Antimicrobial effectiveness across copper content gradients on surfaces against a reference microbial community

Abstract

Microbial spread is occurring especially in confined environments, such as passenger cabins. Pathogens can be easily spread through contact with surfaces. The ongoing silent pandemic is driven by antimicrobial resistance, that are already affecting millions of patients. Copper is known to harbor antimicrobial properties, and in consideration of sustainability and cost-effectiveness, we conducted an experiment to assess the effectivity of varying copper concentrations on surfaces against a reference microbiome, which represents the most prevalent bacterial genera in public transportation. Further, the effect of the used materials is additionally tested against two selected species of the reference microbiome. The test materials are glass slides that are coated with varying amounts of copper, specifically 100 at.%, 79 at.%, 53 at.% and 24 at.%. The results demonstrate that a copper content of 100 at.% is the most effective in reducing the survival of the tested organisms. In contrast, the 79 at.% and 49 at.% copper content surfaces only exhibit an antimicrobial effect on single species, which is not visible in the survival rate but is evident in a reduced metabolic activity of the cells. In general, the reference microbial community is more resilient than the tested single species. Consequently, community testing may be a more realistic approach compared to single model organisms, and higher doses of copper (at least 80 at.%) or increased coating thickness may be necessary to achieve the desired antimicrobial effect.