Blood cultures and predicting positivity in extremely preterm infants admitted to an outborn level IV NICU.

BACKGROUND: To determine if there were clinical factors that could identify patients with positive blood cultures in extremely preterm (EP) infants born at < 27 weeks gestation who underwent sepsis evaluation sometime after admission to a level IV NICU in an all referral children’s hospital. METHODS: An observational study using data from January 1, 2015 to December 31, 2020. RESULTS: Of the 530 EP infants admitted during the study, 345 EP infants (64%) had at least one blood culture drawn, of whom 64 (19%) had at least one positive blood culture. A total of 714 blood cultures were drawn at a median age of 41 days (IQR 15–87 days), of which 70 (9%) were positive. For the positive cultures, 47% grew gram positive bacteria, 44% grew gram negative bacteria, and 9% grew yeast. EP patients with positive blood cultures were more frequently on invasive mechanical ventilation and more often had a central line compared to EP patients with negative cultures. EP infants with positive blood cultures had greater mortality and surgical NEC than EP infants without positive cultures. Using logistic regression modeling, abnormal band counts (OR 1.03, 95% CI 1.003–1.06) and the initiation of vasopressors at the time of sepsis evaluation (OR 2.61, 95% CI 1.21–5.65) were the only clinical factors associated with a positive culture. CONCLUSIONS: Most EP infants admitted to an all-referral Level IV NICU had a blood culture drawn. The rate of positive cultures was relatively low, although EP infants with positive blood cultures had higher rates of mortality and morbidities. Further work to develop biomarkers for the rapid identification of sepsis in EP infants is urgently needed.