Which Hand Sanitizer Kills Bacteria the Best. Matt Olon Grade 9 Pittsburgh Central Catholic High School

Transcription

1 Which Hand Sanitizer Kills Bacteria the Best Matt Olon Grade 9 Pittsburgh Central Catholic High School

2 Background on Purell Most commonly used hand sanitizer Main use- reduce bacteria on the skin Active ingredient: 70% Ethyl Alcohol...Antimicrobial Ingredients (inactive): water, isopropyl alcohol, caprylyl glycol, glycerin, isopropyl myristate, tocopheryl acetate, C10-30 alkyl acrylate crosspolymer, aminomethyl propanol, parfum

3 Background on generic Commonly used to replace big brands such as Purell. The hand sanitizer used in this experiment was up&up (Target) generic hand sanitizer Main use- to decrease bacteria on the skin that could cause disease Active ingredient: 70% Ethyl Alcohol...Antiseptic Ingredients (inactive): water, glyceryl caprylate/caprate, glycerin, isopropyl myristate, tocopheryl acetate, C10-30 alkyl acrylate crosspolymer, benzophenome-4

4 Water temperature Each test tube was heated in one of the following temperatures 40 C 48 C- just about the average temperature for washing hands in warm/hot water 56 C

5 Escherichia coli Large and diverse group of gram (-) bacteria Free living, symbionts, or pathogens Live in the intestinal tract of many mammals. Most strains are not pathogenic Serve as a common prokaryotic cell model.

6 Purpose The purpose of this experiment is to determine whether Purell or Generic hand sanitizer is more effective against E. coli growth at water temperatures of 40, 48, and 56 C.

7 Hypotheses Null hypothesis- Neither hand sanitizer will significantly affect bacterial growth Alternative hypothesis 1- Hand sanitizer will significantly affect the amount of E. coli growth Alternative hypothesis 2- Exposure to Purell will result in less colonies than Generic at the every temperature

8 Materials LB Media (0.5% yeast extract, 1% tryptone, 1% sodium chloride ) Purell and generic hand sanitizers Micro and Macro-pipettes and sterile tips SDF (100mM KH 2 PO 4, 100mM K 2 HPO 4, 10mM MgSO 4, 1mM NaCl) Spreader bars LB agar plates E. coli DH5 alpha Bunson Burner Ethanol (for cleaning) Vortex Incubator Hot plates with water at 40, 48, and 56 C 18 sterile test tubes

9 Procedure 1. E. coli was grown overnight in sterile LB media. 2. Sample of the overnight culture was added to fresh media in a sterile sidearm flask. 3. The cultures were incubated at 37 C until a density of 50 Klett spectrophotometer units was reached. (Cell density approximately 10 8 cells/ml). 4. The cultures were diluted in a sterile dilution fluid to a concentration of approximately 10 5 cells/ml. 5. The selected experimental variables were diluted with sterile water to the chosen concentrations to a total of 9.9 ml.

10 Purell Chart of Concentrations Purell 0% 0% 0% 0.01% 0.01% 0.01% 1% 1% 1% Water temperature E. Coli 0.1ml 0.1ml 0.1ml 0.1ml 0.1ml 0.1ml 0.1ml 0.1ml 0.1ml Sterile Water 9.9ml 9.89ml 8.9ml 9.9ml 9.89ml 8.9ml 9.9ml 9.89ml 8.9ml Purell hand sanitizer 0ml 0.01ml 1ml 0ml 0.01ml 1ml 0ml 0.01ml 1ml Total 10ml 10ml 10ml 10ml 10ml 10ml 10ml 10ml 10ml

11 Generic Chart of Concentrations Generic 0% 0% 0% 0.01% 0.01% 0.01% 1% 1% 1% Water temperature E. coli 0.1ml 0.1ml 0.1ml 0.1ml 0.1ml 0.1ml 0.1ml 0.1ml 0.1ml Sterile Water 9.9ml 9.89ml 8.9ml 9.9ml 9.89ml 8.9ml 9.9ml 9.89ml 8.9ml Generic hand sanitizer 0ml 0.01ml 1ml 0ml 0.01ml 1ml 0ml 0.01ml 1ml Total 10ml 10ml 10ml 10ml 10ml 10ml 10ml 10ml 10ml

12 Procedure (continued) mL of cell culture was then added to the sterile test tubes, resulting in a final volume of 10 ml. 7. The solutions were mixed by a vortex and then sat in water of either 40, 48, or 56 C for 15 minutes. 8. After vortexing again, 0.1 ml of each solution was removed and spread on LB agar plates with 4 replicates for each solution. 9. The resulting colonies were counted and recorded.

13 Colonies Survivorship of E. coli (at 40 C) P value: P value: % 0.01% 1.00% Concentration of Variable Purell (P value 6.13E-9) Generic (P value 7.11E-8)

14 Colonies Survivorship of E. coli (at 48 C) P value: P value: % 0.01% 1.00% Concentration of Variable Purell (P value 7.68E-8) Generic (P value 1.5E-7)

15 Colonies Survivorship of E. coli (at 56 C) P value: P value: % 0.01% 1.00% Concentration of Variable Purell (P value 2.73E-7) Generic (P value 6.05E-5)

16 Purell Dunnett s test (40 C) Concentration T-value Significant? Generic T crit: 2.5 Alpha: % 3.46 Significant 1% 4.29 Significant Concentration T-value Significant? 0.01% 3.12 Significant 1% 3.95 Significant

17 Purell Dunnett s test (48 C) T crit: 2.5 Alpha: 0.05 Concentration T-value Significant? Generic 0.01% 3.58 Significant 1% 4.33 Significant Concentration T-value Significant? 0.01% 3.09 Significant 1% 3.91 Significant

18 Purell Dunnett s test (56 C) T crit: 2.5 Alpha: 0.05 Concentration T-value Significant? Generic 0.01% 3.67 Significant 1% 4.52 Significant Concentration T-value Significant? 0.01% 3.4 Significant 1% 4.12 Significant

19 Conclusions Reject null hypothesis and accept alt. hypothesis 1, because all concentrations of both hand sanitizers proved to have a significant effect on E. coli survivorship after an ANOVA and Dunnett s test. Alternative Hypothesis 2: Purell hand sanitizer did result in less colonies than Generic at all concentrations

20 Limitations Only two kinds of hand sanitizers Only 3 different, and close temperatures Only one microbe Between aliquots, the test tubes may have been contaminated or changed There is controversy on whether Purell s function is affected or changed by water Only survivorship was tested

21 Extensions More replicates Wider temperature ranges Various sanitizers Infusion of agar plates Growth curve analysis

22 References basey/abstracts%202007/14.htm ay/agriculture/ecoli.html