Phage Therapy
Phages (or bacteriophages) are natural enemies of bacteria. If not phages, have “engulfed” every living organism, only bacteria would probably exist on Earth today.
Phages are micro-organisms that do not have their own nucleus, and in order to reproduce and survive, they must find bacteria with the exact matching genetics, penetrate them and multiply inside, using the host DNA. The multiplied phages burst the bacteria, get out, and then attack other bacteria. So they spread in a chain reaction until all bacteria are killed, and then they die too because they can no longer reproduce.
All types of bacteria in nature have their matching phage. Remarkably, phages attack their respective bacteria and are absolutely harmless to other types of bacteria, as well as to human, animal and plant cells. Therefore, unlike antibiotics, by using phages it is possible to destroy only "bad" bacteria, and preserve "good" bacteria, which are necessary for the normal metabolism of the organism.