February 2013 Evaluation Of The Febrile Volume 10, Number 2 Young Infant: An Update Author Paul L. Aronson, MD Assistant Professor of Pediatrics, Department of Pediatrics, Abstract Section of Emergency Medicine, Yale School of Medicine, New Haven, CT Peer Reviewers The febrile young infant is commonly encountered in the emergency V. Matt Laurich, MD, FAAP department, and the incidence of serious bacterial infection in these Assistant Professor of Pediatrics, University of Connecticut patients is as high as 15%. Undiagnosed bacterial infections such School of Medicine, Connecticut Children’s Medical Center, as meningitis and bacteremia can lead to overwhelming sepsis and Hartford, CT Deborah A. Levine, MD, FAAP death or neurologic sequelae. Undetected urinary tract infection can Clinical Assistant Professor of Pediatrics and Emergency lead to pyelonephritis and renal scarring. These outcomes necessitate Medicine, New York University School of Medicine, New York, the evaluation for a bacterial source of fever; therefore, performance NY of a full sepsis workup is recommended to rule out bacteremia, CME Objectives urinary tract infection, and bacterial meningitis in addition to other Upon completion of this article, you should be able to: invasive bacterial diseases including pneumonia, bacterial enteritis, 1. Recognize and explain to parents the rationale for performance of the sepsis workup in the well-appearing cellulitis, and osteomyelitis. Parents and emergency clinicians often febrile young infant. question the necessity of this approach in the well-appearing febrile 2. Apply the low-risk criteria to the well-appearing febrile young infant with normal urine, serum, and cerebrospinal young infant, and it is important to understand and communicate studies to avoid unnecessary hospitalization. the evidence that guides the approach to these patients. Recent stud- 3. Consider testing for HSV infection in neonates, especially babies with skin vesicles, hypothermia, ill appearance, ies examining the risk of serious bacterial infection in young infants seizures, or hepatitis. with bronchiolitis and the role of viral testing in the febrile young infant will also be discussed in this review. Prior to beginning this activity, see the back page for faculty disclosures and CME accreditation information. Editor-in-Chief Ari Cohen, MD Division of Emergency Medicine, Tommy Y. Kim, MD, FAAP, FACEP Steven Rogers, MD Chief of Pediatric Emergency Phoenix, AZ Assistant Professor of Emergency Assistant Professor, University of Adam E. Vella, MD, FAAP Medicine Services, Massachusetts Medicine and Pediatrics, Loma Connecticut School of Medicine, Alson S. Inaba, MD, FAAP, Associate Professor of Emergency General Hospital; Instructor in Linda Medical Center and Attending Emergency Medicine PALS-NF Medicine, Pediatrics, and Medical Pediatrics, Harvard Medical School, Children’s Hospital, Loma Linda, Physician, Connecticut Children's Pediatric Emergency Medicine Education, Director Of Pediatric Boston, MA CA Medical Center, Hartford, CT Emergency Medicine, Mount Sinai Attending Physician, Kapiolani School of Medicine, New York, NY T. Kent Denmark, MD, FAAP, FACEP Medical Center for Women & Brent R. King, MD, FACEP, FAAP, Ghazala Q. Sharieff, MD, FAAP, Medical Director, Medical Simulation Children; Associate Professor of FAAEM FACEP, FAAEM AAP Sponsor Center, Professor, Emergency Pediatrics, University of Hawaii Professor of Emergency Medicine Associate Clinical Professor, Martin I. Herman, MD, FAAP, FACEP Medicine, Pediatrics, and Basic John A. Burns School of Medicine, and Pediatrics; Chairman, Children’s Hospital and Health Professor of Pediatrics, Attending Science, Loma Linda University Honolulu, HI; Pediatric Advanced Department of Emergency Medicine, Center/University of California; Physician, Emergency Medicine School of Medicine, Loma Linda, CA Life Support National Faculty The University of Texas Houston Director of Pediatric Emergency Representative, American Heart Medical School, Houston, TX Medicine, California Emergency Department, Sacred Heart Michael J. Gerardi, MD, FAAP, FACEP Association, Hawaii and Pacific Physicians, San Diego, CA Children’s Hospital, Pensacola, FL Clinical Assistant Professor of Robert Luten, MD Island Region Medicine, University of Medicine and Professor, Pediatrics and Gary R. Strange, MD, MA, FACEP Editorial Board Dentistry of New Jersey; Director, Madeline Matar Joseph, MD, FAAP, Emergency Medicine, University of Professor and Head, Department Jeffrey R. Avner, MD, FAAP Pediatric Emergency Medicine, FACEP Florida, Jacksonville, FL of Emergency Medicine, University Children’s Medical Center, Atlantic Professor of Emergency Medicine of Illinois, Chicago, IL Professor of Clinical Pediatrics Garth