To the Editor: It has been well established that improved compliance in hand washing significantly reduces hospital-acquired infections and cross transmission of methicillin-resistant Staphylococcus aureus.1 Although there have been no reports of infections resulting from cross-contamination via stethoscopes, studies have demonstrated that 80%–100% of these appliances are colonised by bacteria.2-5 However, most of the organisms isolated are considered non-pathogenic. The most common potentially pathogenic organism isolated from stethoscopes is S. aureus, with a prevalence of 4.2%–27.5%.2-5 Cleaning with either 70% isopropyl alcohol or benzalkonium chloride wipes can reduce the bacterial count on stethoscopes by 94%–100%.3,5

We undertook a study to assess the prevalence of S. aureus carriage on stethoscopes and hands of staff of the Canberra Hospital, and to measure the effectiveness of cleaning and hand washing in reducing colonisation.

A convenience sample of healthcare workers from various areas of the hospital was obtained over a period of 6 months. The diaphragm of each participant's stethoscope was directly impressed on to mannitol salt agar, before and after being cleaned with a 70% isopropyl alcohol wipe. The dominant hand of each participant was also tested before and after washing with triclosan (1%) antimicrobial handwash and water. S. aureus was identified by standard laboratory methods.

There were 134 participants: 69 doctors, 50 nurses, 10 medical and nursing students and five physiotherapists. Most doctors and physiotherapists used their own stethoscopes, whereas most nurses and students used ward stethoscopes.

S. aureus was isolated from five stethoscopes before cleaning (4%), but from none after cleaning. The organism was also isolated from the hands of 11 people before hand washing (8%) and of one after hand washing (0.7%). Two people had S. aureus isolated from both sites. There was no statistically significant difference between the prevalence of S. aureus on hands and stethoscopes (P = 0.15, McNemar's test).

Hand washing is the best recognised means of preventing cross-contamination in hospitals. However, the simple intervention of cleaning stethoscopes with an alcohol wipe was highly effective, and we believe that this practice should be more widely promoted.