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ANS 302: Veterinary Microbiology > Controlling Microbial Growth > Flashcards

Controlling Microbial Growth Flashcards

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Biology 101 flashcards
1
Q

What is sterilization?

A

Destruction or removal of all viable organisms.

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2
Q

What is disinfection?

A

Killing, inhibiting, or removing disease causing (pathogenic) organisms.

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3
Q

What is sanitization?

A

Reduction of microbial population to levels deemed safe.

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4
Q

What are disinfectants?

A

Agents, usually chemical, used for disinfection, usually used on inanimate objects.

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5
Q

What is antisepsis?

A

Prevention of infection of living tissue by microorganisms.

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6
Q

What are antiseptics?

A

Agents that kill or inhibit the growth of microorganisms when applied to tissue.

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7
Q

What is chemotherapy?

A

Using chemicals to kill or inhibit the growth of microorganisms within host tissue.

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8
Q

What are -cidal agents?

A

Agents that are used to kill specific types of organisms.

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9
Q

What are -static agents?

A

Agents that inhibit the growth of specific types of organisms.

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10
Q

What is the pattern of microbial death?

A

Population declines exponentially.

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11
Q

How is an agent’s killing efficiency measured?

A

By measuring the decimal reduction time.

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12
Q

What is decimal reduction time?

A

The time it takes for the agent to kill 90% of the microbes.
*Must be sure VBNC cells are dead.

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13
Q

What are the 4 methods of microbial control?

A
  1. Physical agents.
  2. Chemical agents.
  3. Mechanical removal methods.
  4. Biological agents.
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14
Q

What does filtration allow for?

A

The reduction of the microbial population by removing microorganisms.

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15
Q

How does liquid filtration work?

A

A porous membrane with defined pore sizes removes microorganisms by physical screening.

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16
Q

How does air filtration work?

A

Similar to how liquid filtration works. In a BSC, laminar air flow and HEPA filters are used.

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17
Q

What are the methods of moist heat control?

A
  1. Pasteurization.
  2. Boiling.
  3. Steam sterilization.
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18
Q

What is moist heat able to destroy?

A
  1. Viruses.
  2. Fungi.
  3. Bacteria.
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19
Q

What can boiling not destroy?

A

Endospores.
*Cannot sterilize.

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20
Q

How does moist heat destroy microbes?

A
  1. Degrade nucleic acids.
  2. Denature proteins.
  3. Disrupt membranes.
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21
Q

At what temperature is steam sterilization carried out?

A

Above 100 C, which requires saturated steam under pressure.

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22
Q

What device uses steam sterilization?

A

An autoclave.

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23
Q

What microbes is steam sterilization effective against?

A

All of them.

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24
Q

What is pasteurization?

A

Controlled heating at temperature well below boiling.

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25
Q

What does pasteurization do?

A

Reduces the total number of pathogens present, slowing spoilage.

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26
Q

What products is pasteurization used on?

A
  1. Milk.
  2. Beer.
  3. Cheese.
  4. Yogurt.
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27
Q

What is dry heat sterilization?

A

Subjecting an item to temperatures of 160-170 C for 2-3 hours.

28
Q

How does dry heat sterilization impact microbes?

A
  1. Oxidizes cell constituents.
  2. Denatures proteins.
29
Q

Why would dry heat be used over moist heat?

A
  1. To avoid corroding glassware and metal instruments.
  2. Less expensive.
30
Q

What wavelength is most bactericidal?

A

260 nm (ultraviolet).

31
Q

What does UV radiation cause?

A

Thymine dimerization, preventing replication and transcription.

32
Q

Why is UV light limited to surface sterilization?

A

It cannot penetrate many substances.
*Has been used to treat water.

33
Q

Why is ionizing radiation used?

A

It can penetrate deep into objects and destroy endospores.
*No always effective against viruses.

34
Q

What processes is ionizing radiation used in?

A
  1. Sterilization.
  2. Pasteurization of hormones, antibiotics, sutures, plastic disposable supplies, and food.
34
Q

What are biological agents for microbial control?

A
  1. Bacteriophages.
  2. Pathogen-specific bacteriophage lysins.
  3. Bacteriocins
35
Q

What are bacteriocins?

