In-Vitro Evaluation of a Shoe-Sole Microbial Decontamination Device: Clinical Study

Tasnuva Rashid, Kelley Poblete, M. Jahangir Alam, Kevin W. Garey


Background: Shoe sole bottoms are commonly contaminated with bacterial pathogens that can be transmitted to healthcare environments and cause subsequent healthcare associated infections (HAIs). Ultraviolet light (UVC) is used in hospitals to decontaminate hospital rooms, but data on UVC decontamination of shoe soles are scarce. The objective of this study was to evaluate the efficacy of an UVC-based microbial decontamination device on shoe-soles spiked with Enterococcus bacteria. 


Method: A randomized, blinded, laboratory-based trial was conducted to determine the efficacy of an UV germicidal device, HealthySole Plus (HealthySole LLC, Minden NV) to reduce Enterococcus faecalis (E. faecalis) on shoe soles. Known concentrations of E. faecalis were spiked on shoe soles, incubated (1-hr), and then shoes were randomized 1:1 to UVC exposure (8 second exposure) of no UVC exposure (controls). Shoes were then swabbed bacterial suspension prepared and serially diluted, plated onto Enterococcus agar, incubated aerobically for 48 hours, and counted (colony forming units/mL (CFU). Investigators who prepared the spiked shoes and evaluated CFU counts were blinded to the intervention. Log reduction in CFU counts were compared between UVC exposed shoes and controls.


Results: Fifty pairs of shoes were spiked with 10(6) to 10(9)/ml concentration of E. faecalis (80 shoe samples). A 2.31 log reduction in E. faecalis CFU count was observed in shoes exposed to the UVC light compared to control shoes (p<0.05). Similar log reduction differences were observed at different spiked concentrations.


Conclusion: Shoe sole exposure to an UVC device for 8 seconds was effective in reducing Enterococci contamination on shoe soles. This result suggests that UVC devices targeting shoe soles may be able to reduce shoe sole transmission of pathogenic bacteria to hospital environs and prevent HAIs.