Something’s Not Adding Up

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About This Module  

Topics: Human health, epidemiology, pathogens (bacteria), antibiotic resistance

Grade levels: 9-12


Students investigate a family health situation when a dad’s cough just keeps getting worse and he refuses to go to the doctor!  He says the doctor will give him antibiotics and he doesn’t want to become resistant to them.  He heard on the news how bad it is to become resistant to antibiotics and he doesn’t want to chance it. The student reports that she had heard the news report, too, and something’s not adding up. How can she help her dad?

Learning Objectives  

To better understand antibiotic resistance, students should be able to:

  • Explain antibiotic resistance and how it can develop.
  • Describe the consequences of antibiotic resistance to patient care.
  • Explain the seriousness of the problem of antibiotic resistance worldwide. 

Next Generation Science Standards

Standards Aligned to PBL Modules

Scenario (with possible answers) 

girl with her head on a desk with booksYour alarm clock goes off and you can barely open your eyes to shut it off.  You are so tired!  How are you going to be able to stay awake in class?  Every time you actually fell asleep, you woke up again as your Dad had another bout of coughing. It is getting worse and as usual, he won’t go to the doctor.

You get ready for school, walk into the kitchen, and hear your Mom and Dad arguing. Your dad coughs every time he tries to talk and the cough sounds pretty bad.

“You have to go to the doctor and get something for this!” You could tell that your mom was going to start yelling pretty soon.

“I’m taking this cough medicine I got from the store, but it’s not working. I don’t want to go to the doctor. He’ll just give me the same thing!” my Dad coughs out.

“Dad, tell him what you took and what didn’t work.  He won’t give you the same thing.  You’re sounding really bad, Dad, and looking even worse. Why not go and get something?  Remember when I got that infection and had to take those antibiotics? They worked pretty fast and I got better.”

man coughing   “You really needed those antibiotics, but I don’t—not yet.  And we just heard on the news that if you take antibiotics, you can become resistant to them and then they don’t work when you really need them.  I don’t want that to happen.”

You think there wasn’t much to say to that one.  You heard the story on the news about how serious antibiotic resistance was and you even had a section in your bio book about it last week, but something wasn’t adding up here.  You are studying bacteria and infections in biology class and you have to choose a topic to research. You had been struggling for a few days to find a topic—always the hardest part of an assignment like that—and now it looks like you have it! You’ll research antibiotic resistance for the assignment topic, find out what wasn’t adding up, and help your dad at the same time.

 Your task:

Find out what antibiotic resistance is, how it occurs, and what the consequences are. Then, be ready to explain it to your teacher and classmates for your assignment and to your mom and dad.  Make sure you investigate the topic thoroughly. Your teacher and your parents will have more questions.

Guiding questions:

  1. What is antibiotic resistance?

Antibiotic resistance is the inability of an antibiotic to kill a bacterial growth. an antibiotic is a drug which fights bacterial infections by either killing the bacteria or by interfering the processes they use to grow and multiply.

Bacteria can become resistant to antibiotic effects. This results is dangerous infections that are difficult to treat and can lead to disability and death.

  1. How does antibiotic resistance develop? What circumstances cause resistance to develop?

Bacteria can develop resistance to an antibiotic naturally. But, other mechanisms can produce resistance and as these mechanisms become more prevalent, incidences of resistance can increase and pose serious health threats.

add in lines about misuse of drugs—in first paragraph after plates with discs

The following processes can cause antibiotic resistance:

  • genetic mutation—Mutations are changes in the bacteria’s genetic code. These genetic changes can produce resistance that never existed in the bacteria before the mutation. Mutations can work in a variety of ways to produce resistance to different antibiotics. Some mutations allow bacteria to produce chemicals that inactivate antibiotics. Other mutations cause the openings in the cell wall that allow the antibiotics to enter to close.

Antibiotic resistance can spread as bacteria move from place to place on people or objects or by way of a vector (an organism that can transmit disease). People pass along the resistant bacteria to susceptible people by coughing or contact.

