CIS Unit
Why Evolution Matters
“Evolution of Antibiotic Resistance”
(9th and 10th grade Biology)
 SC.912.L.15.13: Describe the conditions required for natural selection,
including: overproduction of offspring, inherited variation, and the struggle
to survive, which result in differential reproductive success.
 HE.912.C.1.8: Analyze strategies for prevention, detection, and treatment of
communicable and chronic diseases.
CIS Lesson
Why Evolution Matters
“Evolution of Antibiotic Resistance”
1. Hook Engage:
http://www.pbs.org/wgbh/evolution/library/10/4/quicktime/l_104_03.html
2. Question #1
Predict how the development of antibiotic resistance is related to natural selection.
3.
Distribute article.
4. Pre-teach vocabulary:
a. Eradicate
b. Resurgence
c. Upsurge
d. Paradox
e. Strain
f. Resistance
g. Judicious
h. Legions
i. Detoxification
5. Text-marking:
C = Cause of antibiotic resistance
S = Solutions for antibiotic resistance
X = Consequence of antibiotic resistance
6. Question #2
How is the development of antibiotic resistance related to natural selection? In your reply, be sure to include in
your discussion the following words or their variants: selection pressure, resistance, random mutation, natural
selection, evolution.
7. Note-taking: Take notes on “Who is responsible for the development and cessation of antibiotic resistance?”
8. Vote: With whom does the moral obligation exist to prevent antibiotic resistance: the doctor, the patient, the
government or the pharmaceutical industry?
Group
Individual
Recount Individual
Doctor
Patient
Government
Pharmaceutical Industry
9. A representative from each group will present an argument for the team’s position. Teacher will conduct a
recount to see if any of the arguments lured students away from their original choice.
10. Question #3
According to the text and your discussion, with whom does the moral obligation exist to prevent antibiotic
resistance: the doctor, the patient, the government or the pharmaceutical industry? In your response, explain
how bacteria acquire resistance through the process of natural selection. Synthesize what you viewed in the
video with what you learned from your reading. Also, include in your discussion an examination of the societal
risks that come with increasing antibiotic resistance.
Why Evolution Matters
“Evolution of Antibiotic Resistance”
Hook Video
Watch the
following video:
Since
http://www.pbs.org/wgbh/evolution/library/10/4/quicktime/l_104_03.html
What is happening
in the video?
#1 Predict how the development of antibiotic resistance is related to natural
selection.
#2 How is the development of antibiotic resistance related to natural selection? In
your reply, be sure to include in your discussion the following words or their variants:
selection pressure, resistance, random mutation, natural selection, evolution.
Evolution of Antibiotic Resistance
Forty or fifty years ago, thanks to antibiotics, scientists thought medicine had all but eradicated infectious
agents as a major health threat. Instead, the past two decades have seen an alarming resurgence of infectious
diseases and the appearance of new ones.
Today, the AIDS virus, tuberculosis, malaria, diarrheal diseases and other
infectious agents pose far greater hazards to human existence than any other
creatures.
This upsurge of infectious disease is a problem we have unwittingly created for
ourselves. The rise of rapid, frequent, and relatively cheap international travel
allows diseases to leap from continent to continent. Inadequate sanitation and
lack of clean drinking water are another factor. A third is the "antibiotic paradox" - the overuse of the "miracle drugs" to the point that they lose their potency.
Whenever antibiotics wage war on microorganisms, a few of the enemy are able to survive the drug. Because
microbes are always mutating, some random mutation eventually will protect against the drug. Antibiotics
used only when needed and as directed usually overwhelm the bugs. Too much antibiotic use selects for more
resistant mutants. When patients cut short the full course of drugs, the resistant strains have a chance to
multiply and spread.
In some countries, such as the United States, patients expect and demand antibiotics from doctors, even in
situations where they are inappropriate or ineffective. Our immune systems will cure many minor bacterial
infections on their own, if given the chance, and antibiotics have no effect on viral infections at all. Every time
antibiotics are used unnecessarily, they add to the selective pressure we are putting on microbes to evolve
resistance. Then, when we really need antibiotics, they are less effective. The fact that some bacteria survive,
reproduce, and become the dominate organism in the presence of antibiotics is explained by the theory of
natural selection which states that organisms better suited to their environment survive and reproduce more
successfully.
While drug companies race to develop new antibiotics that kill resistant microbes, scientists are urging
patients and doctors to limit antibiotic use.
That means not asking for penicillin when all you have is a cold, since colds are caused by viruses that are not
affected at all by antibiotics. It means taking all the pills that are prescribed, even if you're feeling better.
Physicians have to resist prescribing the strongest and most broadly effective drugs unless the disease
absolutely requires it. If society adopts these measures rigorously, the drugs may regain at least some of their
lost "miracle" powers.
Available at: http://www.pbs.org/wgbh/evolution/library/10/4/l_104_03.html
Tamar Barlam is director of the Project on Antibiotic Resistance at the Center for Science in the Public Interest, in
Washington, D.C. An M.D. board-certified in infectious disease, she has been involved in antibiotic policy and physician
training in hospitals. She is on leave of absence from Harvard Medical School where she is an assistant professor of medicine.
Available at: http://www.pbs.org/wgbh/evolution/survival/enemy/statement_01.html
As an infectious disease specialist, I have long been concerned about the misuse of antibiotics. Responsible
uses of those precious drugs to minimize antibiotic-resistant infections -- by physicians, veterinarians,
consumers, farmers, and livestock producers -- is crucial, but other steps must be taken.
