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Micro Para Lec > Midterm_Microbial Growth Control > Flashcards

Midterm_Microbial Growth Control Flashcards

1
Q

Methods for Microbial Control

A
  • Physical Agents
  • Chemical Agents
  • Mechanical Removal Methods
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2
Q

Physical Agents for Microbe growth control

A

Heat and Radiation

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3
Q

Physical Agents: Heat

A

Dry
- Incineration for sterilization
- Dry oven for sterilization

Moist
- Steam under pressure for sterilization
- Boiling water, hot water, pasteurization for disinfection

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4
Q

Physical Agents Radiation

A

Ionizing
- X-ray, cathode, gamma for sterilization

Nonionizing
- UV for disinfection

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5
Q

Chemical Agents for Microbe Growth Control

A

Gases and Liquids

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6
Q

Chemical Agents: Gas

A

Sterilization and Disinfection

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7
Q

Chemical Agents: Liquids

A

Animate
- chemotherapy
- antisepsis

Inanimate
- Disinfection
- Sterilization

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8
Q

Mechanical Removal Methods

A

Filtration

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9
Q

Mechanical Removal Methods: Filtration

A

Air for disinfection

Liquids for Sterilization

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10
Q
  • its the destruction or removal of vegetative pathogens but not bacterial endospores
  • used only on inanimate objects
A

Disinfection

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11
Q
  • Complete removal or destruction of all viable microorganisms
  • used on inanimate objects
A

Sterilization

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12
Q

Chemicals applied to body surfaces to destroy or inhibit vegetative pathogens

A

Antiseptics

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13
Q

Chemicals used internally to kill or inhibit the growth of microorganisms within host tissues

A

Chemotherapy

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14
Q

General Principles and Growth Control by Heat
- The killing or removal of all viable organisms within a growth medium

A

Sterilization

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15
Q

General Principles and Growth Control by Heat
- Effectively limiting microbial growth

A

Inhibition

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16
Q

General Principles and Growth Control by Heat
- The treatment of an object to make it safe to handle

A

Decontamination

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17
Q

General Principles and Growth Control by Heat
- Directly targets the removal of all pathogens, not necessarily all microorganisms

A

Disinfection

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18
Q

General Principles and Growth Control by Heat
- most widely used method of controlling microbial growth

A

Heat sterilization

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19
Q

General Principles and Growth Control by Heat
- bacteria produce resistant cells that Can survive heat that would rapidly kill vegetative cells

A

endospores

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20
Q

High temperatures ___________ macromolecules

A

denature

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21
Q

Amount of time required to reduce viability tenfold

A

decimal reduction time

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22
Q
  • sealed device that uses steam under pressure
  • Allows temperature of water to get above 100ºC
  • uses high temperature to kills the microbes
A

autoclave

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23
Q

Physical Control Methods

A
  • Pasteurization
  • Radiation
  • Filtration
24
Q

Physical Control Methods
- process of using precisely controlled heat to reduce the microbial load in heat-sensitive liquids
- Does not kill all organisms

A

Pasteurization

25
Q

can reduce microbial growth

A

Microwaves, UV, X-rays, gamma rays, and electrons

26
Q

Physical Control Methods
- Electromagnetic radiation that produces ions and other reactive molecules
- Generates electrons, hydroxyl radicals, and hydride radicals

A

Ionizing radiation

27
Q
  • has sufficient energy to cause modifications and breaks in DNA
  • useful for decontaminating surfaces
  • Cannot penetrate solid, opaque, or light-absorbing surfaces
A

UV

28
Q

Physical Control Methods
used for sterilization in the medical field and food industry

A

Radiation

29
Q

Sources of radiation

A

cathode ray tubes, X-rays, and radioactive nuclides

30
Q

Physical Control Methods
- avoids the use of heat on sensitive liquids and gases
- has Pores of filter are too small for organisms to pass through but allow only liquid or gas to pass through

A

Filtration

31
Q

Examples of filters

A

Depth filters (HEPA filters) and Membrane filters (Function more like a sieve)

