- 3 Petri dishes prepared with agar
- 1 disinfected swab
- 1 bottle of disinfected water
- A piece of filter paper
- A hole puncher
- 4 test tubes
- 1 measuring cylinder
- 1 pipette with disposable tips
- Benzoyl peroxide
- 1 beaker of water
- P. acne bacteria culture
- 1 forcep
- 1 digital weighing scale
- 1 marker pen
1. Before starting the experiment, make sure you clean your work area with Chlorox and wear gloves at all times. Place your petri dishes on clean paper towels.
2. Prepare three petri dishes with P. acne: Wear gloves and scrape some skin from an infected area on the face (just the surface; no need for pain or blood). Take your samples from a red pimple, not a white one - the white ones are filled with immune cells that are destroying the bacteria, and you don't want to include any of those. Dissolve the scrapings in a small amount of mildly soapy water and cover the agar with the mixture. The water will evaporate, leaving bacteria on agar. Be as clean as possible when doing this. It is hard not to culture more than one type of bacteria, but make sure you clean the area with Chlorox.
3. To grow your samples anaerobically, keep them in a sealed container like a jar with a screw-on top or a plastic Tupperware container. Blow N2 or CO2 over the samples to displace the O2, and then put the lid on. Do this each time you open the container. A CO2 cartridge, like those used by cyclists to inflate tires, is probably the most accessible source of gas. The pressure in the cartridge is very high, so use an inflator and a bicycle tube. Inflate the tube, and then release the CO2 at lower pressure from the tube.
4. P. acne is a slow-growing bacteria, so any colonies that appear in 2-3 days (or less) are something else. Store the petri dishes with the p. acne in a cool dry place for a week.
5. The Petri dishes are labeled with the number for each of the acne medications:...
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