Eric Carnivale Grade 9 Pittsburgh Central Catholic High School

Clorox® Disinfecting Wipes Claims to kill 99.9% of all germs. Contains Dimethyl Benzyl Ammonium Chloride Destroys, neutralizes, or inhibits growth of bacteria Ruptures lipid bilayer of bacterial membrane

Uses of Disinfecting Wipes Used on household surfaces to kill bacteria Claims to kill the flu virus, H1N1,and common bacteria

Escherichia coli Major cause of food-borne illness 70,000 cases/year in U.S. Consumption of undercooked meats Consumption of contaminated vegetables or unpasteurized milk Also resides in fecal matter. Most studied bacteria Resides in the digestive tract of animals. Can survive outside of host organism Not all strains of E.coli can result in sickness or disease

Prevention and Treatment Washing hands Thorough cooking of food Washing food Food employees washing hands and wearing gloves Antibiotics

Purpose To test the effect of Clorox® Disinfecting wipes on the survivorship of Escherichia coli bacteria.

Null hypothesis: The Clorox® disinfecting wipes will have no significant effect on the survivorship of E. coli. Alternative hypothesis: The Clorox® Disinfecting wipes will have a significant effect on the survivorship of E. coli. Hypotheses

Materials E.coli LB media 42 Petri dishes with LB agar 16 Clorox® Disinfecting Wipes 4 empty test tubes Peanut butter jar lid (to fit inside of Petri dish) Scissors Vortex Forceps Incubator Spreading bar Ethanol Bunsen burner Micro Pipette and sterile tips SDF or Sterile Dilution Fluid Pipette rack Klett Spectrophotometer

Procedure Part 1 1. E. coli and was grown over night in LB media. 2. A sample of the overnight culture was added to fresh LB media in a sterile sidearm flask. 3. The culture was incubated at 37°C until a density of 50 Klett spectrophotometer units was reached. This represents a cell density of approximately 10 8 cells/mL. 4. The culture was diluted in sterile dilution fluid to a concentration of approximately 10 3 cells/mL. 5. Prior to E coli addition, Clorox® Disinfecting Wipes were cut to the size of a Petri dish. The Disinfecting Wipes were held down on the surface of the plate for 10 seconds µl of E.coli (approx 100 cells) was pipetted and spread onto each plate. 7. The plates were incubated at 37 degrees Celsius for 1 day. 8. The plates were taken out and the colonies were counted. Each colony is assumed to have risen from 1 cell.

Procedure Part 2 1. A 5cm x 5 cm cut piece of the disinfecting wipe was placed in SDF. 2. The tube with wipe and SDF was vortexed for 1 minute. 3. The wipe was removed and disposed of. 4. Different concentrations were made by pipetting 0, 0.1, 1, and 5 ml’s of the wipe-SDF mixture and combining it with the appropriate amount of E.coli to make a final volume of 10mls. SHOW CHART µl aliquots from each tube were spreadonto sets of 6 LB plates. 6. Plates were Incubated at 37 degrees Celsius for 1 day. 7. The plates were removed from the incubator and the colonies were counted. Each colony is assumed to have arisen from 1 cell.

Surface wipe contact effects on E. coli survivorship Number of Colonies P-Value= 2.27E-06

ANOVA/Dunnetts’ Test The ANOVA is a statistical test used to compare the variation within the groups to the variation between groups. The Dunnetts’ test allows a further pair-wise comparison of the means of each group versus the control group. This is used to determine the source of the variation.

Statistical Analysis for wipe effects on the survivorship of E.coli F-ValueP-ValueF-Critical E Exposure Time(sec)T- ValueInterpretation Significant Significant Significant Significant Significant ANOVA Dunetts’ Test

Surface wipe elutant effects on E.coli survivorship mL’s of wipe-SDF mixture Number of Colonies P-Value= 4.3E-10

Statistical analysis for wipe elutant effect on E.coli survivorship ANOVA Ml’s of stock addedT-valueInterpretation Significant Significant Significant Dunetts’ test F-valueP-ValueF-Critical E

Conclusion The statistical analysis allows for a rejection of the Null hypothesis. Surface wiped plates and wipe elutant resulted in a significant reduction in E.coli survivorship.

Extensions and Limitations Assemble a team of students to speed up plating and spreading and therefore creating more accurate results. Using different bacteria and different brands of anti- bacterial wipes to determine which wipe is the most effective against common bacteria. The wipe was not directly exposed to the E.coli on the plate.

References digestive/disorders/242.html digestive/disorders/242.html dw dw =PC =PC37016