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    Fever in Well Appearing Young Infants – 8-60 days

    Infections, Pediatrics

    Last Updated Oct 25, 2023
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    • The febrile infants aged 0-90 days are vulnerable to serious illness.
    • Well appearing infants, even those who have a viral source for their fever, have a disproportionately high rate of serious bacterial illness.
    • Rectal temperature is the best method to confirm fever in infants. A fever (>/= 38°C) measured at home is considered febrile.
    • Some febrile infants need a partial septic work-up (blood and urine cultures) and others require a full septic work-up (blood, urine, and CSF cultures).

    Diagnostic Process

    Recently published decision aids (‘Step-by-step,’ ‘PECARN’) utilized pro-calcitonin testing – a test not widely available in British Columbia currently – will not be included in the discussion.

    Fever in infants 0-28 days and ill-appearing infants 29-60 days of age:

    • Full-septic work-up should be performed, including blood, urine, and CSF cultures.
      • Admit for IV antibiotics and further monitoring.
      • Empiric antibiotics: Ampicillin and Cefotaxime is preferred over gentamicin.
      • Consider adding acyclovir in infants with:
        • A maternal history of HSV infection.
        • Presence of lesions suspicious for HSV.
        • A coagulopathy or elevated liver enzymes.
        • History of seizures or focal neurologic deficits.

    Well-appearing, febrile infants age 29-60 days of age with no source:

    • For infants who present with no viral source, a partial septic work-up including blood and urine cultures should be performed.
    • Consider chest x-ray, stool culture, and nasopharyngeal swab.
    • Once the partial septic work-up is completed, an additional decision aid (Rochester Criteria) can be used to determine whether these patients require intravenous antibiotics and admission to hospital.
    • Well-appearing febrile infants aged 29-60 days who meet ALL of the following criteria may be discharged home with a follow-up appointment in 24 hours:
      • Infant > 37 weeks gestation.
      • No history of prior hospitalization.
      • No prolonged newborn nursery care or NICU admission.
      • WBC between 5 and 15×109/L (with bands less than 1.5×109/L).
      • Urine WBC of less than 5/HPF, (and urinalysis negative for nitrites or leukocyte esterase).
      • CRP less than 20 mg/L (if available).
      • Procalcitonin than 0.5 mcg/L (if available).
      • No prior antibiotics.
      • No unexplained jaundice.
      • No history of chronic illness.
    • If the patient has a positive urinalysis (+leukocyte esterase, +nitrite, or WBC >5-10/hpf), the infant should be treated with antibiotics (typically intravenous). Well-appearing infants with access to close follow-up who have a UTI may be treated with oral antibiotics (broad-spectrum).

    Bronchiolitis (rhinorrhea, cough):

    The rate of urinary tract infection is still significant. If fever > 39C, or prolonged illness, a partial septic work-up should be completed, at minimum.

    Infants 60-90 days of age:

    Maintain a high index of suspicion for urinary tract infection in this population and consider urinalysis and culture in patients presenting without a clear viral source.

    Consider further investigations if unwell, unimmunized, or has a prolonged illness.

    Quality Of Evidence?


    The quality of evidence supporting these recommendations is of moderate quality. While there have been numerous studies published on the febrile infant, heterogenous inclusion criteria and the limited availability of certain testing modalities threatens the external validity.


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