Microbiological evaluation of ultraviolet C light-emitting diodes for disinfection of medical instruments

Background: Despite the many guidelines for reprocessing of medical instruments, challenges persist such as microbial resistance to biocides, corrosive effects on materials, and timeconsuming reprocessing procedures. Ultraviolet (UV) C light-emitting diode (LED) chambers might provide a solution but the integration in healthcare is still in its infancy. Here, we evaluated the efficacy of a novel ZAPARAYTM UVC LED chamber as a time and energy-efficient alternative for reprocessing of medical instruments for which current disinfection protocols exhibit limitations. Methods: We verified the disinfection efficacy of the UVC LED chamber on a Petri dish and contaminated several medical devices with Staphylococcus aureus ATCC 25923. The bacterial reduction was assessed after 5 min of UVC LED exposure. Additionally, we investigated the impact of rinsing before UVC exposure. Results: We demonstrated a bacterial reduction of 9 log10 10 on a Petri dish. Non-rinsed dental tools exhibited varied reduction levels ranging from a 3.23 log10 10 to a 6.25 log10 10 reduction. Rinsing alone yielded an average reduction of 2.7 log10 10 and additional UVC exposure further reduced the bacterial load by an average of 3.65 log10. 10 . We showed an average 4.90 log10 10 reduction on thermistors, 2 log10 10 or less on orthodontic pliers, and no reduction on handpieces. Conclusions: This study demonstrates that UVC LED chambers may be used as a standardized substitute for specific (manual) disinfection procedures of certain medical devices, offering a time-efficient and more sustainable alternative. However, its use should be preceded by efficacy testing for each specific type of instrument.