Assessment of phage cocktails with extended host range activity against antibiotic resistant strains of Pseudomonas aeruginosa

The appearance of antibiotic resistant strains of Pseudomonas aeruginosa especially pan-drug resistant (PDR) strains has caused efforts to identify alternative antibacterial methods such as phage therapy. The purposes of this study were the isolation and preparing of effective phage cocktails against antibiotic resistant strains of P.aeruginosa. Determination of acquired resistance profiles of these isolates was performed according to new definition of CDC and European Centre for Disease Prevention and Control as multidrug-resistant (MDR), extended-drug resistant (XDR) and PDR, and data were analyzed using WHONET5.6 software. The MDR, XDR, and PDR isolates were selected for finding of their specific bacteriophages from waste waters and hospital sewages. After phage investigation by plaque formation, enrichment, and staining of samples, transmission electron microscopy (TEM) microscope was used for phage morphology and their size determination. Among 96 isolates of P.aeruginosa, 2 (2.1%), 94 (97.9%), 63 (65.6%), and 1 (1.1%) isolates were non-MDR, MDR, XDR, and PDR, respectively. In addition, these 96 strains were in 38 different resistotypes including two non-MDR patterns and 36 MDR patterns that 14 patterns of them belonged to XDR and one pattern corresponded to PDR. In addition, effective antibiotics were polymyxin B, colistin, and fosfomycin and high antibiotic resistance were observed among other antibiotics. The phage cocktails of P.aeruginosa phages was isolated that had extended host range activity against all MDR, XDR, and PDR strains. According to TEM data, three bacteriophages belonging to Cystoviridae, Leviviridae, and Inoviridae families were identified. Phage cocktails used in this study with broad spectrum activity can be as a good alternative of antibiotics against antibiotic resistant strains of P.aeruginosa.