Empirical Antibiotic Initiation for Suspected Early-Onset Neonatal Infection in the Setting of Maternal GBS Screening and Intrapartum Antibiotic Prophylaxis: A Single-Center Retrospective Cohort Study

Background and Objectives: Maternal Group B Streptococcus (GBS) screening and intrapartum antibiotic prophylaxis have reduced early-onset GBS disease. However, suspected early-onset neonatal infection (EONI) remains a broader clinical challenge, as signs prompting empirical antibiotic treatment may also occur in non-infectious disorders of postnatal adaptation. Therefore, this study evaluated the frequency of systemic antibiotic initiation for suspected EONI and the utilization and microbiological yield of blood cultures in a single-center cohort managed with routine maternal GBS screening and intrapartum antibiotic prophylaxis. Materials and Methods: This retrospective cohort study included 2010 mother–newborn dyads delivered between 2019 and 2022. The primary outcome was systemic antibiotic therapy initiated within the first 72 h of life because of suspected EONI. Blood culture utilization and microbiological yield were analyzed separately from the primary treatment outcome. Positive blood culture findings were interpreted descriptively because of the small number of isolates and the possibility of contamination. Results: Empirical systemic antibiotic therapy for suspected EONI was initiated in 71 neonates (3.53%). The observed treatment rates among neonates born to GBS-colonized and non-colonized mothers were 16/402 (3.98%) vs. 55/1608 (3.42%) (RR 1.16, 95% CI 0.67–2.01; p = 0.59). In an exploratory multivariable analysis, the adjusted OR for maternal GBS colonization and antibiotic initiation was 1.33 (95% CI 0.68–2.60; p = 0.408). Lower gestational age was the strongest associated factor. Treated neonates were more frequently preterm and had more respiratory disorders, NICU admissions, pPROM, and lower Apgar scores. Blood cultures were obtained in 79 neonates, including 63 treated for suspected EONI. Nine sampled neonates had positive blood cultures, including seven treated neonates; several isolates were compatible with contamination. No GBS isolates were detected among the sampled neonates. Conclusions: Empirical systemic antibiotics were initiated for suspected EONI in 3.53% of neonates. This treatment frequency does not estimate early-onset sepsis (EOS) incidence. The study did not detect a statistically significant association between maternal GBS colonization and antibiotic initiation, but the wide confidence intervals do not exclude clinically relevant increases in treatment. Selective blood culture sampling, possible contamination, and incomplete microbiological adjudication preclude reliable estimates of culture-confirmed EOS incidence or pathogen distribution.