Stethoscope Study Renews Concerns Over Environmental Pathogens

As health professionals, we treasure our stethoscope as an integral and personal device that enables us to access clinical information about our patients. In fact, many of us spend multiple hours selecting the one that is just right for ourselves and our patients' assessment needs.

However, a new study has shed light on a discomfiting reality regarding this treasured device — and may have big implications for the fight against hospital-acquired infections (HAIs).

Growing Worries About Surface Contamination

HAI remains a significant source of mortality and morbidity, causing an estimated 75,000 deaths nationwide in 2011. Since 2008, federal law has prohibited Medicare from reimbursing hospitals for the care of certain HAIs. The Affordable Care Act provided further penalties by incorporating infection prevention into its value-based purchasing program.
While our profession has done a great job reducing person-to-person transmission of pathogens (think of the WHO's hand washing campaign), we're generally less vigilant about cross-contamination via inanimate surfaces. That's because for a long-time, we believed that "environmental" contamination played a less significant role in disease transmission.
However, research has demonstrated that indirect contamination via environmental surfaces increases the risk of patient-to-patient transmission of HAI-related pathogens. What's more, environmental hygiene really makes a difference. At the Mayo Clinic, a new surface-cleaning protocol cut cases of nosocomial C. difficile by 30 percent in high-risk units.
Still, relatively few hospitals chose to make surface cleaning and environmental hygiene high priorities. Then, in February 2014, researchers at the World Health Organization Collaborating Centre on Patient Safety at the University of Geneva published a paper on stethoscopes as potential pathogen reservoirs.

The Uncomfortable Truth

The Geneva team's work demonstrated that in addition to all the clinical information about your patients your stethoscope enables you to access, it also affords you with a highly effective means of infecting them with MRSA, C. difficile, and other potentially deadly pathogens.
What made this study unique was its rather unusual frame of reference, methodology and data collection methods:
  • Reference point. The reference point for whether stethoscopes contributed to HAI was measured not only by absolute pathogen count but also by comparing pathogen counts between the device and the healthcare providers' hands.
  • Methodology. Researchers rigorously controlled the study to prevent contamination from confounding sources. Three participating physicians performed a total of 83 standardized patient exams using the same brand and model of stethoscope. Patients with active skin infections were excluded from the study. Bacteria counts were taken from the provider's dominant hand only.
  • Data collection. Pathogen count encompassed all parts of the stethoscope, including the flexible tubing and earpieces.
Researchers found that following an examination, aerobic colony count on the diaphragm of the stethoscope was substantially higher than for every location on the providers' hands except their fingertips. Comparable findings were described related to methicillin-resistant Staphylococcus aureus (MRSA) colony forming-unit counts.
These findings suggest that each time you use your stethoscope, it picks up microorganisms from the patient's body surfaces. The bell and diaphragm then serve as a culture medium to sustain and foster microbial growth and transmit those organisms to every subsequent patient that the device touches. It's even possible for us providers to contaminate ourselves.

What Can We Do?

Commentary on the Geneva study noted that infected stethoscopes have been conclusively linked to only one hospital-based infection outbreak. However, it's also possible that we don't fully appreciate the role surface contamination plays in such events. Given the stakes and the weight of the evidence, caution seems in order.
The following steps can help focus teams not only on stethoscope hygiene, but also on the larger issue of environmental contamination:
Make a case for cleaning. The results of the Geneva study suggest we should view our stethoscopes as extensions of our hands. After all, they pick up the same pathogens in roughly the same amounts. So shouldn't they deserve the same care and attention?
Kill those germs. The literature suggests three options for stethoscope cleaning:
  • Isopropyl alcohol wipes
  • Alcohol-based gel or foams
  • Ethanol-based cleansers.
Cleaning should move from less contaminated areas to more contaminated ones —beginning at the earpieces and ear tubes and downward toward the bell and diaphragm.
Make it easy. Leaders can encourage regular cleaning by installing baskets containing a generous supply of alcohol prep pads outside patient rooms and unit entrances.
Hold one another accountable. As with any safety initiative, success relies on systemic change. Hospital leaders need to nurture a culture in which everyone takes responsibility — and holds colleagues accountable — for the safety of patients.
Be an advocate. Educate those around you about the importance of environmental hygiene. Simple practices like wiping down frequently touched surfaces, thorough post-discharge cleaning and training for housekeeping staff can have a huge impact.

[Image credit: "The Stethoscope, Peru," by Alex Proimos, licensed under CC BY 2.0]