According to the report of the World Organization for Animal Health (OIE) World Animal Health Information System (WAHIS), more than 6,000 Highly Pathogenic Avian Influenza (HPAI) cases have occurred during 2016 through 2020, resulting in the disposal of more than 100 million poultries [1]. The transmission of HPAI from one farm to another is believed to be the main cause of massive outbreaks. The HPAI epidemiological investigation report of 2017 through 2018 by the Korean Animal and Plant Quarantine Agency showed that nearly 20% of all HPAI outbreaks were associated with employees working with HPAI-contaminated equipment or vehicles [2]. Similar results were found in the analysis of the 2016 through 2017 HPAI outbreak in France. Researchers in the study found that loosely defined boundaries, which is highly associated with inadequate control of movements and cleaning of facilities, has a decisive effect on HPAI spread in farms [3]. Thus, disinfection becomes essential for the proper protection of animals in livestock farms.

Selection of an appropriate disinfectant from the various commercially available ones depends upon the surface to be disinfected, target pathogen(s), and ambient environment. One challenge faced during surface disinfection is the surface structure, particularly equipment or large machines consist of multi-materials and subtle smaller parts that were too difficult to maintain clean status with a short routine cleaning. Moreover, it is difficult to maintain the disinfected status of a surface for a prolonged period because traditional disinfectants’ efficacy quickly decreases. To overcome this, coating substances with copper or silver, which have sterilizing properties, are often used [4,5]. Materials such as antibacterial glasses or ion creams have been commercially developed to prevent bacterial adhesion and induce bacterial cell death. However, these materials exert disin-fecting effects via leaching of the active components of their chemical structures; thus, there may be a gradual decrease in their disinfecting efficacy upon the contamination of surrounding environments because of a loss of these active components [6]. Importantly, a disinfectant used for the surface disinfection of equipment in livestock facilities should exert a long-lasting effect.

The organosilicon quaternary ammonium salt 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride (Si-QAC) has been recently developed as a surface disinfectant. Si-QAC has two distinctive parts—organosilane and a quaternary ammonium compound [7]. The organosilicon moiety attaches to various types of surfaces, including steel, plastic, and glass, and it does not leach when completely dried [8]. Quaternary ammonium compounds are cationic surfactants that vary in structure based on the length of their carbon chains. These compounds are widely used as potent disinfectants against a broad spectrum of microorganisms [9]. Because Si-QAC has moieties allowing it to adhere to surfaces and exert disinfecting effects [10]. Several attempts were made to exploit the antimicrobial characteristics of Si-QAC. At the early stage of Si-QAC development, it was applied to fabrics to test antimicrobial effects [11,12]. Recently, experimental results of the use of Si-QAC as a disinfectant on medical implants and dental materials were reported [13,14]. However, the effects of Si-QAC have not been tested on a wide range of facilities such as public facilities or animal farms that require large-capacity, rapid disinfecting process of broad surfaces with high levels of hygiene. Based on the results of previous studies, we anticipated that Si-QAC can be used as a long-term surface disinfectant. Thus, in this study, we evaluated the potential of Si-QAC as a surface disinfectant in both laboratory and farm settings.

In the poultry industry, pathogens such as avian influenza virus and Salmonella spp, are harmful to animal health, farmers economic situation, by extension, poultry workers and consumers health. There is much evidence of these pathogens being transmitted to farms because of workers’ activities and tools used. Inappropriate defective disinfection could introduce pathogens to the farms and spread them to animals. Our results provide a basis for using Si-QAC as a surface-coating disinfectant in farm environments. A previous report showed that Si-QAC has chemical disinfec-tion effects through its quaternary ammonium component and that its organosilicon component causes physical damage to the cells of pathogens [16]. Further, two mechanisms underlying the physical disinfection activity of Si-QAC have been suggested [17]. The first mechanism is the polymeric spacer effect, which is induced by long-chain cationic polymers that penetrate the outermost membrane of microbes [18]. The other is the phospholipid sponge effect, which induces ion exchange between short-chain polymers and microbial membranes, which results in the loss of membrane integrity [19].

Importantly, Si-QAC appears to be safe for use by humans; furthermore, it is a non-leaching material [8]. This material does not cause skin irritation [20]. In addition, Si-QAC showed no adverse effects in an inhalation toxicity test in rats over 90 days (data not shown). Moreover, it has a high safety level based on its 50% oral lethal dose, which is greater than 5,000 mg/kg in rats (data not shown). These data suggest that Si-QAC can be used safely with farm animals.

This study is the first report of Si-QAC application on farms. Although most results suggest that Si-QAC can be a potential disinfectant, additional data are required for maximizing the use of this disinfectant in different farm facilities. In livestock facilities, hot water high-pressure cleaning is routinely performed. This process may peel off the Si-QAC-coated layer and gradually decrease the disinfection efficacy. Information regarding factors such as the coating durability and optimal Si-QAC chain length for disinfecting surfaces to eliminate a diverse range of pathogens requires further elucidation.