Time to positive blood cultures in neonatal sepsis evaluations

Emily Willey; Michelle Mitchell; Carey Ehlert; Jacob Swoveland; Tracy Zembles

doi:10.1038/s41372-025-02323-z

Time to positive blood cultures in neonatal sepsis evaluations

J Perinatol. 2025 May 17. doi: 10.1038/s41372-025-02323-z. Online ahead of print.

Authors

Emily Willey¹, Michelle Mitchell², Carey Ehlert², Jacob Swoveland³, Tracy Zembles³

Affiliations

¹ Children's Wisconsin, Milwaukee, WI, USA. ewilley@childrenswi.org.
² Medical College of Wisconsin, Milwaukee, WI, USA.
³ Children's Wisconsin, Milwaukee, WI, USA.

PMID: 40382485
DOI: 10.1038/s41372-025-02323-z

Abstract

Objective: This study evaluates the time to blood culture positivity among neonates evaluated for sepsis to determine when antibiotics may be safely discontinued.

Study design: Retrospective review of clinically relevant blood culture time to positivity from infants in a neonatal intensive care unit. The primary endpoint was overall median time to blood culture positivity. Secondary endpoints compared time to positivity among gram-positive versus gram-negative organisms, early versus late onset sepsis, and a sub-analysis excluding contaminants.

Result: Among 151 cultures, the overall median time to positivity was 17 h (IQR 12-23). Most (47/48, 97.9%) gram-negative organisms resulted within 24 h and most (88/94, 93.6%) gram-positive by 36 h. All (13/13, 100%) early onset cultures resulted within 24 h and most (132/138, 95.7%) late onset by 36 h.

Conclusion: Antibiotics for neonatal sepsis evaluation may be safely discontinued in well-appearing infants without an identified infection source with negative cultures at 36 h.