Effects of Acne Medications on E. Coli

Lewis Richardson

Central Catholic High School

Grade 9

Problem

What effect do acne medications have on the survivorship of E. coli?

Hydrogen Peroxide (3%)

• One of the most commonly

used chemicals for

sterilization.

• Targets germs such as

staph, strep, Salmonella,

and E. coli.

• Used for clearing acne,

whitening teeth, lightening

hair, and other common

uses around the house.

Salicylic acid (0.5%)

• One of the most commonly used chemicals for

treating acne.

• Colorless crystalline organic acid

• Widely used in organic synthesis and functions as a

plant hormone.

Escherichia Coli

• Large and diverse group of

gram (-) bacteria.

• Surrounded by an extra cell

wall composed of

lipopolysaccharides.

• Free living, symbiots, or

pathogens.

• Common prokaryotic cell

model.

• Most are not pathogenic.

Acne Vulgaris

❖ Common human skin disease

❖ Areas of skin with seborrhea (scaly red skin), comedones

(blackheads and whiteheads), pimples, and possible scarring

❖ Excess amount of sebum and dead skin cells: bacteria can thrive

❖ Caused by bacteria, hormones, diet, stress, and medications

❖ Anaerobic bacteria P. acnes, found in sebaceous glands, attributed

to acne

❖ Treated by over-the-counter and prescription medications in the

form of a pill or wash

Purpose

Determine which type of acne medication

works the best at a given concentration.

Previous Studies

❖ Experiment conducted by the University of Southern

California on the effects of home remedy acne methods

in comparison to professional products.

❖ Proactiv tests run using E. coli as an acne substitute

Hypothesis

• Null: The variables will not alter the growth

or survivorship of E. coli.

• Alternative: increasing concentrations of the

variables will significantly reduce

survivorship of E. coli.

Materials

• E. coli DH5 Alpha

• LB agar plates

• Micropipettes

• Sterile Pipette tips

• Sterile Test Tubes

• Sterile Spreader Bars

• Incubator

• Bunsen burner

• Hydrogen Peroxide (3%)

• Salicylic Acid (0.5%)

• SDF (Sterile Dilution Fluid),

(100 mM KH2PO4, 100 mM

K2HPO4, 10 mM MgSO4, 1

mM NaCl)

• Vortex

• Ethanol (sterilization of

instruments)

• Matches

Procedure

1. Labeled all plates and flasks before

experimentation with "Control, 0.1%, 1%,

5%, & 10%."

2. The variables, microbe, and SDF were added

to create mixtures with the desired

concentrations:

Mixtures

Control

Variable 0.1% 1% 10%

Sterile

Water 9.9 mL 9.89 mL 9.8 mL 8.9 mL

Toxic Agent

(Acne

Medication)

0 mL 0.01 mL 0.1 mL 1 mL

E. Coli 0.1 mL 0.1 mL 0.1 mL 0.1 mL

Procedure (cont.)

3. Dipped spreader into ethanol and burned with

matches or Bunsen burner to sterilize it.

4. Evenly spread the mixture on the plate with the sterile

spreader bar.

5. Closed the plate and put into incubator to allow

overnight growth

6. Counted the colonies that have grown on the plates

What is an ANOVA?

❖ An ANOVA test is used to search for significant

variance between data

❖ Used to determine if there is significant variation

between the mean values of groups

❖ If the P- value is smaller than the alpha value

(.05), then at least two of the means varied

significantly

Hydrogen Peroxide Effect on E. Coli Survivorship

754 753

91 3 0

200

400

600

800

Control 0.1% 1% 10%

Num

ber

of S

urv

ivin

g C

olo

nie

s

Concentrations of Acne Medications

P Value=1.02E-14

Dunnett's Test (Hydrogen Peroxide)

Variable

Concentration T-Values Significant?

0.1% 3.596 Not Significant

1% 32.6 Significant

10% 37.0 Significant

T-Critical=4.0

Salicylic Acid Effect on E. Coli Survivorship

754

681 697

527

0

200

400

600

800

Control 0.1% 1% 10%

Num

ber

of S

urv

ivin

g C

olo

nie

s

Concentrations of Acne Medications

P-Value= 0.013546

Dunnett's test (Salicylic acid)

Variable

Concentration T-Value Significant?

0.1% 3.59 Not Significant

1% 2.80 Not Significant

10% 11.2 Significant

T-Critical=4.0

Conclusions

❖ The 1% and 10% concentrations of hydrogen

peroxide significantly lessened the E. Coli

survivorship while 0.1% was not significant.

❖ The 10% concentration of Salicylic acid significantly

lessened the E. Coli survivorship while the 0.1% &

1% did not.

❖ Reject the Null Hypothesis, Accept the Alternative

hypothesis.

Limitations

❖Only one model used

❖Test tubes may have been contaminated

when plating mixtures.

❖Only survivorship was tested

❖Only two kinds of acne medications used

Extensions

❖ More acne products could have been used with more varying concentrations.

❖ More replicates could have been used to ensure human error or contamination was not a factor in the suvivorship.

❖ A growth analysis could have been conducted

❖ Synergistic effects with other drugs

❖ Vary exposure times

❖ Agar infusion or surface wipe exposure

Works Cited

❖ Salicylic Acid.” ChemistryDaily.com. Web. 24 Dec. 2014

❖ “CLINDAMYCIN PHOSPHATE lotion CLINDAMYCIN PHOSPHATE solution CLINDAMYCIN

PHOSPHATE gel” Daily Med Current Medication Information. Web. 24 Dec. 2014

❖ Fredrick, Kurt, Shinichiro Shoji, and Sarah E. Walker. “Ribosomal Translocation: One Step Closer to

the Molecular Mechanism.” ACS Chem. Biol. 93-107. Web. 24 Dec. 2014

❖ Guay, David RP. “Topical clindamycin in the management of acne vulgaris.” Web. 24 Dec. 2014

❖ Kishi, Kenji, and Kazyhiro Hirai. “Clindamycin Suppresses Endotoxin Released by Ceftazidime-

Treated Escherichia coli O55:B5 and Subsequent Production of Tumor Necrosis Factor Alpha and

Interleukin-1 β.” Antimicrobial Agents and Chemotherapy. 616-622. Web. 24 Dec. 2014

❖ Nishijima, S, I Kurokawa, N Katoh, and K Watanabe. “The bacteriology of acne vulgaris and

antimicrobial susceptibility of Propionibacterium acnes and Staphylococcus epidermidis isolated from

acne lesions.” n. p. Web. 24 Dec. 2014

❖ Owens, CD, K Stoessel. “Surgical site infections: epidemiology, microbiology and prevention.” Journal

of Hospital Infection 2008. Web. 24 Dec. 2014

ANOVA (Hydrogen Peroxide)

ANOVA Salicylic Acid

ANOVA (0.1% concentrations)

ANOVA (1% concentrations)

ANOVA (10% concentrations)