Alcohol-Based Sanitizer: For Hands... and Stethoscopes?

Researchers from the Division of Infectious Diseases at Emory University School of Medicine in Atlanta, say that the use of an alcohol-based hand sanitizer to clean hands as well as stethoscopes between patients could become an accepted bedside practice. They emphasize that although cleaning the stethoscope with an alcohol wipe was more effective than the alcohol based hand rub for decontamination of stethoscopes, they acknowledge that most clinicians consider this second step to be impractical and unlikely to be performed reliably. Their research was published in the September issue of the journal Infection Control and Hospital Epidemiology.

Mehta, et al. (2010) note that because they are one of the most commonly used medical devices, stethoscopes become contaminated with a variety of pathogenic bacteria. While not specifically addressed in guidelines, some studies call for cleaning stethoscopes with 70 percent isopropyl alcohol wipes to reduce bacterial contamination. However, this method of cleaning requires a supply of alcohol wipes and involves a procedure separate from hand hygiene. The researchers explain, Given suboptimal compliance rates with hand hygiene and the greater importance of hand carriage of microorganisms, compared with stethoscope carriage, advocacy of a separate procedure for stethoscope hygiene as routine practice appears impractical and misguided.

Mehta, et al. (2010) sought a practical alternative for stethoscope cleaning that would not divert attention from hand hygiene, and note, The advent of alcoholbased handrub as the preferred agent for hand hygiene and its ubiquitous presence in the hospital led us to study the effectiveness of combining hand and stethoscope disinfection in one maneuver that could be done routinely between patient examinations.

The researchers selected a group of medical students, residents and attending physicians on the wards of two Atlanta hospitals to participate in the study; they sampled onehalf of the diaphragm of each participants stethoscope by rubbing that half of the diaphragm with a pre-moistened culture swab and then asked participants to clean the diaphragm of their stethoscope with either alcoholbased handrub or an alcohol wipe. For those using alcohol handrub, the researchers asked the participant to clean their hands as they would do routinely with the available product, either a gel or a foam. While the alcohol product was still on their hands, the participants rubbed the diaphragm of their stethoscopes with their hands until the entire diaphragm surface was covered with the alcohol product. The participants then completed their hand hygiene. Once the surface of the stethoscope dried, the opposite hemicircle of the diaphragm was sampled for culture using a separate swab.

Mehta, et al. (2010) evaluated 84 stethoscopes: 60 were evaluated before and after cleaning with alcohol based handrub, and 24 were evaluated before and after cleaning with 70 percent isopropyl alcohol wipes. Before stethoscope cleaning, there was a median of 34.5 CFU isolated from the 84 stethoscopes; there was no statistical difference in the median pre-cleaning number of colonyforming units for the alcohol handrub group and that for the alcohol wipe group. After cleaning with the handrub, the median colony count was 4 CFU, with no growth in 12 (20 percent) of the 60 post-cleaning cultures. After cleaning with the alcohol wipe, the median colony count was 0 CFU, with 17 (71 percent) of 24 post-cleaning stethoscope cultures yielding no growth. The colony count reduction with the wipes was significantly greater than with the handrub.

According to the researchers, most of the cultured bacteria were normal skin flora, such as coagulasenegative staphylococci. For those stethoscopes that grew S. aureus, the median colony count was 5 CFU. Both cleaning methods effectively reduced S. aureus colonization; elimination of S. aureus was achieved on 3 of 4 stethoscopes in the alcohol wipe group and on 7 of 13 in the handrub group.  

Reference: Mehta AK, Halvosa JS, Gould CV and Steinberg JP. Efficacy of AlcoholBased Hand Rubs in the Disinfection of Stethoscopes. Infect Control Hosp Epidemiol 2010;31:870-872.