Coliform bacteria and your house

A 2011 study by NSF International – a Michigan-based non-profit organization that tests, inspects, and certifies products – revealed that the household items most heavily contaminated with coliform bacteria are dish cloths and sponges used to wipe down kitchen surfaces or clean out pans.

OK, the study is nearly 8 years old, but it’s still eye-opening to learn that about 75 percent of dish sponges and wipes are contaminated by coliform bacteria, a family of bacteria that includes E. coli.

In the study, NSF International asked 22 families to swab 30 everyday household items, ranging from mobile phones to kitchen and bathroom surfaces.

Coliform bacteria:
They’re everywhere

Why dish cloths and sponges? Well, they commonly contain so many coliform bacteria because they are warm and moist, ideal breeding conditions for germs.

Other places coliform bacteria were found included:

• 45 percent of kitchen sinks
• 32 percent of countertops
• 27 percent of toothbrush holders
• 18 percent of cutting boards
• 9 percent of bathroom handles.

Although most coliform bacteria are not dangerous, they are commonly used as a marker for more general fecal contamination. And although they don’t normally get into the kitchen through contact with human feces, they do find their way there thanks to raw meat, which is often contaminated with fecal bacteria.

A study by NSF International discovered that the household items most heavily contaminated with coliform bacteria are dish cloths and sponges used to wipe down kitchen surfaces or clean out pans. Coliform bacteria is a family of bacteria that includes E. coli.

Coliform bacteria:
Surpasses toilet seat

That the kitchen sponge or dish cloth is almost always the dirtiest thing in your house came as no surprise to the University of Arizona’s Dr. Chuck Gerba in an interview with the BBC.

Gerba, a professor of microbiology who studies how diseases are transferred through the environment, has learned that the average toilet seat contains about 50 bacteria per square inch. A kitchen sponge or dish cloth, on the other hand, contains about 10 million bacteria per square inch.

To put it another way: Your kitchen sponge just might be 200,000 times dirtier than your toilet seat.

If you are worried about germs in the kitchen, the best thing to do is keep the dish cloth or sponge as dry as possible and dunk it in bleach weekly.

Coliform bacteria:
More cleaning tips

In December 2017, Good Housekeeping published tips on how to clean a kitchen sponge, including sticking it in the microwave or dishwasher to kill germs.

When it comes to cutting boards, FoodSafety.gov says that stopping cross-contamination is simple: Use one cutting board for fresh produce, and another one for raw meat, poultry, or seafood.

In addition, use separate plates and utensils for cooked and raw foods. Before using them again, thoroughly wash plates, utensils, and cutting boards that held raw meat, poultry, seafood, or eggs.

Coliform bacteria:
Start at the store

Avoiding germs at home really starts at the grocery store. When shopping, keep meat, poultry, seafood, and eggs separate from all other foods, and make sure you aren’t contaminating foods in your grocery bag by placing raw meat, poultry, and seafood in plastic bags to keep their juices from dripping on other foods.

Once you get home, place raw meat, poultry, and seafood in containers or sealed plastic bags to prevent juices from dripping or leaking onto other foods. If you’re not planning to use those items within a few days, freeze them instead.