Presentation Transcript

1. What cleansing agentis most effective for eliminating aerobic bacteria on a person’s hands?

   David Lu Emma Olsson Madeleine Monroe Daniel Kikuchi Tristan Frick
2. Madeleine Monroe Tristan Frick Daniel Kikuchi David Lu Emma Olsson
3. So What??? The point of this experiment was to determine which common hand cleaning products are most effective at reducing the number of aerobic bacteria on one’s hands. From a young age, we are told to wash our hands, and we wanted to identify the most effective bacteria killer.
4. Controlled Variable Chart
5. Variables Independent Variable- Hand cleaning product (Water, Ivory Bar Soap, Hand Sanitizer, Non Anti-Bacterial Liquid Hand Soap, Anti-Bacterial Liquid Soap) Dependent Variable-The number of aerobic bacteria colonies grown on the agar sheets.
6. Materials 10 mL graduated cylinders (30) Dish washer Sterile gloves Sterile pipettes Sterile inoculation loops (30) Agar sheets (30) Incubator Sterilized distilled water Ivory bar soap Liquid hand soap (non anti-bacterial) Liquid hand soap (anti-bacterial) Hand sanitizer Tap water (from sink) Sink Timer Circular “squisher”/spreader
7. Procedure Sterilize the equipment and station Boil distilled water Get materials Put on sterile latex gloves Fill each 10 mL cylinder (30 total) with one mL of water Swipe the right hand of the volunteer Swish an individual’s sample for 10 seconds Have volunteers wash their hands with an assigned cleaning agent for 30 seconds
8. Procedure DO NOT use paper towels, shake hands twice Swipe the right hand of the volunteer again Swish the inoculation loop in an unused graduated cylinder Pour each sample on an individual agar sheet Spread the sample on agar sheet Label the agar sheets Incubate the agar sheets for 48 hours at 37 degrees Celsius
9. Procedure Dispose of inoculation loops and gloves Sanitize work station with bleach water Put the graduated cylinders into the dishwasher on sanitation cycle Take the sheets out of the incubator and put into fridge (5 degrees Celsius) for 24 hours Collect and record data Put the agar sheets in bleach to clean them Wash hands
10. Table 1: Percent Change in the Number of Colonies Before and After Water, Dove Bar Soap, Hand Sanitizer, Liquid Hand Soap, and Anti-Bacterial Liquid Hand Soap were applied for Thirty Seconds
11. Graph 1:
12. Results Hand sanitizer had had the greatest negative percent change (-50%) Then Ivory Bar Soap with an increase of 80% Anti-Bacterial Liquid Soap increase of 100% Water increase of 133.3 %, And Liquid Soap had the greatest positive percent change (1100)
13. Conclusion Liquid hand soap dispensers can be very dirty, especially the pump. Also the generic soap was not anti-bacterial therefore bacteria can grow on bar soap This could transfer more bacteria onto the hands of someone trying to wash their hands, after the sample for the control was taken Anti-bacterial cleaning products can produce resistant strains of bacteria This explains how bacteria could still be left on the participant’s hands after washing them Most bacteria are not harmful to humans This could explain the increase in bacteria on the hands of the participants after washing them with water because tap water could contain bacteria that is not considered harmful
14. Source of Error 1 After using the various hand cleaning solutions all increased the bacteria count except hand sanitizer All hand cleaning solutions utilized water with the exception of hand sanitizer Samples were taken wet- participants did not dry hands after washing The water may have contained bacteria, thus washing your hands in the water would have increased the bacteria count To fix this, participants should wash their hands using sterilized water Boil water to sterilize
15. Source of Error 2 Some people turned off the sink and stopped the timer after watching their hands This could have increased the number of bacteria collected from the participant’s hand To fix this, the testers could have operated the water faucet handle and timer so that the participant’s did not touch anything after washing their hands
16. Future Possible Studies Although liquid soap had the greatest positive percent increase in bacteria colonies The bacteria from the liquid soap many not necessarily be harmful, whereas the bacteria not killed by the hand sanitizer may have be harmful Future studies Identify the specific bacteria grown Determine which are most hazardous to human health
17. Citation Antibacterial cleaning products. (n.d.). Retrieved from http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pag es/Antibacterial_cleaning_products Franklin, D. (2006, March). Hand sanitizers, good or bad? . Retrieved from http://www.nytimes.com/2006/03/21/health/21cons.html Sohn, E. (2011, May). Bacteria-laden soap not so clean. Retrieved from http://news.discovery.com/human/soap-bacteria-clean-1 10506.html Which soap is best? . (2010, November). Retrieved from http://www.health.state.mn.us/handhygiene/how/bestsoap.h tml
18. End