597 - Paired Fetal Umbilical Venous and Neonatal Blood Cultures in Early Onset Sepsis: A single center experience.

Publication Number: 597.6023

Colin Parker, University of California - Irvine, Orange, CA, United States; Cherry Uy, University of California, Irvine, School of Medicine, Orange, CA, United States; Robin Koeppel, University of California, Irvine, School of Medicine, Orange, CA, United States; Lisa Perumean, UCI Health, Orange, CA, United States; Michelle L. Hearron, UC Irvine Health - - Orange, CA, Orange, CA, United States; Fayez Bany-Mohammed, UC Irvine Medical Center, Orange, CA, United States

Background: Culture-negative early onset sepsis (EOS) is a clinical diagnosis often treated with broad-spectrum antibiotics. Some institutions utilize cultures obtained from fetal umbilical venous blood (FUVB) as a substitute or in addition to infant blood cultures.

Objective: We aimed to evaluate the utility of FUVB cultures in helping guide the choice and duration of antibiotics for EOS therapy. To achieve this, we prospectively collected paired FUVB and infant blood cultures on admission.

Design/Methods: This is a single-center, paired-sampling prospective study at a tertiary regional center. All NICU admissions during the period of 11/1/2017 to 6/1/2024 were eligible for inclusion. Admission blood cultures were obtained per our standard of care, informed by the Kaiser neonatal sepsis calculator when applicable. Concurrent FUVB cultures were collected whenever feasible. For any positive culture, risk factors for EOS were reviewed. Five criteria defined a true positive culture: 1) time to positivity < 24h for aerobes and < 36h for anaerobes, 2) presence of a bacterium commonly associated with EOS, 3) growth of 2 organisms or less, 4) presence of at least 1 risk factor for EOS, and 5) blood culture volume of at least 1 mL.

Results: Paired samples were collected on 492 patients out of 10,324 deliveries including 2720 NICU admissions. There were 1016 patients who received an initial dose of antibiotics in the first 6 hours of life, and a total of 50 positive blood cultures of any kind from 49 unique patients drawn in the first 6 hours of life. Of these positive cultures, 25 came from FUVB while 25 grew from infant samples. There was only one case where FUVB and infant blood culture grew the same bacterium (H. influenzae). There was one case of a positive infant blood culture (E. coli) with a negative concurrent FUVB sample out of the 492 paired cultures. The most common bacteria recovered from FUVB included E. coli (32%), E. faecalis (20%), and GBS (8%), while from infant cultures were E. coli (52%), GBS (16%), and E. faecalis (8%). Twenty-nine of 49 patients (59%) were premature. Gestational ages ranged from 23+3/7 to 41 weeks and birth weights from 550 g to 4670 g. Based on clinical course, in addition to inflammatory markers and placental histology, 6 patients of 25 with positive FUVB culture were treated with 2-3 days of antibiotics, and the rest were treated with a 10-day tailored course.

Conclusion(s): FUVB culture is a valuable tool in guiding antibiotic choices for EOS, as it can reveal more pathogens and identify resistance patterns that may not be evident from infant blood culture alone.