An antimicrobial composition comprises an anionic drug and an amine polymer comprising a first repeat unit of formula (2): wherein a′ is an integer equal to 1 or 2, b′ is an integer equal to 1 or 2, and each R′ is an independent monovalent radical selected from the group consisting of hydrogen, methyl, ethyl, and combinations thereof. G′ is a divalent linking group selected from the group consisting of a single bond and groups comprising at least one carbon. X− is a negatively charged counterion. The drug and the amine polymer are bound by noncovalent interactions.