When harmful bacteria invade the body, it is the responsibility of the body’s immune system to locate and destroy the bacteria before the bacteria can do serious harm or even cause death. The system works well until surviving bacteria evolve and become so strong and deadly that the body’s immune system is no longer able to successfully fight off the invaders on its own. Scientists and researchers have developed antibiotic medicines to help the body destroy the bacteria. Unfortunately, surviving harmful bacteria can evolve to be even stronger and deadlier than before, and become resistant to the antibiotics. When one antibiotic is no longer effective, a different one must be used. Researchers continually try to develop new antibiotics, but the improper use of antibiotics is allowing bacteria to evolve so quickly that it has become difficult for scientists and researchers to develop new antibiotics fast enough.
Antibiotics are not only used in humans but are routinely being used in raising livestock. At first, antibiotics were used to treat diseases in cattle, pigs, chickens, and other animals. Then, antibiotics were regularly given to livestock even when they did not have any disease, in attempt to prevent diseases before they occur. Then it was discovered that when livestock are regularly fed antibiotics, they tend to grow faster. That was great news for farmers, because the faster their livestock grow, the faster the livestock can be slaughtered and sold. Livestock can eventually develop diseases due to antibiotic-resistant bacteria, and farmers must find a different antibiotic to use in treating those diseases. Small doses of antibiotics that are fed on a routine basis do not totally kill all the bad bacteria, but in fact enable the bad bacteria to grow stronger and stronger, until they are totally resistant to antibiotics. This can occur in humans also, when a person does not properly complete a prescribed dose of antibiotics but stops taking the medicine when he feels better. If antibiotics are not taken long enough, the bad bacteria are not all killed and surviving bacteria are enabled to grow stronger.
Farmers and ranchers who regularly work with animals which carry antibiotic-resistant bacteria can eventually become infected with the bacteria themselves. The workers may not become sick, but nevertheless can carry and spread the antibiotic-resistant bacteria to others. In fact, the bacteria can invade anyone living within about a mile of the livestock. The bacteria can travel much farther than that, however. When livestock is slaughtered, the antibiotic-resistant bacteria can remain in the meat that is eventually sold in supermarkets and restaurants and can end up being eaten by unsuspecting humans. The only way to prevent illness caused by eating harmful bacteria is to ensure that the meat is cooked hot enough and long enough to kill the antibiotic-resistant bacteria. Not all bacteria will make someone sick, and some may not be harmful at all. But some bacteria, such as Salmonella, can cause severe illness, usually called “food poisoning,” which may require treatment with antibiotics. If the Salmonella bacteria are resistant to the antibiotic, then taking the antibiotic will be useless, and some other antibiotic must be used. If Salmonella bacteria were to become resistant to all available antibiotics, there would be a real problem indeed.
We can learn valuable lessons by studying how bacteria can survive and grow strong enough to become immune to antibiotics. As mentioned already, the bacteria can evolve until they develop resistance. Evolve is the verb; evolution is the noun. Evolution, in this case, is a process in which bacteria are modified (mutated) during reproduction. Some of the cells of the bacteria’s offspring are exposed to an antibiotic. Some of those cells die, but others carry an allele that is more resistant, and they survive. The surviving cells (mutations) reproduce, some of them die, and those which are more resistant to the antibiotic survive. Those survivors reproduce, and so on. Each generation of the mutations becomes stronger and more resistant to the antibiotic. The survival of strong cells and the demise of weak cells is called natural selection. Thus, by evolution and natural selection, harmful bacteria can become antibiotic-resistant harmful bacteria. Another amazing fact is that Salmonella can reproduce every 20 minutes.
Using antibiotics on livestock on a regular basis guarantees production of antibiotic-resistant populations of bacteria. Repetitive development of new antibiotics is not the solution to the problem. One solution would be to stop feeding antibiotics to livestock unless the livestock is really sick. We should find another way to stimulate quick growth of the animals. Surely there are scientists and researchers somewhere in the world who can figure out how to make a non-antibiotic product to stimulate growth. Reserve antibiotics for use only in occasionally treating bacterial diseases, and make sure to use a large enough dose for a sufficient length of time. If these things were done, the antibiotic-resistant bacteria should eventually disappear, by evolution and natural selection.