Defining Operational UV-C Dose Requirements for Autonomous Disinfection of Clinically Relevant Pathogens Across Healthcare and High-Touch Surfaces

Autonomous ultraviolet-C (UV-C) disinfection systems are becoming more common to help with manual surface cleaning, but there is still a lack of evidence-based guidance on the specific UV-C dose requirements needed to effectively target various pathogens across different surfaces in healthcare settings. The aim of this study was to investigate the operational UV-C dose requirements for a range of clinically relevant pathogens on various high-touch healthcare materials and stainless steel under controlled conditions.

The researchers exposed SARS-CoV-2, adenovirus, Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Enterococcus faecalis, Candida auris, and Clostridioides difficile spores to specific UV-C doses on representative materials. They measured the viable recovery of these microbes using recovery methods. They then performed dose-response analysis and used the data to create operational models.

The study found that UV-C exposure significantly reduced the viable counts of all tested pathogens. However, there were differences in the exposure conditions required for inactivation. SARS-CoV-2 showed substantial inactivation at doses as low as 2.6 mJ/cm2, while the highest evaluated doses required for C. difficile spores and C. auris were 1,800 mJ/cm2 and 3,600 mJ/cm2, respectively.

For C. auris, multi-dose data suggested that around 1,410 mJ/cm2 was needed for a 2-log10 reduction, which could be used to estimate exposure times based on the distance from the UV-C source.

In conclusion, the researchers demonstrated that experimentally determined UV-C exposures can effectively reduce microbial loads on diverse surfaces across different pathogen types. By linking the delivered dose to microbial reductions, this study provides a quantitative approach to convert laboratory efficacy into operational parameters for autonomous UV-C disinfection systems in healthcare environments.