So, you think your doctor's stethoscope is clean? More specifically, do you think your doctor cleans that stethoscope after checking each patient?

Two years ago, Ariel Schroeder, now 17 and a senior at St. Joseph High School in the Natrona Heights section of Harrison, heard her mother, Dr. Maryellen Schroeder, a family physician, lamenting that some medical residents don't keep their equipment adequately clean. Ariel, of Tarentum, knew that the law requires physicians to wash their hands with anti-bacterial hand foam before examining each patient.

They are also expected to wipe their stethoscope each time with an alcohol prep pad, the gold standard for stethoscope cleaning. "The problem," Ariel said, "is remembering to carry the pads and use them. When doctors are running from clinic to clinic seeing so many patients, it's hard to do."

Half joking, she suggested, "Why don't the doctors just rub their stethoscopes in their hand foam?" Her mom encouraged her to test the idea.

That simple question led to Ariel's research being published in the August issue of The Journal of Family Practice. The article, "What's Growing on Your Stethoscope? (And What You Can Do About It)," lists Ariel as primary author and her mother as co-author. Ariel completed the research as a sophomore. According to Dr. Schroeder, it is very unusual for the first author in a peer review journal not to have an advanced degree.

Many teenage girls would squeal "Ewwwww!" at the thought of thousands of germs squirming on a stethoscope that just touched their skin. But Ariel approached the problem with the detachment of a veteran research scientist.

Preliminary testing showed that bacteria enjoy the good life on many stethoscopes, and that hand foam could kill the little buggers just as swiftly as alcohol prep pads. Ariel decided the project would work well for the Pennsylvania Junior Academy of Science competition, in which she has participated since seventh grade. She also presented it at the Pittsburgh Regional Science and Engineering Fair.

From planning to final results, the project took about nine months, Ariel said. She took samples several times from doctors' and nurses' stethoscopes at UPMC St. Margaret Hospital, where her mother works, and at Lawrenceville Family Health Center. She used the hospital laboratory to type, count and incubate the bacteria.

Among other things, "I found staphylococcus, including MRSA (methicillin-resistant Staphylococcus aureus), which can make people sick. A lot of the bacteria I found wouldn't affect a healthy individual, but could affect someone with a compromised immune system," Ariel said. "It was shocking to check a stethoscope and find 200 colonies."

But the existence of the bacteria wasn't the point. What mattered was whether the easily accessible hand foam would kill the germs as well as the more cumbersome alcohol prep pads.

"Immersion in the hand foam completely eliminated the MRSA and significantly reduced the other bacteria," she said. "There's no extra cost or time to use the foam. They just rub the stethoscope in it while they're rubbing their hands."

Ariel presented her results at the hospital and at various competitions. At the Pennsylvania Academy of Family Physicians Research Day, she presented in the medical student category. Before that, the academy had never had anyone younger than a med student present research.

"I was really pleased. One doctor said that my findings were the one thing he was going to take back to his practice," Ariel said.

The St. Joseph's senior has also researched bacterial conditions of white lab coats and is considering a college major in infection control. She is expanding the stethoscope project at multiple sites. "Now I'm trying to see if I can change doctors' and nurses' behavior to get them to actually use the hand foam," she said. "It seems like a no-brainer."