KOROHO said:
Viruses do adapt to antibiotics. But they remain viruses.
Viruses do not adapt to antibiotics. First off, antibiotics are useless against viruses. They only work against bacteria, which is completely different from a virus.
You can, however, get vaccinated against certain viruses such as flu. Usually this is done by injecting a weakened or dead sample of the virus into your body. Your body then develops antibodies against that particular virus, so if that particular virus enters your body again, it will be recognized as an enemy and destroyed before it can to any harm.
The problem with flu is that it does mutate and change rapidly and often. Once it mutates, the antibodies that your body has developed are no longer useful against this different strain of the virus. Your body is not able to recognize a different strain of the virus as an enemy, and act against it. But the virus itself does not change as a response to the vaccination. It does not react to the fact that you have been vaccinated, and actively try to do an end-run around the vaccination by mutating. The mutation is random. But the mutation gives the new disease variant the advantage of being able to survive in a body even tho the body has been vaccinated. Thus, the new variant can become dominant since the old variant can no longer survive under these conditions.
With regard to antibiotics and bacterial infections: when you have a bacterial infection, you are infected with millions of enemy bacteria that cause you to become ill. The infection is great enough that your body cannot fight off the infection on its own, so you get some antibiotics. The problem arises when you either don't take all of your medication because you start to feel better before your are done, or the medication itself isn't powerful enough to fully eliminate the bacterial infection. Those last remaining bacteria are stronger than the ones that were killed off. Something in their genetic makeup enabled them to survive the antibiotics. Since they are the only ones left, they are the only ones reproducing. When they multiply (which they do pretty much constantly) they will then pass along the genetic predisposition to be more resistant to the antibiotics that you were taking. Now you get sick all over again, with the same disease, the same bacterial infection, but the same medication no longer works as well, or even not at all. You have to find a different, more powerful antibiotic to kill off the infection. This is a very active example of evolution. The bacteria does not actively react to the medication and seek to change itself to defeat the medication. It is thru random genetic mutations that a small percentage of the bacteria simply are more resistant to the antibiotics.
This becomes a problem when people who are ill insist on being treated with antibiotics, even tho there is no evidence that they have a bacterial infection. Needlessly introducing antibiotics into your body can kill off some harmless bacteria, but leave a small number of stronger bacteria to reproduce, which may become harmful. Or if you fail to take all of your medication and fully eliminate the infection, the remaining bacteria will come back stronger overall. Then we get Super Bacterial infections that don't respond to the normal antibiotics. This is happening with some diseases, because of needless medications and people failing to complete their medications.
