Abstract bacteriophages are prokaryotic viruses, which multiply in bacteria and archaea. These viruses are important in transferring mobile genetic elements such as virulence and antimicrobial resistance genes to bacteria under a process called transduction. Although bacteriophages have long been addressed with their various medical applications, an exciting application of these viruses is linked to their infection treatment potential. Since antimicrobial resistance is rapidly extending in bacterial populations and no novel antibiotics have been introduced to the market in decades, alternative treatment protocols such as phage therapy must be further supported to secure the future of infection treatments. The present review molecularly introduces bacteriophages and their major applications...

First discovered in the 19th century, bacteriophages (phages) are bacterial viruses and the most widespread entities on earth. Phages have multiple important roles in maintaining the bacterial population, carbon cycling, bacterial pathogenicity, and bacterial evolution. They can be used to develop DNA and protein vaccines, novel antibiotics and antiviral drugs, and phage therapy. The International Committee on Taxonomy of Viruses categorizes phages in two major orders of Caudovirales and Ligamenvirales, including five families, nine subfamilies, 145 genera, and 684 species. The most widespread families in nature are Siphoviridae, Myoviridae, Podoviridae, and Inoviridae. Phages are morphologically categorized in two major categories of tailed and polyhedral, filamentous, or pleomorphic phages. They can have either a single- or double-strand DNA or RNA genome. Phages are important for transferring mobile genetic elements, such as virulence genes and antimicrobial resistance determinants to bacteria by transduction, and have been used to treat bacterial infections. In conclusion, phages are important entities because of their roles in bacterial metabolism and surveillance in nature. Further studies can help usobtain a better understanding of the phage mechanism in bacterial evolution.

bacteriophages are the most widespread entities on earth, which are able to invade prokaryotes. bacteriophages play roles in dynamics of bacterial population, pathogenicity, epidemics and evolution. bacteriophages are taxonomically categorized into two major orders of Caudovirales and Ligamenvirales, five families, nine subfamilies, 145 genera and 684 species; from which, family members of Siphoviridae, Myoviridae, Podoviridae and Inoviridae are the most widespread bacteriophages in nature. bacteriophages are morphologically categorized into two main categories of tailed and polyhedral, filamentous or pleomorphic bacteriophages. They can have a single or double stranded DNA or RNA genome. The current review generally introduces bacteriophages using illustrations

Background: Escherichia coli is an important pathogen and microorganism of the normal intestinal flora of humans and animals. One of the important serotypes of E. coli is O157: H7. Because of the excessive and arbitrary use of antibiotics, multiple drug resistance has increased against these organisms. The main problem in treating infections caused by E. coli is its dependence on the administration of a large number of common antibiotics and the resistance of some strains to antibiotics. Phage therapy refers to the therapeutic use of phages to eliminate bacterial infections. In the first step, it is necessary to separate and identify bacteriophages that affect the target bacteria. Therefore, the present study was performed to isolate the phage that was effective on enterohemorrhagic E. coli isolates. Materials & Methods: In this study, after collection of sewage samples, bacteriophages were isolated by filtration and enrichment in an enterohemorrhagic E. coli overnight culture. The presence of bacteriophage was detected by plaque observation in a double layer agar and confirmed by TEM electron microscopy. Results and Conclusion: The results of the observation with electron microscopy revealed the presence of bacteriophage with the appearance of the Cystoviridae, Myoviridae and Podoviridae families. Unfortunately, although the titration of phages and molecular study were not performed in the current study due to the lack of budget, we found antibacterial activity of isolated phages using plaque formation observation, and the presence of phages belonging to Cystoviridae, Myoviridae and Podoviridae families was confirmed by TEM microscopy. Therefore, the effective phage against O157: H7 was successfully identified, isolated, and purified.

Background: Salmonella, a bacterial genus of more than 2500 serotypes is considered as the most significant foodborne pathogen causing infections in humans and animals. Increased antimicrobial resistance and persistence of antimicrobial residues in food matrices warrants the need for alternative infection management strategies. Aims: The present study aimed to isolate and evaluate the lytic activity of bacteriophage against Salmonella. Methods: Twenty-eight Salmonella isolates obtained from the poultry sources were screened for antibiotic sensitivity. Poultry slaughterhouse wastewater was used for the isolation of phage. Host range and random amplified polymorphic DNA (RAPD) are vital tools used for differentiating the phage. Results: The isolates showed a high degree of resistance to nalidixic acid (71%), tetracycline (71%), nitrofurantoin (50%), and ampicillin (43%). Five lytic phages are specific for Salmonella spp. were isolated and characterized by RAPD. In the colony forming unit (CFU) reduction assay, the highest activity of phage was observed at 0. 01 multiplicity of infection (MOI) within 2 h after the addition of phage. PSE5 at 0. 01 MOI was administered to Salmonella Enteritidis seeded on the surface of the chicken egg by immersion method. The results indicated that administration of phage reduced recoverable Salmonella by 2 × 106 CFU/ml relative to the phage-excluded control. Conclusion: The results presented here suggested the application of the bacteriophage treatment has the potential to be used as an alternative strategy to prevent Salmonella infection in poultry farms to prevent vertical transmission of the pathogen.