Evaluate the necessity to treat with antibiotics GAS pharyngitis in children in Switzerland. The null hypothesis is that antibiotic treatment is not necessary for GAS pharyngitis in this population.

All children between 3 -15 years old with clinical symptoms suggestive of pharyngitis (Mc Isaac score ≥3) and a microbiological test (rapid antigen detection) positive for group A Streptococcus (GAS) will be included in the study. In order to assess the strain of GAS as well as to identify co-infected children with respiratory virus, a throat culture and a nasopharyngeal swab will be performed, as well as a standard questionnaire and a standard physical exam. At this time, children will be randomized to either 6 days of amoxicilline or 6 days of placebo treatment. During the treatment period, the investigators will ask the parents/legal guardians of the patients to pay close attention to the evolution of the symptoms (fever, pain, exudates…) as well as the treatment's adverse event, and to report their presence or absence in a dairy form. At day three after initiation of treatment, a standardized clinical evaluation will be completed by phone to identify if the patient still has symptoms of pharyngitis or signs of suppurative complications. One month after the inclusion in the study, a throat culture, a standardized questionnaire as well as a clinical evaluation will be performed to identify if the patient has or had signs of non-suppurative complications and non-resolving infection. Six month and one year after inclusion, a phone call will evaluate the possible relapses, recurrences and complications of GAS infection with a standardized questionnaire. GAS strains will be analyzed to identify their unique fingerprint and viral coinfections will be reported to possibly identify cofactors for increased complication rates.

Inclusion Criteria:

• 3 -15 years old
• Clinical symptoms suggestive of pharyngitis with MC Isaac score ≥3
• Rapid-antigen detection test (RADT) positive for GAS-
• Signed informed parental/patient consent form

Exclusion Criteria:

• Hypersensitivity to B-lactams
• concomitant disease which must be treated with antibiotics
• chronic disease-Immunocompromised
• Antibiotics within 72 h
• history of ARF,scarlet fever,impetigo,acute glomerulonephritis
• Family history of ARF
• Complicated pharyngitis