Phage therapy against Pseudomonas aeruginosa infections in cystic fibrosis patients

Pseudomonas aeruginosa is the most common pathogen found in the lung of cystic fibrosis patients. The use of phage therapy could help in fighting the alarming diffusion of antibiotic multi-resistant strains. A number of new phages were isolated from sewage samples in Milan, and tested for growth on a panel of P. aeruginosa strains collected in Italian hospitals. Comprehensively, we analyzed 23 new phages on 57 clinical or environmental P. aeruginosa strains. Six phages belonging to different classes, i.e. Myoviridae, Podoviridae and Siphoviridae, as assessed by TEM analysis, were mixed in a cocktail. The host range of the phage cocktail was larger than that of individual phages. Infection in liquid culture of strain PAO1 indicated that the phage cocktail efficiently killed the bacterial cells, although resistant mutants appeared at the end. The ability to infect P. aeruginosa growing in biofilm demonstrated that the phage cocktail was able to reduce the biomass of a preformed biofilm. DNA was extracted from the selected phages and send for whole genome shotgun sequencing using the Illumina MiSeq platform at the CNR IBBE institute in Bari. This project is financed by Italian Foundation of Cystic Fibrosis (# 17/2015).