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Fever in a Vaccinated Child? Hold the Blood Cultures

Routine blood cultures are not necessary for febrile children older than 3 months.

During the past decade, children have received routine vaccinations against Haemophilus influenzae type b and pneumococcus, and, as a result, the rate of serious bacterial infections (SBIs) caused by these organisms has plummeted. This change mandates review of the approach to evaluation and treatment of febrile children. These authors studied 68 infants younger than 3 months with either home or emergency department temperatures 100.4°F and 917 children aged 3 to 24 months with ED temperatures 102.3°F who presented to the ED of a tertiary care center in San Diego in 2003. Children younger than 3 months underwent an extensive standardized work-up, and older children underwent testing based on physician discretion.

Overall, 129 children (13%) had 132 cases of SBI (82 cases of pneumonia, 45 of urinary tract infection, and 5 of bacteremia). No white blood cell (WBC) count cutoff predicted SBI. However, the subset of children younger than 3 months was too small to adequately assess the accuracy of WBC counts in this age group. Nonpathogenic bacteria were identified in 4.9% of the 690 blood cultures obtained.

Comment: With the widespread use of the pneumococcal and H. influenzae type b vaccines, most serious bacterial illnesses in children now are either pneumonia or urinary tract infections. Most febrile children older than 3 months have viral syndromes, and routine blood cultures are not suggested by any guideline. However, this small study suggests that bacteremia does occur, infrequently. Clinicians should continue to exercise judgment about when to obtain blood cultures and complete blood cell counts, remembering that children are more susceptible than adults to bacteremia and that blood cultures should not be routinely obtained for febrile vaccinated children older than 3 months (JW Emerg Med Apr 17 2009).

— Diane M. Birnbaumer, MD, FACEP

Published in Journal Watch Emergency Medicine August 14, 2009

Citation(s):

Rudinsky SL et al. Serious bacterial infections in febrile infants in the post–pneumococcal conjugate vaccine era. Acad Emerg Med 2009 Jul; 16:585.