Like many of the items on this list, Escherichia coli (aka E. coli) just sounds like something that you probably want to avoid. The truth is that not all strains of these bacteria are actually harmful. Some are even beneficial to your digestive tract.
A type of fecal coliform, E. coli strains regularly reside in human intestines, and their presence on a cell phone could be a sign of other contamination. In rare cases, a phone could be infected with a very nasty strand called E. coli O157:H7. This is the version of the pathogen that produces the foodborne outbreak scares that we see in movies and local news broadcasts. While it usually leads to severe cramps, diarrhea and vomiting, an outbreak occasionally can have fatal consequences [sources: Locke, Centers for Disease Control and Prevention].