Re: e-coli in bones?
Actually, we all have E. coli in our guts. It is part of the normal intestinal bacteria that help us digest our food. The problem is when it gets into places that it shouldn't be. Food poisoning symptoms caused by E. coli occur when it is ingested and gets into parts of the digestive system that it isn't supposed to be in. There are lots of bacteria that are like this; we need them in our bodies in certain places to do stuff for us, but if they get somewhere else or grow out of control they cause problems.
As for how the bacteria could have gotten there, maybe there was a problem during the liver surgery in which some bacteria were released from the intestines into the abdominal cavity, at which point they migrated to the spine. Or maybe the bacteria overwhelmed his immune system and were able to gain access to his bloodstream. That's the kind of question that may never be answered.
It seems like the important thing is that you support your friend through this difficult time. If you are really concerned about this, maybe you should ask him about it?