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Stethoscopes Are More Germy Than Docs' Palms, Study Finds

Image: A physician assistant wears a stethoscope
Next time you ask your doctor to wash hands before an exam, you might want to ask him to clean the stethoscope, too, experts say. Joe Raedle / Getty Images file

Health care workers’ hands are notorious for spreading germs in hospitals, but a new study suggests that the stethoscopes around their necks may be just as bad.

Researchers in Switzerland found that the diaphragms of stethoscopes — the part that a doctor presses against your chest — were more contaminated with the superbug MRSA than the palm of the hand.

And if the stethoscopes aren’t disinfected between uses — they’re typically cleaned less than once a month, if at all, research shows — they’re just as likely to contaminate the next patient as unwashed hands, they said.

“We consider them as potentially significant vectors of transmission,” wrote experts at the University of Geneva Hospitals, including Dr. Didier Pittet, who frequently studies hospital hand hygiene.

In the study published Thursday in the journal Mayo Clinic Proceedings, Pittet and colleagues measured bacteria collected after exams. Using results from three doctors and 83 patients, they tested four spots on examiners’ hands — fingertips, back and two places on the palm — and two sites on the stethoscopes, the diaphragm and the tube.

As expected, the fingertips were the most contaminated with both general bacteria and methicillin-resistant Staphylococcus aureus, or MRSA, the superbug responsible for potentially life-threatening infections. They showed a median of 467 aerobic colony counts and 12 MRSA colony-forming units, both measures of contamination.

But the stethoscope diaphragms were in second place, with 89 ACCs and seven MRSA CFUs. The fleshy part of the palm under the little finger had only 34 ACCs and just two MRSA CFUs.

Of course, just because the bacteria were present doesn’t mean they actually caused infections. That’s too hard to prove, experts say. But the study does add to evidence that health workers should regularly clean their tools, said Dr. Dan Diekema, president of the Society for Healthcare Epidemiology of America.

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“If you’re rounding from patient to patient, when they put the alcohol sanitizer on their hands, they’ll kind of bathe the stethoscope as well, or use an alcohol wipe,” he said.

On bare skin, with a healthy patient, it probably wouldn’t be a problem, said Elaine Larson, a professor at the Columbia School of Nursing. But on someone with a fresh incision or other skin break, it could be serious.

“It just makes common sense,” she said. “I wouldn’t particularly want a stethoscope used on me when it was known to have been used on someone with MRSA.”