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

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It's true.

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Microorganisms called bacteria[br]were some of the first life forms

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to appear on Earth.

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Though they consist[br]of only a single cell,

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their total biomass is greater than[br]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,[br]on your kitchen table, on your skin,

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even inside you.

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Don't reach for the [br]panic button just yet.

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Although you have 10 times more[br]bacterial cells inside you

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than your body has human cells,[br]many of these bacteria are harmless

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or even beneficial,[br]helping digestion and immunity.

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

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from minor inconveniences to[br]deadly epidemics.

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

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Synthesized from chemicals or[br]occurring naturally in things like mold,

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these antibiotics kill or neutralize bacteria[br]by interrupting cell wall synthesis

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or interfering with vital processes[br]like protein synthesis,

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all while leaving human cells unharmed.

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The deployment of antibiotics [br]over the course of the 20th century

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has rendered many previously dangerous[br]diseases easily treatable.

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But today, more and more[br]of our antibiotics

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are becoming less effective.

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Did something go wrong[br]to make them stop working?

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

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

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Just like any other organisms,[br]individual bacteria can undergo random mutations.

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Many of these mutations[br]are harmful or useless,

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

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an edge in survival.

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And for a bacterium,[br]a mutation making it resistant

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to a certain antibiotic[br]gives quite the edge.

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As the non-resistant bacteria[br]are killed off,

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which happens especially quickly[br]in antibiotic-rich environments,

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like hospitals,[br]there is more room and resources

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for the resistant ones to thrive,[br]passing along only the mutated genes

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that help them do so.

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Reproduction isn't the[br]only way to do this;

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some can release their DNA upon death[br]to be picked up by other bacteria,

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while others use a method[br]called conjugation,

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connecting through pili [br]to share their genes.

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Over time, the resistant genes proliferate,[br]creating entire strains of resistant super bacteria.

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So, how much time do we have[br]before these superbugs take over?

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Well, in some bacteria,[br]it's already happened.

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For instance, some strands [br]of staphylococcus aureus,

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which causes everything from[br]skin infections to pneumonia and sepsis,

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have developed into MRSA,[br]becoming resistant to

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beta-lactam antibiotics,[br]like penicillin, methicillin, and oxacillin.

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Thanks to a gene[br]that replaces the protein

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beta-lactams normally target[br]and bind to,

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MRSA can keep making [br]its cell walls unimpeded.

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Other super bacteria,[br]like salmonella,

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even sometimes produce enzymes[br]like beta-lactams

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

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and E. coli, a diverse group of bacteria[br]that contains strains that cause

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diarrhea and kidney failure,[br]can prevent the function

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of antibiotics, like quinolones,[br]by actively booting

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any invaders that manage[br]to enter the cell.

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But there is good news.

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

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and although development of[br]new antibiotics has slowed in recent years,

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

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Other scientists are investigating[br]alternate solutions,

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such as phage therapy[br]or using vaccines to prevent infections.

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Most importantly, curbing the excessive[br]and unnecessary use of antibiotics,

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

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as well as changing medical practice[br]to prevent hospital infections,

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can have a major impact[br]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,[br]deescalation may sometimes work better

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than an evolutionary arms race.