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MICROPARA [LEC] > Microbial Growth Control > Flashcards

Microbial Growth Control Flashcards

1
Q

The destruction or removal of vegetative pathogens but not bacterial endospores. usually used only on inanimate objects.

A

Disinfection

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2
Q

The complete removal or destruction of all viable microorganism. Used on inanimate objects.

A

Sterilization

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3
Q

Chemicals applied to body surfaces to destroy or inhibit vegetative pathogen.

A

Antisepsis

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4
Q

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

A

Chemotherapy

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5
Q

The killing or removal of all viable organisms within a growth medium

A

Sterilization

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6
Q

Effectively limiting microbial growth

A

Inhibition

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7
Q

The treatment of an object to make it safe to handle

A

Decontamination

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8
Q

Directly targets the removal of all pathogens, not necessarily all microorganisms

A

Disinfection

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9
Q

is the most widely used method of
controlling microbial growth

A

Heat sterilization

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10
Q

High temperatures __________ macromolecules

A

denature

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11
Q

Amount of time required to reduce viability tenfold is
called the ___________.

A

decimal reduction time

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12
Q

Some bacteria produce resistant cells called __________.

Can survive heat that would rapidly kill vegetative cell

A

endospores

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13
Q

The __________ is a sealed device that uses steam under pressure.

  • Allows temperature of water to get above 100ºC
  • It’s not the pressure, but the high temperature, that kills
    the microbes
A

autoclave

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14
Q

__________ is the process of using precisely controlled heat to reduce the microbial load in heat-sensitive liquids

  • Does not kill all organisms, so it is different from
    sterilization
A

Pasteurization

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15
Q
  • Electromagnetic radiation that produces ions and other
    reactive molecules
  • Generates electrons, hydroxyl radicals, and hydride
    radicals
  • Some microorganisms are more resistant to radiation
    than others
  • Amount of energy required to reduce viability tenfold is
    analogous to D value
A

Ionizing radiation

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16
Q

__________ has sufficient energy to cause modifications and breaks in DNA.

  • UV is useful for decontaminating surfaces
  • Cannot penetrate solid, opaque, or light-absorbing surfaces
A

UV

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17
Q

__________ is used for sterilization in the medical field and food industry

  • Radiation is approved by the WHO and is used in the
    USA for decontaminating foods particularly susceptible
    to microbial contamination
  • Hamburger, chicken, spices may all be irradiated
A

Radiation

18
Q

__________ avoids the use of heat
on sensitive liquids and gases

  • Pores of __________ are too small for organisms to pass through
  • Pores allow liquid or gas to pass through
A

Filtration

19
Q

HEPA filters

A

Depth filters

20
Q

Function more like a sieve

  • Filtration can be accomplished by syringe, pump, or vacuum.
A

Membrane filters

21
Q

A type of membrane filter is the_________.

A

nucleation track (nucleopore) filter

22
Q

Antimicrobial agents can be classified as

A

bacteriostatic
bacteriocidal
bacteriolytic

23
Q

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

A

Even though you may think the higher concentration is more effective, experts say 70% is actually better for disinfecting. It has more water, which helps it to dissolve more slowly, penetrate cells, and kill bacteria. The disinfecting power of rubbing alcohol drops at concentrations higher than 80%-85%.

24
Q

is the smallest amount of an agent needed to inhibit growth of a microorganism

  • Varies with the organism used, inoculum size, temperature, pH, etc
A

Minimum inhibitory concentration (MIC)

25
Q

_________ uses solid media

  • Antimicrobial agent added to filter paper disc
  • MIC is reached at some distance
A

Disc diffusion assay

26
Q

Area of no growth around disc

A

Zone of inhibition

27
Q

These antimicrobial agents can be divided into two categories

A

Products used to control microorganisms in commercial
and industrial applications

  • Examples: chemicals in foods, air conditioning cooling
    towers, textile and paper products, fuel tanks

Products designed to prevent growth of human
pathogens in inanimate environments and on external
body surfaces

  • Sterilants, disinfectants, sanitizers, and antiseptics
28
Q

Population size

A

larger populations take longer to kill than smaller populations

29
Q

microorganisms differ markedly in their sensitivity to antimicrobial agents

A

Population composition

30
Q
  • usually, higher concentrations or intensities kill more rapidly
  • relationship is not linear
  • Duration of exposure

“longer exposure = more organisms killed”

A

Concentration or intensity of an antimicrobial agent

31
Q

Temperature

A

higher temperatures usually increase amount of killing

32
Q
  • 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

33
Q

a closed-system microbial culture of fixed volume

A

Batch culture

34
Q

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

A
  • Lag phase
  • Exponential phase
  • Stationary phase
  • Death phase
35
Q

The Growth Cycle

Interval between inoculation of a culture and beginning
of growth

A

Lag phase

36
Q

The Growth Cycle

  • Cells in this phase are typically in the healthiest state
A

Exponential phase

37
Q

The Growth Cycle

  • 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

38
Q

The Growth Cycle

  • If incubation continues after cells reach stationary
    phase, the cells will eventually die
A

Death phase

39
Q

an open-system microbial
culture of fixed volume

A

Continuous culture

40
Q

most common type of continuous
culture device

A

Chemostat

41
Q

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

A

Dilution rate

MICROPARA [LEC] (3 decks)

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