Excluding Clinically Significant Bacteremia by 24 Hours in Otherwise Well Febrile Children Younger Than 16 Years: A Study of More Than 50,000 Blood Cultures.

BACKGROUND: In febrile children given empiric parenteral antibiotics, guidelines advise provisional reporting of negative blood cultures and antibiotic review after 36 hours incubation for neonates and 48 hours for older children. Following improvements in culture processing and childhood vaccination, we revisited this important clinical topic, assessing time to exclude clinically significant bacteremia in well-appearing febrile children with no comorbidities or features of sepsis.

METHODS: We analyzed the results of all 53,276 pediatric blood cultures taken during an 8-year period at a UK hospital.

RESULTS: 1308 (2.5%) cultures were positive, of which 333 (25.5%) grew pathogens typically associated with clinically significant bacteremia. The remaining 975 (74.5%) grew organisms associated with contaminated culture, or with opportunistic infection only in children with relevant risk factors. Time to positivity (TTP) from incubation was significantly shorter for the 333 definite pathogens than the 975 contaminating/opportunistic organisms, with 92% of definite pathogens identified by 24 hours incubation. Only 3 of all definite pathogens were identified after 24 hours in children otherwise eligible for discharge at 24 hours. There was no significant difference in TTP for definite pathogens between neonates and older children. Median time from specimen collection to incubation was 3 hours.

CONCLUSIONS: Clinically significant bacteremia can be excluded by 24 hours incubation in well-appearing febrile children with no comorbidities or features of sepsis. This is the largest dataset of its kind, and the second to compare neonates and older children. Our findings may inform future guidelines, facilitating earlier antibiotic review and discharge.