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Microbiology > Topic 11 > Flashcards

Topic 11 Flashcards

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Biology 101 flashcards
1
Q

What is disinfecting used for?

A

Body surfaces and objects that don’t need to be completely sterile

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2
Q

What is sterilization used for?

A

Surgical and lab equipment, surgical dressings, etc

Prions may be resistant

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3
Q

What are vegetative cells?

A

They actively grow and divide

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4
Q

What type of cell is an endospore?

A

Dormant cell

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5
Q

What are the 3 ways you can control microbial growth outside the body?

A
  • Sanitation
  • Antisepsis
  • Degerming
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6
Q

What is sanitation?

A

Treatments aimed at lowering the # of microbes (in public places)
Ex: drinking water, utensils in restaurants

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7
Q

What is antisepsis?

A

The killing of vegetative microbial cells on the surface of the body

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8
Q

How is antisepsis accomplished?

A

By chemicals (antimicrobials)

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9
Q

What is degerming?

A

Removal of microbes from a limited area of the body
- Mechanical removal (scrubbing)
(Ex: wiping a needle with an alcohol swab before you inject someone)

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10
Q

What are the 3 ways to kill microbes?

A
  1. Alteration of Membrane Permeability
  2. Damage to Proteins
  3. Damage to Nucleic Acids
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11
Q

What is alteration of membrane permeability?

A
  • Damage causes cellular contents to leak out

- The membrane is big target

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12
Q

What does dettol do to a cell?

A

It disrupts the cell wall and cell membrane

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13
Q

What is one of the oldest disinfectants?

A

Phenol (carbolic acid)

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14
Q

How can proteins be damaged?

A
  • Heat
  • pH
  • Chemicals
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15
Q

What are enzymes important for?

A

All cellular functions

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16
Q

What happens if we damage proteins?

A

We can shut down the metabolism of the cell

Proteins do all the work in a cell, they are used as enzymes

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17
Q

Describe damage to nucleic acids

A
  • DNA is damaged by heat/UV/radiation/chemicals

- mutations and replication errors occur

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18
Q

What is the easiest way to damage DNA?

A

UV radiation

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19
Q

What can damage to nucleic acids be used for?

A
  • Food (doesn’t damage the food)

- Quite effective in killing microbes

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20
Q

What does the effectiveness of anti-microbial treatment depend on? (5)

A
  • Object being treated
  • # of microbes
  • Environment (presence of blood, feces, vomit, temperature, biofilms, etc)
  • Exposure time (increase exposure = increased killing) and (increased exposure at lower temp = increased killing)
  • Microbial characteristics/susceptibilities (presence and type of cell wall) and (enveloped virus vs. naked virus)
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21
Q

What does lower temperature mean for microbes?

A

It is easier to kill them and slows their growth

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22
Q

Are gram (-) easier or harder to kill and why?

A

Harder d/t the two membranes

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23
Q

Is an enveloped virus easier or harder to destroy?

A

Easier to destroy

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24
Q

List the most resistant to the most susceptible of microbial susceptibilities to control agents? (10)

A
  1. Prions
  2. Endospores (of bacteria)
  3. Mycobacteria
  4. Cysts (of Protozoa)
  5. Vegetative Protozoa
  6. Gram-negative Bacteria
  7. Fungi (& Fungal Spores)
  8. Non-enveloped Viruses
  9. Gram-positive Bacteria
  10. Enveloped Viruses
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25
Q

Give 2 examples of Enveloped Viruses

A

HIV, Influenza

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26
Q

Enveloped viruses in the body vs a surface

A

Body: harder to kill
Surface: easier to kill if it is on an inanimate object because it is surrounded by a membrane

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27
Q

Growing state of gram (+)

A

Growing state pretty susceptible but can form endospores

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28
Q

How can you kill fungi?

A

Using bleach

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29
Q

What are vegetative protozoa doing?

A

Actively dividing

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30
Q

Are cysts hard to kill?

A

It is tougher to kill dormant cysts

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31
Q

How can you kill endospores

A
  • Flaming an inoculating loop

- Use an autoclave when making media

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32
Q

What is the only way to ensure prions are killed?

