Revisiting time to blood culture positivity: can we decrease antibiotic exposure in the NICU?

OBJECTIVE: We aimed to investigate the time to positivity of blood cultures in our NICU to determine if we can better inform empiric antibiotic duration decisions in both early-onset (≤72 h) and late-onset (>72 h) sepsis evaluations. STUDY DESIGN: Retrospective review of all positive blood cultures isolated from infants admitted to the Rainbow Babies and Children's Hospital NICU from July 1, 2018 to July 1, 2023. RESULT: There were 264 positive blood cultures from 125 infants with a median postmenstrual age of 30.9 weeks. The vast majority (86%) of positive cultures were obtained during the late-onset sepsis period. Gram-negative bacteria grew faster than gram-positive bacteria. Overall, 84% of blood cultures for all pathogenic bacteria (excluding coagulase-negative staph, fungi, and likely contaminants) were positive by 24 h. CONCLUSION: Our data do not support discontinuing empiric antibiotics at 24 h as our a priori target of 90% positivity was not met. These results underline the importance of evaluating an individual NICU's data before implementing a practice change.