DNA tests show stethoscopes loaded with bacteria

DNA testing

We’re used to seeing doctors in white coats with stethoscopes slung round their shoulders. In this way, the medical device is always on hand, ready to help the doctor listen to a patient’s heart or lungs.

However, research reported in the journal Infection Control & Hospital Epidemiology shows that stethoscopes are loaded with diverse bacteria, including some that could be a real risk to health. The study also reviewed the effectiveness of cleaning the device, and found that commonly employed methods leave bacteria behind.

“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”, said Dr Ronald Collman, senior author of the study and a Professor of Medicine, Pulmonary, Allergy and Critical Care at the University of Pennsylvania Perelman School of Medicine.

Contamination research

Researchers used DNA sequencing to develop a complete picture of bacteria on stethoscopes used in an intensive care unit (ICU). This included 20 traditional reusable stethoscopes used by physicians, nurses and respiratory therapists; 20 single-patient-use disposable stethoscopes used in patient rooms; and 10 unused single-use disposable stethoscopes as a control.

The analysis showed all 40 stethoscopes used in the ICU were significantly contaminated with a rich and diverse community of bacteria, including those related to common healthcare-associated infections. Staphylococcus bacteria were found in abundance on all stethoscopes, with more than half of them confirmed as Staphylococcus aureus. Other bacteria that can cause infections, such as Pseudomonas and Acinetobacter, were also widely present on stethoscopes, although in small quantities.

To assess the impact of cleaning on contamination, researchers tested hydrogen peroxide wipes, alcohol swabs and bleach wipes all used for different durations. All cleaning methods reduced the amount of bacteria but failed to consistently bring contamination down to the level of clean, new stethoscopes. A standardized cleaning method was shown to reduce bacteria on half of the stethoscopes to the clean level, while only 10% reached that level when cleaned by the practitioner-preferred method, leaving stethoscopes as a potential vehicle for transmission of infection.

Additional research is now required to determine if the stethoscopes are responsible for transmitting infections. While DNA sequencing allowed researchers to identify all the types and quantity of bacteria, not just specific pathogens they set out to study, the DNA test could not distinguish live from dead bacteria. It is therefore not clear if the stethoscopes are responsible for the spread of disease-causing agents. For information on AlphaBiolabs’ complete range of DNA testing services, call us now on 727-325-2902 or email us at info@alphabiolabsusa.com.