Antibiotic-Resistant Bacteria: A Simple, Realistic Lab Activity

Every now and then I write a blog post about lab activities that worked in my nonmajors biology class. For example, I have written about reptilobirds (an activity combining meiosis and inheritance), staining banana cells to illustrate digestion in plants, and building models of protein synthesis with candy.

Here’s another topic that nonmajors (and everyone else) ought to know about: the development of antibiotic resistance in bacteria. If you teach biology, you might have learned about antibiotic resistance so long ago that you assume everyone else knows about it too. However, I learned this semester that the misuse of antibiotics is still a real problem. During the week before our “Bacteria and Disease” lab, one of my students came into my office with clogged sinuses. He looked miserable and said that he’d been sick for weeks. He then reported that he had taken some of his roommate’s leftover antibiotics, and although he felt better for a while, he soon got worse again. You did what?! Of course you got sick again! How could you not know that was a bad idea?! I scolded him (more gently than that) and mentally reminded myself that education really does matter.

Photo of Staphylococcus aureus

Staphylococcus aureus. Source: Wikimedia commons

Of course, our lab manual already has an activity that addresses antibiotic resistance. I tried it once or twice. Students used different types of colored pencils (representing various strains of bacteria) to fill in a diagram of lungs in the lab manual. When they tried to erase the pencil marks (i.e., used antibiotics to kill the bacteria), they discovered that not all of the marks would disappear. They were supposed to conclude that antibiotics don’t kill all types of bacteria. The activity was so dull, predictable, and ineffective that I soon abandoned it. For many semesters we’ve showed a video about antibiotic-resistant tuberculosis bacteria instead.

But then I read this article by Eva M. Ogens and Richard Langheim in The American Biology Teacher and I decided to give one of the activities a try. It was appealing because it connects antibiotic resistance directly with something that nearly all students have done: taken a prescription of antibiotics. The simulation uses dice and inexpensive pony beads to model the evolution of bacteria over a course of antibiotics. The pony beads are in three colors to simulate three degrees of resistance to the drugs (we used green for least resistant, yellow for resistant, and red for most resistant).

After a brief introduction, each pair of students is given a petri dish containing a “bank” of 20 green, 15 yellow, and 15 red pony beads. Each student transfers 13 green beads, 6 yellow beads, and 1 red bead to a separate dish, which represents the body and the bacteria currently infecting it. Students are told they are taking antibiotics to fight the infection. They are then instructed to roll the die and record the number in a table. Rolling a 1, 3, 5, or 6 means they remembered to take the antibiotics and get to remove 5 bacteria from the body. Least resistant bacteria die most easily, so green ones are removed first. Once there are no more green ones, yellow ones can be removed. Red ones die last. Rolling a 2 or 4 means they forgot to take their drugs.

Antibiotic resistant beads

The die, “body” (dish with four surviving red beads), bead bank (dish with many beads), and data sheet. Photo by M. Hoefnagels.

Critically, the next step is reproduction: Students add one more of each color bead that has survived in the “body.” This was the only stage at which students tended to make mistakes. Some pairs forgot to do the reproduction part entirely; others put green beads back in the body even after all the least resistant bacteria were supposed to be dead. Both errors change the outcome of the activity, so clear instructions are essential.

Students then repeat the roll/removal/reproduction steps. At each round, they record the number of bacteria remaining until no bacteria remain in the dish. Afterwards, they answer questions on the worksheet. Most of the questions are fairly straightforward, but we were surprised at how many students had a hard time articulating the relationship between bead colors (representing genetic diversity) and the events of natural selection (less “fit” bacteria were eliminated first, leaving the best-adapted to pass their resistance alleles to the next generation).

One of the strengths of this activity is that the bacteria fall into a spectrum of resistance. I’ve observed that even thoughtful students have trouble understanding why antibiotic-resistant bacteria would ever die in the presence of antibiotics. The somewhat-resistant yellow beads and the more-resistant red beads remind students that most bacteria are vulnerable to antibiotics, but some are more resistant than others. Natural selection acts on this genetic diversity.

Note that this simulation lends itself well to graphing activities. One simple idea would be to have students graph the number of bacteria of each color over time. Another would be to collect the data from the entire class and have students graph the relationship between the number of times the antibiotics were forgotten and the number of rounds of antibiotics required to kill all the bacteria.

The writeup in The American Biology Teacher is very good, with one exception: It is difficult to discern from the narrative that 5 bacteria should be removed at each round. We developed a handout that clarifies the instructions and includes a detailed table for recording data. If you want a copy, please leave a note in the comments section and I’ll email it to you.

Reference:

Spreading Disease – It’s Contagious! Using a Model & Simulations to Understand How Antibiotics Work. Eva M. Ogens, Richard Langheim. The American Biology Teacher, Vol. 78 No. 7, September 2016; (pp. 568-574) DOI: 10.1525/abt.2016.78.7.568

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144 Responses to Antibiotic-Resistant Bacteria: A Simple, Realistic Lab Activity

  1. Kim says:

    I would love to have a copy of your handout. I think this would be a great visual activity for my high school students.

  2. Stephanie says:

    Hi Mariëlle…I would greatly appreciate a copy of your handout. I’m trying to get ideas together for a non-majors biology course that doesn’t require a lot of equipment and this seems like a good fit.

  3. Jessica Ardis says:

    I would be most grateful if you would email the handout to me. I am searching for activities to do in my large non-majors bio course and this is perfect! Thank you and thank you for your blog.

  4. Jennifer Potter says:

    This looks great, and I would appreciate you passing along your handout. Thanks so much!

