Antimicrobial Properties of Copper in Hearing Aid Users

Objective: 1) Evaluate the antimicrobial properties of copper in hearing aid molds against the most prevalent pathogens of otitis externa in an in vitro system. 2) Determine the most suitable mold material to allow adequate diffusion of copper ions to perform its antimicrobial action.

Method: Experimental study conducted from January to December 2010, consisting of an in vitro system with hearing-aid molds made from different materials with and without copper in them, which were inoculated with external otitis pathogens at different concentrations (S aureus, P aeruginosa, C albicans, and A niger), then determine percentage of bacterial adhesion to materials.

Results: There was a significant reduction in the percentage of microbial adherence to different mold materials with copper in them, in relation to those without copper, at different levels of microbial concentration for S aureus, P aeruginosa, C albicans, and A niger, while the percentages of adherence reduction fluctuated between 27% and 100% in those molds that contained copper. We have observed an inverse relation between the adherence reduction and the concentration of inoculated microorganisms. A greater microbial adherence reduction was shown in molds made of UV sensitive polymer with copper in their interior, compared with other materials.

Conclusion: Results show that copper exerts its antimicrobial properties through different materials, which opens an interesting challenge in the otolaryngological field and public health area to develop clinical studies focused on confirming whether the use of hearing aids with copper sheets inside reduces the risk of infectious external otitis.