In humans, the first choice of treatment for e. coli is just hydration and supportive care, so the body can heal. If a human has to be hospitalized for it, there is more treatment that is done, including sometimes blood transfusions. Antibiotics are often not used unless specific testing is done before hand, as it can cause the infection to worsen sometimes. But that is generally in the digestive tract. When, in a hen, it travels up the oviduct, it's a whole 'nother thing. In my experience, in all of my birds affected over the years, it has been eventually fatal. There are some people who say they've treated it early enough and gotten rid of it. I'm skeptical, but it may be true in some cases. That seems to be more the exception than the common result. Years ago I did a lot of searching for ultimate causes, and there isn't a lot of good information, and some is contradictory. I think some hens get stretched cloaca's from laying, maybe partly genetic for them, and it can allow bacteria to enter easier. Most of my birds that have had it have been breeds that are very heavy layers, like sexlink hybrids. I could find no good information on a rooster being a carrier, though I've seen the question before, and logic would suggest if that were happening then it would be affecting a lot more hens in that flock. I've not found that to be the case, it's sporadic and only one here and there.
