There are bacteria and other micro-organisms in the soil, as the vegetables are grown in and on the animals which we get meat, milk and eggs from. That is why we cannot avoid the fact that there are micro-organisms in the food.
There may be bacteria in our food from several places:
The factory where the food is created
Your own kitchen
Fruit and vegetables have bacteria from the soil they are growing in.
All animals have bacteria in their intestines and on the skin, which can be transferred to meat, milk and eggs. The bacteria can come from the feed, the animals have eaten and from the Earth or straw, they have lived in. If animals are being slaughtered, can there be bacteria onto the meat.
In the kitchen
When you prepare food in the kitchen, one can get to spread the bacteria to the food. It can be bacteria, which you have on your hands, who comes over on the food when you touch it.
You can also spread the bacteria between meat and fruit and vegetables. For example, if you cut with the same knife, as you've cut meat with, you are going to spread bacteria from the flesh to the salad.