A peptide for use as a medicament in the treatment of infection with gram-positive bacteria containing an amino acid sequence according to the general formula A or B: X 1 -N 2 -X 2 -X 3 -P 5 -V 6 -Y 7 -I 8 -P 9 -X 4 -X 5 -R 12 -P 13 -P 14 -H 15 -P 16 (formula A) X 1 -N 2 -X 2 -X 3 -P 5 -V 6 -Y 7 -I 8 -P 9 -X 4 -X 5 -R 12 -P 13 -P 14 -H 15 -P 16 -X 6 -X 7 (formula B) wherein the amino acid sequence according to formula A or B has at least 80% amino acid sequence identity to native apidaecin lb according to SEQ ID No. 2 and in which: X 1 is selected from nonpolar, aromatic, positively charged amino acid residues, amino acid residues with a thiol group, amino acid residues with a selenol group, proline and proline derivatives; N 2, X 2 and P 5 are independently selected from neutral and positively charged amino acid residues; X 3 is selected from positively charged amino acid residues, amino acid residues having a thiol group, and amino acid residues having a selenol group; V 6 is selected from nonpolar amino acid residues having at least 2 C-atoms in the side chain, aromatic amino acid residues, positively charged amino acid residues, amino acid residues having a thiol group, amino acid residues having a selenol group, proline and proline derivatives; Y 7 is selected from tyrosine, positively charged amino acid residues, amino acid residues having a thiol group, and amino acid residues having a selenol group; I 8 is selected from nonpolar, aromatic amino acid residues having at least 2 and a maximum of 8 C-atoms in the side chain, positively charged amino acid residues, amino acid residues having a thiol group and amino acid residues having a selenol group; P 9, P 13, P 14 and P 16 are independently selected from positively charged amino acid residues, amino acid residues having a thiol group, amino acid residues having a selenol group, nonpolar aromatic amino acid residues, heteroaromatic amino acid residues, proline and proline derivatives; X 4 is selected from neutral, positively charged amino acid residues, amino acid residues having a thiol group, and amino acid residues having a selenol group; X 5 is selected from proline, proline derivatives, positively charged amino acid residues, amino acid residues having a thiol group, and amino acid residues having a selenol group; R 12 is a positively charged amino acid residue; H 15 is selected from histidine, positively charged amino acid residues, amino acid residues having a thiol group and amino acid residues having a selenol group; X 6 is selected from positively charged amino acid residues, X 7 is selected from nonpolar amino acid residues, positively charged amino acid residues, amino acid residues having a thiol group and amino acid residues having a selenol group, characterised in that at least one of the positions 2, 5 to 11, 13 to 16 and 18 of SEQ ID no. 2 is modified so that the peptide according to formula A or B has at least one of the following conditions: N 2 is tryptophan or arginine, and/or I 8 is arginine. X 1 is selected from nonpolar, aromatic, positively charged amino acid residues, amino acid residues with a thiol group, amino acid residues with a selenol group, proline and proline derivatives; N 2, X 2 and P 5 are independently selected from neutral and positively charged amino acid residues; X 3 is selected from positively charged amino acid residues, amino acid residues having a thiol group, and amino acid residues having a selenol group; V 6 is selected from nonpolar amino acid residues having at least 2 C-atoms in the side chain, aromatic amino acid residues, positively charged amino acid residues, amino acid residues having a thiol group, amino acid residues having a selenol group, proline and proline derivatives; Y 7 is selected from tyrosine, positively charged amino acid residues, amino acid residues having a thiol group, and amino acid residues having a selenol group; I 8 is selected from nonpolar, aromatic amino acid residues having at least 2 and a maximum of 8 C-atoms in the side chain, positively charged amino acid residues, amino acid residues having a thiol group and amino acid residues having a selenol group; P 9, P 13, P 14 and P 16 are independently selected from positively charged amino acid residues, amino acid residues having a thiol group, amino acid residues having a selenol group, nonpolar aromatic amino acid residues, heteroaromatic amino acid residues, proline and proline derivatives; X 4 is selected from neutral, positively charged amino acid residues, amino acid residues having a thiol group, and amino acid residues having a selenol group; X 5 is selected from proline, proline derivatives, positively charged amino acid residues, amino acid residues having a thiol group, and amino acid residues having a selenol group; R 12 is a positively charged amino acid residue; H 15 is selected from histidine, positively charged amino acid residues, amino acid residues having a thiol group and amino acid residues having a selenol group; X 6 is selected from positively charged amino acid residues, X 7 is selected from nonpolar amino acid residues, positively charged amino acid residues, amino acid residues having a thiol group and amino acid residues having a selenol group, characterised in that at least one of the positions 2, 5 to 11, 13 to 16 and 18 of SEQ ID no. 2 is modified so that the peptide according to formula A or B has at least one of the following conditions: N 2 is tryptophan or arginine, and/or I 8 is arginine. N 2 is tryptophan or arginine, and/or I 8 is arginine.