Transcript CCHS - Central Catholic High School

Effects of Facial Cleaner on E.
coli and Staph
By Ryan Dillon
Central Catholic High School
Grade 9
Problem
• With cosmetics being investigated, does Cetaphil Facial Cleaner have
an effect on normal human microbial flora?
Purpose
To test the effects of Cetaphil facial cleaner on E.coli and Staph
Microbial Flora
• Little is known about the association between humans and their flora
• Effects are mutualistic, parasitic, pathogenic and commensal
• Provide nutritional and digestive benefits, secrete vitamins, stimulate
antibody production, and protect against pathogenic microbes
Hypotheses
• The null hypothesis of the experiment is that the facial cleaner will
not have an effect on the growth of E. Coli and Staph
• The alternative hypothesis is that the facial cleaner will have an
effect on the growth of E. Coli and Staph
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
Staphylococcus Epidermidis
• Staph is a Gram-positive bacterium
• Part of the normal human flora, usually the skin flora
• Not usually pathogenic but can be if a person with a weakened
immune system is infected
• Patients usually infected through hospitals
Prevention and Treatment of E.Coli
• Washing hands
• Thorough cooking of food
• Washing food
• Food employees washing hands and wearing gloves
• Antibiotics
• Micropipettes P1000 and
P200
• E. coli
• Staph
• Sterile Luria broth Agar
Plates (1% Tryptone, 0.5%
Yeast Extract, 1% NaCl)
• Spreaders
• Ethanol
• 10% Stock Clearasil Facial
Cleaner
Materials
•
•
•
•
•
Permanent Marker
Vortex
Incubator
Sterile tips
Tube Racks
Procedure
1. Both bacteria were grown until a density of 50 klett
spectrophotometer density was reached. This was approximately
10^8 cells/mL
2. Both cultures were diluted in sterile dilution fluid to a concentration
of approximately 10^5 cells/mL
3. Took a 10% stock of the Cetaphil Facial Cleaner
4. Concentrations were then added to the test tubes and then 0.1 ml
of bacteria were added to their tubes.
5. The concentrations were vortexed then added to the plates.
(Multiple people spread plates at the same time to prevent lag
time)
Results
Percentage of variable
E. coli
Staph
Control
341
210
O.1%
299
267
1%
274
164
5%
93
140
10%
70
128
400
Staph and E. coli
350
300
250
Number of
Colonies
200
150
100
50
0
0%
P-Value of Staph – 1.4e-05
0.10%
1%
5%
Staph
E. coli
Concentration of Facial Cleaner
P-Value of E. coli – 0
10%
Dunnett’s Test Results: Staph
Concentration
T-Value
T-Critical
Results
0.10%
1.59
3.48
Non significant
1%
3.69
3.48
Significant
5%
5.60
3.48
Significant
10%
6.20
3.48
Significant
Dunnett’s Test Results: E. coli
Concentration
T-Value
T-Critical
Results
0.10%
1.69
3.48
Non Significant
1%
5.11
3.48
Significant
5%
18.75
3.48
Significant
10%
21.44
3.48
Significant
Conclusions
The conclusion of this experiment is that the higher the concentration
the less bacteria could grow and survive. The alternate hypothesis was
significant in all the concentrations for both bacteria besides 0.10%
Limitations/Extensions
• Limitations: High concentrations not tested, Only two species were
tested, and slight variation in the spreading of the plates.
• Extensions: More trials, Different concentrations, using yeast, algae,
or other bacterium, and two variables not just one
One-Way Anova of Staph
One-Way Anova of E. coli
Works Cited
• Centers for Disease Control and Prevention. Centers for Disease
Control and Prevention, 21 Dec. 2015. Web. 27 Jan. 2016.
• "Staph Infection (Cellulitis) Contagious, Causes, Symptoms, Diagnosis,
and Treatment of Staph Infections." WebMD. WebMD, n.d. Web. 27
Jan. 2016.
• "E. Coli Bacteria Infection Symptoms, Causes, Treatments." WebMD.
WebMD, n.d. Web. 27 Jan. 2016.