Why aren't human populations evolving to produce immune systems that are able to fight off MRSA and other "superbugs"?

There are genes that code for different cell receptors that detect foreign substances. And for the immune system to fight these superbugs, the genes encoding these receptors must mutate and evolve. Humans have a slow rate of evolution, slower than bacterial evolution. Then not only human genes mutate at a very slow rate, but insect genes mutate very fast and can improve their strategy to evade the immune system.

Explanation:

A mutation is a random change in the nucleotide sequence or in a gene, which produces a variation in its characteristics and which is not necessarily transmitted to the offspring. They occur spontaneously by the action of mutagens, which are physical, chemical or biological agent that changes the genetic information of an organism and thereby increases the frequency of mutations above the natural level. In multicellular organisms, mutations can only be inherited when they affect the reproductive cells, called gametes (egg and sperm) A consequence of mutations can be, for example, a genetic disease, or it can also be a favorable improvement such as being able to fight against a virus. However, even if in the short term mutations could detrimental, they are essential for our long-term existence becuase without mutations there would be no change, and without change life could not evolve.

The immune system is the body's natural defense against infections, such as bacteria and viruses. The body attacks and destroys invading infectious organisms by the coordinated action of cells and proteins. Any substance or compound produced by an organism is a potential antigen when it is recognized as foreign by the immune system of another organism, whether it is of the same or a different species. In addition, the genes code for different cell receptors that detect these foreign substances. And for the immune system to fight these superbugs, the genes encoding these receptors must mutate and evolve. But, humans have a slow rate of evolution, slower than bacterial evolution. Then not only human genes mutate at a very slow rate, but insect genes mutate very fast and can improve their strategy to evade the immune system. Therefore, the human population may not have mutations that improve the immune system to help it fight againts these superbugs.