Recently, an "action plan" was developed by the Centers for Disease Control and other agencies, but it has not
been adequately funded. Even so, the plan might better be called an "inaction" plan, emphasizing education
and research rather than stronger interventions, such as mandatory programs at hospitals to ensure judicious
antibiotic use. Such programs can be highly successful when overseen by an antibiotics expert.
Pharmaceutical companies play an indispensable role in developing new antibiotics, but they are also part of
the problem. The companies have legions of salespeople that encourage doctors to use their antibiotics.
Antibiotic prescribing should be based on what is best for the patient and what the scientific literature tells us,
not on a sales pitch. Similarly, doctors who receive funding from these companies should be carefully
monitored regarding how they promote and prescribe their antibiotic products.
Antibiotics that are related to human use should be banned from use in food animals. Two years ago, the
Center for Science in the Public Interest and other organizations petitioned the Food and Drug Administration
to do just that, but the FDA has indicated that it likely will never ban most of the agricultural uses of the drugs.
A bill that would make it easier for the FDA to ban inappropriate uses of antibiotics on farms was introduced in
Congress last year but died a quiet death.
It is clear what steps must be taken if the priority is health. The challenge is for health experts and the public
to overcome the political power of the drug companies.
Stephen R. Palumbi is professor of biology at Harvard University, where he teaches evolution, marine biology, and molecular
ecology, and conducts research on populations and molecular genetics of marine animals. He is the author of The Evolution
Explosion (2001), about how evolution, including antibiotic resistance, is sped up by human technology.
Available at: http://www.pbs.org/wgbh/evolution/survival/enemy/statement_04.html
Stuart B. Levy, professor of medicine and of molecular biology and microbiology, is the Director of the Center for Adaptation
Genetics and Drug Resistance at Tufts University School of Medicine and staff physician at the New England Medical Center.
He is president of the international organization Alliance for the Prudent Use of Antibiotics and author of The Antibiotic
Paradox: How Miracle Drugs Are Destroying the Miracle (1992). He is chief scientific officer of Paratek Pharmaceuticals, Inc.
Available at: http://www.pbs.org/wgbh/evolution/survival/enemy/statement_03.html
Approaches to reducing antibiotic resistance include undoing current damage, reversing it, and slowing
evolution down. Undoing damage will often entail new antibiotics that overcome current resistance. But the
basic arms race still churns, costly in terms of new drugs and even lives.
It is possible in some cases to reverse evolution -- to encourage the re-emergence of drug-susceptible bacteria
by removing the selective pressure of drugs. Resistance mechanisms sometimes generate an energetic cost,
like extra proteins that the bacteria must make for drug detoxification. In the drug's absence, non-resistant
bacteria replicate faster, and eventually take over. Unfortunately, few opportunities arise to take advantage of
this tradeoff because many bacteria have evolved low-cost antibiotic resistance.
To slow evolution, we can reduce selective pressure by avoiding antibiotics when they are not useful, (e.g.,
viral infections), or substituting other anti-bacterial strategies instead of chemical control. In agriculture,
integrated pest management employs physical reduction of insect pests and thereby reduces reliance on
insecticides. Hospitals also use this strategy, except they call it hand-washing.
A number of corrective measures can be taken right now. Farmers should be helped to find inexpensive
alternatives for encouraging animal growth rather than using antibiotics at low levels. The public can wash raw
fruit and vegetables thoroughly to clear off both resistant bacteria and possible antibiotic residues. When they
receive prescriptions for antibiotics, patients should complete the full course of therapy (so that all pathogenic
bacteria die). Consumers should not demand antibiotics for colds or other viral infections. They can continue
to put antibiotic ointments on small cuts, but they should think twice about routinely using hand lotions and a
proliferation of other products now imbued with antibacterial chemicals. When possible, physicians should
prescribe an antibiotic targeted specifically to that microbe instead of choosing a broad-spectrum product.
Overall, reversal of the bacterial resistance problem will require public health officials, physicians, farmers,
and the general public to think about the effects of antibiotics in new ways. The time has come for our global
society to accept bacteria as normal, generally beneficial components of the world and not try to eliminate
them -- except when they give rise to disease. Let's revive the drug-susceptible bacteria to out-compete the
drug-resistant ones.
Directed Note-Taking
Why Evolution Matters
“Evolution of Antibiotic Resistance”
Directions: Record notes containing the most important information relevant to the guiding question.
Guiding Question:
Who is responsible for the development and cessation of antibiotic resistance?
Check Relevant Categories
Page/
Paragraph#
Notes
Collaborative Work:
After completing your chart, be prepared to compare your notes with others.
Patient
Doctor
Govern’t
Pharma
Industry
Question Generator
Directions: Carefully review the text for words, phrases or statements that create questions in your mind. Discuss these
questions in your group, and then document your group’s questions below.
Why Evolution Matters
“Evolution of Antibiotic Resistance”
Do your questions pertain to any of the categories on the right? If yes, place a check in the appropriate box.
Page/
Paragraph#
Notes
Collaborative Work:
After completing your chart, be prepared to compare your notes with others.
Patient
Doctor
Govern’t
Pharma
Industry
Directions: Write your response to the following question using information you learned in this unit. You must organize your
position with a thesis statement that is supported in your body paragraphs with evidence from the text. You may also use
research from additional outside sources. Be sure to cite those sources! Your formal argument must include four or more
paragraphs with a clear beginning, middle, and end.
#3 According to the text and your discussion, with whom does the moral obligation exist to
prevent antibiotic resistance: the doctor, the patient, the government or the pharmaceutical
industry? In your response, explain how bacteria acquire resistance through the process of
natural selection. Synthesize what you viewed in the video with what you learned from your
reading. Also, include in your discussion an examination of the societal risks that come with
increasing antibiotic resistance.
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