Evaluation of NOCOSYSTEM® efficacy in disinfecting surfaces by air

Introduction: NOCOSYSTEM® (NS) is a disinfection system composed by NOCOSPRAY® diffuser and NOCOLYSE® disinfectant (stabilized hydrogen peroxide and silver atoms) based on a patented technology of atomization (dry fog).This system is designed to prevent infections by surface decontamination by air. Our study tested NS efficacy in disinfecting a 45m3 room (without aeration) contaminated with increasing concentrations of ATCC bacterial strains (Staphylococcus aureus 29213, Escherichia coli 25922, Pseudomonas aeruginosa 27853, Enterococcus faecalis 29212). Methods: Volumes of bacterial suspensions at different concentrations (104, 105, 106 CFU/ml) were distributed with a sterile spatula on selected surfaces (area 50-200 cm2): floor, wall, doorway, counters, and shelves. Thereafter, the room was treated with NS, delivering NOCOLYSE® for 3’ at the highest concentration (4 ml/m3). After 30’ the surfaces were brushed with moistened sterile swabs, that were immediately inoculated on blood agar plates (bioMérieux, Marcy l’Etoile, France). Results: After aerobically incubation at 35°C for 18-24 h, bacterial grown measured as total colony numbers was significantly lower than controls. In case of low inocula, bacterial grown was 100% inhibited on floors, counters and shelves, whereas this percentage dropped to 80% with an inoculum of 106 CFU/ml. On walls and door the percentage of reduction of bacterial contamination was 100% regardless of the initial bacterial number. Conclusions: Our data confirm the efficacy of NS to determine eradication for low bacterial inocula and significant reduction when using high concentrations, allowing to appreciate the real decrease of surface contamination at different inocula.