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Health & Wellness

Striking photo shows all the bacteria on an 8-year-old's hand

If ever you needed more motivation to wash your hands, this germy, colorful creation ought to do it.

Behold some of the bacteria that grew when an 8-year-old boy who had been playing outside pressed his hand onto a large Petri dish. The photo has been getting lots of buzz after his mom posted it on Microbe World last week.

Tasha Sturm, who works as a microbiology lab tech at Cabrillo College in Aptos, California, is used to seeing students swab objects like cell phones and door knobs for germs as part of basic experiments.

“It’s partly to show that there are microbes everywhere,” Sturm told TODAY, noting her two kids enjoy replicating some of the tests at home and that her son has been particularly interested in checking out what’s on his hands.

Courtesy Tasha Sturm/Cabrillo College/asm.org
The 8-year-old boy had been playing outside before he pressed his hand into the Petri dish.

“He’s been bugging me; he says ‘When do I get to do it?’

Courtesy Tasha Sturm/Cabrillo College/asm.org
This is a close-up of a mystery circle in the upper left corner of the Petri dish. Tasha Sturm believes it's a contaminant.

A couple of weeks ago when he was getting ready for school, Sturm asked him to play outside and pet the family dog. When the boy came back in, she had an agar plate — a sterile Petri dish filled with a substance used to grow bacteria — ready. After he gently put his hand onto the plate, Sturm incubated the dish at body temperature for a day or so and then let it sit out at room temperature.

By the time she took the photo, the bacteria had been growing for about a week. Her son’s reaction to the results?

“He said, ‘that’s cool.’ And then my daughter said, 'Let’s do the dog’s nose, let’s do the paw, let’s do the cat’s tail,'” Sturm recalled.

Courtesy Tasha Sturm/Cabrillo College/asm.org
This is a close-up of the round blob in the lower right corner of the original photo.

Sturm believes the large white circle in the bottom right of the photo is Bacillus, which is commonly found in dirt. Some of the other white spots may be staph, or Staphylococcus, she said, while the yellow and orange spots may be yeast.

“It’s normal stuff that we’re exposed to every day. The skin protects us from a lot of the bad stuff out there,” Sturm said. “The take home message is that to have a healthy immune system, you’ve got to be exposed to stuff.”

Indeed, environments that are extremely clean may make children more sensitive to allergens, according to the “hygiene hypothesis.”

Both of Sturm’s kids know that if they pet the dog or play outside, they should wash their hands before they eat. It’s just basic hygiene, she said.

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