Meckler, MD, MSHS Health System; Department of and Pediatrics, Assistant Chair and Chief of Pediatric Emergency Associate Professor and Christopher Strother, MD Emergency Medicine, Morristown of Pediatrics, Department of Medicine, Albert Einstein College Fellowship Director, Pediatric Assistant Professor, Director, of Medicine, Children’s Hospital at Memorial Hospital, Morristown, NJ Emergency Medicine; Chief, Emergency Medicine, Oregon Undergraduate and Emergency Pediatric Emergency Medicine Montefiore, Bronx, NY Ran D. Goldman, MD Health & Science University, Simulation, Mount Sinai School of Division, Medical Director, Pediatric Richard M. Cantor, MD, FAAP, Associate Professor, Department Portland, OR Medicine, New York, NY Emergency Department, University FACEP of Pediatrics, University of Toronto; of Florida Health Science Center, Joshua Nagler, MD Professor of Emergency Medicine Division of Pediatric Emergency Research Editor Jacksonville, FL Assistant Professor of Pediatrics, and Pediatrics, Director, Pediatric Medicine and Clinical Pharmacology Harvard Medical School; Pediatric Vincent J. Wang, MD, MHA Emergency Department, Medical and Toxicology, The Hospital for Sick Anupam Kharbanda, MD, MS Emergency Medicine Fellowship Associate Professor of Pediatrics, Director, Central New York Poison Children, Toronto, ON Research Director, Associate Director, Division of Emergency Keck School of Medicine of the Fellowship Director, Department Control Center, Upstate Medical Mark A. Hostetler, MD, MPH Medicine, Boston Children's University of Southern California; University, Syracuse, NY Clinical Professor of Pediatrics and of Pediatric Emergency Medicine, Hospital, Boston, MA Associate Division Head, Emergency Medicine, University Children's Hospitals and Clinics of Division of Emergency Medicine, of Arizona Children’s Hospital Minnesota, Minneapolis, MN Children's Hospital Los Angeles, Los Angeles, CA Case Presentation nate is also at risk for neonatal herpes simplex virus (HSV) infection, a rare but life-threatening disease On an August afternoon, a 20-day-old male presents with that is controversial in its workup and manage- 11 his mother to the ED for a rectal temperature of 38°C. ment. Other current controversies include the util- The baby was born by spontaneous vaginal delivery at ity of the full sepsis workup in febrile young infants 39 weeks gestational age. The mother’s prenatal labs with alternative sources of fever such as respiratory were negative, including negative screening for group syncytial virus (RSV) and bronchiolitis. Understand- B streptococcus. The patient feels warm to the parents ably, parents will question why invasive testing today, but otherwise, he has been asymptomatic. The must be performed in their well-appearing febrile baby is feeding 3 ounces every 4 hours and is making an baby, and the emergency clinician needs to clearly appropriate amount of wet diapers. The physical examina- communicate the rationale behind the management tion is normal, including a flat anterior fontanel and good of patients in this high-risk age group. hydration. When you explain to the mother that the baby will need to undergo the full sepsis workup, including Critical Appraisal Of The Literature lumbar puncture, she asks if all the testing is necessary. What is the probability, since her baby looks so well, that An extensive literature search was performed in the he has a serious bacterial infection? After the testing is PubMed database using multiple combinations of completed, will the baby need to be admitted to the hospi- the search terms febrile young infant, low-risk criteria, tal? Can other infections besides bacterial infections cause neonate, serious bacterial infection, neonatal herpes sim- a fever, and does the baby need testing for these? Would plex virus, and infant less than 90 days old. All relevant the testing and treatment strategy change if the baby were articles were selected, reviewed, and included in the 40 days old? What if he had bronchiolitis with a fever? bibliography. Over 80 articles were reviewed, 68 of which are cited in this article. Emphasis was placed Introduction on reviewing the most important historical evidence as well as recent reports, studies, and guidelines. Commonly encountered in the emergency depart- ment (ED), the febrile young infant is defined as Etiology And Pathophysiology an infant < 90 days of age with a rectal temperature 1 ≥ 38.0°C. (See Table 1. ) Due to their immature im- The febrile young infant has an immature immune 12 2 mune systems and unique pathogens, the febrile system and a high incidence of SBI. In this age young infant is at high risk for bacterial infections, in group, SBIs include UTI/pyelonephritis, bacte- particular, urinary tract infection