Blood Cultures in the Emergency Department Evaluation of Childhood Pneumonia

Background Blood cultures are frequently obtained in the emergency department (ED) evaluation of children with community-acquired pneumonia (CAP). Objectives To determine the prevalence of bacteremia in children presenting to the ED with CAP, identify subgroups at increased risk for bacteremia, and quantify the impact of positive blood cultures on management. Methods This case-control study was nested within a cohort of children followed at 35 pediatric practices. Patients from this cohort who were ≤18 years of age, evaluated in the ED in 2006–2007, and diagnosed with CAP were eligible. Cases were those with bacteremia. Controls included those with negative blood cultures and those without blood cultures performed. Results 877 (9.6%) of 9,099 children with CAP were evaluated in the ED. The mean age was 3.6 years; 53% were male. Blood cultures were obtained in 291 children (33.2%). Overall, the prevalence of bacteremia was 2.1% (95% confidence interval [CI]: 0.8%–4.4%). Bacteremia occurred in 2.6% (95% CI: 1.0%–5.6%) with an infiltrate on chest radiograph and in 13.0% (95% CI: 2.8%–33.6%) with complicated pneumonia. Streptococcus pneumoniae accounted for 4 of the 6 cases of bacteremia. Blood culture results altered management in 5 of the 6 bacteremic patients; 1 had an appropriate broadening and 4 had an appropriate narrowing of coverage. The contamination rate was 1.0% (95% CI: 0.2%–3.0%). Conclusion Children presenting to the ED for evaluation of CAP are at low risk for bacteremia. Although positive blood cultures frequently altered clinical management, the overall impact was small given the low prevalence of bacteremia.