How copper kills flesh-eating bacteria

Recently scientists staged a demonstration in which flesh-eating bacteria died off in droves when placed on a copper surface. Find out why copper engages in bactericide.

Hospitals are necessary and efficient institutions meant to gather and train a variety of experts in order to serve any sick person who comes in. They're also festering pits of infection. It's not really their fault. They just have a huge number of very sick people, all of whom are visited by medical staff, administrative personnel, and facilities staff who continue to move through the building, collecting bugs as they go. Though hospitals institute hygienic policies, they remain one of the places where people are at the highest risk for infection. In fact, one of the major places that people pick up MRSA, or flesh-eating bacteria, is in a hospital.

MRSA is notoriously hard to kill, and often requires surgery and stints in hyperbaric chambers. This is why a demonstration of MRSA dying off on a copper was so dramatic. Most instruments in hospitals are stainless steel - a material that does not require much upkeep, is strong, and is easy to shape. The anti-microbial properties of copper make it a tempting alternative. Simple dry copper, and certain copper alloys, kill of bacteria after a few minutes of contact.

Copper's attack on cells is not confined to one approach. It's a renaissance killer, and it unleashes a multifaceted wave of destruction. First, it storms the cell. Cells maintain a certain voltage difference between their bodies and the outside world. The cell wall keeps this difference in electrical potential going. Copper manages to let the electrical energy in the cell flow through to the outside world, short circuiting the cell and weakening the wall. Copper ions also tend to react with oxygen (this causes the green patina that appears on the surface of copper pennies or the Statue of Liberty). If it reacts with oxygen while in contact with certain cell proteins or fatty acids, the whole thing turns into a version of the green patina and the cell wall is 'rusted' away.

Once the cell wall is destroyed, there's free flow into and out of the cell. Potassium and glutamate tend to flow out, draining the cell of needed components. Copper ions flow in. They bind to enzymes in the cell, causing the enzymes to become inactive, and disrupting nutrient processing and cell recreation. The cell is usually dead in minutes.

Various organizations, usually organizations with a lot of copper to sell, are pushing to have things like hand rails, beds, and doorknobs resurfaced with copper or copper alloys, especially in hospitals. Since copper is harmless to humans, it would be a painless way to reduce infections. Although copper tarnishes, it still manages to kill bacteria, and is sometimes shown to kill more bacteria if it looks a little grody. Alternately, doctors, nurses, and staffers could just try to handle a lot of pre-1982 pennies. Those who want to see MRSA die on copper can check out a video of it here.

Via Science Daily, Antimicrobial Copper times two, and Antimicrobial Touch Surface.