Background and Objective:
Healthcare-associated infection (HAI) is a major global issue for patient safety and public health. The role of environmental contamination (especially _high-touch_ surfaces) is well established and there are strong recommendations to improve cleaning and disinfection protocols, considering the utilization of _no-touch _automated systems. The study evaluated the effectiveness of an automated mobile UV-C radiation device to reduce environmental contamination in addition to standard protocols in critical settings.

Methods:
A 2-month prospective cross-over study was performed at the Cardiovascular and Thoracic Surgery ward of Pisa teaching hospital (Italy) from April 14th to June 16th 2021. 160 _high-touch_ surfaces were sampled for total microbial load three times: before and after performing standard cleaning and disinfecting protocol and after UV-C treatment in 2 Surgery rooms (Sr), 1 ICU room (ICUr) and 1 Patient room (Pr) occupied by 1 patient colonized by carbapenemase-producing _Klebsiella pneumoniae_.

Results:
After Standard Protocol we observed a reduction of the number of contaminated surfaces (Sr: -25%, ICUr: -12%; Pr: -5%) and a reduction of the mean microbial load (Sr: -45%, ICUr: -63%) except for Pr (+130%). After UV-C treatment, the number of contaminated surfaces (Sr: -66%, ICUr: -75%, Pr: -100%) and the mean microbial load (Sr: -83%, ICUr: -86%, Pr: -100%) decreased further in every setting. The 95% of surfaces received a dose >200 mJ/cm2, the rest received a dose >50 mJ/cm2. Globally, standard protocol in association with UV-C treatment reduced the number of contaminated surfaces (Sr: -74%, ICUr: -78%; Pr: -100%) and the mean microbial load (Sr: -91%, ICUr: -95%, Pr: -100%). The pair-matched analysis data using Sign test showed a relevant reduction of microbial load after UV-C treatment (p