The Centers for Disease Control and Prevention (CDC) reports that ˜72,000 hospital patients with healthcare-acquired infections (HAIs) died during their hospitalization in 2015. ¹ HAI mortality thus represents the equivalent of a jet airliner crashing, with zero survivors, every day in the United States. Although great effort has been undertaken to combat this tragedy by hand hygiene, the stethoscope, which drapes around necks, is placed in pockets, and is touched by unwashed hands day in and out, has predominately been ignored. The lack of attention to stethoscope hygiene belies contemporary data. Current Centers for Disease Control and Prevention (CDC) guidelines ^{Reference Rutala and Weber2} clearly state that “the stethoscope can be contaminated and spread disease.” ^{Reference Guinto, Bottone, Raffalli, Montecalvo and Wormser3,Reference Queiroz, Melo, Santos Calado, Cavalcanti and Sobrinho4} Pathogens cultured from the medical practitioner’s fingers are duplicated on the stethoscope diaphragm, ^{Reference Longtin, Schneider and Tschopp5–Reference Tschopp, Schneider, Longtin, Renzi, Schrenzel and Pittet7} which functions as a third hand ^{Reference Jenkins, Monash, Wu and Amin8} in the spread of disease. Furthermore, the ability of the stethoscope to transmit bacteria from the diaphragm to the patient has also been documented. ^{Reference Marinella, Pierson and Chenoweth9–Reference Vasudevan, Bin Thani, Aljawder, Maisel and Maisel12} Despite data reflecting the need to disinfect it before use, stethoscope hygiene is essentially ignored in contemporary clinical practice. ^{Reference Boulée, Kalra, Haddock, Johnson and Peacock13–Reference Holleck, Merchant, Lin and Gupta16}

The CDC defines the stethoscope as a noncritical surface ^{Reference Rutala and Weber2} and states that weekly disinfection with alcohol is acceptable unless it is visibly soiled. Although this would never be acceptable for the hands, the tool with identical pathogens and that is rubbed on the skin of a majority of patients is subject to vastly different disinfection recommendations than hands. The differences in the recommendations between the hands and the stethoscope should be addressed, especially now that the possibility of stethoscope-related coronavirus disease 2019 (COVID-19) transmission must be considered. ^{Reference Vasudevan, Bin Thani, Aljawder, Maisel and Maisel12,Reference Pasquarella, Colucci and Bizzarro17} How many stethoscope transmissions may have occurred in the COVID-19 era?

The evidence suggests that isopropyl alcohol is partially effective in stethoscope disinfection. ^{Reference Parmar, Valvi and Sira18} Recent studies show that disinfected stethoscopes can maintain significant rates of pathogen colonization. ^{Reference Parmar, Valvi and Sira18–Reference Knecht, McGinniss and Shankar24} And after decades of alcohol disinfectant use, some pathogenic resistance to its sterilization effects have become apparent. ^{Reference Pidot, Gao and Buultjens25,Reference Wilcox and Fawley26} Ultimately, although some pathogens are unaffected by alcohol (eg, Clostridioides difficile spores), ^{Reference Jabbar, Leischner and Kasper27} the critical intervention to prevent their spread is the actual disinfection of the stethoscope. Unfortunately, no observational study, of the many that have been performed, has ever documented a reasonable rate of disinfection practice. ^{Reference Jenkins, Monash, Wu and Amin8,Reference Boulée, Kalra, Haddock, Johnson and Peacock13–Reference Alali, Shrestha, Kansakar, Parekh, Dadkhah and Peacock15,Reference Jones, Hoerle and Riekse28} Clearly, current CDC recommendations are inconsistent with the overwhelming number of publications demonstrating that self-disinfection by medical providers is ineffectual, ^{Reference Alali, Shrestha, Kansakar, Parekh, Dadkhah and Peacock15,Reference Zachary, Bayne, Morrison, Ford, Silver and Hooper20,Reference Nunez, Moreno, Green and Villar29} inconsistent, ^{Reference Smith30,Reference Muniz, Sethi, Zaghi, Ziniel and Sandora31} and almost never practiced. ^{Reference Boulée, Kalra, Haddock, Johnson and Peacock13,Reference Vasudevan14,Reference Saunders, Hryhorskyj and Skinner32} In fact, when medical practitioners are asked, their self-reported stethoscope disinfecting rates commonly exceed 50%; however, when cultured, the growth rate from stethoscopes reported to have been disinfected >50% of the time is similar to that of observational stethoscope disinfection studies with disinfection rates in the single digits. ^{Reference Jenkins, Monash, Wu and Amin8,Reference Boulée, Kalra, Haddock, Johnson and Peacock13–Reference Alali, Shrestha, Kansakar, Parekh, Dadkhah and Peacock15,Reference Jones, Hoerle and Riekse28} Clearly, self-reported hygiene rates are not a reliable metric.

