Real-world testing of the durability claims of a commercially available spray-on surface biocide.

Self-disinfecting biocidal surfaces have been proposed as a solution to prevent infections caused by the transmission of microorganisms from frequently touched surfaces in hospitals and other settings. For example, surface anchoring quaternary ammonium salt (SAQAS)-based biocides are purported to maintain their antimicrobial potency for up to 30 days and are available as spray-on formulations. We tested the 30-day potency claim of a commercially available spray-on SAQAS-based biocide ("SAQAS-A") under "real-world" conditions in a microbiology laboratory where regular cleaning is routine. To do this, we determined the background microbial burden on high-traffic floor areas, routinely used bench areas, frequently touched handles, and glass surfaces for 30 days before and after applying SAQAS-A. Experiments were repeated three times, and data were analyzed using two generalized linear mixed models (GLMM). We observed that for >80% of bench samples, the number of viable bacteria recovered was below the highest acceptable level of 2.5 colony-forming units (CFU)/cm IMPORTANCE: We tested the claim that a commercially available spray-on biocide could protect surfaces from microbial contamination for 30 days. In the presence of routine disinfection, we found that spray-on applications of the surface anchoring quaternary ammonium salt-based biocide did not protect frequently touched surfaces in a working microbiology research lab for up to 30 days. Our data show that users of this type of product should be aware of the limitations of manufacturers' claims of "continued protection", and manufacturers should consider formulations that more reliably attach to surfaces. Similarly, regulatory and consumer protection agencies should provide clear guidance for companies wishing to make durability and longevity claims for biocidal surface applications.