Virus says: Die, E. coli, die!

Bacteriophages are viruses. Given this, it must be said that they won't cause that cold of yours. This is because viruses have only a small range of organisms that they can attack. You probably noticed that "bacteria" and "bacteriophage" have a high number of letters in common. So, even idiots (this actually also includes geniuses, so don't feel like I'm insulting you) can realize that bacteriophages attack bacteria.