DNA analysis finds that stethoscopes used in the ICU are teeming with bacteria

A study conducted by researchers at the University of Pennsylvania has found that stethoscopes carried by healthcare practitioners in an intensive care (ICU) setting are loaded with a wide range of bacteria.

Stethoscope on blue background - picture by catshila

catshila | Shutterstock

The study also compared cleaning methods and found that the standardized approach is better at eliminating bacteria than various other methods practitioners chose to use.

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, Senior Author

For the study, Collman and team used DNA sequencing to investigate bacteria present on 40 stethoscopes found in an intensive care unit (ICU).

Twenty instruments were reusable stethoscopes, 20 were single-use disposable instruments and 10 were single-use, disposable instruments that had not been used.

As reported in the journal Infection Control & Hospital Epidemiology, all 40 of the stethoscopes that were in use were contaminated with an abundance of various bacterial communities, including those related to common infections, although it was not established whether the stethoscopes ever made patients unwell.

Staphylococcus was found on all instruments, with more than half confirmed as being contaminated with S. aureus.

Other infection-causing bacteria identified were Pseudomonas and Acinetobacter, although these were only present in small quantities.

To compare cleaning methods, the team assessed 10 more stethoscopes before and after cleaning using the standardized method - cleaning with a hydrogen peroxide wipe for 60 seconds. They also assessed 20 more instruments before and after cleaning by practitioners who used their preferred method, including wiping with alcohol swabs, bleach wipes or hydrogen peroxide wipes for different amounts of time.

The study showed that all types of cleaning reduced the number of bacteria, but failed to consistently make the stethoscopes as contamination-free as new, clean stethoscopes.

The standardized method reduced bacteria to the clean level on half of the instruments, while only 10% of the stethoscopes cleaned using an individual’s preferred method met this level of cleanliness.

Although the molecular sequencing allowed all types of bacteria to be detected, it could not determine whether bacteria were dead or alive, meaning it is unclear whether the instruments are responsible for spreading disease.

Further research is now needed to establish whether stethoscopes are accountable for the spread of infection.

Collman says those studies should also use similar molecular approaches, study bacteria found on medical devices and in the healthcare setting and also focus on antibiotic resistance.


DNA study shows stethoscopes loaded with bacteria, including staphylococcus.

Sally Robertson

Written by

Sally Robertson

Sally first developed an interest in medical communications when she took on the role of Journal Development Editor for BioMed Central (BMC), after having graduated with a degree in biomedical science from Greenwich University.


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