Background: Kaiser Sepsis Calculator (KSC) reduces antibiotic use, testing and intravenous infiltrates but there are concerns about the missed early onset sepsis (EOS) cases. We sought to apply the KSC score for culture-positive infants retrospectively in infants born in the last 10 years in our hospital.

Methods: In a retrospective cohort study, the comparison groups were divided into Group A (no antibiotics recommended by KSC) and Group B (antibiotics recommended).

Results: Overall, 17/24 (71%) infants would have been started on antibiotics per KSC but 7/24 (29%) would not. The initial EOS risk was not significantly different between the groups (Group A vs. Group B: 0.44 vs. 0.76, P = 0.41), but the final risk score was (0.33 vs. 9.41, P < 0.001). In Group A (no antibiotics), 3/7 infants became symptomatic between 9 and 42 hours.