Growth Inhibition of Staphylococcus epidermidis and Escherichia coli Using Various Escherichia coli Using Various

Anti-microbial Agents.

Domonique Jackson, Janecia Wilson, Railene Echevarria, Kijhauna Stevens

IntroductionS. epidermidis –

• Gram positive

• Found on the skin

E. coli

• Found in the intestines, bad

• Investigations:

1. Listerine on S. epidermidis

and E. coli

2. Environmental Microbes• Found in the intestines, bad

when found in the blood

• Gram negative

Antiseptic – used on living things

Detergent – used on fomites

Antibiotics – products of living

things (mold)

2. Environmental Microbes

1. What agents can inhibit

the growth of

S.epidermidis and E. coli?

2. What Antibiotics work on

yourself?

Purpose

1. To determine if Listerine will inhibit the growth of S. epidermidis and E. coli

2. To analyze if bacterial growth on fomites

3. To determine which cleaning agents work better on bacteria

4. To determine the effectiveness of antibiotics on human natural flora

Materials & Methods Part 1:

1. Add 5 mL of Tryptic Soy Broth (TSB) into test tube marked control. 2. Add 5 mL of Listerine into another test tube.3. Add 5 mL of stock of Staph into each of the two test tubes4. After 1 minute, add 100 μL from the test tube containing Listerine and Staph into a flask

containing 100 mL of TSB marked 1 minute.5. After 5 minutes, add 100 μL from the test tube containing Listerine and Staph into another

flask containing 100 mL of TSB marked 5 minutes.6. Place 100 μL from control test tube into the flask containing 100 mL of TSB marked control. 6. Place 100 μL from control test tube into the flask containing 100 mL of TSB marked control. 7. Set the spectrophotometer to 550 nm and place the TSB blank in the machine to set to 0

absorbance.8. Take 100 μL from control flask and place in a cuvette9. Place into spectrophotometer and take absorbance reading10. Repeat steps 7-9 for the 1 minute and 5 minute flasks11. After recording the absorbance of all three flasks, place them in an incubator at 37°C for 48

hours total taking periodic measurements in the same fashion as described above.12. Repeat steps 1-11 for E. coli. Part 2:

1. Dip a sterile cotton swab in water and swab a large area of the surface being tested (i.e. elevator button).

2. Then, wipe cotton swab all over a Tryptic Soy Agar (TSA) plate and cover. 3. Repeat for each designated place, then incubate the plates at 37 degrees Celsius for 24

hours.

Materials & Methods

Part 3:

1. Swab each plate with a sterile cotton swab (as described in Part 4) containing stock solution of Staph or E-coli

2. Draw a line down the middle of plates3. Get 8 disks and dip one in a corresponding cleaning agent4. Place two disks, containing the cleaning agents, on each plate according to their

number designationnumber designation5. Place all the plates in the incubator at 37°C or 98.6°F for 24 hours6. Measure the diameter of the zones of inhibition after 24 hoursPart 4:

1. Swab the area behind your ear using a cotton swab. Incubate on a TSA plate at 37 degrees Celsius. Recolonize after 24 hrs the bacteria onto 2 plates onto two TSA plates using the previous TSA plate.

2. Place the 6 disks containing 6 different antibiotics onto the plates (3 on each)3. Incubate the plates for 24 hrs at 37 degrees Celsius4. Then, the zones of inhibition were measured and compared against a table of data

to determine resistivity, and intermediate effect, or sensitivity to each of the antibiotics

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8sorbents (550nm)

Control

1 Minute

5 Minute

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Absorbents (550nm)

Control

1 Minute

5 Minute

Figure 1: Inhibition of Growth using Listerine on Staph (left graph) and E. coli (right graph)

-0.2

0

0.2

0.4

0 1000 2000 3000

Time (Minutes)

Abs

-0.2

0

0.2

0.4

0 1000 2000 3000

Time (Minutes)A

0

10

20

30

40

50

60

ysolorox

Tilex

rine

xide

ohol

oap

lete

Zones Of inhibition (mm)

Staphepidermidis

E.coli

Figure 2: Inhibition of Growth using

Different Cleaning Products

LysoChlorox

Tilex

Listerine

Hydrogen Peroxide

Rubbing Alcoho

Dawn Soap

Dial Complete

Cleaning Products

Figure 3: Zone of Inhibition of Dawn (7) and Dial Complete Antibacterial

Soap (8)

Figure 4: Environmental Microbes

Figure 5: Environmental Microbes

Table 1: Zones Of Inhibition

Resistant Intermediate Sensitive

Ampicillin CD, LB, JW, KS, DJ, RE <28 mm

- >29 mm

Bacitracin CD, LB, JW, KS, 9-12 mm >13 mm Bacitracin CD, LB, JW, KS, DJ, RE <8 mm

9-12 mm >13 mm

Chloramphenicol <17 mm RE 18-20 mm CD, LB, JW, KS, DJ >21 mm

Neomycin RE <12 mm JW 13-16 mm CD, LB, KS, DJ >17mm

Penicillin CD, LB, JW, KS, DJ, RE <28 mm

- >29 mm

Tetracycline CD, JW <18 mm DJ, RE 19-22 mm LB, KS >23 mm

Conclusions

• Listerine may have had an effect on slowing the growth of E. coli and S. epidermidis

• Anti-microbial agents differed in effectiveness based on gram positive versus gram negativebased on gram positive versus gram negative

• Be aware of what products used on which types of bacteria

• Bacteria can be beneficial depending on location

• All were resistant to ampicillin and penicillin because they were same family

Conclusions

• Sources of Error:

• Contamination

• Pipetting incorrectly

• Further Experiments:

• Different volumes

• Different cleaning agents, i.e. Natural cleaning products