Medical professionals generally understand the vector potential of the stethoscope. Although calls for regular stethoscope hygiene are not unusual, ^{Reference Lecat, Cropp, McCord and Haller33} why are these disinfection practices universally ignored? It is the simple math of time. If a medical practitioner seeing 30 patients per day is expected to engage in a before-and-after stethoscope disinfection of 60 seconds, this equates to an hour per day dedicated to stethoscope disinfection. At this time cost, medical practitioner stethoscope hygiene between patients is not a viable strategy for promoting stethoscope hygiene. A more acceptable strategy could be disinfecting the stethoscope while introducing themselves or while having a discussion with the patient.

Alternatives to washing have been suggested. The most popular suggestion, and the one recommended by the CDC, ^{Reference Whittington, Whitlow and Hewson22} is the disposable stethoscope. With this strategy, a patient receives an inexpensive stethoscope that every subsequent medical provider shares. This option is a tremendously undesirable solution for 2 reasons. First, medical providers are generally not interested in sharing what is likely a contaminated device among a group of practioners. Is there a more effective way of innoculating all your staff ^{Reference Marinella34} than sharing the same undisinfected equipment? Second, disposable stethoscopes are lack quality and functionality. In a study of >200 auscultations, 10.9% of cardiac murmurs were simply misdiagnosed by physicians using the disposable stethoscope. In comparison, when high-quality stethoscopes with aseptic barriers were used, there was a 0% misdiagnosis rate. ^{Reference Kalra35,Reference Kalra, Shewale and Peacock36}

Finally, the CDC recommends that if dedicated disposable devices are not available, the stethoscope should be disinfected after use on a patient who is on contact precautions before using this equipment on another patient. ^{Reference Rutala and Weber2} This implicit strategy of “the medical pratitioner should wash it” relies upon interventions, such as education, that have been uniquivocally proven to fail. ^{Reference Holleck, Merchant, Lin and Gupta16} Self-administered stethoscope hygiene has inherent human compliance challenges and logistical drawbacks that undermine its success to the point that it simply does not work.

Another common approach to preventing the spread of disease between patients is for the medical practitioner to wash their hands and then place a disposable glove over the stethoscope diaphragm. Although this solution is likely acoustically superior to the disposable stethoscope, handling the stethoscope diaphragm effectively shares contaminants between it and the medical pratcitioner’s just-washed hands.

Clearly, hand washing saves lives. In fact, the World Health Organization advocates that effective hand hygiene is the single most important practice to prevent and control HAIs. ^{Reference Hughes37,Reference Pittet, Allegranzi and Sax38} Because pathogens on the hands are identical to the pathogens on the stethoscope, it follows that if removing pathogens from the hands by washing is an effective infection control intervention, then preventing the same bugs from being spread by the stethoscope could have similar beneficial effects.

Recently, disposable barriers to prevent the spread of pathogens have been evaluated and recommended ^{Reference Smith30} because they allow high-fidelity acoustic performance. ^{Reference Kalra35,Reference Kalra, Shewale and Peacock36} Disposable barriers that can be applied via a touch-free dispsenser (thus preventing contamination with hand pathogens) have been documented to prevent the transmission of many HAI pathogens, including methicillin resistant Staphylococcus aureus, C. difficile, and vancomycin-resistant Enterococcus. ^{Reference Vasudevan, Shin and Chopyk39–Reference Peacock, Kalra and Vasudevan41} Such barriers are acoustically invisible to the sound transmission of the stethoscope. Although data demonstrating that compliance with stethoscope barriers would be superior to that of standard cleaning/disinfection is unavailable, some have even recommended that barriers be impregnated with antibiotics or copper to inhibit bacterial growth. ^{Reference Schmidt, Tuuri and Dharsee42} However, these latter solutions are probably inferior to the simple barrier becaudse they are likely to ultimately result in higher rates of bacterial resistance.

Ultimately, the “triple aim” ^{Reference Jenkins, Monash, Wu and Amin8} of patient care includes quality, experience, and costs. Fewer HAIs would clearly contribute to higher quality, improved patient experience, and markedly lower costs. Use of an aseptic membrane as a barrier between the patient and a contaminated stethoscope diaphragm would contribute to all aspects of this triple aim. The logic of resistance to adopting disposable aseptic stethoscope diaphragm barriers as a standard of care is unclear given our current healthcare environment.

We are currently amid a COVID-19 pandemic, with the potential to amplify deficiencies in infection control. Our HAI prevention strategies need to reflect contemporary interventions that are universally easy to use. Since 2008, >20 publications have asserted the need to elevate the priority of stethoscope hygiene. During this period, innovation has brought highly effective aseptic barriers to market that have the potential to block pathogen transmission, improve provider compliance, and save clinician’s time. We recommend that the CDC consider the research that has evolved in the area of stethoscope hygiene and effective solutions and contemporize its guidance to elevate stethoscope hygiene to that of hands. Stethoscope disinfection or the use of disposable barriers should be required between every patient encounter.