Phage therapy is garnering renewed interest as bacterial resistance to antibiotics becomes widespread. This therapy can be considered as an alternative or a complementary treatment to antibiotics in treating lung infections in cystic fibrosis patients. Phage therapy predicted advantages are to target only specific bacteria, to adapt to those resistant and to penetrate inside bacterial biofilms. This project is an extension of the pilot project FFC#17/2015, that led to isolate 6 new phages. They were shown to efficiently fight Ps. aeruginosa in vitro. To test their in vivo effects the traditional mice model, and a less expensive and more ethically acceptable model based on the Galleria mellonella larvae, will be used.