This is a randomized, controlled trial studying the effects of various antimicrobial treatments on the intestinal microbiome of small children. The participating children with acute otitis media are treated wither with amoxicillin, amoxicillin-clavulanate or without antibiotics. The children with allergy to amoxicillin receive a course of macrolide and they will be monitored as a separate group. The main outcomes of this trial are the changes in the intestinal microbiome after the treatment.