The present invention relates to the field of antimicrobial agents. In particular, the present invention relates to polypeptides comprising the sequence of a peptidoglycan hydrolase and a peptide sequence heterologous to the peptidoglycan hydrolase wherein said heterologous peptide sequence comprises a specific sequence motif which 16, 17, 18, 19 or 20 amino acids in length. The present invention relates also to corresponding nucleic acids, vectors, bacteriophages, host cells, compositions and kits. The present inventions also relates to the use of said polypeptides, nucleic acids, vectors, bacteriophages, host cells, compositions and kits in methods for treatment of the human or animal body by surgery or therapy or in diagnostic methods practiced on the human or animal body. The polypeptides, nucleic acids, vectors, bacteriophages, host cells, compositions and kits according to the invention may also be used as an antimicrobial in, e.g., food or feed, in cosmetics, or as disinfecting agent.