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.
Write a 1-2 page paper on how you think the further evolution of
antibiotic resistance can or cannot be prevented |
