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Microbiology :O > Chp. 7 > Flashcards

Chp. 7 Flashcards

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1
Q

What are the two high resistance microbes?

A
  • Bacterial endospores
  • Prions
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2
Q

What are the conditions for autoclaving?

A
  • High temp 121 degrees C
  • High pressure 15 PSI
    15-30’
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3
Q

_______ kills most vegetative cells and is applied on inanimate objects whereas _______ causes 100% death including endospores and prions

A

Disinfection
Sterilization

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4
Q

The cleansing technique that removes microbes mechanically is known as ______

A

Sanitizing

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5
Q

What are the two types of physical agents?

A
  • Radiation
  • Heat
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6
Q

Radiation has two subtypes. What are they and which one is used to sterilize and which one is used to disinfect?

A
  • Ionizing: X-ray, cathode, gamma
    STERILIZES: can penetrate through surface
  • Non-ionizing: UV
    DISINFECTS: cannot penetrate through surface
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7
Q

Heat has two subtypes. What are they and which one is used to sterilize and which one is used to disinfect?

Which is better to use and why?

A
  • Dry: STERILIZES through incineration and dry oven
  • Moist: BOTH sterilizes AND disinfects

MOIST better to use because it requires less time

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8
Q

Bacterial contamination is ______ whereas the absence of significant contamination is ________

A
  • Sepsis
  • Asepsis
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9
Q

What are some factors that affect the death rate?

A
  • # and nature of microbes in population
  • temp and pH of environment
  • Concentration or dosage of agent
  • Presence of solvents, organic matter, or inhibitors
  • Mode of action of the agent (it could target the cell membrane, DNA or RNA, or the protein)
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10
Q

What is an example of a microbistatic agent?

A

Antibiotics

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11
Q

What is the difference between thermal death point and thermal death time?

A

Thermal death point is the lowest temp that kills all cells IN 10 MINUTES, whereas thermal death time is the MINIMUM TIME for all bacteria to be killed at a particular temp

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12
Q

If we cannot autoclave a substance, what do we use?

A

Tyndallization (boiling on 3 separate days to ensure all bacteria is killed)

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13
Q

Is boiling water disinfection or sterilization?
Is pasteurization disinfection or sterilization?

A

Both are disinfectant methods as it does not kill all bacteria

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14
Q

63-66 degrees C for 30 minutes is which method of pasteurization?

A

Batch

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15
Q

71.6 degrees C for 15 seconds is which method of pasteurization?

A

Flash

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16
Q

The time it takes to kill 90% of the population is known as ________

A

Decimal Reduction time

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17
Q

***Moist heat sterilization

18
Q

How does filtration work? What is it used for?

Study These Flashcards
A
  • It passes a substance through a screen-like material
  • Used for heat-sensitive materials
19
Q

High-efficiency particulate air (HEPA) filters remove microbes ______ whereas membrane filters remove microbes _____

Study These Flashcards
A
  • more than 0.3um
  • more than 0.22um
20
Q

The absence of water that prevents metabolism is known as ______

21
Q

How does ionizing and nonionizing radiation damage DNA?

Study These Flashcards
A

Ionizing causes lethal mutations

Non-ionizing creates thymine dimers

22
Q

What is ionizing radiation used to sterilize?

What is non-ionizing radiation used to sterilize?

Study These Flashcards
A

Ionizing sterilizes medical supplies and food products

Non-ionizing sterilizes air, water, or surfaces

23
Q

What are the 4 principles of effective disinfection?

Study These Flashcards
A
  • Concentration
  • Organic matter
  • pH: the more extreme (2,3,13,14) the better the disinfectant
  • Time
24
Q

What are 6 good qualities of a disinfectant?

Study These Flashcards
A
  • Low % of dilution (cheaper and less toxic)
  • Soluble in water or alcohol
  • Broad spectrum, low toxicity
  • Penetrating
  • Non-corrosive and non-staining
  • Affordable and readily available
25
What are the different levels of chemical decontamination?
High level: kill endospores, may be sterilants Intermediate level: kill fungal spores but not endospores Low level: destroy vegetative bacteria, vegetative fungal cells, and some viruses
26
What are the 4 factors that affect germicidal activity of chemicals?
- Nature of material being treated (is it glass, wood, etc?) - How big is the degree of contamination - Time of exposure - Concentration of germicide
27
What is: - Toxic to anaerobes - Produces reactive hydroxyl-free radicals which damages protein and DNA - Antiseptic at low concentrations
Hydrogen peroxide
28
What: - Disrupts cell walls and membranes and precipitate proteins?
Phenolics
29
Two phenol groups connected by a bridge is a ________. This also disrupts plasma membranes What are two examples?
Bisphenols Hexachlorophene and triclosan
30
Which halogen is an oxidizing agent, and is found in bleach and chloramine?
Chlorine
31
Which halogen stops protein synthesis and alters membranes, and is found in tincture?
Iodine
32
True or False: Alcohols have no effect on endospores and nonenveloped viruses.
TRUE
33
What level of chemical decontamination are ethanol and isopropanol? What is their best working %?
- Intermediate - 50-95%
34
- Oligodynamic action (small amounts exert antimicrobial activity) - Denaturing proteins - Low level are all compounds of _____
Heavy metals
35
- Sulfur dioxide (prevents wine spoilage - Organic acids (sorbic, benzoic acid, calcium phosphate) - Nitrates and nitrites (prevent endospore germination) are all examples of _______
Chemical food preservatives
36
What do the following acids and alkalis do? What level are they? - Organic acids - Acetic acid - Propionic acid - Lactic acid - Benzoic and sorbic acid
- Organics prevent spore germination and bacterial and fungal growth - Acetic inhibits bacterial growth - Propionic retards molds - Lactic prevents anaerobic bacterial growth - Benzoic and sorbic inhibit yeast
37
What are the two types of aldehydes and what are their chemical levels?
- Formaldehyde: intermediate to high level - Glutaraldehyde: high level
38
What does chemical sterilization do and what is it used for?
- The gas sterilants cause alkylation which replaces hydrogen atoms of a chemical group with a free radical - It cross links nucleic acids and proteins - Used for heat sensitive material
39
What chemical level are gases and aerosols and what are they used for? What are 2 examples of gases?
- High level - Sterilize and disinfect plastics and prepackaged devices and foods - Ethylene oxide and propylene oxide
40
True or False: Oxygen cannot be used to kill bacteria
FALSE O3, H2O2, and peracetic acid can be used to kill bacteria. They are oxidizing agents

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