At home, my family prefers to be barefoot. When we walk in the door, we shed the confines of our footwear because it's more comfortable, not to keep the floors clean. (With two adults, two kids and two cats, our floors don't stay clean for long.) And we tell guests to leave their shoes on or take them off — whichever they prefer.

But the no-shoes policy might become a firm rule for everyone entering my house. After all, there's a good reason why many cultures and countries, including most of Scandinavia, China, Japan, Hawaii, Thailand, Turkey, India and much of the Middle East, have traditionally shunned wearing shoes inside the home.

For a study for CIRI, the Cleaning Industry Research Institute,, Dr. Charles Gerba, a microbiologist at the University of Arizona, wore a new pair of shoes for two weeks, then analyzed the results. He found that 420,000 units of bacteria made themselves at home on the soles and another 3,000 units of bacteria landed inside the shoes. He repeated the experiment with 10 participants and got similar results.

Here's a sample menu of some of the disgusting bacteria found: E. coli, known to cause intestinal and urinary tract infections; meningitis and diarrheal disease; Klebsiella pneumonia, a common source for wound and bloodstream infections as well as pneumonia; and Serratia ficaria, a rare cause of infections in the respiratory tract and wounds.

The soles of your shoes are rich in bacteria

woman's feet on forest trail You pick up a lot of unwanted hitchhikers when you walk — and we don't mean basic dirt. (Photo: Stasique/Shutterstock)

"The common occurrence (96 percent) of coliform and E. coli bacteria on the outside of the shoes indicates frequent contact with fecal material, which most likely originates from floors in public restrooms or contact with animal fecal material outdoors," said Gerba. "Our study also indicated that bacteria can be tracked by shoes over a long distance into your home or personal space after the shoes were contaminated with bacteria."

Gerba worked with research specialist Jonathan Sexton, who wanted to find out how effectively that bacteria contaminated the surfaces with which it came in contact. A volunteer wore shoes and walked over several uncontaminated floor tiles. More than 90 percent of the time, the bacteria transferred directly onto the clean tiles, Sexton said.

So basically, the bad news is that by wearing shoes out in the world and continuing to wear them around your home, you're tracking in excrement, fungus and potentially deadly bacteria.

The good news is that Gerba found that washing the shoes in the washing machine with a little detergent reduced the bacteria by 90 percent. But of course, not all shoes are washing machine-safe. Might I suggest a Clorox wipe on those soles?

Angela Nelson ( @bostonangela ) is an exhausted mom of two young daughters and two old cats, and a Pulitzer Prize-winning digital editor with more than 15 years of experience delivering news and information to audiences worldwide.

Why you should never wear shoes in the house
Studies show that we track fecal matter, potentially deadly bacteria and fungus into our homes when we wear our shoes inside.