Discloses a composition comprising an isolated LukE polypeptide that is less than 100 amino acids in length and comprises the amino acid sequence of amino acid residues 3-13 of SEQ ID NO:11, amino acid residues 32-47 of SEQ ID NO:11, amino acid residues 126-139 of SEQ ID NO:11, amino acid residues 151-156 of SEQ ID NO:11, amino acid residues 272-283 of SEQ ID NO:11, amino acid residues 57-75 of SEQ ID NO:11, amino acid residues 162-198 of SEQ ID NO:11, or amino acid residues 230-273 of SEQ ID NO:11, and use of such compositions to treat Staphylococcus aureus infection, wherein the sequences are as defined in the complete specification.