Antibiotics are one of humankind's most amazing
discoveries.
Ever since that fateful day in 1928 when Scottish
physician Alexander Fleming noticed a funny
mold growing in one of his petri dishes, antibiotics
have been kicking bacterial butt.
That famous mold, of course, was producing
penicillin, the founding antibiotic superstar,
which has since extended the average human
life by at least a decade.
It fundamentally changed the face of medicine.
Antibiotics, or antimicrobials, are basically
selective poisons designed to either kill
or slow the growth of bacteria to the point
where your body's own immune system can clean
up.
These drugs target a specific part of bacteria
or some important stage in their development
without damaging the body's host cells.
And they're really great their job.
Until they aren't.
Lately, antibiotic technology has been having
a hard time keeping pace with bacterial evolution.
We've talked here on SciShow about how lots
of your die-hard, go-to favorite antibiotics
are starting to lose their mojo in the face
of sneaky and rapidly evolving bacteria.
The US Centers for Disease Control and Prevention
estimates that at least 2,000,000 Americans
became infected with drug-resistant bacteria
in 2012, and 23,000 of them died as a result.
These superbugs are deadly serious and could
quickly unleash a global health crisis if
we don't find a way to keep them in check.
The problem is we've already hit up many of
the most obvious sources of antibiotics, like
fungi, which includes penicillin, and synthetic
molecules.
Fortunately, we humans have big, delicious
brains, and some of the best of them are hard
at work trying to invent all-new ways to kill
dangerous bacteria or find other organisms
on the planet that are better at it than we
are so we can steal their secrets.
And while they're finding some promising leads,
I gotta say, they're looking in some pretty
weird places.
[Intro]
You know how everyone jokes that after some
big global disaster, only cockroaches will
survive?
Well, we recently found what may partially
explain their famous, and infuriating, tenacity.
Research from the University of Nottingham
suggests that certain insects, like roaches
and locusts, have brain tissues that are infused
with super-powered antibiotic juju.
The researchers found nine different antibiotic
molecules tucked into the roaches' nervous
systems that may be protecting them from otherwise
lethal bacteria.
They're all a type of molecule known as peptides,
short chains of amino acids that make up proteins,
kinda like proto-proteins.
And these peptides are specific to the bugs'
brains.
They seem to be chemicals that roaches'' brain
cells use to communicate with each other,
y'know, whenever a cockroach is sitting around
thinking about stuff, which I guess can happen,
and although we're not sure how these peptides
actually work, laboratory tests have shown
that they're incredibly effective at eliminating
some of our least favorite bacteria, like
the most dangerous strains of e.coli, which
cause gastrointestinal infections.
And even MRSA, a super-resistant type of staphylococcus
bacterium that can cause unstoppable deadly
infections in humans, particularly in hospitals.
In lab trials, these roach brain molecules
killed over 90% of MRSA bacteria, without
harming any host cells.
So I can guess what you're thinking: shut
up and take my money!
Well, hold on a sec, because we're a bit away
from having cockroach brains on the pharmacy
shelves.
There's still loads of technical hurdles to
overcome, tests to conduct, basic things we
need to figure out, like how exactly these
molecules work.
But roaches aren't the only hardy animals
out there.
Alligators are some of the Earth's most rugged
beasts.
They essentially live in cesspool swamps teeming
with bacteria and fungus and other microbes,
and more than that, they're known brawlers.
Put just a few territorial 800 pound toothy
reptiles together in a dirty swamp, and you
will no doubt come out with some serious bite
marks and bloody wounds, even missing limbs.
But amazingly, what you probably won't find
are any infections.
This got some bayou scientists to thinkin'!
Dr. Mark Merchant, a biochemist at McNeese
State University in Louisiana, helped conduct
a decade long study that investigated what
makes alligators so unusually resistant to
bacterial and fungal infection.
Turns out, it's in their blood.
An alligator's immune system is largely innate,
meaning it can fight off harmful micro-organisms
without having any prior exposure to them.
They just pop right out of their eggs ready
to do battle.
