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Microbiology 39 > Exam #2 Lecture > Flashcards

Exam #2 Lecture Flashcards

1
Q

Sterilization

A

The process by which ALL living cells, spores, and viruses are destroyed on an object.

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2
Q

Distinfection

A

Killing or removal, of a disease-producing organisms from INANIMATE SURFACES.

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3
Q

Antisepsis

A

Killing or removal, of a disease-producing organisms from the surface of LIVING TISSUE

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4
Q

Sanitation/Decontamination

A

Mechanically removal of microorganism

  • Filtration
  • Air(decontamination)
  • Liquids(Sterilization)
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5
Q

Chemical Agents

A

Gases and liquids

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6
Q

Gases

A

Sterilization and disinfection

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7
Q

Liquids

A
  • On animate objects- Antisepsis

* On inanimate objects- Disinfection & Sterilization

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8
Q

Physical agents

A

Heat and Radiation

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9
Q

Heat

A
  • Dry
  • Incineration(Sterilization)
  • Dry Oven (Sterilization)
  • Moist
  • Steam under pressure (Sterilization)
  • Boiling water, hot water, pasteurization (Disinfection)
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10
Q

Radiation

A
  • Ionizing
  • X ray, cathode, gamma (Sterilization)

*Nonionizing
UV (Disinfection)

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11
Q

What is the most resistant microbial entities?

A

Bacterial endospores

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12
Q

What is the goal of sterilization?

A

To destroy the Bacterial Endospores, so that it can kill any less resistant microbial forms.

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13
Q

List most resistant to less resistant microbes:

A
  1. Prions
  2. Bacterial endospores
  3. Mycobacterium
  4. Staphylococcus and Pseudomonas
  5. Protozoan trophozoites
  6. Most gram-negative bacteria
  7. Fungi and fungal spore
  8. No enveloped viruses
  9. Most gram-positive bacteria
  10. Enveloped viruses
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14
Q

Least Selective agents

A

Tend to be effective against the widest range of microbes (heat and radiation)

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15
Q

Selective agents

A

Target only a singular cellular component (drugs)

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16
Q

Cellular target of physical and chemical agents?

A
  • Cell wall
  • Cell membrane
  • Cellular synthetic processes
  • Proteins
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17
Q

Cell wall effects of agents

A

Chemical agents can damage the cell wall by;

  • blocking its synthesis
  • digesting the cell wall
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18
Q

Cell wall examples of agents

A
  • Chemicals
  • Detergents
  • Alcohol
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19
Q

Cytoplasmic membrane effects of agents

A

Agents physically bind to lipid layer, open it up and allow injurious chemicals enter and important ions to exit the cell

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20
Q

Cytoplasmic membrane examples of agents used

A

-Detergents

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21
Q

Cellular synthesis effects of agents

A

Agents can interrupt the synthesis of proteins via ribosomes:

  • inhibiting proteins growth
  • metabolism
  • preventing multiplication.
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22
Q

Cellular synthesis examples of agents used

A
  • Formaldehyde
  • Radiation
  • Ethylene oxide
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23
Q

Proteins effects of agents

A
  • Agents can denature proteins (breaking protein bonds)

- Agents may attach to the active site of protein, so it can not interact with chemical substrate

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24
Q

Moist heat temp and time to sterilize

A

121 degrees —-> 15min
125 degrees —-> 10min
134 degrees —-> 3 min

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25
Q

Dry Heat temp to time sterilized

A

121 degrees —-> 600 min
140 degrees —-> 180 min
160 degrees —-> 120 min
170 degrees —-> 60 min

26
Q

The cold treatment

A

Slows growth of cultures and microbes in food during processing and storage, it retards the activities

27
Q

Things that don’t adversely addictive microbes?

A
  • Gradual cooling
  • Long-term refrigeration
  • deep-freezing
28
Q

What temperature preserves cultures of bacteria, viruses, and fungi for long periods of time?

A

(-70) degrees C to (-135) degrees C

29
Q

Desiccation

A
  • Vegetative cells directly exposed to normal room temp gradually become dehydrated
  • Some are killed and others no effect
30
Q

Lyophilization

A
  • A combo of freezing and drying
  • Method to preserve microbes

*Pure cultures frozen instantaneously exposed to vacuum that removes water avoiding ice crystals

31
Q

Radiation

A

Energy emitted from atomic activities and dispersed at high velocity through matter or space

Increasing energy to low energy

  1. Gamma rays
  2. X-rays
  3. Ultraviolet radiation
32
Q

What is the wave length in Ionizing radiation?

A

-Wave length shorter than 1nm- electron beans gamma rays and X rays

33
Q

What does ionizing radiation do?

