If they use tainted meat with e-coli for dog food how do they properly handle it so employee handling it don't get sick?

Because you have to eat it to get sick.

Porperly handling it means not cutting other foods on cutting boards that you cut meat on

Cross contamination Be Smart - Keep Foods Apart

E-coli can be deadly to pets and people. I have had it, and it is not fun. Like NoHelp said, it needs to be ingested. I would be more worried about the animals that are eating this food if it's contaminated. Always buy quality dog food, and report any cross contamination with dog food to the authorities. Our pets trust us to take care of them, as well as ourselves.

"Cooking would render any pathogen harmless,"
"An E. coli . . . contaminated beef product must not be distributed until it has
been processed into a ready-to-eat product," according to federal regulations.
The regulations do not require companies to disclose whether products contain
Cooked, recalled meat. There is no record of anyone getting sick from eating
A product made with cooked recalled meat.