You mentioned Cruzefeld-Jacob disease and it's a 'prion disease', which apparently even the Bad Astronomer, author of 'Death from the Skies' finds scary! Just how worried should we be about bacteria?

In addition, is it true that kids are being 'too removed' from getting into dirt and the 'cleanliness' of modern day life hurting their ability to build up immunity (this was on an ep of House I saw recently, so it's getting into pop-culture messages!). Thanks, fantastic show!! :)

Just a nitpick, It would have been good Lisa Hammet had mentioned the e-word (evolution) when talking about how bacteria become resistant to drugs.

I was surprised that she did not know why you can't have large bacteria - the reason is the surface area to volume ratio. As a cell grows, the surface area increases exponentially but the volume increases cubically. So the larger you get the harder it is for your surface area to compensate for the huge volume.