Copper surfaces kill MRSA in minutes, study shows

Copper surfaces killed methicillin-resistant Staphylococcus aureus (MRSA) within minutes after the surfaces were contaminated by touch, according to a study published online January 29, 2016 in the journal Applied and Environmental Microbiology.

This finding suggests that hospitals and other facilities could incorporate copper alloy surfaces to help reduce the spread of this and other harmful pathogens, the researchers recommended.

In prior studies, the researchers simulated “droplet contamination”—representing a sneeze or a splash—and showed that MRSA was killed rapidly on copper and copper alloy surfaces. But the researchers reasoned that surface contamination often occurs by fingertip touch which, unlike visible droplets, dries rapidly and may be overlooked by cleaning practices.

“Our latest research shows that in simulated fingertip contamination of surfaces with millions of MRSA or MSSA [methicillin-sensitive Staphylococcus aureus], the cells can remain alive for long periods on non-antimicrobial surfaces—such as stainless steel—but are killed even more rapidly than droplet contamination on copper and copper alloys,” said the study’s lead author Sarah Warnes, PhD, of the Centre for Biological Sciences at the University of Southampton, in Southampton, United Kingdom.

In this study, Dr. Warnes and co-author Bill Keevil, Chair in Environmental Healthcare at the University of Southampton, observed a 5-log reduction of a hardy epidemic strain of MRSA (EMRSA-16) after 10 minutes on a copper surface, and 4-log reduction in 15 minutes on copper nickel and cartridge brass alloys.

“The real life bacterial bioburden is considerably less than tested here, suggesting kill times may be even faster,” the researchers wrote.

These results indicate that MRSA dies on copper surfaces due to a multifaceted attack from copper ions and reactive oxygen species. “Exposure to copper damages the bacterial respiration and DNA, resulting in irreversible cell breakdown and death,” Dr. Warnes said.

Also, copper doesn’t promote antimicrobial resistance. “Our work shows that copper targets various cellular sites, not only killing bacterial and viral pathogens, but also rapidly destroying their nucleic acid genetic material so there is no chance of mutation occurring and nothing to pass on to other microbes—a process called horizontal gene transfer. Consequently, this helps prevent breeding the next generation of superbug,” Dr. Keevil said.

Although life-threatening MRSA infections in health care settings have declined in recent years, MRSA is still a major patient threat. In 2011, more than 80,000 invasive MRSA infections and 11,285 related deaths occurred in the US, according to the Centers for Disease Control and Prevention.

“Incorporation of copper alloy biocidal surfaces could help to reduce the spread of this dangerous pathogen,” the authors wrote. “A hospital trial has already shown incorporation of just 6 copper surfaces in intensive care units significantly reduced MRSA colonization and healthcare-acquired infection over a 12-month period.”