Here’s What Happens When YouCulture the Bacteria on an Eight-Year-Old’s HandLots of cooties growMarissa Fessenden

A handprint from an eight-year-old boy after he came in from playing outside (Tasha Sturm, Cabrillo College

via ASM)

smithsonian.com June 9, 2015

The world is teaming with microbes. That fact is never so graphically apparent as

when someone actually takes the time to culture the bacteria and yeast growing oneverything — from pillowcases to toilets to eyeballs. Fortunately many of thesemicrobes are vital to human health. So perhaps this photo of the stuff previouslyliving on an eight-year-old boy’s hand can be appreciated rather than reviled.

The Facebook page for the American Society for Microbiology (ASM) recentlyshared a photo of a large bacterial culture plate bearing a handprint made ofmicrobial colonies taken by Tasha Sturm. Sturm, who works as a lab tech at CabrilloCollege in California, created the evocative culture by pressing her son’s hand into anagar plate after he was playing outside. Agar is commonly used to culture microbesbecause it provides a nutrient-rich base for microorganisms to grow. She posted thehand print microbe portrait at MicrobeWorld.org, run by the ASM.

Sturm explains in detail how the plate needs to be cultured and incubated to get thebest results — apparently some of the colonies of yeast and fungi only take on colorwhen they are grown at room temperature. Sturm has printed both of her kids’ handsfor a few years now and saves the results for microbiology classes at the college. Sheexplained more in an email to Smart News:

I used to do my daughter’s hand until her hand became too big for the largeplates and then started doing my son. I save the plates and give it to theinstructors to use as a demo for the class. My kids think it is “cool” and thestudents like it as well.

Determining the exact species would require some more testing, but Sturmadded some tentative IDs in the comment section of the original post. White coloniesare probably a form of Staphylococcus, which lives in people’s noses and skin. Moststrains are harmless or even beneficial but some can cause disease when they growwhere they shouldn’t, especially when they develop antibiotic resistance. Sturm alsoposted two close ups of colonies that are either species of Bacillus — a common soilbacterium, though one species is responsible for making feet stinky — or a yeast.

Researchers are still working to explain exactly what this abundance of microbes onthe body and its stunning diversity means for human health and disease. But one

thing that is increasingly evident is that a germ-laden hand is perfectly normal andcan even be beautiful.

A close up of one of the largest colonies, probably a type of Bacillus by Tasha Sturm, Cabrillo College

A colony from outside the handprint may be contamination by Tasha Sturm, Cabrillo College