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A study has recently been conducted with the findings released just yesterday, (24th April 2019) on the potential for the Stethoscope as a carrier of Multi-Drug Resistant Bacterial Pathogens.

Readers of this website will have seen that I have discussed elsewhere on the dangers inherent in poor stethoscope hygiene and the dangers such behaviour represents, however the findings of the study conducted by investigators at the College of Medicine at the Catholic University of Korea in Seoul, are no less alarming.

The study was actually prospective observational in nature. The aim of the research was to determine whether stethoscopes could in practice carry nosocomial multidrug-resistant bacteria.

A total of 89 doctors and nurses were involved with the study, and a total of 86 stethoscopes made the final sample.


doctor and bacteria

The study involved having the diaphragm of each stethoscope pressed against blood agar plates 6-10 seconds, (this was carried out by the investigators in controlled circumstances).

Bacterial loads were calculated by total colony-forming units (CFU). Potential nosocomial pathogens existing in the samples were also identified.

The results of the study:
  • In total 85 of the 86 stethoscopes (98.8%) were contaminated
  • The mean CFU of each contamination was 27.91 ± 32.46.
  • 20 of the 85 contaminated stethoscopes (23.5%) had at least 1 potential pathogen
  • Staphylococcus aureus was detected in 13 of the 20 contaminations.

Other detected isolates included:

No isolates of the following were detected:

Stethoscope Hygiene Practices

doctor stethoscope

Cleaning methods were collated via questionnaires completed by the health workers. (This revealed further information on the demographics of those taking part; 58 of the 89 participants (65.2%) were female and 44 (49.4%) were doctors.)

The results of the stethoscope hygiene analysis:
  • Only 19 of the 89 participants (21.3%) reported cleaning their stethoscopes at least 1 time a day.
  • Physicians were less likely to clean their stethoscopes (gender adjusted; p= 0.001; odds ratio [OR], 12.750; 95% confidence interval [CI], 2.730-59.546)
  • Interestingly, physicians would use their own stethoscopes rather than an instrument designated for examining isolated patients infected with MDR pathogens (gender adjusted; p<0.001; OR, 8.762; CI, 2.911-26.373).

Evaluating the study

stethoscope and doctor

The findings of were presented on the 24th April 2019 during the poster presentation of the Society for Healthcare Epidemiology of America Spring Conference.

While the results have the potential to cause concern, the investigators were quick to state that:

 “there were no significant risk factors associated with the contamination rate and bacterial load when multivariate regression analysis performed using variables such as gender, job, age group, department, cleaning method, and frequency of stethoscope cleaning.”

Furthermore, the fact that a large proportion of the stethoscopes ended up being contaminated, yet only 23.5% were contaminated by nosocomial pathogens is a good reason to remain pragmatic over the results.

The stethoscope hygiene data does show that this area continues to be problematic however.

The study clearly shows that physicians fail to clean their personal stethoscopes to an adequate degree, and they also fail to use designated stethoscopes in an effort to reduce the risk of infection.

It also clear that despite this lack of hygiene, no significant risk factors were associated with contaminated stethoscopes.

About Hannah Drake

Hannah Drake, RN, CSP is a registered nurse and owner and founder of Nurse Focus. Her nursing career spans almost two decades, and in that time she has developed her skill base across a variety of settings, including med surg nursing, clinical informatics system administration and implementation, and healthcare community management. Contact Hannah.

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