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    Evolution of antibiotic resistance in bacterial populations

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    The evolution of antibiotic resistance in bacterial populations is a direct consequence of natural selection applied by widespread use of antibiotic drugs. When a new antibiotic is first introduced, it kills the vast majority of bacteria exposed to it. The surviving bacterial cells, however, may include individuals whose genomes happen to include a mutant gene that confers resistance. As Darwin understood, individuals carrying the resistance gene will leave behind a disproportionately large share of offspring, which inherit the gene. If the environment consistently contains an antibiotic, bacteria carrying the resistance gene will eventually come to predominate. Because bacteria reproduce so rapidly and have comparatively high rates of mutation, evolutionary change leading to resistant populations is often rapid.

    We have accelerated the pace of the evolution of antibiotic resistance by introducing massive quantities of antibiotics into the bacteria's environment. Each year, U.S. physicians prescribe more than 100 million courses of antibiotics; the Centers for Disease Control estimate that about half of these prescriptions are unnecessary. An additional 20 million pounds of antibiotics are fed to farm animals annually. The use of antibacterial soaps and cleansers has become routine in many households. As a result of this massive alteration of the bacterial environment, resistant bacteria are now found not only in hospitals and the bodies of sick people but are also widespread in our food supply and in the environment. Our heavy use (many would say overuse) of antibiotics means that susceptible bacteria are under constant attack and that resistant strains have little competition. In our fight against disease, we rashly overlooked some basic principles of evolutionary biology and are now paying a heavy price.

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    Solution Preview

    As the first sentence in your question stated, "The evolution of antibiotic resistance in bacterial populations is a direct consequence of natural selection applied by widespread use of antibiotic drugs." This is very true. To prove this fact, take a look at the book entitled Evolution of Infectious Disease by Paul W. Ewald (1994). Get the book. Read it from cover to cover. It's a little technical at times, but it's absolutely excellent. It shows with example after example - all well documented - that bad human behaviour has facilitated the microevolution of microbes towards more and more lethal and deleterious forms.

    This essay question is just excellent, because it outlines a significant issue that the pharmaceutical industry has been trying to keep silent for years. And don't you think that the medical profession (doctors and pharmacists) are innocent bystanders, because they're not. They get a cut ($) out of each and every prescription they give out. It's a money game. It's not about health. It's about big bucks.

    We will not be able to prevent further antibiotic resistance until we stop trying to kill microbes with antibiotics. It's really that simple. The evidence is so obvious, it's not funny.

    What we have been doing and what we will continue to do is produce more and more lethal and very harmful antibiotic resistant microbes. Consider TB (tuberculosis). At one time, it was a ...

    Solution Summary

    The response to this question describes the important work of Paul Ewald, particularly his 1994 book entitled "Evolution of Infectious Disease." In addition, we look at the role of diet, human behaviour, scientific research, and big pharma, each of which contributes to the widespread emergence of virulent antibiotic resistance bacteria.

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