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Science Project 2005
PURPOSE The purpose of this experiment was to compare the bacterial content before and after the use of Clorox wipes on the inside and outside door handles of restrooms. I became interested in doing a project on bacteria because I am interested in a career in medicine, biology or microbiology. In addition my mom has taught me about avoiding bacteria in restrooms and encouraged me to use a paper towel instead of my hand to open the door when leaving. I thought it would be good to study this scientifically. The information gained from this experiment affects almost everybody on earth today but it should especially help store and restaurant owners in trying to keep their bathrooms clean. The bacteria on bathroom door handles could possibly cause sickness and disease and needs to be dealt with properly. HYPOTHESIS My first hypothesis was that there would be more bacteria on the inside of the door handle than the outside due to the germs picked up from the restroom and people not washing their hands. My second hypothesis was that there would be more bacteria in supermarket restrooms such as Wal-Mart or Fred Meyer because there are usually more people cycling through. My third hypothesis was that the Clorox wipes would reduce the amount of bacteria significantly. EXPERIMENT DESIGN The constants in this study were: ∑ Time frame project conducted ∑ Amount of time handles were swabbed ∑ Pressure swab was pressed against handle when collecting bacteria. ∑ Type of swab used ∑ Type of agar ∑ Type of Petri dish ∑ Time incubated ∑ Temperature incubated ∑ Type of incubator ∑ Type of bleach used ∑ Same time to dry ∑ Same time wiped with Clorox The first manipulated variable was the location of sampling: supermarkets, homes, and restaurants. The second manipulated variable was whether the sample was collected on the inside or outside of the restroom door. The third manipulated variable was sampling before and after the use of Clorox. The responding variable was the amount of bacteria on the door handles. To measure the responding variable the bacteria colonies were counted. MATERIALS
PROCEDURES 1. Go to Hospital Lab and obtain 18 sterile swabs. 2. Go to first destination. 3. Go to bathroom and locate outside doorknob. 4. Take out sterile swab 5. Collect Bacteria: a. Rub halfway around doorknob as steadily as possible using even pressure for ten seconds using stopwatch. b. Try to collect bacteria from entire surface. 6. Label Swab with three items. a. Place bacteria were collected. b. Inside or outside of bathroom door. c. Before or after use of Clorox wipe. 7. Put swab back in carrying case. 8. Go inside bathroom. 9. Repeat steps four through seven. 10. Take out Clorox wipe. 11. Scrub down doorknob with Clorox wipe for 15 seconds using stopwatch. 12. Restart stopwatch 13. Let knob dry 60 seconds. 14. Repeat steps four through seven except on opposite side. 15. Repeat steps two through fourteen at all other destinations. 16. Go to Hospital Lab. 17. Put on Lab coat. 18. Transfer Bacteria from swabs to agar by rubbing in three different directions turning Petri dish 60 degrees each time. 19. Label Plates (as in step 6) 20. Repeat step 19 through 20 for all remaining swabs. 21. Incubate plates for 48 hours in incubator at 35° C. 22. Wash hands. 23. Count the number of colonies. If number is to large divide Petri dish into four sections, count each section and add together. 24. Record number of colonies. 25. Repeat steps 23 through 25 on all Petri dishes. 26. Wash hands 27. Sterilize Petri dishes by putting them in an autoclave. Incinerate swabs. RESULTS The original purpose of this experiment was to see the effect of Clorox wipes on the bacterial content on bathroom doorknobs. The results of this experiment were that there was about 50% more bacteria on the inside than the outside door handle. The disinfectant wipe reduced it 100%. There was an equal amount of bacteria in restaurants and supermarkets and there was a little less that a quarter more in the homes. See My Table And Graph CONCLUSION The first original hypothesis was that there would be more bacteria on the inside door handle than the outside. The results indicate that my 1st hypothesis should be accepted because there was over twice as much in the inside than the outside. My second hypothesis was that there would be more bacteria in supermarket restrooms. My 2nd hypothesis should be rejected because the supermarkets and restaurants had the same amount and the homes had approximately 25% more. My third hypothesis was that the Clorox wipes would reduce the amount of bacteria significantly. This hypothesis should be accepted because the Clorox wipes reduced the amount of bacteria 100% for all the trials. My fourth hypothesis was that the Clorox wipes would not reduce the amount of bacteria entirely. This hypothesis should be rejected because the Clorox wipes reduced the amount of bacteria 100%. I realize there was a small flaw in this experiment. Maybe the bacteria weren’t removed by the Clorox disinfectant itself but instead by the process of rubbing the doorknob with the wipe. To solve this problem I could have tried using a spray instead of a wipe or towel. This could have solved my problem because I would have known if it was the disinfectant itself or the rubbing. I also could have solved the problem by rubbing with a wipe without disinfectant to see if rubbing alone removed the bacteria. Because of the results of this experiment, I wonder how much bacteria would be reduced by high heat instead of applying disinfectant. For example, would a heat gun be an effective tool for killing bacteria on door knobs or other surfaces? ACKNOWLEDGEMENTS I would like to thank the following people for helping make my project possible:
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