A

-It creates ions by ejecting electrons from atoms they strike

  • Ions disrupt
  • hydrogen bonding
  • Oxidize double covalent bonds

*Ions create
Hydroxide ions, that denature other molecules (DNA)

34
Q

Ionizing radiation- Electron beams

A 
*Effective kill, but has bad penetration 
Uses:
-Sterilize sliced meats 
-microbiological plastic ware
-medical/dental supplies
35
Q

Ionizing radiation- Gamma rays

A 
*Penetrate well, but needs hours to kill microbes
Uses:
*Sterilize 
-meats
-Spices
-Fresh fruits
-Veggies
36
Q

Ionizing radiation- X-rays

A

Requires to much time to be practical for growth control

37
Q

What is the length of Non-ionizing radiation?

A

Wavelength greater than 1nm

38
Q

What does non-ionizing radiation do?

A
  • Excites electrons and causes them to make new covalent bonds.
  • affects the 3-D structures in proteins & nucleic acids
39
Q

What are some examples of non-ionizing radiations?

A
  • UV light causes thymine dimmers in DNA
  • UV light does not penetrate well
  • Suitable for disinfecting
  • air
  • transparent fluids
  • surfaces of objects
40
Q

Filtration

A

An effective method to remove microbes from air and liquids

41
Q

Examples of filtration?

A
  • Fluid strained through filter with openings for fluid to pass, but not microbes
  • Pore sizes can be controlled to permit true sterilization by trapping viruses or large proteins
42
Q

How is filtration used?

A
  • To prepare liquids that cant withstand heat:
  • serums
  • blood products
  • vaccines
  • drugs
  • IV fluids
  • enzymes
  • media
  • A good alternative method:
  • decontaminating milk to keep its flavor
  • important for water purification

*can not remove toxins

43
Q

Osmotic pressure

A

Adding large amounts of salt or sugar to foods creates a hypertonic environment for bacteria, causing plasmolysis

44
Q

Examples of Osmotic pressure?

A
  • Pickling
  • Smoking
  • Drying foods

*Is never a sterilizing technique

45
Q

What are the chemical agents in microbial control?

A
  • Occur
  • Liquid
  • Gaseous
  • Solid states
  • Range from:
  • Disinfectants
  • Antiseptics
  • Sterilants
  • preservatives
46
Q

Selecting a microbicidal chemical

A
  • Rapid action- even low concentrations
  • Solubility/long term stability- in water or alcohol
  • Broad spectrum- without being toxic to human and animal tissue
  • Penetration- of inanimate surfaces to sustain a cumulative action
  • Resistance- to become inactivated by organic matter
47
Q

Selecting a microbicidal chemical (continued)

A
  • Noncorrosive or nonstaining
  • Sanitizing and deodorizing
  • Affordability and ready availability
  • No chemical can fulfill all of these requirements
  • Glutaraldehyde and hydrogen peroxide are close
48
Q

How are germicides evaluated?

A

By their effectiveness in destroying microbes in medical and dental settings

49
Q

What are the high, intermediate, and low levels of germicides?

A
  • High level germicides- Kill endospores and can be used as sterilants
  • Intermediate level germicides- Kill fungal, but not bacterial spores, resist pathogens, and viruses
  • Low level germicides- Eliminate only vegetative bacteria, vegetative fungal cells, and some viruses
50
Q

Factors affecting the germicidal activities of chemicals?

A
  • Nature of microorganisms be treated
  • Nature of material being treated
  • Degree of contamination
  • TIme of exposure
  • Strength and chemical
51
Q

Composition of material being treated?

A
  • Smooth, solid objects are more likely disinfected than those with pores or pockets
  • Large amounts of organic material can hinder penetration
  • Adequate cleaning instruments and reusable materials my continue use of a germicide or sterilant.
52
Q

Phenol

A

Denatures protein

53
Q

Iodine

A

Membrane damage

54
Q

Chlorhexidine

A

Membrane disruption and protein desaturation

55
Q

Alcohols

A

Protein denaturation, dissolve membrane lipids

56
Q

Hydrogen peroxide

A

Hydroxyl radicals attack membrane lipids, DNA, protein

57
Q

Antimicrobial agents- Dyes

A
  • Active against gram positive bacteria and fungi

- Limited application because they stain and have a narrow spectrum of activity

58
Q

Antimicrobial agents- acids and alkalis

A
  • Very low or ugh pH can destroy or inhibit microbial cells
  • Limited in applications due to corrosive, caustic, hazardous nature
  • Ammonium hydroxide used in detergents, cleaners, deodorizer
  • Organic acids used in food preservation
59
Q

Gaseous agents

A

-Ethylene oxide
-Propylene oxide
Used in closed chambers to sterilize items

*Denature proteins and DNA by cross-linking functional groups

60
Q

Where are gaseous agents?

A

-Used in hospitals and dental offices

  • Can be:
  • hazardous to people
  • Often highly explosive
  • extremely poisonous
  • Potentially carcinogenic

Microbiology 39 (77 decks)

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