"I've never been sure about that. Maybe if you take bacteria from your colon and put them in your stomach you could have a problem?"
e.Coli is commonly found throughout the intestinal area. Occasionally in the stomach, but I believe simple paristolosis keeps the numbers down to a minimum when coupled with lining-shed, and enzymes/chemicals produced for normal digestion.
Here is an excerpt from the Centers for Disease Control:
Escherichia coli (E. coli) bacteria normally live in the intestines of people and animals. Most E. coli are harmless and actually are an important part of a healthy human intestinal tract. However, some E. coli are pathogenic, meaning they can cause illness, either diarrhea or illness outside of the intestinal tract. The types of E. coli that can cause diarrhea can be transmitted through contaminated water or food, or through contact with animals or persons.
E. coli consists of a diverse group of bacteria. Pathogenic E. coli strains are categorized into pathotypes. Six pathotypes are associated with diarrhea and collectively are referred to as diarrheagenic E. coli.
Again, this is a "maybe".
I spent a couple hours looking trhough all the medical stuff on line, but I didn't run across it, though there was some mention of it that infants could be suseptible. Unclear if this applies to adults due to socization or biology. All the documents were pretty much like the above. If you use resonable precautions, like a clean spoon, boiling foods, using your other hand for eating "Arabic" style, I don't think there is much to worry about.
Again, if you have one of the above mentioned pathogenic types, you will likly be imune to it anyway, since you *must* have had it *sometime before* going hiking for it to be present. Or, it is no longer present and poses no threat, since you would be sick if it was present. Sort of a Catch 22. You surley wouldn't go camping if you already were sick. But, you MIGHT be "that other person" if you go with a group.
Unclear...like you say...