  5. Skye Long says:

    This is my first year teaching nonmajors and this seems great! Can I please get a copy?

  6. P. Lin says:

    Hi, this activity sounds great. Could I also have a copy?

  7. Katie says:

    This looks like an awesome activity! Would you mind sending me your handout? I think I’ll try it with my students. Thanks for the article, it’s hard to find interesting activities I can do that don’t require a higher-tech lab than I have available.

  8. Julia Tarlton says:

    I would love a copy of your handout!

  9. Jill Bucher says:

    I would love a copy of your handout, too.

  10. Laurie H. says:

    I’d love a copy of your handout. Thanks for sharing!

  11. Roberta Harnish says:

    I would love a copy of this activity! Thanks!!
    Roberta C. Harnish
    Indiana University Northwest

  12. Mary E Gard says:

    Hi Dr. Hoefnagels!
    I love this idea and I know students will have fun with it and learn!
    Can I get a copy?
    Thanks! 😀

  13. Lauren Allen says:

    This looks like a great activity! Could I have a copy of your handout? Thanks for sharing!

  14. Lisa says:

    I would love a copy of this activity! Thank you for sharing this wonderful idea!

  15. Ashley Lynn says:

    This sounds great. Could I get a copy of the handout for the activity?

  16. Juanita MacLean says:

    could I get a copy too?

  17. Calvin says:

    I would like to see the handout for this activity. Looks like a fun activity!

  18. Jillian Moore says:

    Hi, I’m a student teacher this semester and I’d love a copy of your handout to use with my students. We’re using antibiotic resistant bacteria as a phenomenon and I think this lab would really drive the point home!

  19. Tammi Kreckel says:

    Hi. May I please have a copy of your worksheet. I teach HS and I would like to try this with my students.

  20. Tracy Espinosa says:

    Very cool! May I also have a copy?

  21. MR says:

    Good evening,

    This is an awesome activity! I teach HS biology and my students generally have a hard time comprehending this at first. Where did you find the activity sheet to accompany this? I would love to try it.

    Thank you!

  22. Cheryl Hach says:

    Hi! Can you please send me a copy of the handout? I’m very excited to try this with my class. Thanks so much!

  23. DM says:

    Would love a copy of the handout too. I’m planning a traditional classroom version of an online course I’ve been teaching to non-majors where they research ARB for discussion posts, but needed something hands-on for the lab and this is perfect – thank you so much!!

  24. K Soto says:

    Would love a copy! Thank you!

  25. L Onsum says:

    Could you also send me a handout? Thank you!

  26. Jennifer Livergood says:

    I would appreciate a copy of the handout!

  27. marcia steeby says:

    This activity looks great. I would love to have a copy of the handout. Thank you

  28. Kristen Piehl says:

    Thank you for being willing to share your handout; I’d love a copy. I’ve tried more complex labs in my non-majors biology course and it ends up being a complete disaster. This sounds like a great activity to teach this concept without the mess!

  29. Asma says:

    I would love to have the copy—If it is in the word document, would be great.

  30. julie says:

    Hello, its is such a relevant activity and I would appreciate if you send me a copy of the word document.

  31. Suzie Flegel says:

    Hello,
    This is exactly what I was looking for. I would love a copy of this activity!

  32. Sara D'Amico says:

    Hi. Thank you so much for your offer of sharing this excellent activity. I am interested in a copy of the handouts. I appreciate your kindness! Have a great day.

  33. Luisa McHugh says:

    May I please have a copy of this activity and worksheet as well.
    Thank you so much.

  34. jami grant says:

    I would love a copy of the activity! Thanks!

  35. Emily Perling says:

    I would love a copy of this!

  36. Karin says:

    This looks great! I would love to have a copy as well! Thank you so much

  37. Jess O'Boyle says:

    I’d love a copy please. Looks great

  38. Zac Stone says:

    Great article! I really like the simplicity of it. May I have a copy of the handout? Thanks!

  39. R. Jeremy Johnson says:

    Thanks for sharing the activity. I love games in the classroom. I look forward to trying it in my own nonmajors science course. Can you please send me a copy of the handout?

  40. Pingback: Antibiotic resistance in the lab … with actual bacteria! | Teaching nonmajors biology

  41. Cheryl Laursen says:

    I would like to receive a copy of the handout for my nonmajors biology class. It will be a welcome addition to the lab. thank you.

  42. Shawn Snaples says:

    Could I please get a copy of the worksheet & any other write up on it? Thanks!

  43. Leah C says:

    Hi there! I’m doing my masters in AMR research and am doing a presentation for some highschool students in my lab. Would you mind sending me the handout so that I could do this with them?
    Thanks so much!

  44. SG says:

    Hey! My students are learning this right now, and I would love to look at a copy of your handout for the activity so that I can try it with my classes!

  45. Rebecca Dix says:

    Hi. After doing other versions of an activity like this I came across your entry. I’m an AP Bio teacher and would like to have a copy of your writeup.

  46. Alissa Petrelli says:

    Thanks for sharing! This activity looks great for my AP Bio class. Would love to see your handout! Thanks again for sharing!

  47. Vyjayanti Joshi says:

    I would greatly appreciate a copy of the handout. Thanks!

  48. J. J. says:

    I would also really appreciate the handout!

  49. Mary Bolles says:

    May I please have a copy of the lab? Great activity!!

  50. Michelle Hughes says:

    I would love to have a copy of instructions to this lab. This would make a great hands on visual aid for my students!
    Thanks!

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