Isolation and Characterization of Lytic Bacteriophages Infecting Escherichia coli Antibiotic-Resistant Isolates from Urinary Tract Infections in North-west of Iran

One of the most prevalent bacterial infections, urinary tract infection (UTI), affects millions of people yearly worldwide. To control the increasing antibiotic-resistant infections, it is essential to introduce alternative approaches such as phage therapy. In this study, isolation, purification, and enrichment of eight lytic bacteriophages, which are active against antibiotic-resistant Escherichia coli strains from human urinary tract infections, were carried out. Molecular analysis of the bacteriophages was performed using two endonuclease enzymes (EcoRV and XbaI). Then, two of eight isolated bacteriophages with the highest host range were further characterized to determine their morphology, one-step growth, latent period, burst size, and stability under different environmental conditions. Allbacteriophage isolates (n=8) showed genome variation as it was evidenced by the enzyme digestion process (EcoRV). Both phages with the broadest host ranges (PEcMa2/17 and PEcMa3/17) showed an efficient lytic activity against five bacterial isolates. Electron microscopy confirmed that selected phages belong to Siphoviridae and Myoviridae families. The latent period of both propagated phages was determined as 15min. The burst size was estimated to be 100pfu/ml and 120pfu/ml in PEcMa2/17 and PEcMa3/17, respectively. Both phages showed more than 50% stability at 37ºC and lower investigated temperatures, and they were survived efficiently in pH=7. It was while their genome properties were different. The introduced bacteriophages showed high stability and strong antibacterial potential against Escherichia coli strains from UTIs. As candidates for phage therapy, more characterization steps, such as molecular analysis and experimental assays are needed before the therapeutic application.