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

  • It's true.

  • Microorganisms called bacteria were some of the first life forms

  • to appear on Earth.

  • Though they consist of only a single cell,

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

  • And they live virtually everywhere:

  • on the ground, in the water, on your kitchen table, on your skin,

  • even inside you.

  • Don't reach for the panic button just yet.

  • Although you have 10 times more bacterial cells inside you

  • than your body has human cells, many of these bacteria are harmless

  • or even beneficial, helping digestion and immunity.

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

  • from minor inconveniences to deadly epidemics.

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

  • Synthesized from chemicals or occurring naturally in things like mold,

  • these antibiotics kill or neutralize bacteria by interrupting cell wall synthesis

  • or interfering with vital processes like protein synthesis,

  • all while leaving human cells unharmed.

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

  • has rendered many previously dangerous diseases easily treatable.

  • But today, more and more of our antibiotics

  • are becoming less effective.

  • Did something go wrong to make them stop working?

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

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

  • Just like any other organisms, individual bacteria can undergo random mutations.

  • Many of these mutations are harmful or useless,

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

  • an edge in survival.

  • And for a bacterium, a mutation making it resistant

  • to a certain antibiotic gives quite the edge.

  • As the non-resistant bacteria are killed off,

  • which happens especially quickly in antibiotic-rich environments,

  • like hospitals, there is more room and resources

  • for the resistant ones to thrive, passing along only the mutated genes

  • that help them do so.

  • Reproduction isn't the only way to do this;

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

  • while others use a method called conjugation,

  • connecting through pili to share their genes.

  • Over time, the resistant genes proliferate, creating entire strains of resistant super bacteria.

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

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

  • For instance, some strands of staphylococcus aureus,

  • which causes everything from skin infections to pneumonia and sepsis,

  • have developed into MRSA, becoming resistant to

  • beta-lactam antibiotics, like penicillin, methicillin, and oxacillin.

  • Thanks to a gene that replaces the protein

  • beta-lactams normally target and bind to,

  • MRSA can keep making its cell walls unimpeded.

  • Other super bacteria, like salmonella,

  • even sometimes produce enzymes like beta-lactams

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

  • and E. coli, a diverse group of bacteria that contains strains that cause

  • diarrhea and kidney failure, can prevent the function

  • of antibiotics, like quinolones, by actively booting

  • any invaders that manage to enter the cell.

  • But there is good news.

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

  • and although development of new antibiotics has slowed in recent years,

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

  • Other scientists are investigating alternate solutions,

  • such as phage therapy or using vaccines to prevent infections.

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

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

  • as well as changing medical practice to prevent hospital infections,

  • can have a major impact by keeping more non-resistant bacteria alive

  • as competition for resistant strains.

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

  • than an evolutionary arms race.

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

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B2 US TED-Ed bacteria resistant antibiotic beta wu

【TED-Ed】What causes antibiotic resistance? - Kevin Wu

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    Ashley Chen posted on 2014/09/10
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