Evaluation of the Sterilray Far-Ultraviolet Irradiation Wand for Environmental Decontamination of Clostridium difficile and other Healthcare-associated pathogens

Background: Environmental surfaces play an important role in transmission of healthcare-associated pathogens. There is a need for new disinfection methods that are effective against Clostridium difficile spores, but also safe and rapid. The Sterilray^TM Disinfection Wand device is a hand-held room decontamination technology that utilizes far-ultraviolet irradiation (190-220nm) to kill pathogens.

Objective: To examine the efficacy of environmental disinfection using the Sterilray device in the laboratory and in rooms of hospitalized patients.

Methods: Cultures for C. difficile, methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE) were collected before and after use of the Sterilray device from inoculated surfaces in the laboratory and from commonly-touched surfaces in rooms of hospitalized patients.

Results: On inoculated surfaces in the laboratory, application of the Sterilray device at a radiant dose of 100 mj/cm² for ~ 5 seconds consistently reduced recovery of C. difficile spores by >3-4 logs, MRSA by >4-5 logs and of VRE by >6-7 logs. A >3 log reduction of MRSA and VRE was achieved in ~2 seconds at a lower radiant dose, but killing of C. difficile spores was significantly reduced. However, the presence of organic material significantly reduced the lethal effect of the far-ultraviolet radiation. In hospital rooms that were not pre-cleaned, disinfection with the Sterilray device reduced the frequency of positive C. difficile cultures by 61%, MRSA cultures by 41% and VRE cultures by 58%. On gloved hands contaminated with C. difficile spores, disinfection with a radiant dose of 100 mj/cm² for ~ 5 seconds reduced transfer of spores by 3 logs.

Conclusions: The Sterilray^TM Disinfection Wand is a novel environmental disinfection technology that rapidly kills C. difficile spores and other healthcare-associated pathogens on surfaces and on gloved hands. However, the presence of organic matter decreases the efficacy of the far-ultraviolet radiation, possibly explaining the more modest results observed on surfaces in hospital rooms that were not pre-cleaned.