Design: Pragmatic randomised non-inferiority trial
Population: 201 children under 14 after open appendicectomy for perforation, Brazil
Primary outcome: Surgical-site infection and treatment success
Effect: SSI RR 0.82 (0.54–1.24); treatment success RR 1.01 (0.92–1.12)

A Brazilian randomised non-inferiority trial enrolled 201 children under 14 after open appendicectomy for perforated appendicitis. One group received metronidazole 30 mg/kg once daily, the other 10 mg/kg three times daily; both received gentamicin 5 mg/kg once daily.

Once-daily dosing was non-inferior for surgical-site infection (RR 0.82, 95% CI 0.54–1.24), organ-space infection (RR 0.82) and treatment success (RR 1.01). No severe antibiotic-related adverse events occurred. Treatment durations were similar.

Once-daily metronidazole fits well with once-daily gentamicin, freeing nursing time and simplifying ward rounds and home transition. Several centres already use it; this trial adds randomised support in children.

Consider metronidazole 30 mg/kg once daily with once-daily gentamicin after perforated appendicitis in children
Monitor gentamicin levels and renal function as usual
Agree the regimen with your microbiology or antimicrobial stewardship team before changing protocol
Note that all children in the trial had open surgery

Why it matters

A simpler antibiotic schedule saves nursing time on busy paediatric surgical wards.

The statistics, in plain English

In a non-inferiority trial the question is whether the new regimen is not meaningfully worse. Confidence intervals that run up to about 1.24 mean a modest increase in infection cannot be fully excluded with 201 children, so judgement depends on the margin the authors set.