I mean that's why you should wash your veggies and cook your food. Food grows/lives in a bacteria rich environment, fertilized soil. There's also a reason that human stomach acid is closer in pH to scavengers then other animals, to kill all the nasty shit (literally this time lol).

The problem is when the bacteria gets in processed stuff that can't be rinsed/washed, and/or comes pre cooked. Like cereal. And I'm guessing US food regulations allow a lot of nasty stuff in that.