eli5 why does E-coli is in our digestive system even though it’s dangerous

Question

Okay so of course everyone know what E-coli is, it’s a bacteria that can cause food poisoning. But a few years ago in biology class I realized it’s also a microbe in our gut system. So how does something that’s dangerous live inside our gut without affecting us?

In: 2

Answer 1

I’ll try to go for a true ELI5 here. The E. coli which lives in our gut is harmless because it’s the domesticated variety. But sometimes these bacteria can become wild and dangerous, and that is the pathogenic variety. They will attempt to make a living from the parts of a human body that they are not supposed to, causing disease.