Survival of bacteria on metallic copper surfaces in a hospital trial

Abstract

Basic chemistry of copper is responsible for its Janus-faced feature: on one hand, copper is an essential trace element required to interact efficiently with molecular oxygen. On the other hand, interaction with reactive oxygen species in undesired Fenton-like reactions leads to the production of hydroxyl radicals, which rapidly damage cellular macromolecules. Moreover, copper cations strongly bind to thiol compounds disturbing redox-homeostasis and may also remove cations of other transition metals from their native binding sites in enzymes. Nature has learned during evolution to deal with the dangerous yet important copper cations. Bacterial cells use different efflux systems to detoxify the metal from the cytoplasm or periplasm. Despite this ability, bacteria are rapidly killed on dry metallic copper surfaces. The mode of killing likely involves copper cations being released from the metallic copper and reactive oxygen species. With all this knowledge about the interaction of copper and its cations with cellular macromolecules in mind, experiments were moved to the next level, and the antimicrobial properties of copper-containing alloys in an "everyday" hospital setting were investigated. The alloys tested decreased the number of colony-forming units on metallic copper-containing surfaces by one third compared to control aluminum or plastic surfaces. Moreover, after disinfection, repopulation of the surfaces was delayed on copper alloys. This study bridges a gap between basic research concerning cellular copper homeostasis and application of this knowledge. It demonstrates that the use of copper-containing alloys may limit the spread of multiple drug-resistant bacteria in hospitals.

Survival of Escherichia coli Cells on Solid Copper Surfaces Is Increased by Glutathione

“…Bacteria, bacterial biofilms, yeasts, and viruses are inactivated on moist or dry copper surfaces, and this may be useful to control the spread of pathogenic entities in hospitals (5,7,9,17,58). On the other hand, some bacterial strains are able to survive on solid copper surfaces, such as on coins (19).…”

“…If copper surfaces are employed to limit the spread of bacteria in hospitals (17,18), it is essential to understand the molecular mechanisms behind the killing process, to optimize the handling and cleaning of copper surfaces, and to avoid the evolution of copper-surface-resistant pathogenic bacteria (19). Since copper ions are the mediators of the inactivation process, the presence of efflux pumps that remove copper ions from the cells extends the survival time of bacteria and yeasts on these surfaces, although they are killed later on nevertheless (11,12,16,20).…”

Differential Bacteriophage Mortality on Exposure to Copper

“…In public facilities such as hospitals, schools, and nursing homes, antibiotic-resistant bacteria and viruses are often transferred between hosts via contact with surfaces such as countertops, railings, and doorknobs. Because of this, the application of copper to frequently contacted surfaces in public and commercial facilities has gained much traction (6,19,20).…”

Aplicación de la capacidad bactericida del cobre en la práctica médica

“…Se realizaron cultivos diarios de las superficies durante 32 semanas, al cabo de este tiempo los recuentos de bacterias aerobias en las superficies con cobre se redujeron en 63% promedio con relación a los controles, aluminio en las manillas y plástico en los interruptores. La reducción fue significativa en las manillas, los objetos con mayor carga bacteriana 31 . Nuestro grupo participó en un estudio multi- …”