UC San Diego

Objective

To evaluate whether Clostridioides (formerly Clostridium) difficile-contaminated stethoscope diaphragms remained aseptic by the placement of an aseptic diaphragm barrier.

Methods

On November 1, 2019, fresh cultures of C difficile were diluted to 10⁷ colony-forming units (CFU)/mL and used to inoculate 16 stethoscope diaphragms; 8 had an aseptic diaphragm barrier applied and 8 served as nonbarrier controls. Contaminated stethoscopes were anaerobically incubated, 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. Plates were incubated for 48 hours and on November 9, 2019, the resulting colonies were manually counted. Statistical analyses (RStudio, version 1.0.153) used analysis of variance with post hoc Tukey honestly significant difference.

Results

Overall, mean colony count was 33 CFU on stethoscopes without barriers vs zero on those with barriers (P≤.05). Growth was greatest at 48 hours, with colony counts as high as 160 CFU. The presence of the barrier resulted in no growth in 100% of stethoscope diaphragms for up to 1 week.

Conclusion

We found that stethoscope diaphragm barriers provide an aseptic patient contact point, thus reducing the potential for transmission of C difficile during the physical examination. In critical care environments, in which many hospitals use acoustically inferior disposable stethoscopes, the option of a disposable aseptic stethoscope barrier may allow high-quality auscultation while reducing the potential for pathogen transmission.