Feet Fungus: Skin Home to 80 Different Types of Fungi

What's home to a bunch of fungi? Your feet, that's what!

According to new research, more than 80 different types of fungi in particular hang out on your tootsies. The tiny organisms cling to a person's skin like flies to garbage, but never fear. It's not quite as disgusting as you think. (Or, at least, we hope.)

According to geneticist at the National Human Genome Research Institute in Besthesda, Md., Julie Sergre, and the coauthor of the study, identifying the differences between healthy and unhealthy fungi could help researchers create better treatments specifically targeted for some foot troubles-like toenail infections or athlete's foot.

 "This study will get people's attention," said physician and microbiologist Martin Blaser of the New York University School of Medicine. He believes that while many studies have previously focused on bacteria that has accumulated on areas of the foot, fungi is not often discussed. 

Unlike bacteria, fungi are hard to grow in the lab. Culturing fungi from an infected toenail can take weeks, says study coauthor Heidi Kong, a dermatologist at the National Cancer Institute in Bethesda, Md. Instead of tallying up different skin microbes by trying to grow them in the lab, Kong, Segre and their colleagues went hunting for fungal DNA.

The team swabbed 13 skin sites (plus toenails) on 10 healthy volunteers, and analyzed the DNA in each sample to figure out which types of fungi lived where. Using molecular tags that stick only to fungal DNA, the researchers could separate their quarry from the genetic material of other organisms such as bacteria, humans and viruses.

Across all areas but the feet, one fungal genus, Malassezia, tended to dominate - with different species dominating spots such as the forehead, the crease behind the ear or the forearm. The feet, however, housed bustling beds of fungal diversity.

Researchers noticed that approximately 40 different types of fungi were found on the toenails, 60 between the toes and 80 at the bottom of the heel. (Ew!) 

Heels and toes usually carry more fungi as feet tend to be cooler than other body parts, and fungi don't like it hot. They also rub against fungi-friendly surfaces such as sweaty socks and locker room floors.

When people hear about the team's results, "they say, 'Eww, I need to take a shower,'" Kong said. "But in fact, these organisms may actually be helping protect us."

In reality though, these fungi help prevent dangerous ones from sticking to our feet, according to Segre. While it still might seem pretty gross (at least, it does to us) we can rest assured that the diverse eukaryotic organisms hanging around on our feet might just be there for a good reason.