MnSCU Partnership > Teaching Activities > Antibacterial soaps, friend or foe: An investigative case study

Antibacterial soaps, friend or foe: An investigative case study

Ann M. Mills
Ridgewater College, Hutchinson Campus
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This activity has been peer-reviewed as a part of the Sharing Our Work Virtual Learning Community.

This activity was submitted by an educator in the Minnesota State Colleges and Universities (MnSCU) System to the Sharing Our Work Virtual Learning Community. Sharing Our Work was the culminating piece of a collaboration between MnSCU and Project Kaleidoscope (PKAL). Information on the the criteria and process of the peer review can be found at

This page first made public: Feb 24, 2010


Germs Anyone
Investigative case studies draw from students' real life experiences which are then applied to scientific reasoning. This lab activity will not only draw on students' real life experiences but will also draw on student's previous lab experiences in proper laboratory techniques and data analysis performed in previous activities. The lab activity that will be particularly important, as students design their own experiment, will be a previous lab where students set up an experiment to test antibiotic effectiveness. The lab will incorporate the use of scientific inquiry methods and strategies while students develop reasonable answers to the questions asked.

Learning Goals

  1. Design a scientific experiment with controls and replications.
  2. Utilize aseptic technique to transfer bacteria from one type of culture media to another.
  3. Critically read scientific literature.
  4. Interpret and communicate scientific data.
  5. Apply microbiological techniques and knowledge to a real life situation.

Context for Use

This lab activity/case study is appropriate for beginning microbiology students at the college level or advanced HS students that have a microbiology background. The project takes approximately 3 weeks to complete (background work, setup, data collection and transferring cultures, data analysis and write up). The activity, as it is written is meant to be a final project for 1st semester microbiology students. I have adapted the activity for use in a general biology course.

Description and Teaching Materials

Mueller Hinton Agar plates (sterile)
blank sterile disks
antibacterial soap
sterile empty petri plates
Nutrient broths (sterile)
sterile swabs
innoculating loops(optional)
bunsen burners (optional)
strikers (optional)

Germs Anyone? Lab packet (Microsoft Word 2007 (.docx) 28kB Feb19 10)

Teaching Notes and Tips

  1. I have students work in groups of 2, rarely 3.
  2. Experiment is conducted through 4 rounds, about 150 MH plates and 150 nutrient broths are required to complete the activity, based on 12 groups.
  3. Students should design as much of the experiment as they are capable of, depending on the the group of students and time constraints, I have provided very little to a great deal of help in experiment design.
  4. Students should read the articles and answer the questions prior to starting on the experiment write up. I spot check the questions in lab to insure that everyone has read the articles for background information.
  5. Here is an adapted version that could be used in an online class or for a nonmicrobiology course. evolution in action case study (Microsoft Word 2007 (.docx) 1.2MB Feb19 10)


A grading rubric is utilized to assess student success on the activity.
  1. Background reading/answering the questions associated with the readings.
  2. Experiment write up.
  3. Data collection and analysis
  4. cross resistance write up (If conducted).

References and Resources

Aiello, A. E., and Larson, E. 2003. Antibacterial cleaning and hygiene products as an emerging risk factor for antibiotic resistance in the community. The Lancet 3, 501-506.

Cole, E. C., Addison, R.M., Rubino, J.R., Leese, K.E., Dulaney, P.D., Newell, M.S., Wilkins, J., Gaber, D.J., Wineinger, T., and Criger, D.A. 2003. Investigation of antibiotic and antibacterial agent cross-resistance in target bacteria from homes of antibacterial product users and nonusers. Journal of Applied Microbiology. 95, 664-676.

Courvalin, P. 2005. Antimicrobial Drug Resistance: "Prediction Is Very Difficult, Especially about the Future. Emerging infectious diseases. 11, 1503-1506. Accessed online 10/25/2008 @

De la Cruz F, Davies J. 2005. Industrial revolution and microbial evolution. In The Influence of Cooperative Bacteria on Animal Host Biology, M McFall-Ngai, B Henderson, E Ruby (eds) pp 73–82. Cambridge, UK: Cambridge University Press.

Hadhazy, A.T. 2008. Antibacterials: Good for now, good for germs later? Scienceline: A project of NYUs science, health and environmental reporting program. Accessed online 5/5/2008 @

Levy, S.B. 2002. Antibacterial household products: cause for concern. Emerging infectious diseases. 7, 512-515. Accessed online 2/16/2008 @

Stanley, E. and M. Waterman. 2008. Using investigative cases. Accessed online 10/25/2008 @ .

Stanley, E. and M. Waterman. 2005. Picture Perfect. Biological inquiry: A workbook of investigative cases 2nd edition. Benjamin Cummings. San Francisco, CA. pp iv-13.

Welden, C. W. and Hossler, R. A. 2003. Evolution in the lab: Biocide resistance in E. coli. The American Biology Teacher. 65, 56-61.