Objectives To describe the epidemiology, age at infection, clinical characteristics and outcome of listeria infection in young infants to inform management and empiric antibiotic choice in young infants.

Design Prospective 2-year surveillance of Listeria monocytogenes infection in young infants detected through the British Paediatric Surveillance Unit ‘orange card’ system and triangulated with the public health laboratories.

Setting National population study (England, Wales, Scotland and the Ireland)

Patients All infants under 90 days with proven or probable invasive listeriosis

Main outcome measures Incidence, mortality, age of infection, clinical characteristics and outcome

Results During a 2-year period (2017–2019), 27 cases of listeriosis in infants <90 days of age were reported. The incidence of listeriosis in this study was 1.8 per 100 000 live births with 7% mortality (2/27). Nearly all cases presented within the first 24 hours of life (26/27). The majority (20/27, 74%) were born preterm and 16/24 (67%) were born to women from ethnic minority backgrounds.

Conclusions Invasive listeriosis in young infants in the UK and Ireland is rare and presents early in the neonatal period. National guidelines that recommend the use of amoxicillin as part of empiric regimes for sepsis and meningitis in infants over 1 month of age should be modified.