EMERGENCY AND CRITICAL CARE MEDICINE: Edited by Jean Klig and Clifford W. BogueFebrile infant updateDorney, Kate; Bachur, Richard G.Author Information Division of Emergency Medicine, Boston Children's Hospital, Boston, Massachusetts, USA Correspondence to Kate Dorney, MD, Division of Emergency Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA. Tel: +1 617 355 6624; e-mail: email@example.com Current Opinion in Pediatrics: June 2017 - Volume 29 - Issue 3 - p 280-285 doi: 10.1097/MOP.0000000000000492 Buy Metrics Abstract Purpose of review The approach to febrile young infants remains challenging. This review serves as an update on the care of febrile infants less than 90 days of age with a focus on the changing epidemiology of serious bacterial infection (SBI), refinement of management strategies based on biomarkers, and the development of novel diagnostics. Recent findings There is high variability in the emergency department management of febrile young infants without significant differences in outcomes. C-reactive protein (CRP) and procalcitonin have emerged as valuable risk-stratification tests to identify high-risk infants. When interpreting automated urinalyses for suspected urinary tract infection (UTI), urine concentration influences the diagnostic value of pyuria. Novel diagnostics including RNA biosignatures and protein signatures show promise in better identifying young febrile infants at risk of serious infection. Summary The majority of febrile infants with an SBI will have a UTI but the diagnosis of invasive bacterial infection in infants continues to be challenging. The use of procalcitonin and CRP as biomarkers in prediction algorithms facilitates identification of low-risk infants. Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.