UC San Diego

Abstract Background Healthcare-associated infections (HAIs), such as C. difficile colitis, pose a significant health risk. C. difficile is a spore-forming gram-positive anaerobic bacillus capable of surviving on various surfaces. While a strong emphasis has been placed on hand-washing and environmental cleaning with bleach products to limit the spread of C. difficile, stethoscope contamination has been poorly addressed. Studies have demonstrated that the stethoscope diaphragm harbors similar levels and type of contamination to one’s hands. While a non-alcohol-based solution is recommended for stethoscope hygiene in settings at risk for C. difficile, the use of an aseptic stethoscope diaphragm barrier has not been evaluated. Our purpose is to evaluate whether C. difficile-contaminated stethoscope diaphragms remain aseptic by the placement of an aseptic diaphragm barrier. Methods Fresh cultures of C. difficile were diluted to 107 CFU/mL. After inoculating 16 stethoscope diaphragms with C. difficile, 8 had an aseptic diaphragm barrier applied, and 8 served as non-barrier controls. Contaminated stethoscopes were placed in an anaerobic incubator, then swabbed at 15 and 30 minutes, 2 and 4 hours, and 1, 2, 3, and 7 days after inoculation, and subsequently plated onto blood, chocolate, and cycloserine-cefoxitin fructose agar. These plates were incubated for 48 hours, and resulting colonies were manually counted. Statistical analysis was performed (RStudio version 1.0.153) by ANOVA (Analysis of Variance) with post-hoc Tukey HSD (Honestly Significant Difference). Results Overall, mean colony count was 33 CFU on the 8 stethoscope diaphragms without barriers, vs zero on those with barriers (p≤ 0.05). Growth rates were greatest at 48 hours, with colony counts as high as 160. While stethoscope diaphragms without barriers had increasing rates of C. difficile culture growth, the presence of the barrier resulted in no growth in 100% of stethoscope diaphragms for up to 1 week after contamination (Figure 1). C. difficile colony counts from stethoscope diaphragms at time-points up to 1 week. Conclusion Aseptic barriers allow C. difficile-contaminated stethoscope diaphragms to remain without bacterial growth for up to a week. Disposable aseptic diaphragm barriers may be effective in preventing the spread of C. difficile. Disclosures William F. Peacock, MD, AseptiScope Inc. (Board Member)