THE AFFECT OF ACNE MEDICATION ON THE GROWTH OF S. EPIDERMIDIS BACTERIA

TYPES OF ACNE A comedo is when a follicle is clogged with

dirt, bacteria, and dead skin cells.Blackheads- a partially blocked pore which

allows some of the dead cells and dirt to escape. The black color is a result of a reaction between the skin’s melanin and oxygen.

Whitehead- a completely blocked pore, clogged with oil, dead skin cells, and bacteria.

Pustule Papule Nodule Cyst

BACKGROUND Each hair follicle on the skin contains a

sebaceous gland which produces sebum. Sebum is an oily substance that coats the skin and protects it.

Acne is formed when dead skin cells and dirt clog the pore and then sebum starts to build up in the follicle. Then propionibacterium acnes (P.acnes) “…infects the sebum and multiplies inside. The follicle gets filled with sebum and the bacteria that are multiplying” ("Acne: How Acne Forms?").

QUESTION What’s the affect of acne medication on

the growth of S. epidermidis bacteria?

HYPOTHESIS Acne medication with the highest

percent of the main acne killing ingredient will have the largest effect on the growth of bacteria and therefore the largest zones of inhibition

MATERIALS 3 different acne

medications 6 Petri dishes

prepared with agar 6 sterile swabs 16mL of sterile water Culture of S.

epidermidis bacteria 24 discs 4 empty Petri dishes 4 pipettes

Incubator Gloves Lab coat Balance Tweezers Tape Bunsen Burner Timer Goggles Sharpie marker

NEUTROGENA RAPID CLEAR GEL (A)

Salicylic Acid 2% Alcohol Denat. 38% Hamamelis Virginiana

(Witch Hazel) Water Water Polyquaternium-37 Glycerin Glycolic Acid Butylene Glycol Cyclohexasiloxane C12-15 Alkyl Lactate Cyclopentasiloxane Cetyl Lacate Polysorbate 20

Portulaca Oleracea Extract Sodium Benzotriazolyl

Butylphenol Sulfonate Cocamidopropyl PG-

Dimonium Chloride Phosphate

Sodium Hydroxide Sodium Chloride Bisabolol Benzalkonium Chloride Yellow 6 Red 40 Fragrance (988-145)

ACNEFREE CLEAR SKIN TREATMENTS: ACNE AND BLACKHEAD TERMINATOR GEL (B)

Benzoyl Peroxide 2% Water (aqua) SD Alcohol 39-C Methylpropanediol Triethanolamine Carbomer Lactic Acid Willow Bark Extract Phenoxyethanol

Ethylhexylglycerin Triclosan Tetrasodium EDTA Propylene Glycol 

CVS PHARMACY: ACNE TREATMENT GEL (C)

Benzoyl Peroxide 10% Water Laureth-4 Carbomer Triethanolamine Hydroxypropylmethylcellulose Disodium EDTA

VARIABLES Independent variable: The different types of

acne medication Dependent variable: The size of the zones

of inhibition Control variable: A disk soaked in 4mL of

sterile water and no acne medication Constant variables: The type of bacteria,

the same amount of acne medication and water in each solution, the same temperature of the surrounding air, the same amount of time each disc soaked in the solution, the same amount of time kept in the incubator, and the same kind of Petri dishes and discs.

PROCEDURE 1. Filled 6 dishes with agar using sterile technique2. Hydrated bacteria using sterile technique3. 24 hours later; label all 6 Petri dishes.4. Weigh 1 gram of the first acne medication and mix

it with 4mL of sterile water in an empty Petri dish. 5. Repeat step 4, 2 more times using a different acne

medication each time.6. Put 4mL of sterile water in an empty Petri dish.7. Put 6 discs in each of the 4 empty Petri dishes with

3 different acne medications and one with just sterile water.

8. Let discs soak.

PROCEDURE9. Swab S. epidermidis bacteria on the agar using

sterile technique.10. After discs soak for 20 minutes, put a disc from

each of the 3 mixtures and one of water in each of the 6 Petri dishes with bacteria.

11. Each dish should have 4 discs in it. 12. Tape Petri dishes.13. Let the 6 Petri dishes sit in the incubator for 24

hours. 14. Measure the zones of inhibition after 24 hours. 15. Autoclave the dishes and then dispose of

them.

DATA TABLE OF RESULTS  Neutrogena AcneFree CVS Water

Trial 1 20 50 30 10

Trial 2 20 50 30 10

Trial 3 20 40 30 10

Trial 4 20 40 25 10

Trial 5 20 40 25 10

Trial 6 25 40 25 10

Average 20.83333333 43.333333 27.5 10

StDev 1.863389981 4.7140452 2.5 0

Neutrogena Acne Free CVS Water0

5

10

15

20

25

30

35

40

45

50

The Affect of Acne Medication on the Growth of S. epidermidis

bacteria

Solutions

Aver

age

Zone

s of

Inhi

biti

on

(mill

imet

ers)

RESULTS CONTINUEDSUMMARY

Groups Count Sum Average Variance

Column 1 6 125 20.83333 4.166667

Column 2 6 260 43.33333 26.66667

Column 3 6 165 27.5 7.5

Column 4 6 60 10 0

* P-value = 5.08E-13* T-Test : * Neutrogena v. CVS = 0.0007447 * Water v. Neutrogena = 1.3715E-07

LIMITATIONS These results will most likely not be the same

if a different type of bacteria is used. Even though sterile technique was used

throughout the experiment there is always the risk of contamination somehow.

Medications that had volatile materials such as alcohol may have evaporated under incubation.

CONTINUATION To further this experiment, different bacteria

or a combination of dead skin cells and dirt could be used.

In addition, acne medication with other types of main ingredients could be used as well as prescription medication or natural remedies.

CONCLUSION In this experiment, the AcneFree brand gel with 2% Benzoyl

Peroxide had the largest zones of inhibition compared to the CVS brand gel which contained 10% Benzoyl Peroxide and the Neutrogena brand gel which contained 2% Salicylic Acid.

One possible explanation for why Benzoyl Peroxide did better than Salicylic Acid in this experiment is because Benzoyl Peroxide acts as an anti-bacterial that removes bacteria in the follicles while Salicylic Acid slows down the process of skin cells shedding inside the hair follicle which clogs the pores.

The AcneFree brand which only had 2% Benzoyl Peroxide might have done better in killing the bacteria than the CVS brand with 10% Benzoyl Peroxide because the AcneFree Brand contained alcohol which is very effective in removing dirt and oil from the skin and preventing the growth of acne.

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