The emergence of bacterial resistance to antibiotics following widespread clinical, veterinary, and animal or agricultural usage has made antibiotics less and less effective. One of the possible replacements for antibiotics is the use of bacteriophages or simply phages as antimicrobial agents. Bacteriophages (phages) are viruses that infect only bacteria. They are non-toxic to other organisms, infecting, and in the case of lytic phages, multiplying rapidly within the bacterial host, ultimately

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... l host, ultimately killing it. Bacteriophages (or 'phages') were independently discovered by Twort and D' Herelle. Phages have a specialized structure with tunnel tails that allows them to bind to the surface of their bacterial targets. Once they are firmly attached the tail injects the viral DNA into the host cell. In a phage encoded protein, the holin, accumulates harmlessly in the cytoplasmic membrane until triggering at an allele-specific time to form micron-scale holes. The effectiveness of phage applications against pathogenic bacteria depends on several factors such as the bacteriophage/bacteria ratio, physico-chemical factors (pH, temperature), phage neutralization or resistance to phage. In the last few years, modified phages are increasingly being explored, mostly due to the limitations of phage therapy using lytic phages.