Phage Therapy Phage therapy ,  viral phage therapy , or  phagotherapy  is the  therapeutic  use of  bacteriophages  to treat  pathogenic   bacterial infections . [1]  Bacteriophages, known as phages, are a form of  viruses . [2]  Phages attach to  bacterial cells , and inject a viral  genome  into the cell. [3]  The viral genome effectively replaces the bacterial genome, halting the bacterial infection. [3]  The bacterial cell causing the infection is unable to reproduce, and instead produces additional phages. [2]  Phages are very selective in the strains of bacteria they are effective against. [3]  Advantages include reduced side-effects and reduced risk of the bacterium's developing resistance. [3]  Disadvantages include the difficulty of finding an effective phage for a particular infection. [3]  However, virulent phages can be isolated much more quickly than other compounds and natural products due to the fact that they can be isolated from the environment with ease. [4]  In