Evaluation of the febrile young infant: an update.

The febrile young infant is commonly encountered in the emergency department, and the incidence of serious bacterial infection in these patients is as high as 15%. Undiagnosed bacterial infections such as meningitis and bacteremia can lead to overwhelming sepsis and death or neurologic sequelae. Undetected urinary tract infection can lead to pyelonephritis and renal scarring. These outcomes necessitate the evaluation for a bacterial source of fever; therefore, performance of a full sepsis workup is recommended to rule out bacteremia, urinary tract infection, and bacterial meningitis in addition to other invasive bacterial diseases including pneumonia, bacterial enteritis, cellulitis, and osteomyelitis. Parents and emergency clinicians often question the necessity of this approach in the well-appearing febrile young infant, and it is important to understand and communicate the evidence that guides the approach to these patients. Recent studies examining the risk of serious bacterial infection in young infants with bronchiolitis and the role of viral testing in the febrile young infant will also be discussed in this review.