29-60 days |
Ceftriaxone plus ampicillin |
Ampicillin added for Listeria coverage [3] |
Start antibiotics immediately whenever meningitis remains on the differential.
Guide LP decisions with the Meningitis Score →
Clinical pearl. A 20-day-old with fever and poor feeding, no neck stiffness on exam, should still be treated as a meningitis risk based on age alone. Do not use absence of neck stiffness to lower suspicion in this age group.
Sepsis Risk Stratification
Neonatal early-onset sepsis risk incorporates maternal and infant factors [5][6]:
Maternal factors:
- Maternal fever
- Rupture of membranes >18 hours
- Chorioamnionitis
- GBS colonization [5]
Infant factors:
- Prematurity
- Low birth weight
These factors are combined into a quantitative risk estimate for early-onset sepsis [6].
Calculate risk in Neonatal Sepsis Risk →
Management
| Risk tier |
Criteria |
Action |
| Very low-risk |
Well-appearing, normal labs, normal urinalysis, low risk scores, reliable follow-up |
Discharge home without antibiotics. Mandatory same-day phone call and 24-hour re-evaluation [1] |
| Lower-risk |
Some risk but not high-risk criteria |
Oral antibiotics (cephalexin or amoxicillin-clavulanate), outpatient observation, cultures pending [1] |
| Higher-risk |
Ill-appearing, abnormal labs, high risk scores |
Admit for IV antibiotics, lumbar puncture, full workup [1] |
Caution. Empiric antibiotics for an infant who truly meets very low-risk criteria are not a safe hedge. Unnecessary treatment discourages reliable follow-up and contributes to antibiotic resistance without a clear safety benefit [1].
Disposition Counseling
Before
References
- Pantell RH, Roberts KB, Adams WG, et al. Evaluation and Management of Well-Appearing Febrile Infants 8 to 60 Days Old. Pediatrics. 2021;148(2):e2021052228. doi:10.1542/peds.2021-052228
- Shaikh N, Hoberman A, Hum SW, et al. Development and Validation of a Calculator for Estimating the Probability of Urinary Tract Infection in Young Febrile Children. JAMA Pediatr. 2018;172(6):550-556. doi:10.1001/jamapediatrics.2018.0217
- Puopolo KM, Benitz WE, Zaoutis TE, et al. Management of Neonates Born at ≥35 0/7 Weeks of Gestation With Suspected or Proven Early-Onset Bacterial Sepsis. Pediatrics. 2018;142(6):e20182894. doi:10.1542/peds.2018-2894
- Nigrovic LE, Kuppermann N, Macias CG, et al. Clinical prediction rule for identifying children with cerebrospinal fluid pleocytosis at very low risk of bacterial meningitis. JAMA. 2007;297(1):52-60. doi:10.1001/jama.297.1.52
- Verani JR, McGee L, Schrag SJ. Prevention of Perinatal Group B Streptococcal Disease: Revised Guidelines from CDC, 2010. MMWR Recomm Rep. 2010;59(RR-10):1-36. doi:10.1542/peds.2013-1689
- Escobar GJ, Puopolo KM, Wi S, et al. Stratification of Risk of Early-Onset Sepsis in Newborns ≥34 Weeks Gestation. Pediatrics. 2014;133(1):30-36.