Isolation and characterization of lytic bacteriophages against Pseudomonas aeruginosa isolates from human infections in the north-west of Iran

With the emergence of Pseudomonas aeruginosa antibiotic-resistant strains, using the antibacterial potential of bacteriophages could be an effective approach to combat bacterial infections.

In this study, after evaluation of antibiotic sensitivity of 20 clinical bacterial isolates of Pseudomonas aeruginosa, isolation of lytic phages was performed against 15 isolates using double-layer agar overlay technique. Molecular analysis of isolated phages was carried out using EcoRV and HindIII endonucleases. Then, the host range of the phages was evaluated and the phage with the broadest host range (PPaMa1/18) was selected to morphological characteristics by TEM. Also, its one-step growth curve was determined and the stability of the phage to environmental parameters (temperature and pH) was evaluated.

All isolates of Pseudomonas aeruginosa were resistant to five antibiotics. In total, 15 phages were successfully isolated from the sewage sources against each of 15 used bacterial isolates. Molecular analysis of the phages showed a high rate of genomic variation. In the morphological analysis of the selected phage (PPaMa1/18) using TEM, an icosahedral head with a size of 90 nm × 75 nm and a long contractile tail (215 nm) were observed which indicated its similarity to the Myoviridae family. The latent period of the PPaMa1/18 was about 20 minutes and its burst size was estimated to be 58 PFU/cell. Also, the PPaMa1/18 phage antibacterial activity was not significantly affected at pH 4-10 and temperature 4-40C°.

Findings demonstrated that isolated bacteriophage (PPaMa1/18) with wide host range, strong lytic effect and high stability can be used as a promising candidate for the treatment of antibiotic-resistant infections caused by Pseudomonas aeruginosa.