P-502. Neonatal Listeriosis in Israel 2012-2022, Clinical presentation and Outcome

Abstract Background The goal of this study was to characterize the incidence clinical features, microbiologic characteristics and outcome associated with neonatal listeriosis. We also analyzed presentation, neonatal outcome at discharge, and predictors of severe presentation and outcome. Methods We performed a multicenter retrospective observational cohort study, including all live newborns aged 0-30 days with microbiology-confirmed maternal and/or neonatal Lm infections, from 14 participating medical centers in Israel born between January 1, 2012, and July 1, 2022. Clinical and laboratory data were retrieved from the medical records and microbiology laboratories. Results A total of 98 cases were included, corresponding to mean annual incidence of 7.2 per 100,000 live births. Among the neonates, 98% were classified as early onset. Preterm births accounted for 74% of cases with a median gestational age of 34 weeks. Symptomatic neonates comprised 79% of cases. Neonatal mortality reached 17%, and 21% of neonates had long-term sequels. Maternal symptoms—either flu-like or obstetric—were reported in over 60% of cases. Only 40% of mothers received antibiotic treatment ≥1 day before delivery. Of these, 33% received appropriate anti- Lm therapy Appropriate maternal antibiotic treatment was associated with a significant reduction in neonatal morbidity: 89% of neonates born to the untreated mothers were symptomatic versus 58% of the neonates in the treated mothers group (P=0.006). Conclusion Neonatal listeriosis in Israel is almost always early onset and occurs within the first 2 days of life with a high case-fatality rate. In addition to gestational age at birth, another critical parameter that influenced neonatal severity was antenatal maternal antimicrobial treatment that was associated with reduced neonatal listeriosis severity. This strongly supports preemptive maternal antimicrobial therapy when maternal listeriosis is suspected. Enhanced clinical awareness and timely intervention are essential to reduce the burden of neonatal listeriosis as well as strategies to prevent pregnancy-associated listeriosis. Disclosures All Authors: No reported disclosures