Sub-MIC kill kinetics of copper and silver in Escherichia coli

Copper and silver are often considered to share antibacterial mechanisms and defense responses. Here, we show that at sub-MIC concentrations, copper gradually inhibits the growth of Escherichia coli , while silver appears to extend the lag phase through initial killing followed by normal regrowth. The distinct kinetics indicate that copper and silver may differentially influence tolerance and resistance development, with implications for risk assessment and the design of metal-based antimicrobial applications.