Cationic antimicrobial peptides (CAMPs), essential components of the innate immune system, due to a peculiar mechanism of action, rarely give rise to resistant strains and can strengthen and complement the action of conventional antibiotics. Moreover, they often show anti-biofilm and anti-inflammatory activities. Unfortunately, CAMPs are generally sensitive to host and bacterial proteases. A possible solution is to develop antimicrobial peptidomimetics, which, even if structurally and functionally similar to CAMPs, are resistant to proteases (peptoids). The main aim of this project is to explore the efficacy in vitro and in vivo of peptoid P13#1, an antimicrobial peptidomimetic designed to mimic a group of natural CAMPs. As P13#1 has already shown its efficacy in vivo against a reference strain of S. aureus, it will be assayed in a mouse model of S. aureus lung infection by intra-tracheal administration. At the same time, researchers will study the efficacy of P13#1 in vitro against other S. aureus strains from CF patients and against P. aeruginosa (reference strain PAO1 and CF clinical isolates). In case of positive results, researchers will consider the possibility of patenting P13#1 as a new antimicrobial of the CAMPs family having the interesting feature of protease-resistance.