How Clean Is Your Doctor's Stethoscope?

Stethoscopes are used by every primary care physician, and are a universal tool of the trade. Nevertheless, few physicians put much thought into sterilizing them.

Although concerns about stethoscope hygiene have been voiced for decades, there has been little heed paid to stethoscope hygiene. Recent studies show that few or no physicians sterilize their stethoscopes before examining patients.  

Across 28 studies, the average rate of stethoscope contamination with bacteria was 85 percent, and ranged from 47 to 100 percent. In other words, the vast majority of stethoscopes pick up bacteria.

Although most of the bacteria found on stethoscopes are non-pathologic, or don’t cause illness, there’s concern that unsterilized stethoscopes harbor Staphylococcus aureus, Pseudomonas aeruginosa, vancomycin-resistant enterococci, and Clostridium difficile, all of which cause disease.

Moreover, research has shown that these bacteria can be transferred from the stethoscope to the skin.  One recent study showed that during the physical exam, a stethoscope becomes just as contaminated with bacteria as does the physician’s dominant hand used during the examination. In other words, if your physician is using the right hand to examine you, this hand is just as contaminated with bacteria as the stethoscope.

To date, no studies have examined the association between unsterilized stethoscopes and healthcare-associated infection.

How often stethoscopes are cleaned affects their contamination rates with bacteria. Research shows that frequent disinfection dropped contamination rates from 84 percent to 33 percent. Most importantly, cleaning significantly decreased contamination rates with MRSA, an antibiotic-resistant organism.

Notably, 100 percent of decontaminated stethoscopes become recontaminated with bacteria after exposure to five or more patients.

Research also shows that health-care providers who regularly wash their hands between seeing patients also have lower rates of stethoscope contamination.

It’s recommended that non-critical medical devices, such as stethoscopes, are cleaned with ethyl or isopropyl alcohol. The alcohol-based hand sanitizer that physicians use to wash their hands can also be used to disinfect stethoscopes.

For best results, hand hygiene and stethoscope hygiene should be combined. One preferred method for stethoscope decontamination involves first covering the diaphragm of the stethoscope with alcohol-based hand rub, then engaging in hand hygiene while the stethoscope is drying.

Alternatively, ethanol-based hand cleaners, alcohol wipes, or alcohol-based hand foam can be used to clean stethoscopes.

In a 2017 study, Holleck and co-authors examined rates of stethoscope hygiene among house staff, medical students, and attending physicians. During this pilot program, participants were educated about stethoscope hygiene using a PowerPoint presentation, flyers were posted to remind everyone to clean their stethoscopes, and cleaning supplies were made readily available.

Study participants were secretly observed from outside the rooms for occurrences of hand hygiene and stethoscope hygiene. After the training and education, no one was observed disinfecting their stethoscopes. In other words, despite being educated to clean their stethoscopes, nobody did it.

To be fair, this study was small. After the intervention, only 41 people were observed for stethoscope hygiene practices. Nevertheless, these findings are in line with those of other studies examining rates of stethoscope hygiene. Specifically, another study found that only 4.6 percent of trainees working at three academic centers disinfected their stethoscopes during an 11-month period.

According to Holleck and co-authors:

"Despite limitations, we think this highlights an important, but often overlooked infection control issue by discovering how rarely stethoscope hygiene is done, and suggests that standard education may not be the answer. We believe that stethoscope hygiene should be included in all hospital hand hygiene initiatives. Perhaps accountability can be increased by designating a team member, such as a senior resident physician, to be the team leader and champion to remind and ensure that stethoscope and hand hygiene are performed."

It’s apparent that very few physicians clean their stethoscopes before they examine a patient. Although most of the bacteria found on stethoscopes don’t cause illness, more dangerous bacteria (and viruses) also make their way onto stethoscopes. This bacteria can be transferred from stethoscopes to skin and could serve as a source of infection.

If you notice that your physician or other healthcare provider has failed to clean their hands or stethoscope, you should request that they do so. Physicians are busy people, and it’s very likely that they forget to clean their stethoscopes on a regular basis. By reminding your physician or other healthcare provider about proper hygiene, you can help prevent infection.

Physicians and other healthcare professionals need to realize that stethoscopes can become just as contaminated as hands and need to be disinfected after each use. Doing so can improve patient care and limit the risk of spreading infection—especially with antibiotic-resistant bacteria like MRSA.