Bacteria Hitch a Ride on Stethoscopes

Standardized cleaning method decreases contamination better than practitioner-preferred methods.

Stethoscopes are a symbol of healthcare. But a new study in the journal Infection Control & Hospital Epidemiology finds they also carry bacteria that can cause healthcare-associated infections.

The effectiveness of cleaning methods was also reviewed, and researchers found a standardized approach to be more effective at removing bacteria than healthcare practitioners' various approaches to cleaning.

 "This study underscores the importance of adhering to rigorous infection control procedures, including fully adhering to CDC-recommended decontamination procedures between patients, or using single-patient-use stethoscopes kept in each patient's room," Ronald Collman, MD, a professor of medicine, pulmonary, allergy and critical care at the University of Pennsylvania Perelman School of Medicine and senior author of the study, says in a news release.

HAIs compromise patient safety and increase healthcare costs, according to the Agency for Healthcare Research and Quality. The organization reports one million HAIs occur in the U.S. healthcare system annually, "leading to the loss of tens of thousands of lives and adding billions of dollars to health care costs."

Researchers analyzed bacteria present on various types of stethoscopes used in an intensive care unit including:

• 20 traditional reusable stethoscopes used by physicians, nurses and respiratory therapists
• 20 single-patient-use disposable stethoscopes used in patient rooms
• 10 unused single-use disposable stethoscopes as a control

All of the 40 stethoscopes in use were significantly contaminated with multiple types of bacteria, including those that cause common HAIs. Staphylococcus, the bacteria responsible for Staph infections, was found on all stethoscopes, and more than half were contaminated with S. aureus. Other bacteria that can cause HAIs were also widely present in small quantities.

The Most Effective Cleaning Method
 

To compare the effect of cleaning on contamination, researchers sampled 10 additional practitioner stethoscopes before and after 60 seconds of cleaning with a hydrogen peroxide wipe, and 20 more practitioner stethoscopes before and after cleaning by the practitioner according to their usual methods.

Practitioner methods included using alcohol swabs, hydrogen peroxide wipes, or bleach wipes for various durations. While all cleaning methods reduced the number of bacteria, they failed to consistently bring contamination to the level of clean, new stethoscopes. The standardized cleaning method reduced bacteria to the "clean" level on half of the stethoscopes. The practitioner-preferred methods only achieved the clean level on 10% of the stethoscopes.

The study was not able to differentiate live bacteria from dead bacteria thus additional research is required to determine if stethoscopes are responsible for transmitting infections.

Collman says future research should identify improved cleaning methods and study bacteria present on multi-patient medical devices and in the healthcare environment.