Neonatal bacterial infection and sepsis: Viva

Branch 1: Risk assessment

The candidate should identify that this infant has multiple risk factors for early-onset sepsis: maternal GBS colonisation, inadequate intrapartum antibiotic prophylaxis (defined as less than 4 hours of antibiotics before delivery), and the presenting signs of temperature instability and poor feeding. This constellation warrants immediate evaluation. [1]

The Neonatal Early-Onset Sepsis Calculator is a validated tool for infants born at 34 weeks gestation or more that integrates maternal risk factors (GBS status, duration of membrane rupture, intrapartum fever, adequacy of intrapartum prophylaxis) with the infant's clinical presentation to estimate the probability of early-onset sepsis. The updated 2024 version uses a contemporary cohort reflecting current epidemiology. [3]

However, this infant is already symptomatic, so the clinical assessment overrides the calculator. Symptomatic infants need full evaluation and empiric antibiotics regardless of the calculated probability. The calculator guides decisions for asymptomatic or equivocally symptomatic infants. [1]

Branch 2: Investigation and empiric therapy

The full septic workup includes a blood culture with adequate volume (at least 1 mL), a complete blood count with differential and immature-to-total neutrophil ratio, baseline CRP repeated at 24 hours, and lumbar puncture for CSF analysis if the infant is stable. [2]

Empiric therapy is benzylpenicillin 25 mg/kg intravenously plus gentamicin 5 mg/kg intravenously, with the gentamicin dosing interval adjusted for gestational and postnatal age. Add cefotaxime 50 mg/kg intravenously if meningitis is suspected, as it achieves therapeutic cerebrospinal fluid concentrations. [2]

Branch 3: Stewardship and counselling

If blood cultures are negative at 48 hours, CRP is normal, and the infant is feeding well, apply the STOP stewardship criteria: Sterile cultures, Trending-down CRP, Observationally well, and Plan to stop. With all criteria met, stop antibiotics. The negative predictive value of a normal CRP at both baseline and 24 hours exceeds 99 per cent. [1]

When counselling parents, explain that the team treated for the worst-case scenario because neonatal sepsis is dangerous and treatable, that the cultures have come back negative which is reassuring, and that the antibiotics can now be safely stopped. Frame antibiotic stewardship as a patient-safety benefit rather than a cost-cutting measure. [1]