A microbiological survey of stethoscopes in Australian teaching hospitals: potential for nosocomial infection?

Our study aimed to investigate how frequently ward-based stethoscopes in high-risk areas are colonised with potential pathogens, and to compare that with the colonisation rates for personal stethoscopes. We performed a survey of microbiological flora on stethoscopes, with single-blinded laboratory analysis, based in immunologically high-risk areas in three tertiary teaching hospitals in Newcastle, Australia. Onn hundred fifty-five doctors and medical students working in pre-selected areas of each hospital at the time of the survey were selected for inclusion, and participants' stethoscopes and the ward-based stethoscopes used in the same areas were swabbed and cultured. Participants also completed a questionnaire regarding their stethoscope use and cleaning. The stethoscopes were compared on the basis of total colony count and pathogenic organisms, cross-matched against personal characteristics (e.g. doctor or student) and stethoscope use and cleaning habits. We found that there were significantly more organisms isolated from personal stethoscopes (mean colony count (CC) = 50·3, 95% CI 41·7-58·9) than ward-based (mean CC = 29·3, 95% CI 17·9-40.7) (p<0·01). There was no significant relationship between the frequency of stethoscope cleaning and degree of stethoscope contamination, nor was the amount of patients seen per day a significant factor. This study suggests that even regular cleaning of stethoscopes may be insufficient to prevent colonisation with potentially pathogenic organisms, and that patients at high-risk for nosocomial infection should only be examined with stethoscopes that are restricted to single-patient use.