Antimicrobial peptides and admixtures thereof showing antimicrobial activity against gram-negative pathogens

The invention relates to the field of medicine and microbiology, more specifically to means and methods for the treatment of infections caused by Gram-negative pathogens, in particular those showing or being prone to developing drug resistance. Provided is an admixture of (i) an inner membrane acting compound having membrane-permeating activity and/or lipid II binding activity; and (ii) one or more antimicrobial peptide(s) selected from the group consisting of RRLFRRILRWL-NH2 (GNP-6); GNNRPVYIPQPRPPHPRL (GNP-1); RIWVIWRR-NH2 (GNP-5); GIGKHVGKALKGLKGLLKGLGEC (GNP-7); and Xi X2IVQRIKKWLX3- NH2, wherein Xi is absent or K; X2 is R, K or A; and X3 is absent or R; wherein said one or more antimicrobial peptide(s) may comprise or consist of D- or L-amino acids.