Effect of far ultraviolet light emitted from an optical diffuser on methicillin-resistant Staphylococcus aureus in vitro

Drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) are a target for new antimicrobial technologies. Far-UVC technology is an emerging disinfection method that directly kills microorganisms using light. In contrast with conventional UV sterilization, far-UVC light has antimicrobial capabilities without apparent harm to mammalian cells. This study examines the application of 224 nm far-UVC light delivered from a laser using an optical diffuser towards the goal of protecting against bacterial invasion around skin penetrating devices. Delivery of far-UVC using a laser and optical fibers enables exposure to unique geometries that would otherwise be shielded when using a lamp. Testing of the bactericidal potential of diffusing the far-UVC laser output over a large area was tested and yielded qualitative area killing results. The killing of MRSA using this method was also examined using an in vitro survival assay. Results followed a classic log-linear disinfection model with a rate constant of k = 0.51 cm2/mJ, which corresponds to an inactivation cross section of D90 = 4.5 mJ/cm2. This study establishes far-UVC delivered from a laser through an optical diffuser as a viable solution for disinfection of susceptible regions such as around catheters, drivelines, or other skin penetrating medical devices.