Children between 2 months and 3 years of age are atincreased risk for infection with organisms with polysaccharide capsules, including S. pneumoniae, H. influenzae, N. meningitidis, and nontyphoidal Salmonella. Effective phagocytosisof these organisms requires opsonic antibody. Transplacentalmaternal IgG initially provides immunity to these organisms,but as the IgG gradually dissipates, risk of infection increases.In the United States, use of conjugate H. influenzae type b and S. pneumoniae vaccines has dramatically reduced the incidence of these infections. Determining the child’s immunization status is essential to evaluate risk of these infections. An approach to evaluation of these children is outlined inFigure 96-1.
Most episodes of fever in children younger than 3 years of age have a demonstrable source of infection elicited by history, physical examination, or a simple laboratory test. In this age group, the most commonly identified serious bacterial infection is a UTI. A blood culture to evaluate for occult bacteremia, and urinalysis and urine culture to evaluate for a UTI, should be considered for all children younger than 3 years of age with fever without localizing signs. Stool culture should be obtained in those with diarrhea marked by blood or mucous. Ill-appearing children should be admitted to the hospital and treated with empirical antibiotics.
Approximately 0.2% of well-appearing febrile children 3 to 36 months of age vaccinated against S. pneumoniae and
H. influenzae and without localizing signs have occult bacteremia. Risk factors for occult bacteremia include temperature of 102.2° F (39° C) or greater, WBC count of 15,000/mm3 or more, and elevated absolute neutrophil count, band count, erythrocyte sedimentation rate, or C-reactive protein. No combination of demographic factors (socioeconomic status, race, gender, and age), clinical parameters, or laboratory tests in these children reliably predicts occult bacteremia. Occult bacteremia in otherwise healthy children is usually transient and self-limited but may progress to serious localizing infections. Well-appearing children usually are followed as
Assess H and P for “low risk” status Age? <1 mo >1 mo Low risk Not low risk
CBC with differential, blood culture, urine culture
All parameters normal? No Yes
All parameters normal? NoYes outpatients without empirical antibiotic treatment or, alternatively, treated with intramuscular ceftriaxone. Regardless of antibiotic treatment, close follow-up for at least 72 hours, including re-evaluation in 24 hours or immediately with any clinical change, is essential. Children with a positive blood culture require immediate re-evaluation, repeat blood culture, consideration for lumbar puncture, and empirical antibiotic treatment.
Children with sickle cell disease have impaired splenic function and properdin-dependent opsonization that places them at increased risk for bacteremia, especially during the first 5 years of life. Children with sickle cell disease and fever who appear seriously ill, have a temperature of 104° F (40° C) or greater, or WBC count less than 5000/mm3 or greater than 30,000/mm3 should be hospitalized and treated empirically with antibiotics. Other children with sickle cell disease and fever should have blood culture, empirical treatment with ceftriaxone, and close outpatient follow-up. Osteomyelitis resulting from Salmonella or S. aureus is more common in children with sickle cell disease; blood culture is not always positive in the presence of osteomyelitis.
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Fever of Unknown Origin
FUO is defined as temperature greater than 100.4° F (38° C) lasting for >14 days without an obvious cause despite a complete history, physical examination, and routine screening laboratory evaluation. It is important to distinguish persistent fever from recurrent or periodic fevers, which usually represent serial acute illnesses.