(FOX 11) - You may want to switch to disposable paper cups in the workplace after you hear this story.
A new study out says 90-percent of mugs in office kitchens are coated in germs. And 20-percent of those cups actually carry fecal matter!
"Coliform bacteria were present on 20 percent of the coffee cups before and 100 percent of the coffee cups after wiping with a dishcloth or sponge," Gerba writes. "No E. coli was found on cups prior to wiping. However, 20 percent of coffee cups were positive for E. coli after wiping.
The University of Arizona research says rarely changed communal kitchen sponges are the key culprit in spreading bacteria.
The best way around this problem: bring your coffee mug home every night for a thorough scrub.