Evaluation of Antiseptics and Disinfectants Questions 1 PDF

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Evaluation of Antiseptics and Disinfectants lab answer sheet...

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Evaluation of Antiseptics and Disinfectants answer Sheet Pre-Laboratory Questions 1. What is the difference between an antiseptic and a disinfectant? Though both terms refer to substances which reduce the number of microbes on a particular surface, the surface in which they act upon differ. Disinfectants work on inanimate, nonliving surfaces or in liquids while antiseptics work living tissues. Disinfectants are capable of damaging tissue and therefore should not be used on or in living tissues. 2. Would a disinfectant necessarily kill bacterial endospores? Why or why not? Disinfectants would not necessarily kill bacterial endospores as they are resistant to most antimicrobial agents. Sterilization is needed in order to purge endospores from a surface. 3. List five factors that can influence the effectiveness of antimicrobial agents. Five factors that can influence the effectiveness of antimicrobial agents are 1. Type of microbe 2. Amount of microbes 3. Antimicrobial chemical concentration 4. Nature of the surface material being treated 5. Temperature 4. Several antimicrobial agents denature proteins. What does this mean and how does protein denaturation affect microbes? Denaturing refers to the alteration of microbial proteins’ shapes. If microbes’ proteins are not shaped correctly then they will be rendered useless and incapable of working properly which will lead to the microbes death.

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Observations Data Table 1: Disinfectant and antiseptic concentrations and bacterial growth Fill out the table below based on the instructions listed in the lab Treatment

Growth

Control

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0.01% Bleach

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0.1% Bleach

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1.0% Bleach

+

25% Lysol®

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50% Lysol®

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100% Lysol®

+

0.03% Hydrogen Peroxide

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0.3% Hydrogen Peroxide

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3.0% Hydrogen Peroxide

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10% Isopropyl Alcohol

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30% Isopropyl Alcohol

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50% Isopropyl Alcohol

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Observations Take a picture of each tube at the designated time, and insert them below (be sure to label each photo with organism, name of disinfectant or antiseptic, incubation time and temperature:

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10% Lysol

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5%

2.5% Lysol

5

50% Isopropyl

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30% Isopropyl

10% Isopropyl

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Post-lab Questions

1. Based on your results, which antimicrobial agent(s) best inhibited the growth of E. coli? What was the lowest effective concentration of the agent(s)? According to my findings all of the antimicrobial agents works well at their full strengths and prevented any bacterial growth. At their weakest concentrations isopropyl alcohol seemed to work the best as it was the clearest tube. Depending on how we describe effective would determine what concentrations we would consider effective. If we are looking for reducing the number of microbes then the middle percentages would be considered effective for each substance. However if we are looking for which percentage prohibited the growth of bacteria then the highest concentrations for all would be considered the effective percentage. 2. What can you conclude from your results about the relative effectiveness of antiseptics vs. disinfectants in preventing the growth of E. coli? According to my results the relative effectiveness of both antiseptics and disinfectants seem to be about the same. At their highest concentration all of the solutions prevented E. coli growth while their lowest concentrations did not inhibit growth. At their middle concentrations they also all seemed similar in the amount of growth that occurred.

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3. Why is it useful to know and use the lowest effective concentration of an antimicrobial chemical? Its extremely important to know the lowest effective concentration of an antimicrobial chemical in order to know the degree in which microbes are being eliminated. In a situation where there are dangerous microbes present we need to know that the solution we are using is completely eliminating them so we don’t assume they are gone but end up spreading and furthering contamination. 4. Were there any discrepancies between what you saw in your experiment and what you expected to see based on the lab manual and your readings in this section? There were not any discrepancies that I faced with the outcome of my experiment. All of the solutions worked to prevent growth of E. coli at their strongest concentrations and did not at their lowest. Besides this fact I did expect slightly more growth to occur in the middle concentrations of these solutions.

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