Potential action of copper surfaces on meticillin-resistant Staphylococcus aureus

Authors


  • All the authors have agreed to this submission and have agreed that the corresponding author L. Weaver may act on their behalf throughout the review and publication process.

Louise Weaver, presently at Institute of Environmental Science and Research Ltd, Christchurch Science Centre, 27 Creyke Road, Ilam, Christchurch 8041, New Zealand. E-mail: louise.weaver@esr.cri.govt.nz

Abstract

Aims:  Studies to date have shown rapid killing of bacterial cells when exposed to copper surfaces. The mechanistic action of copper on bacterial cells is so far unknown.

Methods and Results:  To investigate potential mechanisms involved, meticillin-resistant Staphylococcus aureus (MRSA) cells (107 CFU) were inoculated onto coupons of copper or stainless steel and stained with either the viability fluorophore 5-cyano-2,3-ditolyl tetrazolium (CTC), to detect respiration, or BacLight™ (SYTO9/propidium iodide), to determine cell wall integrity. Coupons were then observed in-situ using epifluorescence microscopy. In addition, DNA from cells inoculated onto either copper or stainless steel surfaces was isolated and analysed by agarose gel electrophoresis. An effect on cellular respiration with CTC reduction was evident but no effect on cell membrane integrity (BacLight™) was observed. Results from the DNA isolation indicated a copper-induced detrimental effect on MRSA genomic material as no bands were observed after exposure to copper surface.

Conclusions:  The results indicate that exposure to copper surfaces rapidly kills MRSA by compromising cellular respiration and damaging DNA, with little effect on cell membrane integrity.

Significance and Impact of the study:  This research provides a mechanistic explanation in support of previous suggestions that although copper surfaces do not affect membrane integrity of cells, there is still a rapid antimicrobial effect.

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