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What if I told you there were trillions
of tiny bacteria all around you?

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It's true.

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Microorganisms called bacteria
were some of the first life forms

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to appear on Earth.

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Though they consist of only a single cell,

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their total biomass is greater than
that of all plants and animals combined.

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And they live virtually everywhere:

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on the ground, in the water,

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on your kitchen table, on your skin,

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even inside you.

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Don't reach for the panic button just yet.

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Although you have 10 times
more bacterial cells inside you

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than your body has human cells,

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many of these bacteria
are harmless or even beneficial,

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helping digestion and immunity.

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But there are a few bad apples
that can cause harmful infections,

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from minor inconveniences
to deadly epidemics.

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Fortunately, there are amazing medicines
designed to fight bacterial infections.

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Synthesized from chemicals or
occurring naturally in things like mold,

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these antibiotics kill
or neutralize bacteria

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by interrupting cell wall synthesis

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or interfering with vital processes
like protein synthesis,

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all while leaving human cells unharmed.

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The deployment of antibiotics
over the course of the 20th century

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has rendered many previously
dangerous diseases easily treatable.

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But today, more and more
of our antibiotics

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are becoming less effective.

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Did something go wrong
to make them stop working?

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The problem is not with the antibiotics
but the bacteria they were made to fight,

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and the reason lies in Darwin's theory
of natural selection.

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Just like any other organisms,

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individual bacteria
can undergo random mutations.

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Many of these mutations
are harmful or useless,

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but every now and then,
one comes along that gives its organism

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an edge in survival.

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And for a bacterium,

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a mutation making it resistant
to a certain antibiotic

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gives quite the edge.

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As the non-resistant bacteria
are killed off,

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which happens especially quickly
in antibiotic-rich environments,

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like hospitals,

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there is more room and resources
for the resistant ones to thrive,

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passing along only the mutated genes
that help them do so.

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Reproduction
isn't the only way to do this.

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Some can release their DNA upon death
to be picked up by other bacteria,

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while others use a method
called conjugation,

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connecting through pili
to share their genes.

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Over time, the resistant
genes proliferate,

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creating entire strains
of resistant super bacteria.

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So how much time do we have
before these superbugs take over?

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Well, in some bacteria,
it's already happened.

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For instance, some strands
of staphylococcus aureus,

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which causes everything from
skin infections to pneumonia and sepsis,

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have developed into MRSA,

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becoming resistant
to beta-lactam antibiotics,

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like penicillin, methicillin,
and oxacillin.

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Thanks to a gene that replaces the protein
beta-lactams normally target and bind to,

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MRSA can keep making
its cell walls unimpeded.

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Other super bacteria, like salmonella,

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even sometimes produce enzymes
like beta-lactams

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that break down antibiotic attackers
before they can do any damage,

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and E. coli, a diverse group of bacteria

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that contains strains that cause
diarrhea and kidney failure,

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can prevent the function of antibiotics,

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like quinolones, by actively
booting any invaders

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that manage to enter the cell.

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But there is good news.

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Scientists are working to stay
one step ahead of the bacteria,

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and although development
of new antibiotics

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has slowed in recent years,

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the World Health Organization has made it
a priority to develop novel treatments.

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Other scientists are investigating
alternate solutions,

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such as phage therapy
or using vaccines to prevent infections.

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Most importantly, curbing the excessive
and unnecessary use of antibiotics,

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such as for minor infections
that can resolve on their own,

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as well as changing medical practice
to prevent hospital infections,

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can have a major impact

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by keeping more
non-resistant bacteria alive

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as competition for resistant strains.

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In the war against super bacteria,
deescalation may sometimes work better

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than an evolutionary arms race.