Would you like a slice of lemon and a little bacteria on the side?

I saw this on the news a few weeks ago and again last night on our local news.
It makes you think twice before asking for that slice of lemon at a restaurant.
I wonder if it's the same with limes? :D Because our immune systems are
potentially lower in the winter perhaps we should do without the lemon. They
found the lemons you buy at the supermarket to be without bacteria. You
just need to wash them first, use clean knifes, and clean hands. Duh?