Febrile Infant Workup

Use age-specific risk stratification only after confirming that the infant is well appearing and has fever without an apparent source. The 2021 AAP clinical practice guideline applies to term infants born at 37 weeks' gestation or later who are 8 to 60 days old; preterm infants are outside that guideline population and require individualized evaluation. publications aappublications aapRate of Urinary Tract Infections, Bacteremia, and Meningitis in Preterm and Term Infants | Pediatrics | American Academy of Pediatrics

Do not downgrade a documented home fever simply because the infant is afebrile in the emergency department. Infants with reported fever at home have a non-negligible UTI risk and a similar invasive bacterial infection prevalence compared with infants febrile on presentation; manage them with the same age-based pathway. acepacepAsk the Expert-Management of the Well-Appearing Febrile Young Infant: Integrating the AAP Guideline into Practice | Pediatric Emergency Medicine

Separate invasive bacterial infection from UTI when making procedural and disposition decisions. Among well-appearing febrile infants younger than 60 days, reported rates are approximately 5% to 17% for UTI, 1% to 2% for bacteremia, and 0.2% to 1% for meningitis. publications aappublications aapRate of Urinary Tract Infections, Bacteremia, and Meningitis in Preterm and Term Infants | Pediatrics | American Academy of Pediatrics

Obtain urinalysis and urine culture as the foundational bacterial assessment because UTI is the dominant serious bacterial infection in this population. A normal urinalysis is a key component of low-risk classification; leukocytes on dipstick or leukocyturia moves the infant out of low-risk pathways used for outpatient management. NEJM+1NEJMSuccessful Outpatient Management of Febrile Infants Without a Lumbar Puncture or Antibiotics | NEJM ClinicianPubMedOutpatient management of selected young febrile infants without antibiotics - PubMed

For infants being evaluated for invasive bacterial infection, obtain a CBC with ANC, blood culture, and inflammatory markers. Modern prediction strategies use urine and blood testing to identify infants aged 22 to 60 days at substantially lower risk for bacteremia and bacterial meningitis, but risk is not zero even when screening results are normal. BMJ+1BMJDisparities and implicit bias in the management of low- risk febrile ...publications aapGuideline-Based Risk Stratification for Febrile Young Infants Without Procalcitonin Measurement | Pediatrics | American Academy of Pediatrics

Use procalcitonin preferentially when available because it has better discrimination for invasive bacterial infection than CRP, WBC count, or ANC in young febrile infants. Published low-risk procalcitonin cutoffs vary from 0.12 to 1.71 ng/mL; therefore, interpret the value within a validated institutional pathway rather than substituting an arbitrary standalone threshold. PubMedPubMedUse of Procalcitonin in a Febrile Infant Clinical Pathway and Impact on Infants Aged 29 to 60 Days - PMC

For the youngest eligible infants, maintain a low threshold for lumbar puncture because invasive bacterial infection risk declines over the first weeks of life and evidence-based risk stratification is most useful in older infants. The outpatient literature does not recommend outpatient management for infants younger than 28 days, whereas selected infants older than 21 days have been studied after short emergency observation. ScienceDirect+1ScienceDirectEvaluation of the febrile infant younger than 3 months of age with no source of infection - ScienceDirectPubMedOutpatient management of selected young febrile infants without antibiotics - PubMed

For infants aged 29 to 60 days, a normal urinalysis and normal blood-based risk assessment identify a group at substantially lower risk of invasive bacterial infection in whom lumbar puncture, empiric antibiotics, and hospitalization may be avoided when follow-up is reliable. This is a risk-reduction strategy, not proof that bacterial meningitis is impossible. BMJ+1BMJDisparities and implicit bias in the management of low- risk febrile ...publications aapGuideline-Based Risk Stratification for Febrile Young Infants Without Procalcitonin Measurement | Pediatrics | American Academy of Pediatrics

An abnormal urinalysis does not by itself establish meningitis, but it prevents simple designation as a low-risk febrile infant. Pair the urine result with blood culture and inflammatory markers when deciding whether cerebrospinal fluid testing and parenteral treatment are warranted. BMJ+1BMJDisparities and implicit bias in the management of low- risk febrile ...PubMedOutpatient management of selected young febrile infants without antibiotics - PubMed

Respiratory viral positivity is associated with lower prevalence of UTI, bacteremia, and meningitis in febrile young infants, but clinically important bacterial infection remains non-negligible. Continue age-appropriate urine and bacterial evaluation rather than using viral detection as a rule-out test. JAMA+1JAMAUrinary Tract Infection, Bacteremia, and Meningitis Among Febrile Young Infants With SARS-CoV-2 andJAMAPrevalence of Urinary Tract Infection, Bacteremia, and Meningitis Among Febrile Infants Aged 8 to 60 Days With

SARS-CoV-2-positive infants aged 8 to 60 days have lower prevalence of UTI, bacteremia, and meningitis than virus-negative infants, especially those aged 29 to 60 days with normal inflammatory markers. The most useful role of SARS-CoV-2 testing is therefore as a risk modifier after—not instead of—urinalysis and inflammatory-marker assessment. JAMAJAMAPrevalence of Urinary Tract Infection, Bacteremia, and Meningitis Among Febrile Infants Aged 8 to 60 Days With

For infants aged 61 to 90 days, respiratory viral infection is also associated with lower UTI prevalence; reported UTI rates among influenza-, RSV-, or SARS-CoV-2-positive infants were 2.2% to 5.2%. That residual rate supports continued urine-focused assessment when clinical evaluation indicates UTI risk. publications aappublications aapRisk of Bacterial Infections in Febrile Infants 61 to 90 Days Old With Respiratory Viruses | Pediatrics | American Academy of Pediatrics

Prospective outpatient management without lumbar puncture or antibiotics has been reported for selected infants older than 21 days who were well appearing, had no urine leukocytes, ANC 10,000/mm3 or lower, CRP 20 mg/L or lower, procalcitonin below 0.5 ng/mL, and no clinical deterioration during an emergency stay of less than 24 hours. Among 586 such infants managed as outpatients, two had serious bacterial infection and no patient returned with an invasive bacterial infection. PubMedPubMedOutpatient management of selected young febrile infants without antibiotics - PubMed

For U.S. practice, use the more stringent age-specific AAP-oriented framework for infants 29 to 60 days: normal urinalysis and reassuring inflammatory markers support avoiding lumbar puncture, empiric antibiotics, and hospitalization in selected patients, but the disposition requires reliable follow-up and a plan to act on culture results. BMJ+1BMJDisparities and implicit bias in the management of low- risk febrile ...publications aapGuideline-Based Risk Stratification for Febrile Young Infants Without Procalcitonin Measurement | Pediatrics | American Academy of Pediatrics

Do not discharge based on normal early testing when the clinical trajectory is worsening. In the outpatient cohort, absence of deterioration during observation was an explicit low-risk requirement; in an external evaluation of Step-by-Step, an infant presenting within 6 hours of fever onset had normal urinalysis and biomarkers but Staphylococcus aureus bacteremia. BMJ+1BMJApplication of Step-by-Step and Paediatric Emergency Care Applied Research Network (PECARN) Clinical Decision Aids in the management of young febrile infants in a UK cohort | Emergency Medicine JournalPubMedOutpatient management of selected young febrile infants without antibiotics - PubMed