Characteristics Associated With Positive Bacterial Blood Cultures in Pediatrics

Evaluation for bacterial bloodstream infections (BSIs) is commonly associated with prescribing empiric antibiotics while awaiting blood culture results. In an effort to identify opportunities for diagnostic and antibiotic stewardship, we examined clinical characteristics associated with positive cultures treated as BSI vs contaminant and BSI time-to-positivity (TTP).

A retrospective review was conducted of all positive bacterial blood cultures collected from patients at a pediatric healthcare system between March 2021 and June 2022. Cultures were classified as BSIs or contaminants based on management by treating clinicians. Demographics, clinical characteristics, and culture data were analyzed to identify factors associated with BSIs vs contaminations and prolonged TTP (>24 hours).

Among 1068 positive cultures, 71% (n = 756) were treated as BSIs. The median age of patients with positive blood cultures was 3.7 years (IQR 0.5-12.4 years). Among those with BSI (n = 756), 734 (97.1%) had one of the following characteristics: age <90 days, fever or hypothermia, hypotension, a central line, or severe neutropenia. Most BSIs (93%) showed positivity within 36 hours, and prolonged TTP was most associated with peripheral draws, single positive cultures, and absence of fever (P < .01). Isolation of a priori defined high-likelihood pathogenic organisms was less likely to be associated with prolonged TTP (P < .01).

We defined clinical characteristics associated with children who had clinically significant BSI. These data should be considered when developing guidance for which children warrant blood culture collection for BSI evaluation. The majority of BSIs are identified within 36 hours of collection.