A high school student's discovery indicates that teenage nail-biters have the least germs under fingernails, and that short-clipped nails had more germs than long nails.

The study was conducted by high school sophomore, Jamie Yohn, who attends the Academic Magnet High School and was mentored by MUSC faculty. To answer her science fair project question: "Which fingernail length is most prone to bacteria?" Yohn worked in MUSC's microbiology lab under the mentorship of Lisa Steed, Ph.D., director of Diagnostic Microbiology, and Andrew Annand, D.O., medical director of Kidney and Pancreas Transplantation.

"What I found was the exact opposite of what I had thought I would find," said Yohn. "I assumed that because people's mouths contain so many germs that nail-biters would have more germs under their nails. The opposite was true. In fact, people who clipped their nails short had the most germs under their nails." Her findings did confirm the importance of frequent hand-washing in staving off germs. "People who washed their hands most often showed the least amount of germs," Yohn said.

To make this determination, Yohn surveyed 30 fellow students about their hygiene habits and whether they bite their nails before taking a sample from under the nails of the person's dominant hand.

Though Yohn said it was difficult to determine the exact type of germs, she said that most of the germs found were staphylococcus, which she said was not surprising. "This is an organism that lives on the skin," she said. The other types of germs found were varying types of bacillus. She said the germs could have included e-coli or hepatitis.

Annand said that he did not find the results surprising, but he is concerned that they indicate that nail-biting is a hedge against hand germs, and stresses that conclusions should not be considered a pass for nail-biters, who may be ingesting the germs rather than leaving them under their nails.

"The fact that longer nails had fewer bacteria than shorter ones is probably a matter of the nail bed being protected by the `umbrella' of a longer nail," Annand said. "Thus long nails lead to less colonization than short nails, while nail biters appear to have the cleanest nails but are probably just ingesting most of the bacteria and are thus ultimately the most prone to becoming ill."

After the study, Yohn informed her fellow students of the results. "They were pretty disgusted," she said. "They said, `I'm going to buy some Germ-X.'"

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