Arm 1: Twice a day oral amoxicillin-clavulanate (22.5mg/kg/dose) for 10 days Arm 2: Twice a day oral amoxicillin-clavulanate (22.5mg/kg/dose) for 3 days followed by oral placebo for 7 days The random treatments will be allocated via computer generated number sequence and will be supervised by a statistician.