Evo Magz v4.7

Because of that, infections passed from person to person are a serious concern. And now, a new study suggests one possible way illnesses may be transmitted to unsuspecting patients: According to an analysis of 40 stethoscopes used in a hospital setting, this vital doctor’s tool is commonly loaded with bacteria—including some seriously dangerous strains.

The study, published this week in Infection Control & Hospital Epidemiology, was carried out at the University of Pennsylvania Perelman School of Medicine. Researchers used molecular sequencing to determine the bacterial makeup on the surface of 20 reusable stethoscopes and 20 single-use stethoscopes that were currently being utilized in the hospital’s intensive care unit. They also analyzed 10 unused stethoscopes, to serve as a control group in the study.

What they found was concerning, although not totally surprising, says lead author Ronald Collman, MD, professor of medicine, pulmonary, allergy, and critical care at the university. All 40 of the in-use stethoscopes were “significantly contaminated with a rich and diverse community of bacteria,” according to the study. More than half contained Staphylococcus aureus, a germ that can cause serious and potentially fatal staph infections.

Before you freak out, however, the study doesn’t mean that every stethoscope patients come into contact with will be covered in germs. It all depends on how the instruments are used, Dr. Collman tells Health, and how they’re cleaned between use. (The researchers also could not determine if the bacteria on the stethoscopes was alive or dead—or if the stethoscopes in the study ever made patients ill—so they can’t say whether these devices have transmitted infections to patients.)

The study actually looked at practices for disinfecting stethoscopes between use, and—no surprises here—found that when hospital staff followed a standardized, CDC-recommended approach (using hydrogen peroxide wipes for 60 seconds), the stethoscopes were much cleaner than when they used what the study described as their usual methods, which involved alcohol swabs, bleach wipes, or hydrogen peroxide for different durations.