Do All Children Admitted with CAP Need a Blood Culture?

July 16, 2019

Written by Clay Smith

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Overall yield of blood culture for pediatric community acquired pneumonia (CAP) was low; 91 blood cultures were needed for one positive result. But in children admitted to the ICU, one child had bacteremia for every 24 cultures obtained; one for every 12 in children with parapneumonic effusion.

Why does this matter?
A blood culture is recommended in children admitted to the hospital with pneumonia, but they are low yield, seldom change management, and may result in false positives from contaminants. Should we be more selective in whom we select to obtain blood cultures?

A cultured response
The Epidemiology of Pneumonia in the Community (EPIC) study enrolled 2,358 children under age 18 years, 91% of whom had a blood culture obtained. Of these, 2.2% (46/2143) had a positive blood culture. Cultures grew S. pneumoniae (50%), S. aureus (13%), and S. pyogenes (9%). Several factors were associated with presence of bacteremia, but the two most important were presence of an effusion and need for ICU admission. For all comers with CAP admitted to the hospital, the number needed to culture for one positive was 91; but the number to culture to detect bacteremia for ICU admission dropped to 24 and was just 12 for children who had a pleural effusion. Obtaining cultures in children with effusion or ICU admission would still capture 76% of the positive cultures in this study. Given that management is seldom changed and the expense of following up false positives, it may be reasonable to only obtain culture if these two factors are present.

Source
Prevalence, Risk Factors, and Outcomes of Bacteremic Pneumonia in Children. Pediatrics. 2019 Jun 19. pii: e20183090. doi: 10.1542/peds.2018-3090. [Epub ahead of print]

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Reviewed by Thomas Davis