Matt Alice: I'm totally confused over this whole Escherichia coli ordeal I learned in microbiology that E. coli exists in our intestines. What's up with E coli 0157:H7? Where did it come from? How does it hurt people? And how is it related to our own friendly intestinal fauna of the same name? Coevolutionarily yours, Sean, P.B.

Good. Gut bugs. Maybe we’ll get an answer that doesn’t make us want our money back. E coli comes in hundreds of different strains in different animals. The 0157:H7 type lives in cows’ intestines; we have our own varieties. Seems when the 0157:H7 guys get into our guts when we eat poop-tainted meat or perhaps vegetables that have fallen into manure and not been adequately washed, all hell breaks loose. They do their bacteria thing and the resulting toxin gives us liver and kidney damage. (Our cuddly E. coli might do the same to cows. Who knows.) The number-letter designation is a physical description of this particular strain of E. coli, meaningful to biochemists and to lawyers suing the heck out of food processors.