An antimicrobial peptide, the peptide comprising 2 to 20 variable domains, each variable domain is a sequence of 2 to 20 consecutive basic amino acids, wherein (a) the variable domains are separated from each other by a variable linker, (b) the variable linker can have 1 to 20 any amino acids other than two or more consecutive basic amino acids, and (c) the peptide has no more than 100 amino acids.