Mutant Strains of Escherichia coli and Methicillin-Resistant Staphylococcus aureus Obtained by Laboratory Selection To Survive on Metallic Copper Surfaces

Abstract

Microbes are rapidly killed on solid copper surfaces by contact killing. Copper surfaces thus have an important role to play in preventing the spread of nosocomial infections. Bacteria adapt to challenging natural and clinical environments through evolutionary processes, for instance, by acquisition of beneficial spontaneous mutations. We wish to address the question of whether mutants can be selected that have evolved to survive contact killing on solid copper surfaces. We isolated such mutants from Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) by artificial laboratory evolution. The ability to survive on solid copper surfaces was a stable phenotype of the mutant population and not restricted to a small subpopulation. As a consequence, standard operation procedures with strict hygienic measures are extremely important to prevent the emergence and spread of copper-surface-tolerant persister-like bacterial strains if copper surfaces are to be sustainably used to limit the spread of pathogenic bacteria, e.g., to curb nosocomial infections.