NSF International visited 22 Michigan homes a few years ago and took swabs of the 26 locations thought to be the most touched by people living there. These are the places where we pick up germs or leave germs behind for other family or friends to contact.
Many bacteria are harmless or maybe even helpful, of course, but some might be the sources of illness, including foodborne illness. NSF is a product testing, inspection and certification organization.
The researchers then measured the concentration of bacteria they collected from each spot.