32
Q

A type of membrane filter

A

nucleation track (nucleopore) filter

33
Q

Filtration can be accomplished by syringe, pump, or vacuum

A

Membrane filters

34
Q

3 Classifications of Antimicrobial Agents

A
  1. bacteriostatic
  2. bacteriocidal
  3. bacteriolytic
35
Q

Chemical Methods

A
  • Phenol
  • Phenolics
  • Alchohols
  • Halogens
  • Oxidizing agents
  • Surfactants
  • Heavy Metals
  • Aldehydes
  • Gaseous agents
  • Antimicrobials
36
Q

why 70% ethanol is more effective than 100% ethanol for sterilization

A
  • to prevent skin breakdown
  • prevent quick evaporation of alcohol before killing the microbe intended
37
Q

smallest amount of an agent needed to inhibit growth of a microorganism
- Varies with the organism used, inoculum size, temperature

A

Minimum inhibitory concentration (MIC)

38
Q
  • uses solid media
  • Antimicrobial agent added to filter paper disc
  • MIC is reached at some distance
A

Disc diffusion assay

39
Q

Area of no growth around disc during Disc diffusion assay

A

Zone of inhibition

40
Q

antimicrobial agents can be divided into two categories

A
  1. Products used to control microorganisms in commercial and industrial applications
    - chemicals in foods, air conditioning cooling towers, textile and paper products, fuel tanks
  2. Products designed to prevent growth of human pathogens in inanimate environments and on external body surfaces
    - Sterilants, disinfectants, sanitizers, and antiseptics
41
Q

Conditions Influencing the Effectiveness of Antimicrobial Agent Activity

A
  • Population size
  • Population composition
  • Concentration or intensity of an antimicrobial agent
  • Duration of exposure
  • Temperature
  • Local environment
42
Q

Conditions Influencing the Effectiveness of Antimicrobial Agent Activity
- larger populations take longer to kill than smaller populations

A

Population size

43
Q

Conditions Influencing the Effectiveness of Antimicrobial Agent Activity
- microorganisms differ markedly in their sensitivity to antimicrobial agents

A

Population composition

44
Q

Conditions Influencing the Effectiveness of Antimicrobial Agent Activity
- usually higher concentrations or intensities kill more rapidly
- relationship is not linear

A

Concentration or intensity of an antimicrobial agent

45
Q

Conditions Influencing the Effectiveness of Antimicrobial Agent Activity
- longer exposure = more organisms killed

A

Duration of exposure

46
Q

Conditions Influencing the Effectiveness of Antimicrobial Agent Activity
- higher temperatures usually increase amount of killing

A

Temperature

47
Q

Conditions Influencing the Effectiveness of Antimicrobial Agent Activity
- many factors (e.g., pH, viscosity and concentration of organic matter) can profoundly impact effectiveness
- organisms in biofilms are physiologically altered and less susceptible to many antimicrobial agents

A

Local environment

48
Q
  • closed-system microbial culture of fixed volume
A

Batch culture

49
Q

Growth Cycle

Note: Typical growth curve for population of cells grown in a closed system is characterized by four phases

A
  1. Lag Phase
  2. Exponential Phase
  3. Stationary Phase
  4. Death Phase
50
Q

Growth Cycle, Identify the phase
- Interval between inoculation of a culture and beginning of growth

A

Lag phase

51
Q

Growth Cycle, Identify the phase
- Cells in this phase are typically in the healthiest state

A

Exponential phase

52
Q

Growth Cycle, Identify the phase
- Growth rate of population is zero
- Either an essential nutrient is used up, or waste product of the organism accumulates in the medium

A

Stationary phase

53
Q

Growth Cycle, Identify the phase
- If incubation continues after cells reach stationary phase, the cells will eventually die

A

Death phase

54
Q

an open-system microbial culture of fixed volume

A

Continuous culture

55
Q
  • most common type of continuous culture device
  • Both growth rate and population density of culture can be controlled independently and simultaneously
A

Chemostat

56
Q

rate at which fresh medium is pumped in and spent medium is pumped out

A

Dilution rate

Micro Para Lec (7 decks)

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