A

Through burning

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33
Q

What do non-enveloped viruses have to do first?

A

Denature the protein coat first

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34
Q

What are the physical methods of microbial control?

A
  • Heat
  • Low temperatures
  • Filtration
  • Desiccation
  • Radiation
  • Osmotic Pressure
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35
Q

When deciding to kill something, what should you consider

A

How it will affect the infected material (biotic and abiotic)

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36
Q

What is pasteurization?

A

Using high heat for a short period of time

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37
Q

What does freezing kill?

A

Some microbes but not bacteria . Multicellular parasites (ex: sushi) will be killed by freezing the meat

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38
Q

What is filtration?

A

physically removing microbes by passing a filter through the microbes

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39
Q

What is desiccation?

A

Will not kill endospores but will cause the item to make endospores

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40
Q

Radiation and Microbial Control

A

UV and higher ionizing radiation is quite effective of killing bacteria

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41
Q

What are the 3 ways of providing heat to control microbes?

A
  1. Pasteurization
  2. Moist heat/High pressure
  3. Dry heat
42
Q

What does heat do to proteins?

A

Denture them and increases membrane fluidity

43
Q

What will pasteurization leave behind?

A

Endospores

44
Q

What will endospores give rise to

A

Vegetative cells (expiry date)

45
Q

What is pasteruization?

A

Heat food enough to kill the microbes, but not ruin the food

46
Q

What may survive pasteurization?

A

Thermophilic organisms and endospores may survive

- May germinate after the “best before” date

47
Q

What does Moist heat (boiling) kill?

A

Most bacteria, fungus, protozoa, and viruses

48
Q

What does moist heat destroy?

A

May destroy endospores or thermophiles

49
Q

What does moist heat do?

A

Denatures and causes the coagulation of proteins

50
Q

What is autoclaving (moist heat)

A

Steam under pressure kills vegetative cells and endospores in 20 mins

51
Q

What is autoclaving used for?

A

Solid objects and solutions

52
Q

What is autoclaving used for?

A

To sterilize waste and the media. The pressure will damage cell walls and the high heat will denature proteins
(Will not kill prions but those are rare)

53
Q

What is a physical method of microbial control (D.H)

A

Dry heat: using intense heat

54
Q

How does dry heat kill microbes?

A

It kills by oxidation (burning) through flaming, incineration, and hot-air sterilization

55
Q

How does freezing kill microbes? (physical method of microbial control)

A

The cells are ruptured by the ice crystals

56
Q

Does freezing have an effect on endospores?

A

No

57
Q

What effect does freezing have on vegetative cells

A

They will survive but become dormant

58
Q

What does freezing drying prevent?

A

Microbial metabolism

59
Q

What is freezing drying - low temperatures (physical methods of microbial control)?

A

AKA Lyophilization

- Rapid freezing followed by sublimation (skip the liquid phase)

60
Q

What does the temperature 0-7 degrees celsius do?

A

Slows down metabolic pathways of microbes

61
Q

Name an organism that is not affected by refrigeration

A

Psychrophiles which grow well in cold temperatures

Ex: some moulds, Listeria monocytogenes

62
Q

Name a type of physical method to control microbes (F)

A

Filtration

63
Q

What is desiccation (Physical method)

A
  • Removal of water
  • Microbes often remain viable
  • Viruses and endospores are unaffected only inactive until the material becomes moist again
64
Q

What is osmotic pressure (Physical method)

A

Adding solute (eg. sugar, salt) to a solution makes it hypertonic (increases the osmotic pressure)

65
Q

What is osmosis?

A

Movement of water across a membrane

66
Q

What is radiation?

A

High energy waves/particles damage DNA

67
Q

What is UV radiation effective on?

A

Making breaks in DNA and really good at sterilizing food or plastic because it does not change the structure or chemistry of the object being radiated

68
Q

What is radiation?

A

High energy waves/particles damage DNA

69
Q

What is UV radiation effective on?

