Methods to assess porous and non-porous antibacterial, antifungal and antiviral surfaces in relation to touch and droplet transfer in medical and transport applications: a gap analysis and suggested approaches.

To help assess whether a potentially antimicrobial material, surface, or coating provides antimicrobial efficacy, a number of standardised test methods have been developed internationally. Ideally, these methods should generate data that supports the materials efficacy when deployed in the intended end-use application. These methods can be categorised based on their methodological approach such as suspension tests, agar plate/zone diffusion tests, surface inoculation tests, surface growth tests or surface adhesion tests. To further support those interested in antimicrobial coatings to make appropriate decisions on their method selection, this paper brings together an exhaustive list of methods (for porous and non-porous materials), exploring the methodological (e.g. microorganism) and environmental (e.g. temperature and relative humidity) parameters to test bacteria, fungi, and viruses. This analysis demonstrates that methods that test either fungi or viruses are generally lacking, whilst methods that test bacteria, fungi and viruses are not designed to simulate end-use/lack realistic conditions. As such, a number of applications for antimicrobial activity across medical touch screens, medical textiles and gloves and transport seat textiles are explored, providing guidance on modifications to existing methods that may better simulate the intended end-use of antimicrobial materials.