This prospective observational study examined stethoscopes as a potential source of nosocomial infections for veterinary patients. Bacterial cultures were taken from 10 participants’ stethoscopes q1wk for 3 weeks. Then, cultures were obtained from the same participants’ stethoscopes immediately before and after cleaning with 70% isopropyl alcohol q1wk for 3 weeks. Cleaning the stethoscope diaphragm with alcohol effectively eliminated bacteria after cleaning but did not decrease the frequency of contamination found before cleaning. Cultures were positive for 67% of samples during the first part of the study, and for 60% of samples obtained before daily cleaning during the second part of the study. Organisms cultured included normal skin flora, opportunistic infectious agents, and potential pathogens. Most isolates were normal skin inhabitants of dogs and cats, suggesting that organisms can be transmitted from patient fur to stethoscopes during auscultation.

Bacillus was the only genus repeatedly recovered from the same stethoscope for >2 consecutive weeks; it did not persist on stethoscopes after cleaning with isopropyl alcohol. Also isolated were methicillin-resistant Staphylococcus intermedius, of which infections are reportedly increasing in dogs. Other potential antimicrobial-resistant species, including Escherichia coli and Enterococcus faecium, were isolated. Although daily cleanings did not reduce prevalence of contamination in precleaning culture samples, cleaning stethoscopes after use on patients infected with pathogenic bacteria and before use on immunocompromised patients may decrease the risk for transmission of nosocomial infections.

Commentary
I think my stethoscope is about 20 years old and has been transferred from the pocket of a dirty clinic coat to a clean one without a thought of ever cleaning it—until now! How many of us have done the same thing? Actually, the problem probably goes deeper than this; we just do not know how extensive nosocomial infection is in veterinary medicine because we have never really looked for it systematically. We are, of course, aware of the problem in human medicine. It has been conservatively estimated that each year in the United States 1.7–2 million patients develop hospital-acquired infections, nearly 100,000 of which result in death. We know the importance of washing our hands—and, if necessary, wearing gloves—but what else should we be doing? The British National Health Service banned the wearing of neckties, jewelry, and watches by doctors in 2006 because of their potential role as fomites. Scrubs should not be worn outside the hospital, yet I regularly see staff at a nearby human hospital go to work or a nearby sandwich shop in their scrubs. Last week I bumped into one of our graduates at a local plant shop wearing her surgical scrubs. Is this important? I honestly do not know, but it certainly merits consideration.—Colin F. Burrows, BVetMed, PhD, Hon FRCVS, DACVIM

Source
Bacterial contamination of stethoscope chest pieces and the effect of daily cleaning. Fujita H, Hansen B, Hanel R. JVIM 27:354-358, 2013.

This capsule is part of the WSAVA Global Edition of Clinician's Brief.