AbstractBackgroundThe Kaiser Permanente early onset sepsis (EOS) calculator was introduced in 2016 for infants who were born at ≥35 weeks gestation or more (≥35GA) at a principal referral and specialist hospital for women and newborns in Western Australia to reduce unnecessary antibiotic administration in healthy neonates.AimThe aim of this study was to determine the effect of the EOS calculator on antibiotic orders aseptically prepared by the pharmacy.MethodsThe study retrospectively compared pharmacy data over two periods, before (2015) and after (2016) implementation.ResultsAfter implementation, the number of gentamicin prefilled syringes (PFS) distributed decreased by 41.6% (1466 doses). In addition, the number of ≥35GA neonates receiving benzylpenicillin PFS decreased by 33.9% (222 neonates), and the overall rate (number of neonates receiving a benzylpenicillin PFS/occupied bed days) decreased from 2.24% to 1.48% (p < 0.0001).ConclusionThe introduction of the EOS calculator has reduced the empirical antibiotic use in ≥35GA neonates at the King Edward Memorial Hospital.