Lecture 13 Flashcards
Name the three major factors that contributes to the rate and effectiveness of chemicals killing microorganisms.
- Characteristics of the microorganisms
- Characteristics of the chemical bing used.
- Factors influencing the interaction between the two.
Name one bacteria that is quite resistant to chemicals.
Mycobacterium tuberculosis.
Name the three characteristics that deems a microorganism to be resistance to chemicals. Elaborate on each point.
1: Resistance of non-endospore forming bacteria (some non-endospore are very resistant to chemicals due to large fatty lipids in their cell wall)
2: Resistance of bacterial endospores (some endospores are extremely resistant to chemicals)
3: Number of microorganisms (larger amount of microbes make it more difficult to kill by chemical).
Why are non-endospore forming bacteria resistant to chemicals?
Due to their large amounts of lipids in their cell wall.
Name 2 bacterias that are sensitive to chemicals.
1: Neisseria gonorrhoeae
2: Neisseria meningitidis
Explain why it is more difficult to deal with a large amount of microorganisms when attempting to kill with chemicals. Give 2 points.
1: The cells clumps together which interferes with the penetration of the chemicals.
2: There is a greater chance that resistant cells are present in the mix
Name what chlorine is of little value as and what it’s very effective as.
It’s very little effective as a disinfectant but very effective as a chlorine gas. ( calcium hypochlorite and sodium hypochlorite. (Ca(OCl)2) and NaOCl
True or false. Concentration of the chemical is of significant consideration when using it.
True.
Define what surface tension is.
It refers to the force which act to minimize the surface area of a given volume of liquid. *think of a drop of water.
The surface tension of a disinfectant should be low. Elaborate on this statement.
Mercury has a high surface tension (at 466 dynes/cm) and it does not come into contact with objects or surfaces, but rather draws itself away into spheres. Alcohol has a low surface tension (28 dynes/cm) and it comes into intimate contact with objects.
Explain why tincture of iodine is a good disinfectant while Lugol’s solution (aqueous solution of iodine) is not.
Tincture of iodine has a low surface tension making it great for prepping skin pre surgery. An aqueous solution of iodine has a higher surface tension (77 dyes/cm) therefore, is not a good disinfectant.
How can you reduce a solution’s surface tension?
By adding a surface tension reducer to it, also known as- surface active agents and surfactants.
Name two agents that have surface reducer added to them.
Wescodyne and Ioclide.
True or false. You can use a poisonous or toxic chemicals on bedpans to disinfect them?
False. They are corrosive and can damage the human tissue.
Explain how a warm solution is more effective than a cold when speaking of disinfection.
A warm solution has a lower surface tension and heat increases the rate of the reactions involved in disinfection.