Silver as an Antimicrobial Agent: The Resistance Issue

This chapter provides a comprehensive overview of the use and toxicity of silver compounds as antimicrobial agents. In particular, the bacterial resistance mechanisms to silver are discussed. The extensive use of silver-based products in many applications is based on the strong antimicrobial properties of silver ions without exhibiting immediate and serious risk for human health. In contrast, the risks associated with the emerging use of silver nanoparticles are less studied and need to be further elucidated to draw conclusions. However, the increasing and widespread use of (nano)silver compounds could increase their release in the environment, which can have negative impacts on ecosystems. Moreover, silver resistance determinants are widely spread among environmental and clinically relevant bacteria and these determinants are often located on mobile genetic elements, which facilitate their spread. Therefore, detailed knowledge of the toxicity of (nano)silver compounds and the molecular mechanisms of resistance to them can improve their applications and lead to a better understanding of the impact on human health and ecosystems.