The antibacterial efficacy of a copper–silver alloy coating under conditions resembling build up of dry surface bacterial biofilms is successfully demonstrated according to US EPA test methods with a ≥99.9% reduction of test organisms over a 24 h period. A tailor‐made confocal imaging protocol is designed to visualize in situ the killing of bacterial biofilms at the copper–silver alloy surface and monitor the kinetics for 100 min. The copper–silver alloy coating eradicates a biofilm of Gram‐positive bacteria within 5 min while a biofilm of Gram‐negative bacteria are killed more slowly. In situ pH monitoring indicates a 2‐log units increase at the interface between the metallic surface and bacterial biofilm; however, the viability of the bacteria is not directly affected by this raise (pH 8.0–9.5) when tested in buffer. The OH⁻ production, as a result of the interaction between the electrochemically active surface and the bacterial biofilm under environmental conditions, is thus one aspect of the contact‐mediated killing of the copper–silver alloy coating and not the direct cause of the observed antibacterial efficacy. The combination of oxidation of bacterial cells, release of copper ions, and local pH raise characterizes the antibacterial activity of the copper–silver alloy‐coated dry surface.

Coating surfaces with a copper-silver alloy in clinical settings can be an alternative or complementary antibacterial strategy to other existing technologies and disinfection interventions. A newly developed copper-silver alloy coating has a high antibacterial efficacy against common pathogenic bacteria in laboratory setups, and the purpose of this study is to determine the antibacterial efficacy of this copper-silvery alloy in real-world clinical settings. Two field trials were carried out at a private clinic and a wound care center. Door handles coated with the copper-silver alloy had a lower total aerobic plate count (1.3 ± 0.4 Log CFU/cm² and 0.8 ± 0.3 Log CFU/cm², CFU stands for Colony Forming Units) than the reference uncoated material on-site (2.4 ± 0.4 Log CFU/cm² for the stainless steel and 1.7 ± 0.4 Log CFU/cm² for the satin brass). The copper-silver alloy did not selectively reduce specific bacterial species. This study points to the possibility of a successful long-term implementation of the copper-silver alloy coating as an antibacterial strategy.