Stethoscopes have more bacterial contamination than doctors' hands

28 February 2014

University of Geneva Hospitals has found the level of bacterial contamination on the diaphragm of stethoscopes is greater than on  doctors’ hands, following a single physical examination. The study appears in the March issue of Mayo Clinic Proceedings.

In this study, 71 patients were examined by one of three doctors using sterile gloves and a sterile stethoscope. After they completed the examination, two parts of the stethoscope (the tube and diaphragm) and four regions of the doctors' hands (back, fingertips, and thenar and hypothenar eminences) were measured for the total number of bacteria present.

The researchers found the stethoscope’s diaphragm was more contaminated than all regions of the doctor's hand except the fingertips. Further, the tube of the stethoscope was more heavily contaminated than the back of the physician’s hand. Similar results were observed when contamination was due to MRSA after examining MRSA-colonized patients.

“By considering that stethoscopes are used repeatedly over the course of a day, come directly into contact with patients’ skin, and may harbour several thousands of bacteria (including MRSA) collected during a previous physical examination, we consider them as potentially significant vectors of transmission,” commented lead investigator Didier Pittet, MD, MS, Director of the Infection Control Program and WHO Collaborating Centre on Patient Safety, University of Geneva Hospitals. “From infection control and patient safety perspectives, the stethoscope should be regarded as an extension of the physician’s hands and be disinfected after every patient contact.”

This work is the first to compare directly the level of contamination of doctors’ hands and stethoscopes. Stethoscope contamination is not trivial and is comparable to the contamination of healthcare workers’ fingertips, the hand region most implicated in microbial cross-transmission. So doctors must be aware of the need to disinfect their stethoscope after each use, say the researchers.



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