The causative agent of botulism --
Clostridium botulinum -- is a spore former. When it encounters adverse circumstances (like oxygen -- it's an anaerobe), it condenses and dehydrates its DNA and just enough cytoplasmic material to remain viable into a hard, dry little nugget inside the cell.
Bacillus anthracis (anthrax) does this as well.
The spores are completely metabolically inactive -- so antimicrobial stuff that interferes with their metabolism can't hurt them -- and contain virtually no water -- so antimicrobial stuff that has to be absorbed into the bacterial cell can't hurt them.
Pressure cooking does do them in, but sloppy technique can let a few slip through -- which is why you never eat from a can or jar that has a high pressure inside. There's a good chance in those instances that clostridial spores have "come back to life" post-canning, multiplied, and elaborated their toxin into the food.
As to honey and babies in particular (from
howstuffworks)...
Quote:Babies get botulism from honey in a different way. Bees naturally collect botulism spores as they are collecting nectar and mix them into the honey. Most people can eat these spores without difficulty because we have bacteria in our intestines and robust immune systems that eliminate the spores. Infants do not yet have these defenses. So when a baby eats honey, the spores find themselves in the oxygen-free intestine and come to life. They produce the toxin while inside the baby.