  • selective pressure—Bacteria evolve over time and can adapt to their environment. If their environment becomes threatening, as in the introduction of an antibiotic, those microbes that have genes that carry resistance to the antibiotic survive. These survivors are the microbes that replicate and pass on the resistance capability. Soon, resistance is the dominant feature of the bacterial population.
  • genetic transfer—Microbes may get genes from other microbes that may include genes for drug resistance
  • inappropriate antibiotic use—Overuse of antibiotics can lead to antibiotic resistance, as can prescribing broad spectrum antibiotics instead of a more narrow spectrum antibiotic.
  • antibiotic use in agriculture—Scientists believe that adding antibiotics to agricultural feed produces antibiotic resistance bacterial populations. Over half of the antibiotics in the United States are used in food animal production and antibiotics for animal use are the same as or close to those used in humans.
  1. Is there something “not adding up” with your dad’s comment about not wanting to become resistant to antibiotics? Can your Dad become antibiotic resistant by taking antibiotics? Explain.

Her Dad thinks that taking antibiotics will make him resistant to them and then they will not work to kill another bacterial infection he may get. People do not become resistant to the antibiotic.  It is the bacteria that become resistant.

  1. What are you going to tell your dad about going to the doctor to find out if he needs an antibiotic?

Her Dad should go to the doctor and be evaluated.  If he has a bacterial infection, he may need an antibiotic to get better.  If the doctor prescribes an antibiotic, her Dad should take the antibiotic as directed. Improper antibiotic use can result in antibiotic resistant bacteria.

Her Dad is susceptible to being infected with an antibiotic resistant bacteria whether he takes antibiotics or not. If the bacteria have become resistant through any one of the various mechanisms that can cause resistance, then he will have a problem with treatment choices even if he had never taken an antibiotic. People don’t develop resistance; the bacteria develop resistance.

  1. How serious is the problem of antibiotic resistance? Should we be concerned? What are some of the consequences of antibiotic resistance?

Antibiotic resistance is a serious problem worldwide. Multi-drug resistant strains of bacteria cause serious illness that is difficult to treat. In some cases, lack of effective treatment results in death. Treatment is less effective, the illness is much more severe, and the cost of treating the patient is much higher than in a non-resistant infection.

Part II (Optional):  

Devise an experiment that demonstrates the ability of a bacterium to develop antibiotic resistance.

What would be your hypothesis concerning the outcome of the experiment?

What would your data look like from this experiment?

Teacher Note: Answers will vary. Look for the use of the scientific method for experimentation, including variables, controls, procedures, data collection, and conclusions based on the results of the experiment.

Hypotheses and expected data will reflect experimentation selection.

Sample Rubric 

Information about constructing and implementing rubrics for problem-based learning strategies can be found in Developing Rubrics in the Teacher Professional Development section.


► Have the students watch the video “Frontline: The Nightmare Bacteria”. This excellent PBS Frontline report (54:11 minutes) details three case studies of infections from “Superbugs”— bacteria that are antibiotic resistant. Background content about bacteria and antibiotic resistance is highlighted.

The Teacher Study Guide for this video is in the Teacher Pages section.

► Invite a microbiologist from a local university to discuss antibiotic resistance with your class.

► Invite someone from the local hospital microbiology lab department to discuss how they test for antibiotic resistance during culture and sensitivity testing on bacterial specimens. They may be able to bring sealed culture specimens with antibiotic discs showing resistance or susceptibility. If not, you may be able to take your students on a tour of the microbiology lab.

► Show the following short videos as you review antibiotic resistance with your students. The concept is sometimes a difficult one to grasp and many students and adults mistakenly think what the father in the scenario thought—that the patient develops a resistance to antibiotics.

CDC—The Threat of Antibiotic Resistance
A 1:28 minute animated video describing the threat of antibiotic resistance to public health.

CDC—Making Health Care Safer: Stop the Spread of Antibiotic Resistance
A 2:18 minute video describing the status of the spread of antibiotic resistance in healthcare facilities.

Additional Resources 

Additional resources about bacteria and antibiotic resistance can be found:

in the Key Resources section in the Pandem Disease Center at

in the Something’s Not Adding Up background materials at

in the Internet Resources for Antibiotic Resistance information at