One of the issues dealing with conventional drug therapies is the penetration of biofilms. Drugs have a difficulty in being effective in the presence of a biofilm. Phage therapy doesn’t have this issue since the phages could bypass the biofilm and destroy the bacteria.
In drug therapies, bacteria can evolve to develop resistances against drugs, as in the case with MRSA. With phage therapy, the evolution of resistance to the phages theoretically should be balanced out with the evolution of the phage to continued infection of the bacteria. One study showed promising results in the use of phage therapy.
Another possibility for phage therapy is to be used in conjunction with conventional drug therapies. Since some bacteriophages are lysogenic, these phages are able to combine their genetic material with the bacterial cell’s DNA. This insertion of genetic material may be able to code for proteins and enzymes that could weaken the bacteria’s defenses. After the weakening of the defense mechanism, conventional drug therapies would then destroy the bacteria as they normally would.