What bacteria is on your shopping cart? 10 carts were tested for germs and this is what we found.

What bacteria is on your shopping cart? 10 carts were tested for germs and this is what we found.
Published: May. 31, 2018 at 12:00 AM EDT|Updated: May. 31, 2018 at 3:22 PM EDT
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(Source: WIS)
(Source: WIS)
(Source: WIS)
(Source: WIS)

COLUMBIA, SC (WIS) - You're surrounded by germs each day, and a lot of them are in places you go every day.

Think about when you go shopping for food at the grocery store. You walk through the door, grab a cart, grab your groceries off the shelves, but most people never think twice to wipe the cart down.

Do you ever think what's on the handle you're touching and putting your food on?

With the help of the University of South Carolina and Piggly Wiggly in Northside Plaza, we did a test to find out how much bacteria and what kind of bacteria sits on a shopping cart handle.

Ten carts were sampled to capture a snapshot of what could be on them. Five of the carts in this test were wiped at 7 a.m. when the store opened. The other five were left unwiped.

Dr. Isaac Hagenbuch, an instructor and lab coordinator from the University of South Carolina, conducted the study. Hagenbuch swabbed the 10 carts at 7 a.m., noon, and again at 8 p.m., an hour before the store closes.

After swabbing each handle, the samples were brought back to the lab at USC and were then put in an incubator at room temperature for 48 hours.

Hagenbuch says his hypothesis is, I think that we'll find bacteria on the carts even the ones that we've wiped but that we're going to find much less on them after we've wiped them."

Just 48 hours later, the Petri dishes were taken out of the incubator. Each sample was tested on different Petri dishes to show different bacteria.

The yellow dish tested for anything that grows at human body temperature. Results for the yellow dish show the average number of bacterial colonies increased over time and that the carts that were unwiped had more bacteria at every time point and they also gained bacteria faster than the ones that had been wiped.

There are fewer bacteria on the handles in the morning, wiped or not. Throughout the day, the number of bacteria is higher on unwiped cart handles and unwiped handles more quickly accumulate bacteria.

The orange dish tested for bacteria that will grow on human skin and if anything showed up yellow, that is a form of Staphylococcus aureus. The data shows there is no real difference in the number of bacteria or rate of increase regardless of whether the cart handle was wiped or unwiped.

Skin bacteria were not affected by the morning wipe, and while they do increase over time, they aren't the ones driving the increase in overall bacteria. The red Petri dish tested for organisms associated with feces - some of the same germs you'd find in your bathroom.

We found that the unwiped cart handles had more bacteria by the end of the day, and the morning wipe slowed down the accumulation of those bacteria. Fecal bacteria are affected by the wipes and are part of what is driving the increase in overall bacteria.

"What we didn't find were any organisms like E. coli for instance or fungi like ringworm which was surprising to me because it was quite warm when we did the sampling, people's hands were sweaty that tends to facilitate transfer of micro-organisms but we didn't see any of them in the samples," Hagenbuch said.

While the Petri dishes look pretty scary and gross, we concluded that all of these bacteria are normal and generally wouldn't be dangerous unless you have a compromised immune system.

The Centers for Disease Control has a list of tips on how to treat your shopping cards and other ways to avoid both foodborne and other illnesses.

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