The rug in the room where everyone hangs out may contain as much as 200,000 bacteria per square inch, said Reynolds in this article, who has isolated E. coli, Salmonella, and MRSA, a type of staph bacteria that causes skin infections, in carpet fibers. The skin cells, food particles, pollen, and pet dander that collect in carpets serve as a smorgasbord for germs. When you walk on the rug, or your kids roll around on it, you disrupt the little buggers, bringing some closer to the surface.