Efficacy of Amoxicilline/Clavulanic Acid in Patients Affected by Tic Disorder Colonized by Group A Streptococcus

This study is an extension of the European Multicentre Tics In Children Studies (EMTICS) COURSE study for which a separate study protocol exists; Aim of this clinical trial is to study the efficacy of treatment with antibiotics in reducing severity of tics and associated neuropsychiatric symptoms in patients with a tic disorder colonised by GAS. Primary Objective: Test the hypothesis that antibiotic treatment of GAS colonisation compared to placebo is associated with a larger reduction of tic and associated neuropsychiatric symptoms in the short-term (1 month) in patients with a tic disorder colonised by GAS. Secondary Objective: Test the hypothesis that antibiotic treatment of GAS colonisation is superior to placebo in the long-term (1 year) reduction of tic and associated neuropsychiatric symptoms in patients with a tic disorder colonized by GAS. Patients affected by a chronic tic disorder followed in the EMTICS- Longitudinal Course Study that show a positive culture for GAS at any microbiological examination during their follow-up will be considered eligible for the treatment trial. Patients showing GAS positivity will be invited to participate in the clinical trial. The patients enrolled will be randomly assigned to antibiotic or placebo in a 1:1 ratio. All participating patients will undergo a microbiological, serological and clinical assessment 1 month after the date of entering in the treatment trial (i.e. around 20 days after the end of treatment). Then, the patients will be followed with clinical, laboratory and microbiological assessments every four months for 1 year. Patients will be deblinded at the end of the treatment trial follow-up (1 year after the recruitment). Patients who will develop a true GAS infection or who otherwise need to be prescribed antibiotics for any clinical reason during the follow-up will be withdrawn from the study and immediately deblinded. Data of such patients would, however, remain part of the study analyses, followin