We humans also have some innate immunity,
provided by things like our skin and white
blood cells, but a big part of our immunities
are adaptive, meaning we often develop a resistance
to specific diseases only after being exposed
to them.
Which of course is not ideal all the time,
but alligators get to skip this step.
Researchers examining blood samples from American
alligators isolated their infection fighting
white blood cells and then extracted the active
proteins working in those cells.
And these two included a special class of
peptides which seemed to have a knack for
weakening the membranes of bacteria, causing
them to die.
When pitted against a wide range of bacteria
including drug-resistant MRSA, these tough
little peptides proved to be effective killers.
They also wiped out 6 of 8 strains of candida
albicans, a type of yeast infection that's
particularly troublesome for AIDS and transplant
patients with weakened immune systems.
Such compounds may also be found in similar
animals, like crocodiles, Komodo dragons,
and the skins of some frogs and toads.
So far, lab trials have shown that gator blood
can kill at least 23 different strains of
bacteria including salmonella, e.coli, staph,
and strep infections AND even a strain of
HIV.
For now, scientists are working to find the
exact chemical structures at work in four
of these promising chemicals and pinpoint
which types are best at killing which microbes.
One problem so far: high concentrations of
gator blood serum have already been found
to be so powerful that they are toxic to human
cells.
So other biologists are taking a different
approach in the search for the next generation
of antibiotics.
Rather than looking at other animals, they're
exploring strange, new places, like cave soils
and deep-sea sediments.
Researchers have recently discovered evidence
of promising new fungi strains living way
down in hundred million year old nutrient-starved
sediments in the Pacific Ocean.
Everyone thought this was a near-dead zone
for life, too harsh and remote an environment
for something like fungi to survive in.
Just a decade ago, the only living things
known to inhabit such deep sediment layers
were single-celled bacteria and archaea, organisms
known to flourish in extreme environments.
But while examining dredged up sediments from
as deep as 127 meters into the sea floor,
scientists found fungi of at least eight different
types, four of which they successfully cultured
in the lab.
Some of the fungi even belonged to the genus
Penicillium, which we have to thank for the
development of penicillin.
Now, we're not exactly sure how old these
fungi are, but they are definitely quite old
and maybe, more importantly, they appear to
have been living in isolation for eons.
If that's the case, they may have evolved
specific and unusual defenses against bacteria,
which, just like their penicillin kin in that
famous petri dish, could end up being a new
and powerful source of antibiotics.
And there's one more strategy that scientists
are using, one that works in espionage as
well as in medicine.
And that is seeing what the enemy is up to.
While exploring life in strange new places
around the world, some biologists are looking
for bacteria that have never been exposed
to our drugs, but still appear to be naturally
resistant to them.
Wherever we find the most naturally resistant
bacteria, we might also find natural antibiotics
that we never knew about.
And here, one of the most promising leads
is again in one of the hardest-to-reach places:
New Mexico's Lechuguilla cave, a place that
was isolated from all human contact until
it was discovered in the 1980's.
One of the many fascinating things that scientists
have discovered here is that the cave bacteria
seem to be resistant to everything.
Even though they've never been exposed to
us or our drugs, all of the bacteria have
proven to be resistant to at least one major
antibiotic, and many tend to fend off more
than a dozen of the most powerful antimicrobials
we have.
This suggests to scientists that the bacteria
have evolved to be this way because they live
in an environment that's rich in naturally
occurring antibiotics, ones that the germs
we live with up here on the surface have never
encountered.
Now we just have to find out what exactly
those compounds are.
So look, I'm not going to lie to you: we have
a lot of work to do.
While we might discover a new super-drug lurking
in a cave or under the sea or in a cockroach's
head, there's a big difference between finding
a substance that cleans house in a petri dish
and actually putting a new antibiotic in the
vein of a human patient.
So the bummer is, as promising as some of
these bold new discoveries may be, none of
them has yet yielded an actual marketable
drug.
Still, there's a long list of successful antibiotics
that we've managed to derive from strange
sources, starting with Dr. Fleming's rogue
fungus.
So if we keep exploring strange new places
and studying how other animals deal with the
problems we're facing, we just might find
the next penicillin before the superbugs get
the best of us.
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