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Once-daily Amoxicillin versus Twice-daily Penicillin V in Group A β-Hemolytic Streprococcus Pharyngitis
  1. Diana R Lennon, FRACP (d.lennon{at}
  1. University of Auckland, New Zealand
    1. Elizabeth Farrell, MHSc (efarrell{at}
    1. Counties Manukau District Health Board, New Zealand
      1. Diana R Martin, PhD (diana.martin{at}
      1. Institute of Environmental Science and Research Ltd., New Zealand
        1. Joanna M Stewart, MSc (j.stewart{at}
        1. University of Auckland, New Zealand


          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.

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