1. The Effects of antibacterial hand soap on bacteria survivorship
David Lukac
Grade 9
Pittsburgh Central Catholic High School

2. Problem People all over the world use hand soap to clean themselves
Does an antibacterial hand soap significantly affect the survivorship of human microflora
Problem

3. Escherichia coli Major cause of food-born illnesses
From consumption of undercooked meats and contaminated or unpasteurized milk
Not all strands of E. coli result in disease or sickness
Also resides in fecal matter and digestive tract of animals
Very commonly used in the lab
Gram-negative bacteria
Escherichia coli

4. Staphylococcus epidermidis
Part of the normal human flora
Typically the skin flora and more rarely with the mucosal flora
Associated with intravascular device infections
Gram-positive bacteria
Staphylococcus epidermidis

5. Variable Personal Care antibacterial hand soap Triclosan free
Active ingredient is Chloroxylenol
Water, sulfate, citric acid, ammonium chloride (inactive)
Use is for hand washing to decrease bacteria on the skin
May cause irritation and redness
Variable

6. To determine the effect hand soap has on the survivorship of Staph e
To determine the effect hand soap has on the survivorship of Staph e. and E. coli
Purpose

7. Null hypothesis: The antibacterial hand soap will have no significant effect on the survivorship of E. coli and Staph
Alternative hypothesis: The antibacterial hand soap will have a significant negative effect on the survivorship of E. coli and Staph
Hypotheses

8. Materials Latex gloves Spreader bar Escherichia coli (DH5-alpha)
Agar plates
Ethanol
Matches
Vortex
Hand soap
0.22 Micron sterile filter
64 LB Agar Plates (0.5% yeast extract, 1% tryptone, 1% sodium chloride)
Escherichia coli (DH5-alpha)
Staphylococcus epidermidis
Micropipettes
Micro tubes
Sterile dilution fluid [SDF] (100mM KH2PO4, 100mM K2HPO4, 10mM MgSO4, 1mM NaCl)
Bunsen burners
Materials

9. 1. E. coli and Staph. e. were grown overnight in sterile LB media.
2. Samples of the overnight culture were added to fresh media in a sterile sidearm flask.
3. The cultures were incubated until a density of 50 Klett spectrophotometer units was reached. This represents a cell density of approximately cells/ml.
4. The cultures were diluted in sterile dilution fluid to a concentration of approximately 105 cells/ml. 5 )
5. The hand soap was diluted with sterile dilution fluid to concentrations of 0%, 0.1%, 1%, and 10% to total 10 mL
Procedure

10. Table of concentrations0%
0.1% 1%
10%
Sterile fluid
9.9 mL
9.89 mL
9.8 mL
8.9 mL
Hand soap
0 mL
0.01 mL
0.1 mL
1 mL
Microbe
Total volume
10 mL
Table of concentrations

11. ml. of cell culture was then added to the test tubes, yielding a final volume of 10 ml. and a cell density of approximately 10^3 cells/ml.
2. The tubes were allowed to incubate at room temperature for 10 minutes.
3. After vortexing to evenly suspend cells, 0.1 ml. aliquots were removed from the tubes and spread on LB agar plates.
4. The plates incubated at 37°C overnight.
5. The resulting colonies were counted. Each colony is assumed to have arisen from one cell.
Procedure

12. P- Value: 8.9 x 10^-12
Alpha: 0.05

13. Concentration of hand soap
T-Critical: 2.88
Alpha: 0.05
Concentration of hand soap
T-Value
Significant?
0.1%
7.75
Significant 1%
10.45
10%
11.81
Dunnett's test (e.coli)

14. P-Value: 6.12 x 10^-9
Alpha: 0.05

15. Concentration of hand soap
T-Critical: 2.88
Alpha: 0.05
Concentration of hand soap
T-Value
Significant?
0.1%
5.07
Significant 1%
6.97
10%
9.1
Dunnett's test (staph)

16. Limitaions and extensions
Limitations
Extensions
Only two species used
Plating was not synchronized perfectly
Only one type of exposure
Small variation in exposure time
More trials could be run to get a better evaluation of the results
Vary exposure time
Add another species to test
Agar infusion
Limitaions and extensions

17. Conclusion Staph. E. E. Coli Null hypothesis can be rejected
Alternate hypothesis can be accepted
Null hypothesis can be rejected
Alternate hypothesis can be accepted
Conclusion

18. References https://en.m.wikipedia.org/wiki/Staphylococcus_epidermi dis
youll-never-get-sick
ons/S%20epidermidis/sepidermidis.html
References

19. Surviving colony results (E. Coli)
0 %
0.1% 1%
10%
142 97 52 34
178 68 40
197
102 58 53
129 89 59 54
115 95 66 42
133 88 47
185 73 49
148 60 83 61
Surviving colony results (E. Coli)

20. E. Coli anova P-value was 8.9 x 10^-12 Alpha was 0.05
This number is less than 0.05 so Dunnett's tests must be run
Alpha was 0.05
E. Coli anova

21. Surviving colony results (Staph)
0 %
0.1% 1%
10%
197
109
102 96
158
165
126
172
129
119 93
163
134
128 99
193
155
143
164
137
115
104
225
106
105 95
186
167
124
110
Surviving colony results (Staph)

22. Staph E. anova The p-value was 6.12 x 10^-9 Alpha was 0.05
This number is less than 0.05 so Dunnett's tests must be run
Alpha was 0.05
Staph E. anova