Cats, feral or domestic have a very nasty bacteria ridden mouth. A good bite from one left untreated could do some seriose damage. As with any bacteria infection it could presumably kill a human. I don't think it happens often in todays medicine era, but it is definatly not impossible.
Rusty
PS ask any vet, vet tech, dog groomer who they would rather be bitten by, a dog or a cat. With all the bites I have experienced I would rather be bitten by a good sized shepard then a cat believe it or not.