A Question Regarding e coli Evolution

I understand that the e coli bacteria has been around forever. It is present in the intestines of all animals, and helps humans in the absorption of certain nutriments.
As a host for this bacterium, humans are ideal-they eat frequently, and defecate constantly. So the bacteria has a nice place to live (the human gut), and is able to travel between hosts.
Now, if a mutation produces a deadly strain, things go wrong-instead of a good willing host, humans die from the new bacterium.
Clearly, this is not in the interests of humans or e coli. What corrects this?
Will the deadly strain eventually die out and be replaced with milder ones?

Evolution. The strain that doesn’t kill the host will outlive the strain that kills or seriously harms the host.

Remember that evolution does not have a plan or purpose in mind. There is no mind to evolution. It’s a name for a process that happens, regardless of best interests.

Gravity is also not in the best interests of people when you fall off a cliff. Nevertheless, it happens. You can correct for it by being cautios or building railings to prevent the falling-off part; similar, we could rein in globalized agriculture, where it turns out to be impossible to trace back the farm one cucumber was grown on; and establish better practices where human shit doesn’t get into contact with veggies on a field unless it’s safe.

That is both in our interest and do-able. Convincing the bacteria that swapping parts of their DNA to become killer bacteria is against their own interests has low chances of success.

Yes, most likely. Though the doctors rather hope to find the source and stop the further spread first, because letting it run its course naturally means a high toll of dead or incapacitated people.

Possibly. If most people being infected were getting exposed from other people, then yes, a deadly strain wouldn’t be spread very much, because the hosts are dead. In fact, in many diseases, researches have seen a shift over time from extremely deadly to less so.

But I think most E. Coli infections (at lest the deadly strains we worry about in the first world) aren’t human-to-human transmitted, but rather from (non-human) animal sources. Conceiveably, a strain could have a mutation that makes them deadly to humans, but gives them an advantage in cows. Then, infected humans are kind of a by-product, and there wouldn’t be any direct selection against deadliness in humans. Though humans might try and aggressively wipe out such deadly strains,so they could be driven to extinction, but that’s kind of a different mechanism.