LOS ANGELES — One in five stethoscopes used by hospital physicians was contaminated with Staphylococcus aureus, including one that harbored methicillin-resistant S. aureus, according to a study presented at the annual meeting of the Society for Healthcare Epidemiology of America.
Cultures taken from stethoscopes also grew Enterococcus species and Enterobacter aerogenes.
Skin flora, including diphtheroids, α-hemolytic streptococci, and coagulase-negative staphylococci, were the most common microorganisms found on 84 randomly tested stethoscopes from house staff, medical students, and attending physicians at Grady Memorial and Emory Crawford Long Hospitals, Atlanta.
The median number of colony-forming units isolated from stethoscopes was 35, with a range of 0–247. The stethoscopes were tested by investigators from Emory University, Atlanta.
“We don't mean to claim stethoscopes are the scourge of civilization, or that they are anywhere near as important in transmitting disease as hand carriage,” James P. Steinberg, M.D., an associate chief of medicine and hospital epidemiologist, said in an interview. “But they can be colonized.”
In a related survey of stethoscope users, 10 said they cleaned their stethoscopes between patients. Another 35 cleaned them daily, 30 did so weekly, 7 cleaned them monthly, and 2 never cleaned them.
When 24 of the stethoscopes were wiped with an alcohol pad as part of the study, the median number of colony-forming units plummeted to 0, with a range of 0–59.
However, because there is no “smoking gun” linking contaminated stethoscopes with disease, Dr. Steinberg said it seems excessive to recommend that all health professionals clean their stethoscopes with alcohol wipes before and after every patient contact.
Use of alcohol hand rubs, on the other hand, is already routinely recommended before and after patient contacts, so Dr. Steinberg and associates set out to determine whether a quick rub of the stethoscope might suffice.
Indeed it did.
Among 60 stethoscopes with a median of 33.5 colony-forming units at baseline (range, 1–247), the median colony-forming units dropped to 4 (range, 0–60) after the stethoscopes were swiped with an alcohol hand rub.
“Combining stethoscope 'rubbing' with routine hand hygiene provides a practical and effective method of stethoscope disinfection that could be incorporated into routine bedside practice,” Dr. Steinberg's poster presentation concluded.