Abstract: The invention relates to medicine and the chemical and pharmaceutical industry, in particular to antibiotic preparative forms. The inventive antimicrobial composition contains antibiotic selected from a group of lincosamides, broad-spectrum penicillins, cephalosporins, macrolides, tetracyclines, and lactulose at the active component ratio of 1:1-1:100. The mean particle size of lactulose ranges from 100 nm to 200 ?m. Said composition is embeddable in a solid state and in the form of a syrup or a suspension. When applicable, pharmaceutically acceptable excipients are added into the composition in such a way that it takes a form acceptable for peroral administration.