The stethoscope and healthcare-associated infection: a snake in the grass or innocent bystander?

There is a concern that stethoscopes may transmit infectious agents which could result in healthcare-associated infection (HCAI). The aim of this review was to evaluate the available literature as to the role of the stethoscope in the development of HCAI. A literature search was conducted across several databases for relevant studies and reports. Stethoscopes were consistently shown to harbour bacteria. The mean rate of stethoscope contamination across 28 studies was 85% (range: 47-100%). The majority of bacteria isolated were deemed to be non-pathogenic. The most frequently isolated organisms were coagulase-negative staphylococci. The mean level of contamination was in excess of the French Normalization standard for cleanliness (which equates to <20 colony-forming units per membrane) in all six studies in which contamination levels were quantified. Potentially pathogenic organisms cultured from stethoscopes included: Staphylococcus aureus, Pseudomonas aeruginosa, vancomycin-resistant enterococci, and Clostridium difficile. There was evidence that bacteria can transfer from the skin of the patient to the stethoscope and from the stethoscope to the skin. However, studies were not designed to detect a correlation between stethoscope contamination and subsequent HCAI. Surveys assessing cleaning practices revealed a suboptimal commitment to stethoscope disinfection among doctors and medical students. The optimum method for stethoscope cleaning has not been defined, although alcohol-based disinfectants are effective in reducing bacterial contamination. In conclusion, a link between contaminated stethoscopes and HCAI has not yet been confirmed, but transfer of bacteria between skin and stethoscope has been shown. The available information would suggest that stethoscopes should be decontaminated between patients.