Lecture 13 Flashcards

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1
Q

Name the three major factors that contributes to the rate and effectiveness of chemicals killing microorganisms.

A
  1. Characteristics of the microorganisms
  2. Characteristics of the chemical bing used.
  3. Factors influencing the interaction between the two.
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2
Q

Name one bacteria that is quite resistant to chemicals.

A

Mycobacterium tuberculosis.

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3
Q

Name the three characteristics that deems a microorganism to be resistance to chemicals. Elaborate on each point.

A

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).

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4
Q

Why are non-endospore forming bacteria resistant to chemicals?

A

Due to their large amounts of lipids in their cell wall.

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5
Q

Name 2 bacterias that are sensitive to chemicals.

A

1: Neisseria gonorrhoeae
2: Neisseria meningitidis

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6
Q

Explain why it is more difficult to deal with a large amount of microorganisms when attempting to kill with chemicals. Give 2 points.

A

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

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7
Q

Name what chlorine is of little value as and what it’s very effective as.

A

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

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8
Q

True or false. Concentration of the chemical is of significant consideration when using it.

A

True.

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9
Q

Define what surface tension is.

A

It refers to the force which act to minimize the surface area of a given volume of liquid. *think of a drop of water.

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10
Q

The surface tension of a disinfectant should be low. Elaborate on this statement.

A

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.

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11
Q

Explain why tincture of iodine is a good disinfectant while Lugol’s solution (aqueous solution of iodine) is not.

A

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.

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12
Q

How can you reduce a solution’s surface tension?

A

By adding a surface tension reducer to it, also known as- surface active agents and surfactants.

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13
Q

Name two agents that have surface reducer added to them.

A

Wescodyne and Ioclide.

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14
Q

True or false. You can use a poisonous or toxic chemicals on bedpans to disinfect them?

A

False. They are corrosive and can damage the human tissue.

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15
Q

Explain how a warm solution is more effective than a cold when speaking of disinfection.

A

A warm solution has a lower surface tension and heat increases the rate of the reactions involved in disinfection.

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16
Q

True or false. Organic materials are easy to disinfect. Elaborate.

A

False. They essentially compete with the disinfectant molecules and reduce the concentration of the disinfectant.

17
Q

True or false. Is contact important when disinfecting? Define contact.

A

True. The product must come into contact. Contact is related to the surface tension and the presence or organic materials.