814 - A Quasi-Experimental Study on Stethoscopes Contamination with Multidrug-Resistant Bacteria: Its Role as a Vehicle of Transmission

Background: Stethoscopes have been suggested to be a possible vector of contact transmission. However, only a few studies have focused on the prevalence of contamination by multidrug-resistant (MDR) bacteria and the effectiveness of disinfection training to reduce. The aim of this study is to investigate the burden of stethoscope contamination with nosocomial pathogens and multidrug-resistant (MDR) bacteria and to analyze habit changes in the disinfection of stethoscopes before and after education and training.

Methods: We performed a prospective pre and post quasi-experimental study. All participants were surveyed on their disinfection behavior and stethoscopes were cultured by pressing the diaphragm directly onto a blood agar plate before and after education on disinfection. Pulsed-field gel electrophoresis (PFGE) was performed to determine the relatedness of MDR bacteria.Fig. 1. Study flow for pre and post quasi-experimental study. Abbreviations. PFGE, Pulsed-field gel electrophoresis


Results: Most of the stethoscopes were contaminated with microorganisms, 97.9% before and 91.5% even after intervention. The contamination rate of nosocomial pathogens before and after education was 20.8 % and 19.2%, respectively. Stethoscope disinfection habits were improved (55.1% vs 31%; p< 0.001), and the overall bacterial loads of contamination were reduced (median CFUs 15 vs 10; p=0.019) after the intervention. However, the contamination rate by nosocomial pathogens and MDR bacteria did not decrease significantly. A carbapenemase-producing Klebsiella pneumoniae from the stethoscope was closely related to isolates from the patients admitted at the same ward where the stethoscope was used.Fig. 2. Changes in colony forming units of bacteria isolated from stethoscopes between pre and post intervention period. Abbreviations. CFUs, colony forming units; ns, non-specific
Fig. 3. Result of PFGE and dendrogram of carbapenemase-producing K. pneumoniae from the stethoscope and the patients where the stethoscope was used. Percentage similarities are shown above the dendrogram. Note. ST_7W, K. pneumoniae from the stethoscope; SM 01 to 03, K. pneumoniae isolates form the patients; PFGE, Pulsed-field gel electrophoresis
Table 1. Contamination rates caused by nosocomial pathogens and proportion of MDR bacteria


Conclusion: Stethoscopes were contaminated with various nosocomial pathogens including MDR bacteria and were very likely to be a vehicle of MDR bacteria. Healthcare workers feel the need for education and think it helps, but continuous, consistent education and training should be done in multifaceted approach to reduce the nosocomial transmission via stethoscopes.