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Bacteria undergo genetic mutations at a much quicker rate than humans. Often this will prove fatal to the mutated bacteria, but since bacteria are so plentiful, and since they reproduce so quickly, this poses no threat to the overall bacteria populations.

Every once in a while, just by chance, one of these genetic mutations causes the bacteria to become resistant to a particular antibiotic. For example, a bacteria's DNA may mutate and begin producing a chemical which inactivates penicillin.

Now imagine that the mutated bacteria finds its way into a human host. When the human realizes she is sick and begins taking penicillin, all of the non-mutated bacteria cells are killed, leaving only the mutant bacteria to thrive. It can reproduce without risk from the penicillin, and in short order the patient has an infection consisting ENTIRELY of mutated, penicillin resistant bacteria. The patient can then spread the infection to others, and penicillin will prove useless to combat the illness.

In short, it is the frequent genetic mutation, large bacteria population, and short reproductive time which allows such quick resistance to develop.

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βˆ™ 2011-04-07 13:54:15
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Q: Why are antibiotic resistance able to evolve in bacteria so quickly?
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Why does antibiotic resistance evolve in bacteria?

A random mutation in one bacteria can result in this. think of a huge population of bacteria. billions of bacteria. and only 5 or so have the resistance by a random chance (random mutation). the antiobiotics will kill all of bacteria, except for the 5 with the resistance. Then, only those 5 will reproduce. since they reproduce asexually, this resistance will be passed on to all of the daughter. Then, all of sudden, there are a lot of bacteria around that are resistant to the antibiotic... it can also occur by conjugation, which is when a bacteria inserts its DNA into another bacteria. this can result in the second bacteria having the resistance too. this is a very basic description of the process.

Why are bacteria developing resistance to antibiotics?

Like all living organisms, bacteria evolve through mutations. Repeated exposure to antibiotics means that those mutations which have evolved resistance are better able to survive and pass on the antibiotic-resistant genes.

What is wrong with antibiotics?

Nothing, except people that use them inappropriately or incorrectly allowing bacteria to evolve resistance (making the antibiotic useless). The problem is people, not the antibiotics.

Why does an antibiotic not work the same for all bacteria?

Bacteria also do evolve. If one bacteria is mutated, and survives an attack by antibiotic, he multiplies and forms more bacteria which are more resistant against antibiotic. As days of surviving antibiotics and multiplying eventually creates a bacteria which is resistant against it.

What is antimicrobial resistance?

Antimicrobial resistance is similar to antibiotic resistance. Microbes evolve to survive exposure to both antimicrobials and antibiotics when such products are used excessively or inappropriately.

How do viruses and bacteria evolve so quickly?

Because of their ability to undergo _____, viruses can rapidly evolve.

Can antibiotics cause resistance in bacteria?

Not directly, a individual bacterial cell can not suddenly develop a resistance to an antibiotic but bacteria in general can develop resistant to particular antibiotics. The mechanism for this development of resistance is natural selection/evolution, bacteria evolve to become resistant - in the presence of antibiotics the more resistant individuals are preferentially selected (they survive) and gradually the whole population is made of resistant individuals. This happens because bacteria reproduce so fast.

What Species of bacteria can evolve more quickly than species of mammals because bacteria have?

Most bacteria evolve quickly (in relation to mammalian evolution) because their reproductive cycle is much shorter than "higher" life forms.

Why do some bacteria become resistant to antibiotics?

Bacteria will evolve the molecular structures in various components to become resistant to antibiotics. For example, if an antibiotic works by competitive inhibition (ie - the antibiotic binds to the active site of the protein in it's cell membrane instead of another element the bacteria needs to survive), the bacteria may evolve an alternate molecular structure of that protein so the antibiotic won't fit in the binding site.

Is antibiotic resistance irreversible?

In my opinion, a simple answer to this would be yes. By using antibiotics or actively trying to kill bacteria, you are actively putting a selective process on that bacterial culture. When an antibiotic is first in use in a clinical setting, generally most (>99%) of the bacteria are susceptible to the antibiotic and therefore will die - however a very small number will have a slight variation (the range of resistance mechanisms are wide and diverse - from enzymes that can break the antibiotic down - to efflux pumps in the membrane that can actively pump the antibiotic out of the cell) that will allow them to survive. This surviving "resistant strain" will then continue to grow and spread as the susceptible strain is continually selected against by the continued use of that antibiotic. This eventually leads to the resistant strain dominating the overall community, and so antibiotic resistance has become prevalent. There are many type of antibiotic that act to kill bacteria in a variety of ways (penicillins break down bacterial cell walls, tetracyclines inhibit protein synthesis), so in the past when bacteria have become resistant to one type of antibiotic, we simply treated them with another type. The difficulty of this is that it means we have continually selected for bacteria that are resistant to more and more types of antibiotic, leading to MDR (multi-drug resistance). With a limited number of antibiotics available and the number of new antibiotics being discovered annually having decreased over the last decade, these MDRs are causing infections that are very difficult to treat. As such, coming back to the question, no antibiotic resistance cannot be reversed because it is a natural for bacteria to adapt and evolve antibiotic resistance when antibiotic use in clinical settings provide a perfect selection process. However, its not all doom and gloom. Many biotech and pharmaceutical companies have now realised that the future of antibiotics is to intelligently design molecules (drugs) that target antibiotic resistance, making these strains susceptible again, or even to develop drugs that bacteria can't gain resistance to due to their design. P.S Antibiotic Resistance has also been observed in bacterial cultures that have been grown from soil samples obtained from permafrost thousands of years old (D'Costa et al 2011). Therefore antibiotic resistance has been present in numerous bacterial species well before humans started using antibiotics in a clinical setting. A link to the D'Costa et al article can be found in related links.

Why is a lysogeny advantageous to a bacteriophage?

The genetic material of the bacteriophage can be passed on to future generations of host cells. Causes resistance on bacteria. Causes the bacteria to evolve.

How do bacteria change and evolve?

how do bavteris change and evolve

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