How well does antibacterial soap work?

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Kaitlin
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Joined: Sat Oct 25, 2003 10:38 am

How well does antibacterial soap work?

Post by Kaitlin »

I want to do a science fair project on how well anitbacterial soaps really work? I talked to a doctor who said I would need to use agar (spelling?) dishes for the experiment. I am not sure what that equipment is or how to get it. He said I should use sterile swabs to take the bacteria off my hands and plate it in the dish. Then I should wash my hands with one of the soaps and use a sterile swab to take what bacteria is still on my hands and put that in the agar dish. He was not sure if I would need some way to incubate the dishes for the bacteria to grow. Do I need to? I would repeat the process for each type of antibacterial soap. I would count the bacteria colonies that grow to tell which soap works the best. Is this the best way to go about this experiment? Where do I get the equipment that I need? Thanks, Kaitlin
Kaitlin
Ken
Posts: 30
Joined: Thu Oct 16, 2003 8:33 pm

Post by Ken »

Hi Kaitlin,

Pam Moy, a biology teacher, helped me prepare this response.

I found a description of how to investigate whether coins are covered with germs. That's pretty close to what you're interested in doing, and I'm sure you could modify the procedure to fit your idea. You can find the description here:
http://www.science-projects.com/BBMicro-Coins.htm AND this same website also has some information on agar plates (you spelled it correctly!) http://www.science-projects.com/NAplates.htm

Your science teacher may have the supplies you need. Check with him or her first. (In fact, you should do this experiment at school under your teacher's supervision. See the note about safety below.)

You can either make your own agar plates using powdered agar, or buy them ready to go. You'll see two companies that carry supplies for doing microbiology experiments on our Science Fair Supplies and Materials page, Carolina Biological Supply Company and Science Kit and Boreal Laboratories: https://www.sciencebuddies.org/mentorin ... lies.shtml

AN IMPORTANT NOTE ABOUT SAFETY: You might have a small number of harmful bacteria on your hands that your body's natural defenses can defeat without trouble (even if you put your fingers in your mouth). However, when you "culture" bacteria on an agar plate, you multiply their numbers by many thousands. It's possible that you could get a "colony" of pathogenic bacteria that would be too many in number for your body's defenses, creating the risk that you could get ill if you did not follow the proper safety procedures. The Intel International Science & Engineering Fair specifically prohibits studies involving pathogenic agents or potential pathogenic agents in the home environment. The Illinois State Science Fair bans all projects that take bacteria samples from the body. In almost every science fair you would need to have your project approved by a Scientific Review Committee (SRC). See https://www.sciencebuddies.org/mentorin ... _src.shtml for more details. The bottom line is that you should definitely check the rules your science fair follows before you procede with this experiment.

Good luck with your project!

Ken
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