Time Effectiveness of Ultraviolet C Light (UVC) Emitted by Light Emitting Diodes (LEDs) in Reducing Stethoscope Contamination

Abstract

Today it is well demonstrated that stethoscopes can be as contaminated as hands, which are a recognized source of Health-Care Associated Infections (HCAIs). Ultraviolet C (UVC) light has proven disinfection capacity and the innovative UVC technology of Light Emitting Diode (LED) shows several potential benefits. To verify whether the use of UVC LEDs is effective and reliable in stethoscope membrane disinfection after prolonged use, a pre-post intervention study was conducted. A total of 1668 five-minute cycles were performed on two UVC LEDs to simulate their use; thereafter, their disinfection capacity was tested on stethoscope membranes used on a previously auscultated volunteer. Then, a further 1249 cycles were run and finally the LEDs were tested to assess performance in reducing experimental contamination by Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli on the stethoscope membrane. Baseline volunteer contamination identified 104 Colony Forming Units (CFUs) while treated Petri dishes had 12 and 15 CFUs (p < 0.001). Statistically significant differences (p < 0.001) were also found relating to the reduction of specific bacteria: in particular, after treatment no CFU were observed for S. aureus and E. coli. UVC LEDs demonstrated the capacity to maintain high levels of disinfection after more than 240 h of use and they were effective against common microorganisms that are causative agents of HCAIs.

Methods of Disinfecting Stethoscopes: Systematic Review

“…The membrane was disinfected with alcohol, before and after each use of the stethoscope. A total of 104 CFU were found at baseline, while 12 CFU and 15 CFU were found after two independent tests (p < 0.001) [23].…”

“…Moreover, 70 studies were commentaries or full articles not in line with the aim of the study and we have excluded them after a careful examination of the abstracts and of the full texts. Finally, we detected 17 publications [3,5,6,9,11,13,[17][18][19][20][21][22][23][24][25][26][27]. Among these, we included four letters to the editor (Figure 1).…”

“…These unexpected results are perhaps due to the presence of the embossing that may protect bacteria from cleaning agents. However, the authors suggest the need to conduct further and larger studies to confirm these findings [23]. The cost/benefit ratio of the various disinfection methods is also worth mentioning.…”

“…It has also been shown that the UVC-LED was still effective to reduce microbial contamination after prolonged use (more than 240 working hours). Since it can be attached to the pocket of the medical coat, the positive aspect of this device is that it can make the disinfection of the stethoscope an automatism repeated after each use [23].…”

Total Internal Reflection of Deep-Ultraviolet Light in a Water Waveguide and Its Application to Water Disinfection Technologies

“…Since the development of DUV-LED devices holds great promise, it is useful to consider not only their replacement of mercury vapor lamps but also their use in applications characteristic of LEDs. Various unique applications that typically use LEDs have been proposed for these devices [36][37][38][39][40][41], such as the sterilization of small medical devices [37,38] and germicidal DUV-LED lamps with multiwavelength radiations [39][40][41], as higher efficacies of inactivation of pathogens can be achieved with DUV-LEDs compared to the widely used mercury vapor lamps.…”