Bugs may be listening in on unclean stethoscopes
First report of VRE on scopes in hospital setting
Clinicians who do not routinely clean or disinfect their stethoscopes between patients may be giving multidrug-resistant bacteria a free ride from patient to patient, researchers are finding.
Research has been mounting that the ubiquitous stethoscope can become contaminated in routine use, and epidemiologists recently added another nosocomial pathogen to the list of cultured microorganisms: vancomycin-resistant enterococci (VRE).1 High rates of contamination of stethoscopes with bacteria, particularly coagulase-negative staphylococci and Staphylococcus aureus, have been documented in prior investigations.2-4
"To my knowledge, this is the first report that VRE has been recovered from stethoscopes," Christoph G. Lange, MD, PhD, tells Hospital Infection Control. Nosocomial VRE outbreaks have been well documented and often are attributed to the spread of the organisms by health care workers either after direct patient contact or via a contaminated environment. Contaminated electronic thermometers, but not stethoscopes, have been implicated as possible vectors of VRE transmission.5,6
Lange, a fellow in infectious diseases at University Hospitals of Cleveland, and colleagues found evidence that VRE may be picked up via stethoscopes from patients who have not yet been recognized to be VRE-infected or colonized. While those with VRE would be placed under isolation with dedicated stethoscopes, the well-described VRE iceberg beneath the tip of known cases would appear to add credence to his theory.
"We do not know which people are actually VRE positive or not before they go into isolation," he reasons. "We can spread organisms from patients who are not in isolation just by environmental tools. And I think the stethoscope is the most obvious environmental tool that everybody is carrying around, touching patients with, and then touching the next patient without cleaning [the scope]."
Lange undertook a one-day point prevalence study of stethoscope diaphragms, looking for VRE in two teaching hospitals in Cleveland with high rates of endemic VRE stool colonization. Both hospitals perform active surveillance for VRE stool colonization and isolate patients with known colonization. Stringent policies to reduce the transmission of VRE include use of gowns, gloves, and dedicated stethoscopes for isolated patients. One of 11 dedicated stethoscopes was contaminated, and two of 71 (3.4%) scopes used on general wards were positive for VRE. Health care workers also were questioned about whether they routinely cleaned their stethoscopes between patient contacts. Only one of 71 health care workers reported cleaning the membrane of the stethoscope after each patient contact with an alcohol- moistened swab. The practice is now being reinforced at the hospitals, Lange says.
"We tell people to clean their stethoscopes after each usage," he says. "Alcohol swabs are very effective."
Although the contamination of stethoscope diaphragms with VRE was low in the two hospitals studied, higher rates of contamination may occur in hospitals with less stringent VRE policies, he says. He theorizes that stethoscopes could provide a low level of transmission during VRE outbreaks, but the epidemiologic evidence awaits documentation in an outbreak investigation.
References
1. Lange CG, Morrissey AB, Donskey CJ. Point-prevalence of contamination of healthcare workers’ stethoscopes with vancomycin-resistant enterococci (VRE) at two teaching hospitals in Cleveland, Ohio. Abstract 385. Infectious Disease Society of America. New Orleans; Sept 7-10, 2000.
2. Brook I. The stethoscope as a potential source of transmission of bacteria. Infect Control Hosp Epidemiol 1997; 18:608.
3. Bernard L, Kereveur A, Durand D, et al. Bacterial contamination of hospital physicians’ stethoscopes. Infect Control Hosp Epidemiol 1999; 20:626-628.
4. Breathnach AS, Jenkins DR, Pedler SJ. Stethoscopes as possible vectors of infection by staphylococci. BMJ 1992; 305:1,573-1,574.
5. Livornese LL, Dias S, Samel C, et al. Hospital acquired infection with vancomycin-resistant Enterococcus faecium transmitted by electronic thermometers. Ann Intern Med 1992; 117:112-116.
6. Porwancher R, Sheth A, Remphrey S, et al. Epidemiological study of hospital-acquired infection with vancomycin-resistant Enterococcus faecium: Possible transmission by an electronic ear-probe thermometer. Infect Control Hosp Epidemiol 1997; 18:771-773.
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