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High-Yield Facts


  • The risk of serious bacterial illness (SBI) is greatest during the neonatal period, defined as birth to 28 days of life. Some authorities recommend that a child born prematurely should have the degree of immaturity subtracted from the child's chronological age for this consideration.

  • It is generally accepted that a fever is a temperature of ≥38°C or 100.4°F taken with a rectal thermometer.

  • A neonate who had a documented fever by any method but is afebrile on admission to the ED should be treated as a febrile neonate whether or not antipyretics have been given.

  • The most frequent bacterial pathogens in the neonatal period are group B Streptococcus (GBS), Escherichia coli, and Listeria monocytogenes.

  • Hypothermia is a rectal temperature less than 36°C or 96.8°F and, in the neonatal period, may actually be a more common presentation than elevated temperature. All neonates with hypothermia should be treated as septic.

  • Causes other than SBI, especially herpes simplex virus (HSV) infection, should be considered and, if suspected, treated expectantly.

  • Noninfectious problems, such as congenital heart disease (CHD) and inborn errors of metabolism, may present in a similar way and must always be on the list of potential causes of the septic-appearing infant.

  • If the child is exhibiting signs of shock, such as tachycardia, mottling, apnea, or prolonged capillary refill time, aggressive fluid resuscitation must be immediate.

  • Antibiotics should be started after cultures have been obtained.

  • If the child is unstable, the lumbar puncture may need to be postponed.


Fever is one of the most common presenting complaints of children evaluated in the emergency department (ED). Of particular concern to both parents and practitioners is the febrile neonate (0–28 days), since fever is often the only clinical sign of SBI in this age group. Neonates are at a particularly high risk of SBI due to a relatively immature immune system; including decreased T-helper cell activity, opsonization, antibody titers, macrophage, neutrophil, monocyte, and complement activity compared to older infants.13 (Some authorities recommend that a child born prematurely should have the degree of immaturity subtracted from the child's chronological age for this consideration.) The resultant inability to adequately contain bacterial infections results in higher morbidity for neonates with SBI. In addition, due to developmental immaturity, clinical indicators of wellness are not universally present in the neonate. For example, acquisition of the social smile, one of the most commonly used signs to judge the clinical appearance of infants, generally does not develop until 4 to 8 weeks of age.


Fever is generally defined as a rectal temperature ≥38.0°C (100.4°F). Temperatures obtained by the axillary, otic, temporal artery, or noncontact mid-forehead infrared routes tend to underestimate the rectal temperature and are often unreliable. Neonates with a documented rectal fever obtained by a reliable caretaker at home or in the office setting, who are afebrile on presentation to the ED, have the same risk of SBI as those with ...

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