Dummies Guide to microbial resistance to antibiotics

It takes 1000 bugs (bacteria) to cause an infection.

The average immune system can only handle 200 bugs by itself.

Doc Prescribes Antibiotics -

- Patient A takes his antibiotics as prescribed for a full 10 days even though at around 300 bugs, or 3 days, he starts to feel better.
- His number of bugs drops to 199.
- His body handles the rest because at that point the immune system has created tools to kill the 199 little frickers. No transfer of genes --> No supermutant bugs.

- Patient B takes his antibiotics for 3 days and then stops because he starts to feel better.
- His dumb arse is left with 500 bugs.
- Let's say 4 of those bugs are not affected by antibiotics due to a random chance or luck.
- His body can't handle all 500 of those bugs and because his dumb arse stopped taking his antibiotics. He doesn't have enough tools yet to fight off all 500. Only 199.
- Next the 4 little frickers start give their resistant instructions any of the 500 bugs left the body hasn't killed itself. They can also replicate creating little fricker grandchildren.
- Then this dumb arse goes and coughs on grandma.
- She gone.

Obviously, it is much more complex.

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Posted by jlc05

Member since Nov 2005

32909 posts

Posted on 5/26/16 at 10:16 pm to boosiebadazz

quote:
The CDC and Department of Defense are involved and they're re-tracing her steps so it must be serious

"I'm from the government and I'm here to help"

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Posted by Gevans17

Member since Dec 2007

1135 posts

Posted on 5/26/16 at 10:25 pm to boosiebadazz

because bugs are smarter than people.

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Posted by Hopeful Doc

Member since Sep 2010

15057 posts

Posted on 5/26/16 at 10:31 pm to boosiebadazz

quote:
quote:
What do antibiotics do, what are they used to kill, why are they successful, and why do we develop an immunity to them?

YOU never develop immunity to them. Your body isn't the problem. Antibiotics kill bacteria living inside your body by a number of mechanisms.

Basically, there are different groups of antibiotics, each of them doing something different. Broadly, they usually either:
1) stop the bacterial cell wall from being constructed (no cell wall = cell death. This is how penicillin (and the rest of the beta lactams) work
2) stop proteins from being made or folded correctly (these are required for cell replication, so when you stop them, the bacteria can't grow or produce its toxins, so your body can fight it off quicker)
Of course, this is a greatly abbreviated version skimming lots and lots of details. That's what antibiotics do and how they kill/slow bacteria.
Bacteria, however, aren't dumb. They can produce new proteins required for resistance and pass them along, even after they've died, to other bacteria.
The majority of what bacteria do to gain resistance is
1) change the protein the drug binds to slightly so the drug can't bind but the protein still works
2) pump out the protein from the bacterial cell (efflux pump)
3) actually produce an anti-antibiotic (like a beta lactamase, which destroys penicillin. We then add a beta lactamase inhibitor, and instead of amoxicillin, you get amoxicillin-clavulinic acid (Augmentin). It has all the activity of the original + activity against bacteria which produce anti-penicillin beta lactamases. Probably a bit above the level of the answer I think you're asking for, but it's meant to show that there's kind of a dance going between human and bacteria. We find what kills them, they create a type of resistance, so we make the ones we have more potent or attack along a different path).

Feel free to ask any more specific questions you'd like. I'm happy to go into greater detail about any of the above.

And in terms of why they develop resistance, the number 1 and 2 causes are over prescription of antibiotics when they aren't needed, selecting for resistant organisms in our normal flora + frequency with which people don't finish the antibiotic course they were prescribed.