Jacob Thyrsted1 , Stine Yde Nielsen1 , Christian Kanstrup Holm1*, Søren Helbo Skaarup2 , Andreas Fløe Hvass2 , Elisabeth Bendstrup2 , Pernille Hauschildt2* and Sara Moeslund Joensen 3
Background: Hospital aquired infections are a considerable challenge for vulnerable patients. Traditional anti-microbial mercury lamps emit light at 254 nm and have well established anti-microbial effects. Their use in populated areas is, however, hindered by their carcinogenic properties. This is in contrast to anti-microbial lamps based on Krypton Chloride (KrCl), demonstrated to have no carcinogenic potential. These lamps emit light with a peak intensity at 222 nm and have broad bactericidal and viricidal effects including inactivation of SARS-CoV2. It is, however, unclear how 222 nm lamps perform in a real-life setting. In this study we aimed to assess the anti-microbial efficacy of filtered 222 nm excimer lamps in a real-world setting at an out-patient pulmonology clinic.
Methods: Filtered KrCl 222nm excimer lamps (UV222 TM lamps) were installed in an out-patient waiting area at the pulmonology section ta AarhuUs niversity Hospital. Furniture sufaces were sampled for bacterial load in a single-arm interventional longitudinasl tudy with and without exposure to filtered 222 nm UVC-light. Furthermore, bacterial species were identified using MALDIToF mass-spectrometry.
Findings: Filtered 222 nm UVC- light significantly reduced the number of colony-forming-units. Pathogenic bacteria such as Staphylococcus aureus and Staphylococcus epidermidis were detected only in the non-exposed areas suggesting that these species in particular are highly sensitive to inactivation by 222 nm UVC-light.
Conclusion: Filtered UVC-Light is efficient in reducing bacteria from exposed surfaces in the real-life setting of patient waiting area and hereby supports the use of the 222 nm UVC technologies to reduce bacterial load and thus the spread of infectious disease in a hospital setting.