Skin bacteria and the effect of antiseptics(H2O2& Ethanol 70%) We ran an experim

Question

Skin bacteria and the effect of antiseptics(H2O2& Ethanol 70%)

We ran an experiment with half the class using ethanol and other half using hydrogen peroxide to see which gets rid of bacteria more off of the thumb. Both antiseptics had no effect. The antiseptic-treated side shows less bacterial growth than does the initial no-antiseptic side for both the ethanol and hydrogen peroxide.

1. how do these results compare with the claims made on a container of hand sanitizer?

Culturing Bacteria from cell phones

We ran another experiment where we treated one side of a culture plate using a sterile swab dipped in sterile water and the other side with a sterile swab dipped in sterile water and then rubbed over one surface of your cell phone.

- means the sterile water only side shows less bacterial growth than does the cell phone side

0 means the sterile water only side shows about the same level of growth of bacteria as does the cell phone side.

+ means the sterile water only side shows a stronger growth of bacteria than the cell phone side.

2. summarize the results of this exercise. were more bacteria cultured from te class's cell phones than from the sterile water?

3. compare the results of this exercise with the results of the above exercise(everyone had a -score for the above results). how do the class's set of thumbs compare with their cell phones as a source of bacteria?

4. how might you refine or follow-up this exercise, and why?

Score of Bacterial Growth (-, 0 or +) 0                                                    +                                                    -                                                    -                                                    -                                                    - no growth                                                    -                                                    - no growth                                                    -                                                    -                                                    -                                                    - no growth                                                    -                                                    -                                                    - no growth                                                    -                                                    -

Explanation / Answer

The anti-septic properties of ethanol and hydrogenperoxide vary with their concentrations. Hydrogen peroxide is good at 3% H2O2 is demonstrated as good anti-septic towards gram positive bacteria, and it is ineffective or less effective below this dilution. Catalase containing bacteria are generally resistant to H2O2. Experiments demonstrated that H2O2 is not effective in decreasing bacteria count.

Ethanol in above its 70% v/v dilution, act as an effective ant-septic. Ethanol denatures proteins and lipids of cells and causes cell death. Ethanol is ineffective against spore forms and some bacteria are also resistant to ethanol. Ethanol is generally used as hand sanitizer.

The anti-septic activity of hydrogen peroxide and 70% ethanol is not broad as we expected, which may be because of bacterial resistance.

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