Background: Rheumatic fever is a preventable chronic disease preceded by group A β-hemolytic streptococcus (GABHS).
Objective: To test the non-inferiority of once-daily (QD) oral amoxicillin to the recommended twice-daily (BID) oral penicillin V in GABHS pharyngitis.
Design: Randomised non-inferiority trial.
Setting: School-based clinic in New Zealand.
Patients: Children presenting with GABHS pharyngitis.
Interventions: Children were randomised to oral amoxicillin 1500mg BID (or 750mg if bodyweight was ≤30kg) or to oral penicillin V 500mg QD (or 250mg if bodyweight was ≤20kg) for 10 days. Observed medication and weekend diary cards were used to monitor adherence. OUTCOME: Eradication of GABHS, determined with follow-up throat cultures on days 3-6, 12-16 and 26-36. GABHS isolates were serotyped to distinguish bacteriologic treatment failures (and relapses) from new acquisitions. Non-inferiority was defined as an upper 95% confidence limit (CL) for the difference in success of eradication in the amoxicillin and penicillin V treatment groups of ≤10%.
Results: 353 children with positive throat swabs for GABHS were randomised to amoxicillin (n=177) or penicillin V (n=176). The upper 95% CL for the differences in positive cultures between the antibiotics was 4.9% at days 3-6, 6.5% at days 12-16 and 8.5% at days 26-36. Treatment failures (including relapses) occurred at each visit in 5.8%, 12.7% and 10.7% of amoxicillin recipients and 6.2%, 11.9% and 11.3% of penicillin V recipients respectively. No significant differences in resolution of symptoms were noted between treatment groups.
Conclusion: In this adequately-powered study, once-daily oral amoxicillin is not inferior to twice-daily penicillin V for the treatment and eradication of GABHS in children with pharyngitis.