Medicine has changed a lot in the last hundred years.
We have better technology to look for problems, and if we find one, we’re much more likely
to be able to fix it.
And one of the most important fixes is that these days, we have antibiotics, which are
really good at killing off harmful bacteria.
Or at least, they have been, so far.
But the more we use those antibiotics, the more bacteria develop resistance to them,
so we keep having to find new ones that the bacteria haven’t figured out how to fight
yet.
Which is why scientists are looking at the possibility of bringing metal back into our
anti-bacterial arsenal.
Metals like copper and silver have been used to kill bacteria for thousands of years -- even
before anyone knew what bacteria were.
For example, one of the oldest books in the world, an Egyptian medical text called the
Edwin Smith Papyrus, describes the use of copper for preventing infections in chest
wounds..
And many ancient cultures believed that copper and silver pots kept water safe to drink for
longer.
Then, in 1928, a guy named Alexander Fleming came along, found some funky mold in his lab,
and promptly changed history forever.
He’d discovered penicillin, the first of many antibiotics.
When it was released, the world went crazy for it.
Antibiotics were hailed as “miracle drugs” and medical metals were all-but forgotten
about.
If only it were that easy, though.
Bacteria evolve fast, and highly resistant bacteria seem to show up almost as fast as
we can invent new drugs.
The antibiotics work a bit like an arrow, precisely hitting one weak point of the target.
It works great until the weak point is covered up – like when bacteria evolve antibiotic
resistance.
If today’s antibiotics are like arrows, metals act more like grenades -- they hit
bacteria harder and in multiple places at once, making it much more difficult for them
to evolve resistance.
Back in the 1980s, researchers noted that bacteria landing on surfaces made of copper
-- or alloys that contain copper, like bronze and brass -- usually die off within minutes
or hours.
It’s a process known as contact killing, and recently, health professionals have started
using it to their advantage.
Hospitals across the world are studying what happens when they switch out stainless steel
surfaces like door handles and bed rails with copper and brass.
One 2010 study in Birmingham, England studied the bacteria-fighting properties of copper
and brass.
They found 90-100% fewer bacteria on copper and brass surfaces than on stainless steel
– even after six months.
And only the steel surfaces had MRSA, the multidrug resistant bacteria that’s often
fatal.
Scientists still aren’t clear on all the details when it comes to copper’s contact
killing, but it probably has to do with electric charge.
Positive copper ions dissolve off the metal surface, attracted to negative charges on
the bacterial membrane.
Those ions punches holes in the membrane, letting more copper in.
Then, once they’re loose in the cell, the metal ions can wreak all kinds of havoc.
Through various reactions copper ions can generate high energy hydroxyl radicals -- an
oxygen bonded to a hydrogen, with an unpaired electron that REALLY wants to bond with stuff.
They’ll react with -- and damage -- pretty much any biological molecule, including DNA,
proteins, and carbohydrates.
Which makes it great at killing bacteria.
But even though it’s so deadly, small amounts of copper -- like many other metals -- are
important for life.
Right now, for instance, copper is working inside proteins that keep your skin elastic,
produce the skin pigment melanin, and use oxygen to make energy.
Bacteria also need copper, and figuring out how they process it will be a big part of
understanding how best to use it against them.
Another metal that’s turning out to be a useful weapon against bacteria is silver.
And unlike copper, we don’t know of any useful functions for silver inside cells.
It can be deadly even in tiny amounts if it gets in.
In case you’re now staring at your jewellery in horror, I should mention that silver metal
in that bulky form is harmless.
It’s just too unreactive.
On the other hand, particles of nano silver -- just a few billionths of a meter across
-- might be an important part of the future of medicine.
Things behave very differently at that scale.
Their tiny size gives nanoparticles a lot more surface area, making them much more reactive.
Nanosilver is already being embedded into or used as a surface coating for medical implants,
releasing metal ions steadily over time to kill bacteria.
It’s also being studied as an antibacterial agent in fields like dentistry, eye treatment,
surgery, and pharmaceuticals.
But don’t expect to be popping copper or nanosilver /pills/ to cure infections just
yet -- ingesting something isn’t the same as using it as a surface, and researchers
are still studying how these metals interact with bacteria -- and plain old cells -- in
the human body.
But it does look like those ancient Egyptians were onto something.
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