Predictors of Stethoscope Contamination are Explored

The relative contribution of stethoscopes in microbial cross-transmission in comparison to the examiners hands has not been well described. Researchers from Geneva University Hospital in Switzerland endeavored to compare stethoscope versus hand contamination following a physical exam and identify predictors of stethoscope contamination.

Following a standardized physical exam using sterile gloves and a sterile stethoscope, bacterial contamination of the following regions were assessed using contact plates: stethoscope diaphragm, stethoscope tube, fingertips, thenar region, hypothenar region and back of physicians dominant hand. Total aerobic colony count (ACC) were determined on digital photographs using a counting tool.

A total of 56 patients (62 percent males; median age, 66) were recruited. Median (IQR) contamination (in ACC/25cm2) of examiners dominant hand and stethoscope were as follows: fingertips: 835 (IQR, 332-1638), stethoscope diaphragm: 173 (IQR, 36-535), stethoscope tube: 116 (IQR, 34-321), hypothenar region: 16 (IQR, 8-59), thenar region: 15 (IQR, 4-71) and dorsum of hand: 3 (IQR, 1-16). The stethoscope diaphragm and tube were significantly more contaminated than the thenar or hypothenar regions (Wilcoxon ranksum test: p<0.001). There was no difference between the level of tube and diaphragm contamination. Diaphragm contamination was strongly associated with the patients level of skin contamination (p<0.001), the patients BMI (p=0.01) and the degree of humidity of the patients skin (p<0.001).

Schneider, et al. say their results suggest that stethoscopes diaphragm and tube are significantly contaminated following a physical exam and identify predictors of heavy contamination. These findings suggest the need to decontaminate stethoscopes following each use. Their research was presented at the International Conference on Prevention & Infection Control (ICPIC) held in Geneva, Switzerland June 29-July 2, 2011.

Reference: A Schneider, C Tschopp, Y Longtin, G Renzi, A Gayet-Ageron, J Schrenzel, D Pittet. Predictors of stethoscope contamination following a standardized physical exam. Presentation at International Conference on Prevention & Infection Control (ICPIC). BMC Proceedings 2011, 5(Suppl 6):P304