Efficacy of a Nanometric Mist Disinfection System in Reducing Bacterial Surface Contamination in Surgical Rooms: A Quasi-Experimental Study in a Tertiary Hospital

Abstract Healthcare-associated infections (HAIs) remain a major global patient safety challenge, with operating room surfaces playing an important role in pathogen transmission. Conventional cleaning protocols frequently leave residual microbial contamination, underscoring the need for innovative automated disinfection technologies. This quasi-experimental, pre-post intervention study evaluated the efficacy of an automated nanometric mist disinfection system (Higia Plus®) in reducing bacterial surface contamination in three surgical rooms of a tertiary military hospital in Curitiba, Paraná, Brazil, in June 2026. A total of 48 surface samples were collected using standardized RODAC (Replicate Organism Detection and Counting) contact plates—sixteen sampling points per room—immediately before and after system application. The primary outcome was the percentage reduction in colony-forming units (CFU). Pre-intervention CFU totals were 53 (Room 01), 187 (Room 02), and 97 (Room 03). Post-intervention counts decreased to 1, 4, and 12 CFU, respectively, yielding room-specific efficacies of 98.1%, 97.9%, and 87.6%, and an overall system efficacy of 94.5% (from 337 to 17 CFU across all 48 samples). All three rooms surpassed the predefined efficacy threshold of ≥ 80% CFU reduction. These findings indicate that nanometric mist disinfection is a robust and promising complementary strategy for environmental decontamination in surgical settings, with potential to reduce HAI risk. Future studies should evaluate specific pathogen profiles, clinical outcomes such as surgical site infection rates, and cost-effectiveness.