The contamination level of a clinician’s stethoscope after a single physical examination may be substantial and may even exceed the level of contamination on the practitioner’s dominant hand, suggest the results of a Swiss study.

“By considering that stethoscopes are used repeatedly over the course of a day, come directly into contact with patients’ skin, and may harbor several thousands of bacteria, including [methicillin-resistant Staphylococcus aureus] collected during a previous physical examination, we consider them as potentially significant vectors of transmission,” explained Didier Pittet, MD, MS, in a statement accompanying the release of his group’s study.

The study was conducted over a five-month period in 2009 in a Swiss university teaching hospital. One of three physicians examined a total of 71 patients while wearing sterile gloves and using a sterile stethoscope. After each examination, the stethoscope and the physician’s hands were measured for presence of bacteria.

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The diaphragm of the stethoscope proved to be more contaminated than all four measured regions of the provider’s hand (back, fingertips, and thenar and hypothenar eminences), and the tube of the stethoscope was more contaminated than the back of the provider’s hand.

“[F]ailing to disinfect stethoscopes could constitute a serious patient safety issue akin to omitting hand hygiene,” noted Pittet and coauthors. “Hence, from infection control and patient safety perspectives, the stethoscope should be regarded as an extension of the [clinician’s] hands and be disinfected after every patient contact.”


  1. Longtin Y et al. Mayo Clin Proc. 2014; doi:10.1016/j.mayocp.2013.11.016.