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

  1. Emily Spiering says:

    Hi!
    I would love to use this in my HS class, could I get a copy of the handout?
    Thanks!

  2. Andrea Orji says:

    Could I please have a copy of your worksheet?

  3. Erin Gonzales says:

    This looks great. Could I get a copy? Thanks!

  4. Kayla Duke says:

    Hello, this looks like a wonderful resource. Could you please send me a copy of the handout for this activity?

  5. Paul Cermak says:

    Would it be possible to get a copy of this. Looks like a great activity

  6. Sharon C says:

    I would love a copy as well. This sounds like a great lab! Thank you!

  7. Matt Korbutt says:

    Could I please get a copy of the antibiotic-resistant bacteria activity? I’d like to try it in my microbiology unit. Thank you for the resources!

  8. Morgan C says:

    Hi! This looks awesome for our bacteria unit! Would you mind emailing me a copy of the handout?

  9. Megan says:

    Hi! May I have a copy of the handout? I would love to use this in my high school biology class. I enjoyed the article!

  10. Tami Edwards says:

    Thank You…This sounds awesome! May I use this with my HS bio classes? If so, may I have a copy of your handout? 🙂

  11. Jess says:

    Hi! I’d love a copy of this! Thank you so much for sharing!

  12. Rebecca W Carter says:

    Hi, I would love to use this resource. Thank you for the great lab!

  13. Emily Welch says:

    Hi! This is an awesome activity! Could I get a copy of your materials to use in my human bio course?

  14. Lindy Spicer says:

    Can I also get a copy? We are doing inquiry hub biology and this would be a fun activity to reinforce during our intervention period.

  15. Irene H says:

    Hi, This looks as an awesome activity! May I have a copy of the handout?

    Thank you!

  16. Justine says:

    Hello,
    What a great activity! Could you please send me a copy? Thanks!

  17. Alessandra Barrera says:

    Hello, I would love a copy of your handout.

  18. Krystal Gayler says:

    Can I please have a copy of this handout?

  19. Amy Myszka says:

    Can I please get a copy of the handouts for my Living Environment class? Thank you!

  20. Stephanie Camacho says:

    I would love to have a copy of this handout! Thank you so much!

  21. Jen reader says:

    Hi! This looks super fun – if it is not too much to ask – could I have a copy as well?

  22. Jennifer DesRochers says:

    Hello! I would love a copy of this activity for my anatomy class!

  23. Rachel says:

    This is awesome! Can I get a copy of your handout to try in my class as well?

  24. Eric E. says:

    Hello, I teach a non-majors class as well and this would be a wonderful activity for our evolution section. May I have a copy of the handout as well? Thank you!

  25. Cindy Richards says:

    This is a fantastic resource. Could you please send me a copy of the handout? I’d love to try this with my classes. Thank you!!

  26. Janice Scoville says:

    Thank you for your detailed assessment of the lesson. I have been looking at a few activities. Your insight is very helpful. Can you tell me how you prepared the students ahead of the activity, and of course, may I also have a copy of your handout?

    • Hi! I just sent you the handout. As far as student preparation goes, this activity is included in the lab manual for the course. In theory, students will have read through it before coming to lab. In practice, most are unprepared of course! It’s pretty self-explanatory though, and students will already have learned about natural selection by the time they do the lab. I hope this helps!

  27. I too would appreciate the PDF you created. Thank you.

  28. Kathleen McCarthy says:

    This looks great! Could I please get a copy of the handouts? Thank you.

  29. This sounds wonderful! Could I please have a copy? Thanks so much!

  30. Kensey says:

    Would you please send me this lab?

  31. Lauren says:

    I would love a copy of your handout – thanks for your willingness to share!!

  32. Jenn says:

    Hi! May I have a copy of the handout? I would love to use this in my high school biology class. I enjoyed the article!

  33. Celeste says:

    Hello, I was wondering if I may have a copy of the handout. This seems like a great activity!

  34. Mandy Reynolds says:

    Would love a copy for my biomedical technology emerging and reemerging disease unit!

  35. Jasmine says:

    What a great modelling activity. I think my grade 11s would benefit from the hands on aspect. Can I get the lab sheet? Thanks!

  36. Travis Cox says:

    I would also love to have this activity for my anatomy and physiology course.

  37. Kayla G says:

    Can I please have a copy of the handout – it looks great!

  38. Heather DeLisle says:

    Would it be possible for me to have a copy to use this in my freshman biology class?

  39. JRB says:

    Hello! I am interested in using this lab activity in my non-majors course this semester. Could I get a copy of the handout? Thanks!

  40. Rebecca says:

    Hi,
    If possible I would love a copy of this handout!
    Thanks!

  41. Ho Jia Yee says:

    Hello! It sounds really interesting! Can I get a copy of the worksheet as well? Thanks!

  42. Terri Moore says:

    I would love a copy of this for my high school class. Thank you!

  43. Sheryl Juenemann says:

    This looks great! May I have a copy of your handout, please?

  44. Neal P Fox says:

    Awesome! Would you mind sharing this worksheet with me? Thank you!

  45. Michelle Puig says:

    Hello! Looks like a great activity, can I get a copy of the materials too?
    Thanks!

  46. Tom DiMarco says:

    This looks like a great activity! Could I please get a copy of the handout? Thanks!

  47. Sarah Barnett says:

    Hi. I would love a copy of this activity. I have done a similar activity with marshmallows and candy, but I like this better.

  48. Lindsay says:

    Hi! I do a very similar activity but I’m trying to make it clearer for my students. Can I get a copy of your worksheet too?

  49. Katie says:

    I would love a copy of this for my biology class!!

  50. Barbra Chabot says:

    This looks great! I’d love to try it with my class. Could I get a copy?

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