Objective: To evaluate gaps in universal Group B  Streptococcus (GBS) screening and intrapartum antibiotic prophylaxis (IAP) in Hong Kong after its 2012 implementation, which reduced early-onset GBS disease (EOGBSD) incidence from 1.03 to 0.26 per 1000 live births. Design: Retrospective cross-sectional study. Setting: Eight Hospital Authority obstetric units and thirty-one Department of Health Maternal Child Health Centers (MCHCs), Hong Kong. Population: EOGBSD cases (2012–2022) and their mothers. Methods: Cases were electronically identified; maternal and neonatal records were reviewed for screening adherence, IAP administration, and delivery timing. Main Outcome Measures: EOGBSD incidence, screening gaps (missed tests, delayed results, prolonged screening-to-delivery intervals), and IAP compliance. Results: Among 72 EOGBSD cases, 53 eligible mothers were analyzed: 3 missed screening, 8 lacked results at delivery, and 7 delivered >5 weeks post-screening. Of 17 preterm deliveries, 41% (n=7) received no IAP due to precipitous labor (n=3), prelabor cesarean (n=3), or birth before arrival (n=1). Six neonatal deaths occurred. Conclusions: Despite successful EOGBSD reduction, critical gaps persist, including missed screenings, results unavailable at delivery, and deliveries beyond the 5-week screening validity window. Revising local protocols to address prolonged screening-to-delivery intervals and standardizing management for mothers with unknown GBS status could further reduce EOGBSD. Increased awareness and optimized workflows for preterm deliveries are needed. Keywords: Streptococcus agalactiae; Pregnancy; Antibiotic prophylaxis; Prenatal screening; Neonatal sepsis

Objective: To compare the incidences of early and late onset neonatal sepsis, including group B streptococcus (GBS) and Escherichia coli (E.coli) before and after implementation of universal screening. Design: Retrospective cohort study Setting: Eight public hospitals with obstetrics services under the Hospital Authority and 31 Maternal and Child Health Centres (MCHC) under the Department of Health in Hong Kong Population: 460552 women attending routine antenatal service from 2009 to 2020. Methods: Universal culture-based GBS screening was offered to eligible women since 2012. Total maternity, births, GBS screening tests, GBS isolated in maternal genital tract, neonatal sepsis with positive blood or cerebrospinal fluid were retrieved from clinical and laboratory database of the Hospital Authority using clinical data analysis and reporting system (CDARS) and clinical system of MCHCs. Main outcome measures: Maternal GBS colonisation rate, early onset GBS disease, early onset E. coli infection, late onset GBS disease, and late onset E. coli infection Results: Of 318740 women with universal culture-based screening, 63767 women (20.0%) were screened positive. After implementation of GBS screening, the incidences of both early and late onset neonatal sepsis reduced significantly, including those caused by GBS. There was no change in the incidence of early onset E.coli sepsis, while the incidence of late onset E.coli sepsis reduced. Conclusions: Universal culture-based GBS screening in Hong Kong has been successful in prevention of early and late onset neonatal sepsis, including those caused by GBS. E.coli has become more common than GBS in early neonatal sepsis, although the incidence remained similar.