Edit: I’ve had a lot of fun reading all of your analogies
In: 64
To make an analogy, antibiotics are sort of like a special key that fits into your car’s lock and allows thieves to steal your car. If we duplicate your car 10,000 times while randomly making minor changes to it, chances are that some of those cars will have minor changes to their locks such that the thieves’ key no longer fits and they can’t steal that car. This is like how bacteria can mutate antibiotic resistance.
But heat is more like an anti-tank round. It doesn’t matter what minor changes you made to your car, the anti-tank round is going to destroy it anyway. In fact it would be a real challenge to modify your car to survive it even if you did it intentionally! Heat is going to denature the proteins used to construct the bacteria no matter how they are arranged.
A lot of great answers have been given already that are correct (havent read them all so I hope I dont repeat something said by someone else without giving credit). I just wanted to add some more information.
Most antibiotics are based upon inhibiting a very specific system/ pathway/ structure/ function/ … without disrupting anything else that might also be present in the host.
Heat/ detergents/ … are very rigid methods that destroy a lot of different pathways/ systems/ structures of the bacteria but would also destroy a lot within the host.
A bacteria can more easily circumvent one particular disruption instead of hundreds at once. It becomes statistically impossible, as usually the rely on numbers and short life cycle to outsmart the 1 disruption made by antibiotics.
Hope this helps clear any questions you might had after reading some comments 🙂
Beinj
The same reason you can’t adapt to getting shot through the heart. The adaptation required to support that would be formed by eons of natural selection and evolution.
In that way, bacteria cannot adapt to an autoclave, because the steam literally tears them apart. It de-natures the proteins required for the specimen to live. This would be like melting you over a spit. You just can’t adapt to that within a lifetime or a generation, or a few generations, or many generations, it would take A LOT of generations to adapt to that environment. It isn’t impossible, there are microbiomes around thermal vents, but that is super specialized.
The thing with antibiotics is it targets biological functions of the bacteria; it can’t just tear it apart because you would also tear apart human cells. The few bacteria left over may have some genetic anomaly that makes it resistant to antibiotics. Bacteria go through generations really fast compared to mammals, so after ~94 years of using antibiotics we have some bacterial strains that are very resistant.
We didn’t make up antibiotics from thin air, they are based on many types of naturally occurring compounds. Since antibiotics are molecular compounds that cause specific reactions, and not broad forces like heat or pH changes, they can be specifically combatted. Pretty much all life is very dependent on being within a close temperature and/or pH range so deviations in this can be easily fatal and hard to protect against.
B-lactam antibiotics are based on compounds from a fungus. These cause very specific changes on the bacteria cell wall, ultimately causing death of the bacteria. Some bacteria produce B-lactam inhibitors from natural evolution before we even had antibiotics. Later we as humans created B-lactam inhibitor inhibitors to keep our B-lactams from being stopped (Augmentin is a common example). Just like your hair color is based on genes so are the instructions to make resistance compounds, and bacteria are able to share genes with each other which allows resistance to spread. Resistance can also be selected for through treatment with ineffective antibiotics or not finishing all the pills.
Soaps decrease surface tension and allow germs to be washed away.
Why can people survive diseases and injuries but not survive being crushed or burned alive?
Antibiotics rely on interacting with something very specific in the bacteria. If that specific part changes a little bit, by, for example, mutation, the antibiotic might not work anymore, and that lets the mutated bacteria replicate, which creates a resistant strain.
Using acid, heat, soap, fundamentally breaks everything that bacteria are made of. To make bacteria resistant to that you’d need to change not just one specific part, but almost everything about the bacteria.
Antibiotic resistance comes about as a result of a genetic mutation. With how frequently bacteria reproduce, these mutations can occur very quickly.
Soaps will break down the cell membrane of the organism. These have remained unchanged from the most ancient archaea that first evolved on earth to modern eukaryotic cells so it’s likely that there just is no other design that would be resistant to them. Some archaea are acidophiles and can exist very happily in low pH conditions.
For the same reason that the skin on your fingers gets harder if you play guitar but you can’t adapt to going through a wood chipper.
They can evolve a resistance to heat. Evolution takes time, it’s all about biodiversity some individuals may be more resistant to heat than others. If you slowly introduce a colony of bacteria to a slightly higher temp, the individual that has a mutation that just so happens to make it survive better than the rest at that slightly higher temp, will survive and pass on its resistance genes while the rest die off. So now on average your colony of bacteria is ever so slightly more resistant to heat. Repeat that multiple times and you have a colony that survived at high temp. (But may not survive at room temp like the original colony) heat can kill bacteria because it basically goes from room temp straight to lethal for all present bacteria. (The freight train analogy from another comment) Without the slow increase in temp, the bacteria doesn’t have a chance to evolve.
The problem with antibiotics is that people don’t finish doses and that lets the slightly more resistant bacteria survive to pass on its gene. While taking the full dose would have killed all (or at least enough that your immune system could handle what’s left). When one person doesn’t take a full dose of antibiotics, then passes the contagious bacteria to another person who also doesn’t take a full dose, the bacteria is slowly exposed to the antibiotics at just the right rate that the resistant ones survive but the non resistant doesn’t. Just like slowly increasing the temp from the example earlier. And the more resistant it becomes the stronger the antibiotics you have to use. If you repeat the same mistake with the stronger antibiotics on the more resistant bacteria, you just make the problem worse.
Antibiotics resistance is easy. It usually takes one single gene to get resistant, and that gene is already out there. Most bacteria becomes resistant by picking up the already existing resistance genes from the environment. So it can happen within the life time of a bacterium.
Becoming heat resistant is difficult. It requires that all genes of the bacteria become heat resistant. There are heat resistant bacteria that live in 70-75°C but they evolved to be like that over long long time, not in one life time. The same is true for every extreme environment such as high salt or acidic. Also note that living in extreme environments is a shift. Bacteria that can live there, cannot live in “normal” conditions anymore.
And chemicals that are destructive to life and don’t exist in nature (such as soap or chlorine), they are virtually impossible to adapt to.
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