Chapter 2 Laboratory Review Questions
A few ideas to get down before answering this lab review.
Sanitizing agents - Reduce microbial contamination by physical removal of microbes.
Antiseptics - Remove and kill at least some of the microbes.
Disinfectants - Kills microbes and even spores, but are too harsh to be used on skin.
1) [CH-02-01] What are mechanisms of action for Triclosan and Povidone?
Triclosan - Targets the fatty acid synthesis mechanism.
Povidone iodine - Iodine permeates through the cell membrane and attacks the bacteria's proteins and DNA.
2)[CH-02-02] What concentration of ethanol or propanol is required for hand antiseptics?
At least 60% alcohol (But less than 100% for reasons stated below in Q3), 60% - 95% is optimal.
3)[CH-02-03] Why isn't 100% ethanol effective against bacteria?
100% alcohol rapidly dehydrates the area forming a crust on bacterials cells that prevents the alcohol from permeating into the cell.
4) [CH-02-04] Rate the following in terms of their resistance to disinfectants (1-Least resistant, 7-Most
resistant)
6 Bacterial endospores
1 Enveloped viruses
4 Fungal spores
2 Gram-positive bacteria
5 Gram-negative bacteria
3 Non-enveloped viruses
7 Prions
5) [CH-02-05] How is human immunodeficiency virus (HIV) resistant to disinfectants and antiseptics? Explain why.
HIV is an enveloped virus, which makes them the least resistant to disinfectants. For that reason the virus dies quickly outside the cell and is limited to spreading through bodily fluids.
6) [CH-02-06] Is alcohol an antiseptic or a disinfectant?
Alcohol is an antiseptic as it is often used on skin prior to needle injections or blood draws.
7) [CH-02-07] What is difference between antiseptics and disinfectants?
*Antiseptic - Removes and kills microbes on living organisms.
*Disinfectant - Kills microbes on inanimate objects.
*How they theoretically should be used.
8) [CH-02-08] Name disinfectants effective in killing bacterial spores?
- Bleach (Sodium hypochlorite)
- Aldehydes
- Ethylene oxide
- Peracetic acid
9) [CH-02-09] How is soap effective as an antiseptic?
Weak antiseptic at best (Not that great for killing microbes), soap functions more as a sanitizing agent that achieves its effect by washing microbes off the skin instead of killing them.
10) [CH-02-10] Name 3 bacterial genera whose species make up the normal flora of human skin.
Wiki links provided for those interested in the bacterial genera.
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