In this randomised , controlled , non-inferiority trial , Indigenous Australian children aged 3 months to 13 years with purulent or crusted non-bullous impetigo were randomly assigned ( 1:1:1 ) to receive benzathine benzylpenicillin ( weight-banded injection ) , twice-daily co-trimoxazole for 3 days ( 4 mg/kg plus 20 mg/kg per dose ) , or once-daily co-trimoxazole for 5 days ( 8 mg/kg plus 40 mg/kg per dose ) .