A

Bacterial proteins that inhibit the growth of similar strains of bacteria.

36
Q

What falls under chemical agents?

A
  1. Phenolics.
  2. Heavy metals.
  3. Halogens.
  4. Aldehydes.
  5. Alcohols.
  6. Sterilizing gases.
  7. Quaternary Ammonium Compounds.
37
Q

Where are phenolics commonly used?

A

Laboratories and hospitals as disinfectants.

38
Q

How do phenolics impact microbes?

A
  1. Denaturing proteins.
  2. Disrupting cell membranes.
    *Tuberculocidal.
39
Q

What are the downsides of phenolics?

A
  1. Disagreeable odor.
  2. Can cause skin irritation.
40
Q

Which chemical agent is the most widely used disinfectant, antiseptic, and sanitizer?

A

Alcohols.

41
Q

What are the two most common types of alcohols used?

A
  1. Ethanol.
  2. Isopropanol.
42
Q

What microbes do alcohols kill?

A
  1. Bacteria.
  2. Fungi.
    *Not spores and inactivates some viruses.
43
Q

How do alcohols impact microbes?

A
  1. Possibly dissolve membrane lipids.
  2. Denature proteins.
44
Q

What is the main function of Iodine halogens?

A

Skin antiseptics.

45
Q

How do iodine halogens impact cells?

A
  1. Oxidizes cell constituents.
  2. Iodinates proteins.
    *May kill endospores at high concentrations.
46
Q

What are the downsides of using halogens?

A
  1. Skin damage.
  2. Skin staining.
  3. Allergies.
47
Q

What is the main function of chlorine halogens?

A
  1. To disinfect water supplies and swimming pools.
  2. As a disinfectant in the dairy and food industries.
  3. As a household disinfectant.
48
Q

How do chlorine halogens impact microbes?

A

Oxidizes cell constituents.
*Destroys vegetative bacteria, fungi, and kills spores.

49
Q

What specific metals are used to control microbes?

A
  1. Mercury.
  2. Arsenic.
  3. Zinc.
  4. Copper.
  5. Silver.
50
Q

What is the downside of using heavy metals?

A

They are toxic to the body/have off-target effects.

51
Q

What effect do heavy metals have on microbes?

A

Inactivates proteins and may precipitate cell proteins.

52
Q

What common agents are aldehydes?

A
  1. Glutaraldehyde.
  2. Formaldehyde.
53
Q

What are the characteristic of aldehydes as chemical agents?

A
  1. Highly reactive.
  2. Sporicidal.
  3. Can be used as a sterilant.
54
Q

What are sterilizing gases used for?

A

To sterilize heat sensitive material.

55
Q

What are the characteristics of sterilizing gases?

A
  1. Sporicidal.
  2. Microbial.
56
Q

What two gases are commonly used as sterilizing gases?

A
  1. Ethylene oxide.
  2. Hydrogen peroxide.
57
Q

What agency regulates disinfectants? Agents used on humans and animals?

A
  1. EPA.
  2. FDA.
58
Q

What are 6 conditions that influence the effectiveness of antimicrobial agent activity?

A
  1. Population size.
  2. Population composition.
  3. Concentration/intensity of an antimicrobial agent.
  4. Contact time.
  5. Temperature.
  6. Local environment.
59
Q

How does population size impact effectiveness?

A

Larger populations take longer to kill than smaller populations.

60
Q

How does population composition impact effectiveness?

A

Microorganisms have different sensitivity to antimicrobial agents.

61
Q

How does concentration/intensity of the antimicrobial agent impact effectiveness?

A

Higher concentrations kill more rapidly, but the relationship is not linear.

62
Q

How does contact time impact effectiveness?

A

Longer exposure, more organisms killed.

63
Q

How does temperature impact effectiveness?

A

Higher temperature enhances chemical activity.

64
Q

How does local environment impact effectiveness?

A

The pH, concentration, and viscosity of organic matter determine how well antimicrobial agents can interact with the microbes.
*Organisms in biofilms are less susceptible to many antimicrobial agents.

ANS 302: Veterinary Microbiology (16 decks)

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