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Subscription Information for: American Family PhysicianEvaluation of Fever in Infants and YoungChildrenFebrile illness in children younger than 36 months is common and has potentially serious consequences. With thewidespread use of immunizations against Streptococcus pneumoniae and Haemophilus influenzae type b, the epidemiology of bacterial infections causing fever has changed. Although an extensive diagnostic evaluation is still recommended for neonates, lumbar puncture and chest radiography are nolonger recommended for older children with fever but no other indications. With an increase in the incidence of urinary tract infectionsin children, urine testing is important in those with unexplainedfever. Signs of a serious bacterial infection include cyanosis, poorperipheral circulation, petechial rash, and inconsolability. Parentaland physician concern have also been validated as indications of serious illness. Rapid testing for influenza and other viruses may helpreduce the need for more invasive studies. Hospitalization and antibiotics are encouraged for infants and young children who are thoughtto have a serious bacterial infection. Suggested empiric antibioticsinclude ampicillin and gentamicin for neonates; ceftriaxone and cefotaxime for young infants; and cefixime, amoxicillin, or azithromycinfor older infants. (Am Fam Physician. 2013;87(4):254-260. Copyright 2013 American Academy of Family Physicians.)The evaluation of febrile childrenyounger than 36 months has longpresented the challenge for physicians of ensuring that children withserious bacterial infection are appropriatelyidentified and treated, while minimizing therisks associated with invasive testing, hospitalization, and antibiotic treatment. Theepidemiology of febrile illness in childrenhas changed dramatically with the introduction of several vaccines targeted at this agegroup, and with the use of antibiotic prophylaxis during childbirth. Because of this, earlier guidelines have been questioned.1-3 Thisarticle focuses on previously healthy febrilechildren younger than 36 months. Thosewith significant preexisting conditions (e.g.,prematurity, immune compromise) shouldbe evaluated on a case-by-case basis.EpidemiologyStudies of infants and young children presenting with fever have documented adramatic reduction in the incidence of Streptococcus pneumoniae and Haemophilus influenzae type b (Hib) infections following thewidespread use of immunizations againstthese organisms. Rates of invasive Hib infection, including meningitis, in children fiveyears and younger have fallen by more than99 percent since the 1990s.4 Invasive pneumococcal infection in children declinedby 77 percent from 1998 to 2005,5 and isexpected to decline further with the use ofthe pneumococcal 13-valent conjugate vaccine (Prevnar 13).5 Rates of invasive Hib andS. pneumoniae infections have also decreasedin non- or partially vaccinated children,6perhaps because of herd immunity.Urinary tract infections (UTIs) are themost common source of serious bacterialinfection in children younger than threemonths, commonly from Escherichia colior Klebsiella species.7-11 A case series foundthat pneumonia is the most common serious bacterial infection in children threeDownloaded from the American Family Physician Web site at www.aafp.org/afp. Copyright 2013 American Academy of Family Physicians. For the private, noncommercial254 mber4 Februaryuse of oneFamilyindividualuser of the Web site. All other rights reserved.Contact copyrights@aafp.org for copyrightquestionspermissionrequests. 15, 2013 ILLUSTRATION BY TODD BUCKJENNIFER L. HAMILTON, MD, PhD, FAAFP, Drexel University College of Medicine, Philadelphia, PennsylvaniaSONY P. JOHN, MD, Chester County Hospital, West Chester, Pennsylvania

Childhood Feverto 36 months of age, followed by UTI.12 A large studyfound that the rate of hospitalization for UTI, includingpyelonephritis and urosepsis, in children younger than12 months has notably increased.13 This increase coincides with an increase in E. coli and other infections thatare resistant to penicillin and ampicillin.9,14 The cause forthis shift in infection and resistance patterns is not clear.Clinically Significant FeverA clinically significant fever in children younger than36 months is a rectal temperature of at least 100.4 F(38 C). Axillary, tympanic, and temporal artery measurements have been shown to be unreliable.15-18 Neonateswhose parents report a clinically significant fever mayhave a serious bacterial infection, even if they do not havea fever at the time of their initial medical evaluation.19Age StratificationTraditionally, guidelines for the management of feverin children have been based on age groups: neonates(younger than 30 days2 or 28 days7,20); young infants (upto two months21-23 or three months11,20,24-26); and olderinfants and young children (up to 36 months). Theprecise boundaries delineating these groups are underreview.27 Evidence supporting the use of particular ageranges, especially in children not vaccinated accordingto the recommended schedule, is limited.immunodeficiency virus infection) need more extensiveevaluation and treatment. Conversely, findings that suggest a benign cause for fever, such as vaccination in thepast 24 hours, are reassuring.10 Teething is rarely associated with a fever of more than 100.4 F28 ; therefore,teething should not prevent a thorough examination in ayoung child with a fever.A meta-analysis of febrile children older than onemonth has identified red flags associated with a highlikelihood of serious infection (Table 1).29 The studyidentified no findings with a negative likelihood ratio ofless than 0.1, which would help distinguish children atlow risk of serious infection.Laboratory Testing and ImagingHistory and physical examination cannot identify allchildren with serious bacterial infections; therefore, judicious use of imaging and laboratory testing is valuable.URINALYSIS AND URINE CULTUREBecause UTI is a common cause of serious bacterialinfection, urinalysis is a key factor in the evaluation offever in infancy and early childhood. Although this testis often omitted because of the difficulty with obtaining a specimen, a clinically valid urine sample shouldbe obtained for all children younger than 24 monthswith unexplained fever.30 The sample may be obtainedby catheterization or suprapubic aspiration. In childrenHistory and Physical Examinationwith voluntary urine control, a clean catch method (uriInitial history and physical examination in infants and nation into a specimen container after cleaning the areayoung children with fever is directed at recognition of around the urethra) may be used. Cultures of specimensserious illness. Children known to be immunocom- collected in a urine bag may have an 85 percent falsepromised (e.g., those with cancer, asplenia, or human positive rate,30 and urine dipstick testing has a 12 percentfalse-negative rate.31 All specimens shouldbe sent for formal urinalysis and culture.Table 1. Clinical Red Flags for Serious Infection in ChildrenUTI rates vary with patient sex and age. InOlder than One Monththe first three months of life, UTIs are morecommon in boys than in girls, and muchGlobal assessmentsCirculatory/respiratoryOther factorsmore common in uncircumcised boys. AfterParental concernsCracklesDecreased skinthree months of age, UTIs are more commonelasticityPhysician instinctCyanosisin girls.32Child behaviorChanges in ased breathsoundsPoor peripheralcirculationRapid breathingShortness of breathHypotensionMeningealirritationPetechial rashSeizuresUnconsciousnessThese red flags are associated with a positive likelihood ratio of greater than 5for serious infection in this population.NOTE:Information from reference 29.February 15, 2013 Volume 87, Number 4www.aafp.org/afp BLOOD CELL COUNTS AND BLOOD CULTUREWhite blood cell (WBC) counts and absoluteneutrophil counts have been used to identifyserious bacterial infection, including occultbacteremia. However, recent studies question their utility after early infancy.6,12,33,34Although various suggested cutoff values forthese tests have high sensitivity and reasonably high specificity, the rarity of bacteremiaAmerican Family Physician 255