A

Making breaks in DNA and really good at sterilizing food or plastic because it does not change the structure or chemistry of the object being radiated

70
Q

What are 3 types of radiation?

A
  • X-rays
  • Gamma rays
  • Electron beams
71
Q

What is irradiated food?

A

The bacteria population is reset, killing the existing bacteria. Food will stay fresher for longer

72
Q

What is non-ionizing radiation?

A
  • UV (longer wavelength than ionizing radiation)

- Germicidal lamps in nurseries to purify air

73
Q

Can radiation kill spores?

A

Yes but they need longer exposure

74
Q

Name 3 examples of chemical disinfectants

A

ABX, alcohols, heavy metals

75
Q

What do chemical disinfectants destroy?

A

Can destroy proteins, cell walls, nucleic acids, etc.

76
Q

Define volatile

A

Evaporates very rapidly

77
Q

Describe Phenol and Phenolics (chemical disinfectant)

A
  • denature protein and disrupt liquid
  • stable and persistent
  • smelly and can irritate skin
78
Q

Describe alcohol (chemical disinfectant)

A
  • denature proteins, dissolve lipids
  • effective against fungi and bacteria
  • very volatile
79
Q

What are examples of halogens (chemical disinfectants)

A

Iodine, Bleach

80
Q

What is halogen composed of?

A

Iodine, Chlorine

81
Q

What is an example of peroxygens?

A

Ozone (O3), Hydrogen Peroxide (H2O2)

82
Q

Describe Peroxygens (Chemical Disinfectant) - 4

A
  • Oxidizing agents
  • Generate O2 when they break down
  • Effective against endospores
  • Will denature proteins and enzymes
83
Q

Describe surfactants (4)

A
  • Mostly degerming
  • Some have antimicrobial agents
  • Breakup oils and membranes
  • Hydrophilic/hydrophobic molecules that emulsify oily layers
84
Q

Describe surfactants

A
  • Mostly degerming
  • Some have antimicrobial agents
  • Breakup oils and membranes
  • Hydrophilic/hydrophobic molecules that emulsify oily layers
85
Q

Surfactants and biofilms

A

Detergents and soaps emulsify oils and help remove biofilms

86
Q

Name 3 examples of heavy metals (C.D)

A

Silver (Ag), Mercury (Mg), Copper (Cu)

87
Q

What do heavy metals do? (C.D)

A

Denature proteins by combining with Sulfur on amino acids

88
Q

What is aldehyde used on (C.D)?

A

Hospital instruments and respiration equipment

89
Q

Give an example of aldehyde?

A

Formaldehyde

90
Q

What is a disadvantage of aldehyde?

A

Expensive, Carcinogen

91
Q

Describe aldehyde and what they do

A
  • Effective broad spectrum antimicrobials

- Inactivate proteins by cross-linking them

92
Q

Describe gaseous compounds (3)

A
  • Denatures proteins or cross links them
  • Requires long exposure
  • Easily penetrates porous material and is not persistent
93
Q

Give an example of gaseous compounds and what is it used on? (C.D)

A

Ex: Ethylene oxide

Can be used on medical equipment that cannot be heated (ex: catheters)

94
Q

What are abx used for (C.D)?

A

Molecular biology labs to make selective media and treatment rather than disinfecting

95
Q

How can you evaluate a disinfectant?

A

The In Use Test

96
Q

What is the “the in use test”?

A

Swab before and after disinfection and test for growth

97
Q

What are the cons of “The In Use Test?”

A

Time consuming, Expensive, May lack consistency

98
Q

What is the disk-dissusion test?

A

Filter papers soaked with disinfectant. The zone of inhibition around the disk is measured

99
Q

What are the three different bacterial standards?

A
  1. Salmonella cholerasuis
  2. Staphylococcus aureus
  3. Pseudmonas aeruginosa
100
Q

What is the dilution test?

A
  1. Metal rings dipped in test bacteria and dried
  2. Dried cultures are placed in disinfectant of varying concentrations for 10 mins at 20 degrees Celsius
  3. Rings are transferred to culture media to determine whether bacteria survived treatment

Microbiology (13 decks)

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